Stockfish 14

Official release version of Stockfish 14

Bench: 4770936

---

Today, we have the pleasure to announce Stockfish 14.

As usual, downloads will be freely available at https://stockfishchess.org

The engine is now significantly stronger than just a few months ago,
and wins four times more game pairs than it loses against the previous
release version [0]. Stockfish 14 is now at least 400 Elo ahead of
Stockfish 7, a top engine in 2016 [1]. During the last five years,
Stockfish has thus gained about 80 Elo per year.

Stockfish 14 evaluates positions more accurately than Stockfish 13 as
a result of two major steps forward in defining and training the
efficiently updatable neural network (NNUE) that provides the evaluation
for positions.

First, the collaboration with the Leela Chess Zero team - announced
previously [2] - has come to fruition. The LCZero team has provided a
collection of billions of positions evaluated by Leela that we have
combined with billions of positions evaluated by Stockfish to train the
NNUE net that powers Stockfish 14. The fact that we could use and combine
these datasets freely was essential for the progress made and demonstrates
the power of open source and open data [3].

Second, the architecture of the NNUE network was significantly updated:
the new network is not only larger, but more importantly, it deals better
with large material imbalances and can specialize for multiple phases of
the game [4]. A new project, kick-started by Gary Linscott and
Tomasz Sobczyk, led to a GPU accelerated net trainer written in
pytorch.[5] This tool allows for training high-quality nets in a couple
of hours.

Finally, this release features some search refinements, minor bug
fixes and additional improvements. For example, Stockfish is now about
90 Elo stronger for chess960 (Fischer random chess) at short time control.

The Stockfish project builds on a thriving community of enthusiasts
(thanks everybody!) that contribute their expertise, time, and resources
to build a free and open-source chess engine that is robust, widely
available, and very strong. We invite our chess fans to join the fishtest
testing framework and programmers to contribute to the project on
github [6].

Stay safe and enjoy chess!

The Stockfish team

[0] https://tests.stockfishchess.org/tests/view/60dae5363beab81350aca077
[1] https://nextchessmove.com/dev-builds
[2] https://stockfishchess.org/blog/2021/stockfish-13/
[3] https://lczero.org/blog/2021/06/the-importance-of-open-data/
[4] https://github.com/official-stockfish/Stockfish/commit/e8d64af1
[5] https://github.com/glinscott/nnue-pytorch/
[6] https://stockfishchess.org/get-involved/

.github/workflows/stockfish.yml

@@ -0,0 +1,201 @@
+name: Stockfish
+on:
+  push:
+    branches:
+      - master
+      - tools
+      - github_ci
+  pull_request:
+    branches:
+      - master
+      - tools
+jobs:
+  Stockfish:
+    name: ${{ matrix.config.name }}
+    runs-on: ${{ matrix.config.os }}
+    env:
+      COMPILER: ${{ matrix.config.compiler }}
+      COMP: ${{ matrix.config.comp }}
+      CXXFLAGS: "-Werror"
+    strategy:
+      matrix:
+        config:
+          - {
+              name: "Ubuntu 20.04 GCC",
+              os: ubuntu-20.04,
+              compiler: g++,
+              comp: gcc,
+              run_expensive_tests: true
+            }
+          - {
+              name: "Ubuntu 20.04 Clang",
+              os: ubuntu-20.04,
+              compiler: clang++,
+              comp: clang,
+              run_expensive_tests: false
+            }
+
+    defaults:
+      run:
+        working-directory: src
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: Download required packages
+        run: |
+          sudo apt update
+          sudo apt install expect valgrind g++-multilib
+
+      - name: Download the used network from the fishtest framework
+        run: |
+          make net
+
+      - name: Extract the bench number from the commit history
+        run: |
+          git log HEAD | grep "\b[Bb]ench[ :]\+[0-9]\{7\}" | head -n 1 | sed "s/[^0-9]*\([0-9]*\).*/\1/g" > git_sig
+          [ -s git_sig ] && echo "benchref=$(cat git_sig)" >> $GITHUB_ENV && echo "Reference bench:" $(cat git_sig) || echo "No bench found"
+
+      - name: Check compiler
+        run: |
+          $COMPILER -v
+
+      - name: Test help target
+        run: |
+          make help
+
+      # x86-32 tests
+
+      - name: Test debug x86-32 build
+        run: |
+          export CXXFLAGS="-Werror -D_GLIBCXX_DEBUG"
+          make clean
+          make -j2 ARCH=x86-32 optimize=no debug=yes build
+          ../tests/signature.sh $benchref
+
+      - name: Test x86-32 build
+        run: |
+          make clean
+          make -j2 ARCH=x86-32 build
+          ../tests/signature.sh $benchref
+
+      - name: Test x86-32-sse41-popcnt build
+        run: |
+          make clean
+          make -j2 ARCH=x86-32-sse41-popcnt build
+          ../tests/signature.sh $benchref
+
+      - name: Test x86-32-sse2 build
+        run: |
+          make clean
+          make -j2 ARCH=x86-32-sse2 build
+          ../tests/signature.sh $benchref
+
+      - name: Test general-32 build
+        run: |
+          make clean
+          make -j2 ARCH=general-32 build
+          ../tests/signature.sh $benchref
+
+      # x86-64 tests
+
+      - name: Test debug x86-64-modern build
+        run: |
+          export CXXFLAGS="-Werror -D_GLIBCXX_DEBUG"
+          make clean
+          make -j2 ARCH=x86-64-modern optimize=no debug=yes build
+          ../tests/signature.sh $benchref
+
+      - name: Test x86-64-modern build
+        run: |
+          make clean
+          make -j2 ARCH=x86-64-modern build
+          ../tests/signature.sh $benchref
+
+      - name: Test x86-64-ssse3 build
+        run: |
+          make clean
+          make -j2 ARCH=x86-64-ssse3 build
+          ../tests/signature.sh $benchref
+
+      - name: Test x86-64-sse3-popcnt build
+        run: |
+          make clean
+          make -j2 ARCH=x86-64-sse3-popcnt build
+          ../tests/signature.sh $benchref
+
+      - name: Test x86-64 build
+        run: |
+          make clean
+          make -j2 ARCH=x86-64 build
+          ../tests/signature.sh $benchref
+
+      - name: Test general-64 build
+        run: |
+          make clean
+          make -j2 ARCH=general-64 build
+          ../tests/signature.sh $benchref
+
+      # x86-64 with newer extensions tests
+
+      - name: Compile x86-64-avx2 build
+        run: |
+          make clean
+          make -j2 ARCH=x86-64-avx2 build
+
+      - name: Compile x86-64-bmi2 build
+        run: |
+          make clean
+          make -j2 ARCH=x86-64-bmi2 build
+
+      - name: Compile x86-64-avx512 build
+        run: |
+          make clean
+          make -j2 ARCH=x86-64-avx512 build
+
+      - name: Compile x86-64-vnni512 build
+        run: |
+          make clean
+          make -j2 ARCH=x86-64-vnni512 build
+
+      - name: Compile x86-64-vnni256 build
+        run: |
+          make clean
+          make -j2 ARCH=x86-64-vnni256 build
+
+      # Other tests
+
+      - name: Check perft and search reproducibility
+        run: |
+          make clean
+          make -j2 ARCH=x86-64-modern build
+          ../tests/perft.sh
+          ../tests/reprosearch.sh
+
+      # Sanitizers
+
+      - name: Run under valgrind
+        if: ${{ matrix.config.run_expensive_tests }}
+        run: |
+          export CXXFLAGS="-O1 -fno-inline"
+          make clean
+          make -j2 ARCH=x86-64-modern debug=yes optimize=no build > /dev/null
+          ../tests/instrumented.sh --valgrind
+          ../tests/instrumented.sh --valgrind-thread
+
+      - name: Run with UB sanitizer
+        if: ${{ matrix.config.run_expensive_tests }}
+        run: |
+          export CXXFLAGS="-O1 -fno-inline"
+          make clean
+          make -j2 ARCH=x86-64-modern sanitize=undefined optimize=no debug=yes build > /dev/null
+          ../tests/instrumented.sh --sanitizer-undefined
+
+      - name: Run with thread sanitizer
+        if: ${{ matrix.config.run_expensive_tests }}
+        run: |
+          export CXXFLAGS="-O1 -fno-inline"
+          make clean
+          make -j2 ARCH=x86-64-modern sanitize=thread optimize=no debug=yes build > /dev/null
+          ../tests/instrumented.sh --sanitizer-thread

.gitignore

@@ -0,0 +1,12 @@
+# Files from build
+**/*.o
+**/*.s
+src/.depend
+
+# Built binary
+src/stockfish*
+src/-lstdc++.res
+
+# Neural network for the NNUE evaluation
+**/*.nnue
+

.travis.yml

@@ -1,73 +0,0 @@
-language: cpp
-dist: xenial
-
-matrix:
-  include:
-    - os: linux
-      compiler: gcc
-      addons:
-        apt:
-          sources: ['ubuntu-toolchain-r-test']
-          packages: ['g++-8', 'g++-8-multilib', 'g++-multilib', 'valgrind', 'expect', 'curl']
-      env:
-        - COMPILER=g++-8
-        - COMP=gcc
-
-    - os: linux
-      compiler: clang
-      addons:
-        apt:
-          sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-xenial-6.0']
-          packages: ['clang-6.0', 'llvm-6.0-dev', 'g++-multilib', 'valgrind', 'expect', 'curl']
-      env:
-        - COMPILER=clang++-6.0
-        - COMP=clang
-        - LDFLAGS=-fuse-ld=lld
-
-    - os: osx
-      compiler: gcc
-      env:
-        - COMPILER=g++
-        - COMP=gcc
-
-    - os: osx
-      compiler: clang
-      env:
-        - COMPILER=clang++ V='Apple LLVM 9.4.1' # Apple LLVM version 9.1.0 (clang-902.0.39.2)
-        - COMP=clang
-
-branches:
-  only:
-   - master
-
-before_script:
-  - cd src
-
-script:
-  # Obtain bench reference from git log
-  - git log HEAD | grep "\b[Bb]ench[ :]\+[0-9]\{7\}" | head -n 1 | sed "s/[^0-9]*\([0-9]*\).*/\1/g" > git_sig
-  - export benchref=$(cat git_sig)
-  - echo "Reference bench:" $benchref
-  #
-  # Verify bench number against various builds
-  - export CXXFLAGS=-Werror
-  - make clean && make -j2 ARCH=x86-64 optimize=no debug=yes build && ../tests/signature.sh $benchref
-  - make clean && make -j2 ARCH=x86-32 optimize=no debug=yes build && ../tests/signature.sh $benchref
-  - make clean && make -j2 ARCH=x86-32 build && ../tests/signature.sh $benchref
-
-  #
-  # Check perft and reproducible search
-  - ../tests/perft.sh
-  - ../tests/reprosearch.sh
-  #
-  # Valgrind
-  #
-  - export CXXFLAGS="-O1 -fno-inline"
-  - if [ -x "$(command -v valgrind )" ]; then make clean && make -j2 ARCH=x86-64 debug=yes optimize=no build > /dev/null && ../tests/instrumented.sh --valgrind; fi
-  - if [ -x "$(command -v valgrind )" ]; then ../tests/instrumented.sh --valgrind-thread; fi
-  #
-  # Sanitizer
-  #
-  # Use g++-8 as a proxy for having sanitizers, might need revision as they become available for more recent versions of clang/gcc
-  - if [[ "$COMPILER" == "g++-8" ]]; then make clean && make -j2 ARCH=x86-64 sanitize=undefined optimize=no debug=yes build > /dev/null && ../tests/instrumented.sh --sanitizer-undefined; fi
-  - if [[ "$COMPILER" == "g++-8" ]]; then make clean && make -j2 ARCH=x86-64 sanitize=thread    optimize=no debug=yes build > /dev/null && ../tests/instrumented.sh --sanitizer-thread; fi

AUTHORS

@@ -1,10 +1,17 @@
-# List of authors for Stockfish, as of January 7, 2020
+# List of authors for Stockfish, as of June 14, 2021
 
+# Founders of the Stockfish project and fishtest infrastructure
 Tord Romstad (romstad)
 Marco Costalba (mcostalba)
 Joona Kiiski (zamar)
 Gary Linscott (glinscott)
 
+# Authors and inventors of NNUE, training, NNUE port
+Yu Nasu (ynasu87)
+Motohiro Isozaki (yaneurao)
+Hisayori Noda (nodchip)
+
+# all other authors of the code in alphabetical order
 Aditya (absimaldata)
 Adrian Petrescu (apetresc)
 Ajith Chandy Jose (ajithcj)
@@ -12,12 +19,15 @@ Alain Savard (Rocky640)
 Alayan Feh (Alayan-stk-2)
 Alexander Kure
 Alexander Pagel (Lolligerhans)
+Alfredo Menezes (lonfom169)
 Ali AlZhrani (Cooffe)
 Andrew Grant (AndyGrant)
 Andrey Neporada (nepal)
 Andy Duplain
+Antoine Champion (antoinechampion)
 Aram Tumanian (atumanian)
 Arjun Temurnikar
+Artem Solopiy (EntityFX)
 Auguste Pop
 Balint Pfliegel
 Ben Koshy (BKSpurgeon)
@@ -25,29 +35,39 @@ Bill Henry (VoyagerOne)
 Bojun Guo (noobpwnftw, Nooby)
 braich
 Brian Sheppard (SapphireBrand, briansheppard-toast)
+Bruno de Melo Costa (BM123499)
 Bryan Cross (crossbr)
 candirufish
 Chess13234
 Chris Cain (ceebo)
+Dale Weiler (graphitemaster)
 Dan Schmidt (dfannius)
 Daniel Axtens (daxtens)
 Daniel Dugovic (ddugovic)
-Dariusz Orzechowski
+Dariusz Orzechowski (dorzechowski)
 David Zar
 Daylen Yang (daylen)
+Deshawn Mohan-Smith (GoldenRare)
+Dieter Dobbelaere (ddobbelaere)
 DiscanX
+Dominik Schlösser (domschl)
 double-beep
+Douglas Matos Gomes (dsmsgms)
 Eduardo Cáceres (eduherminio)
 Eelco de Groot (KingDefender)
 Elvin Liu (solarlight2)
 erbsenzaehler
 Ernesto Gatti
+Linmiao Xu (linrock)
 Fabian Beuke (madnight)
 Fabian Fichter (ianfab)
+Fanael Linithien (Fanael)
 fanon
 Fauzi Akram Dabat (FauziAkram)
 Felix Wittmann
 gamander
+Gary Heckman (gheckman)
+George Sobala (gsobala)
 gguliash
 Gian-Carlo Pascutto (gcp)
 Gontran Lemaire (gonlem)
@@ -69,12 +89,14 @@ Jean Gauthier (OuaisBla)
 Jean-Francois Romang (jromang)
 Jekaa
 Jerry Donald Watson (jerrydonaldwatson)
+jjoshua2
 Jonathan Calovski (Mysseno)
-Jonathan Dumale (SFisGOD)
+Jonathan Buladas Dumale (SFisGOD)
 Joost VandeVondele (vondele)
 Jörg Oster (joergoster)
 Joseph Ellis (jhellis3)
 Joseph R. Prostko
+Julian Willemer (NightlyKing)
 jundery
 Justin Blanchard (UncombedCoconut)
 Kelly Wilson
@@ -82,6 +104,7 @@ Ken Takusagawa
 kinderchocolate
 Kiran Panditrao (Krgp)
 Kojirion
+Krystian Kuzniarek (kuzkry)
 Leonardo Ljubičić (ICCF World Champion)
 Leonid Pechenik (lp--)
 Linus Arver (listx)
@@ -94,8 +117,10 @@ Maciej Żenczykowski (zenczykowski)
 Malcolm Campbell (xoto10)
 Mark Tenzer (31m059)
 marotear
+Matt Ginsberg (mattginsberg)
 Matthew Lai (matthewlai)
 Matthew Sullivan (Matt14916)
+Maxim Molchanov (Maxim)
 Michael An (man)
 Michael Byrne (MichaelB7)
 Michael Chaly (Vizvezdenec)
@@ -113,6 +138,9 @@ Nick Pelling (nickpelling)
 Nicklas Persson (NicklasPersson)
 Niklas Fiekas (niklasf)
 Nikolay Kostov (NikolayIT)
+Nguyen Pham (nguyenpham)
+Norman Schmidt (FireFather)
+notruck
 Ondrej Mosnáček (WOnder93)
 Oskar Werkelin Ahlin
 Pablo Vazquez
@@ -122,6 +150,8 @@ Pasquale Pigazzini (ppigazzini)
 Patrick Jansen (mibere)
 pellanda
 Peter Zsifkovits (CoffeeOne)
+Praveen Kumar Tummala (praveentml)
+Rahul Dsilva (silversolver1)
 Ralph Stößer (Ralph Stoesser)
 Raminder Singh
 renouve
@@ -130,34 +160,39 @@ Richard Lloyd
 Rodrigo Exterckötter Tjäder
 Ron Britvich (Britvich)
 Ronald de Man (syzygy1, syzygy)
+rqs
 Ryan Schmitt
 Ryan Takker
 Sami Kiminki (skiminki)
 Sebastian Buchwald (UniQP)
 Sergei Antonov (saproj)
 Sergei Ivanov (svivanov72)
+Sergio Vieri (sergiovieri)
 sf-x
 Shane Booth (shane31)
+Shawn Varghese (xXH4CKST3RXx)
+Siad Daboul (Topologist)
 Stefan Geschwentner (locutus2)
 Stefano Cardanobile (Stefano80)
 Steinar Gunderson (sesse)
 Stéphane Nicolet (snicolet)
+Prokop Randáček (ProkopRandacek)
 Thanar2
 thaspel
 theo77186
 Tom Truscott
 Tom Vijlbrief (tomtor)
+Tomasz Sobczyk (Sopel97)
 Torsten Franz (torfranz, tfranzer)
 Tracey Emery (basepr1me)
+tttak
+Unai Corzo (unaiic)
 Uri Blass (uriblass)
 Vince Negri (cuddlestmonkey)
+zz4032
 
 
 # Additionally, we acknowledge the authors and maintainers of fishtest,
 # an amazing and essential framework for the development of Stockfish!
 #
 # https://github.com/glinscott/fishtest/blob/master/AUTHORS
-
-
-
-

README.md

@@ -0,0 +1,327 @@
+## Overview
+
+[![Build Status](https://github.com/official-stockfish/Stockfish/actions/workflows/stockfish.yml/badge.svg)](https://github.com/official-stockfish/Stockfish/actions)
+[![Build Status](https://ci.appveyor.com/api/projects/status/github/official-stockfish/Stockfish?branch=master&svg=true)](https://ci.appveyor.com/project/mcostalba/stockfish/branch/master)
+
+[Stockfish](https://stockfishchess.org) is a free, powerful UCI chess engine
+derived from Glaurung 2.1. Stockfish is not a complete chess program and requires a
+UCI-compatible graphical user interface (GUI) (e.g. XBoard with PolyGlot, Scid,
+Cute Chess, eboard, Arena, Sigma Chess, Shredder, Chess Partner or Fritz) in order
+to be used comfortably. Read the documentation for your GUI of choice for information
+about how to use Stockfish with it.
+
+The Stockfish engine features two evaluation functions for chess, the classical
+evaluation based on handcrafted terms, and the NNUE evaluation based on efficiently
+updatable neural networks. The classical evaluation runs efficiently on almost all
+CPU architectures, while the NNUE evaluation benefits from the vector
+intrinsics available on most CPUs (sse2, avx2, neon, or similar).
+
+
+## Files
+
+This distribution of Stockfish consists of the following files:
+
+  * [Readme.md](https://github.com/official-stockfish/Stockfish/blob/master/README.md), the file you are currently reading.
+
+  * [Copying.txt](https://github.com/official-stockfish/Stockfish/blob/master/Copying.txt), a text file containing the GNU General Public License version 3.
+
+  * [AUTHORS](https://github.com/official-stockfish/Stockfish/blob/master/AUTHORS), a text file with the list of authors for the project
+
+  * [src](https://github.com/official-stockfish/Stockfish/tree/master/src), a subdirectory containing the full source code, including a Makefile
+    that can be used to compile Stockfish on Unix-like systems.
+
+  * a file with the .nnue extension, storing the neural network for the NNUE
+    evaluation. Binary distributions will have this file embedded.
+
+## The UCI protocol and available options
+
+The Universal Chess Interface (UCI) is a standard protocol used to communicate with
+a chess engine, and is the recommended way to do so for typical graphical user interfaces
+(GUI) or chess tools. Stockfish implements the majority of it options as described
+in [the UCI protocol](https://www.shredderchess.com/download/div/uci.zip).
+
+Developers can see the default values for UCI options available in Stockfish by typing
+`./stockfish uci` in a terminal, but the majority of users will typically see them and
+change them via a chess GUI. This is a list of available UCI options in Stockfish:
+
+  * #### Threads
+    The number of CPU threads used for searching a position. For best performance, set
+    this equal to the number of CPU cores available.
+
+  * #### Hash
+    The size of the hash table in MB. It is recommended to set Hash after setting Threads.
+
+  * #### Clear Hash
+    Clear the hash table.
+
+  * #### Ponder
+    Let Stockfish ponder its next move while the opponent is thinking.
+
+  * #### MultiPV
+    Output the N best lines (principal variations, PVs) when searching.
+    Leave at 1 for best performance.
+
+  * #### Use NNUE
+    Toggle between the NNUE and classical evaluation functions. If set to "true",
+    the network parameters must be available to load from file (see also EvalFile),
+    if they are not embedded in the binary.
+
+  * #### EvalFile
+    The name of the file of the NNUE evaluation parameters. Depending on the GUI the
+    filename might have to include the full path to the folder/directory that contains the file.
+    Other locations, such as the directory that contains the binary and the working directory,
+    are also searched.
+
+  * #### UCI_AnalyseMode
+    An option handled by your GUI.
+
+  * #### UCI_Chess960
+    An option handled by your GUI. If true, Stockfish will play Chess960.
+
+  * #### UCI_ShowWDL
+    If enabled, show approximate WDL statistics as part of the engine output.
+    These WDL numbers model expected game outcomes for a given evaluation and
+    game ply for engine self-play at fishtest LTC conditions (60+0.6s per game).
+
+  * #### UCI_LimitStrength
+    Enable weaker play aiming for an Elo rating as set by UCI_Elo. This option overrides Skill Level.
+
+  * #### UCI_Elo
+    If enabled by UCI_LimitStrength, aim for an engine strength of the given Elo.
+    This Elo rating has been calibrated at a time control of 60s+0.6s and anchored to CCRL 40/4.
+
+  * #### Skill Level
+    Lower the Skill Level in order to make Stockfish play weaker (see also UCI_LimitStrength).
+    Internally, MultiPV is enabled, and with a certain probability depending on the Skill Level a
+    weaker move will be played.
+
+  * #### SyzygyPath
+    Path to the folders/directories storing the Syzygy tablebase files. Multiple
+    directories are to be separated by ";" on Windows and by ":" on Unix-based
+    operating systems. Do not use spaces around the ";" or ":".
+
+    Example: `C:\tablebases\wdl345;C:\tablebases\wdl6;D:\tablebases\dtz345;D:\tablebases\dtz6`
+
+    It is recommended to store .rtbw files on an SSD. There is no loss in storing
+    the .rtbz files on a regular HD. It is recommended to verify all md5 checksums
+    of the downloaded tablebase files (`md5sum -c checksum.md5`) as corruption will
+    lead to engine crashes.
+
+  * #### SyzygyProbeDepth
+    Minimum remaining search depth for which a position is probed. Set this option
+    to a higher value to probe less aggressively if you experience too much slowdown
+    (in terms of nps) due to tablebase probing.
+
+  * #### Syzygy50MoveRule
+    Disable to let fifty-move rule draws detected by Syzygy tablebase probes count
+    as wins or losses. This is useful for ICCF correspondence games.
+
+  * #### SyzygyProbeLimit
+    Limit Syzygy tablebase probing to positions with at most this many pieces left
+    (including kings and pawns).
+
+  * #### Move Overhead
+    Assume a time delay of x ms due to network and GUI overheads. This is useful to
+    avoid losses on time in those cases.
+
+  * #### Slow Mover
+    Lower values will make Stockfish take less time in games, higher values will
+    make it think longer.
+
+  * #### nodestime
+    Tells the engine to use nodes searched instead of wall time to account for
+    elapsed time. Useful for engine testing.
+
+  * #### Debug Log File
+    Write all communication to and from the engine into a text file.
+
+For developers the following non-standard commands might be of interest, mainly useful for debugging:
+
+  * #### bench *ttSize threads limit fenFile limitType evalType*
+    Performs a standard benchmark using various options. The signature of a version (standard node
+    count) is obtained using all defaults. `bench` is currently `bench 16 1 13 default depth mixed`.
+
+  * #### compiler
+    Give information about the compiler and environment used for building a binary.
+
+  * #### d
+    Display the current position, with ascii art and fen.
+
+  * #### eval
+    Return the evaluation of the current position.
+
+  * #### export_net [filename]
+    Exports the currently loaded network to a file.
+    If the currently loaded network is the embedded network and the filename
+    is not specified then the network is saved to the file matching the name
+    of the embedded network, as defined in evaluate.h.
+    If the currently loaded network is not the embedded network (some net set
+    through the UCI setoption) then the filename parameter is required and the
+    network is saved into that file.
+
+  * #### flip
+    Flips the side to move.
+
+
+## A note on classical evaluation versus NNUE evaluation
+
+Both approaches assign a value to a position that is used in alpha-beta (PVS) search
+to find the best move. The classical evaluation computes this value as a function
+of various chess concepts, handcrafted by experts, tested and tuned using fishtest.
+The NNUE evaluation computes this value with a neural network based on basic
+inputs (e.g. piece positions only). The network is optimized and trained
+on the evaluations of millions of positions at moderate search depth.
+
+The NNUE evaluation was first introduced in shogi, and ported to Stockfish afterward.
+It can be evaluated efficiently on CPUs, and exploits the fact that only parts
+of the neural network need to be updated after a typical chess move.
+[The nodchip repository](https://github.com/nodchip/Stockfish) provides additional
+tools to train and develop the NNUE networks. On CPUs supporting modern vector instructions
+(avx2 and similar), the NNUE evaluation results in much stronger playing strength, even
+if the nodes per second computed by the engine is somewhat lower (roughly 80% of nps
+is typical).
+
+Notes:
+
+1) the NNUE evaluation depends on the Stockfish binary and the network parameter
+file (see the EvalFile UCI option). Not every parameter file is compatible with a given
+Stockfish binary, but the default value of the EvalFile UCI option is the name of a network
+that is guaranteed to be compatible with that binary.
+
+2) to use the NNUE evaluation, the additional data file with neural network parameters
+needs to be available. Normally, this file is already embedded in the binary or it
+can be downloaded. The filename for the default (recommended) net can be found as the default
+value of the `EvalFile` UCI option, with the format `nn-[SHA256 first 12 digits].nnue`
+(for instance, `nn-c157e0a5755b.nnue`). This file can be downloaded from
+```
+https://tests.stockfishchess.org/api/nn/[filename]
+```
+replacing `[filename]` as needed.
+
+## What to expect from the Syzygy tablebases?
+
+If the engine is searching a position that is not in the tablebases (e.g.
+a position with 8 pieces), it will access the tablebases during the search.
+If the engine reports a very large score (typically 153.xx), this means
+it has found a winning line into a tablebase position.
+
+If the engine is given a position to search that is in the tablebases, it
+will use the tablebases at the beginning of the search to preselect all
+good moves, i.e. all moves that preserve the win or preserve the draw while
+taking into account the 50-move rule.
+It will then perform a search only on those moves. **The engine will not move
+immediately**, unless there is only a single good move. **The engine likely
+will not report a mate score, even if the position is known to be won.**
+
+It is therefore clear that this behaviour is not identical to what one might
+be used to with Nalimov tablebases. There are technical reasons for this
+difference, the main technical reason being that Nalimov tablebases use the
+DTM metric (distance-to-mate), while the Syzygy tablebases use a variation of the
+DTZ metric (distance-to-zero, zero meaning any move that resets the 50-move
+counter). This special metric is one of the reasons that the Syzygy tablebases are
+more compact than Nalimov tablebases, while still storing all information
+needed for optimal play and in addition being able to take into account
+the 50-move rule.
+
+## Large Pages
+
+Stockfish supports large pages on Linux and Windows. Large pages make
+the hash access more efficient, improving the engine speed, especially
+on large hash sizes. Typical increases are 5..10% in terms of nodes per
+second, but speed increases up to 30% have been measured. The support is
+automatic. Stockfish attempts to use large pages when available and
+will fall back to regular memory allocation when this is not the case.
+
+### Support on Linux
+
+Large page support on Linux is obtained by the Linux kernel
+transparent huge pages functionality. Typically, transparent huge pages
+are already enabled, and no configuration is needed.
+
+### Support on Windows
+
+The use of large pages requires "Lock Pages in Memory" privilege. See
+[Enable the Lock Pages in Memory Option (Windows)](https://docs.microsoft.com/en-us/sql/database-engine/configure-windows/enable-the-lock-pages-in-memory-option-windows)
+on how to enable this privilege, then run [RAMMap](https://docs.microsoft.com/en-us/sysinternals/downloads/rammap)
+to double-check that large pages are used. We suggest that you reboot
+your computer after you have enabled large pages, because long Windows
+sessions suffer from memory fragmentation, which may prevent Stockfish
+from getting large pages: a fresh session is better in this regard.
+
+## Compiling Stockfish yourself from the sources
+
+Stockfish has support for 32 or 64-bit CPUs, certain hardware
+instructions, big-endian machines such as Power PC, and other platforms.
+
+On Unix-like systems, it should be easy to compile Stockfish
+directly from the source code with the included Makefile in the folder
+`src`. In general it is recommended to run `make help` to see a list of make
+targets with corresponding descriptions.
+
+```
+    cd src
+    make help
+    make net
+    make build ARCH=x86-64-modern
+```
+
+When not using the Makefile to compile (for instance, with Microsoft MSVC) you
+need to manually set/unset some switches in the compiler command line; see
+file *types.h* for a quick reference.
+
+When reporting an issue or a bug, please tell us which Stockfish version
+and which compiler you used to create your executable. This information
+can be found by typing the following command in a console:
+
+```
+    ./stockfish compiler
+```
+
+## Understanding the code base and participating in the project
+
+Stockfish's improvement over the last decade has been a great community
+effort. There are a few ways to help contribute to its growth.
+
+### Donating hardware
+
+Improving Stockfish requires a massive amount of testing. You can donate
+your hardware resources by installing the [Fishtest Worker](https://github.com/glinscott/fishtest/wiki/Running-the-worker:-overview)
+and view the current tests on [Fishtest](https://tests.stockfishchess.org/tests).
+
+### Improving the code
+
+If you want to help improve the code, there are several valuable resources:
+
+* [In this wiki,](https://www.chessprogramming.org) many techniques used in
+Stockfish are explained with a lot of background information.
+
+* [The section on Stockfish](https://www.chessprogramming.org/Stockfish)
+describes many features and techniques used by Stockfish. However, it is
+generic rather than being focused on Stockfish's precise implementation.
+Nevertheless, a helpful resource.
+
+* The latest source can always be found on [GitHub](https://github.com/official-stockfish/Stockfish).
+Discussions about Stockfish take place these days mainly in the [FishCooking](https://groups.google.com/forum/#!forum/fishcooking)
+group and on the [Stockfish Discord channel](https://discord.gg/nv8gDtt).
+The engine testing is done on [Fishtest](https://tests.stockfishchess.org/tests).
+If you want to help improve Stockfish, please read this [guideline](https://github.com/glinscott/fishtest/wiki/Creating-my-first-test)
+first, where the basics of Stockfish development are explained.
+
+
+## Terms of use
+
+Stockfish is free, and distributed under the **GNU General Public License version 3**
+(GPL v3). Essentially, this means you are free to do almost exactly
+what you want with the program, including distributing it among your
+friends, making it available for download from your website, selling
+it (either by itself or as part of some bigger software package), or
+using it as the starting point for a software project of your own.
+
+The only real limitation is that whenever you distribute Stockfish in
+some way, you MUST always include the full source code, or a pointer
+to where the source code can be found, to generate the exact binary
+you are distributing. If you make any changes to the source code,
+these changes must also be made available under the GPL.
+
+For full details, read the copy of the GPL v3 found in the file named
+[*Copying.txt*](https://github.com/official-stockfish/Stockfish/blob/master/Copying.txt).

Readme.md

@@ -1,210 +0,0 @@
-## Overview
-
-[![Build Status](https://travis-ci.org/official-stockfish/Stockfish.svg?branch=master)](https://travis-ci.org/official-stockfish/Stockfish)
-[![Build Status](https://ci.appveyor.com/api/projects/status/github/official-stockfish/Stockfish?branch=master&svg=true)](https://ci.appveyor.com/project/mcostalba/stockfish/branch/master)
-
-[Stockfish](https://stockfishchess.org) is a free, powerful UCI chess engine
-derived from Glaurung 2.1. It is not a complete chess program and requires a
-UCI-compatible GUI (e.g. XBoard with PolyGlot, Scid, Cute Chess, eboard, Arena,
-Sigma Chess, Shredder, Chess Partner or Fritz) in order to be used comfortably.
-Read the documentation for your GUI of choice for information about how to use
-Stockfish with it.
-
-
-## Files
-
-This distribution of Stockfish consists of the following files:
-
-  * Readme.md, the file you are currently reading.
-
-  * Copying.txt, a text file containing the GNU General Public License version 3.
-
-  * src, a subdirectory containing the full source code, including a Makefile
-    that can be used to compile Stockfish on Unix-like systems.
-
-
-## UCI parameters
-
-Currently, Stockfish has the following UCI options:
-
-  * #### Debug Log File
-    Write all communication to and from the engine into a text file.
-
-  * #### Contempt
-    A positive value for contempt favors middle game positions and avoids draws.
-
-  * #### Analysis Contempt
-    By default, contempt is set to prefer the side to move. Set this option to "White"
-    or "Black" to analyse with contempt for that side, or "Off" to disable contempt.
-
-  * #### Threads
-    The number of CPU threads used for searching a position. For best performance, set
-    this equal to the number of CPU cores available.
-
-  * #### Hash
-    The size of the hash table in MB.
-
-  * #### Clear Hash
-    Clear the hash table.
-
-  * #### Ponder
-    Let Stockfish ponder its next move while the opponent is thinking.
-
-  * #### MultiPV
-    Output the N best lines (principal variations, PVs) when searching.
-    Leave at 1 for best performance.
-
-  * #### Skill Level
-    Lower the Skill Level in order to make Stockfish play weaker (see also UCI_LimitStrength).
-    Internally, MultiPV is enabled, and with a certain probability depending on the Skill Level a
-    weaker move will be played.
-
-  * #### UCI_LimitStrength
-    Enable weaker play aiming for an Elo rating as set by UCI_Elo. This option overrides Skill Level.
-
-  * #### UCI_Elo
-    If enabled by UCI_LimitStrength, aim for an engine strength of the given Elo.
-    This Elo rating has been calibrated at a time control of 60s+0.6s and anchored to CCRL 40/4.
-
-  * #### Move Overhead
-    Assume a time delay of x ms due to network and GUI overheads. This is useful to
-    avoid losses on time in those cases.
-
-  * #### Minimum Thinking Time
-    Search for at least x ms per move.
-
-  * #### Slow Mover
-    Lower values will make Stockfish take less time in games, higher values will
-    make it think longer.
-
-  * #### nodestime
-    Tells the engine to use nodes searched instead of wall time to account for
-    elapsed time. Useful for engine testing.
-
-  * #### UCI_Chess960
-    An option handled by your GUI. If true, Stockfish will play Chess960.
-
-  * #### UCI_AnalyseMode
-    An option handled by your GUI.
-
-  * #### SyzygyPath
-    Path to the folders/directories storing the Syzygy tablebase files. Multiple
-    directories are to be separated by ";" on Windows and by ":" on Unix-based
-    operating systems. Do not use spaces around the ";" or ":".
-
-    Example: `C:\tablebases\wdl345;C:\tablebases\wdl6;D:\tablebases\dtz345;D:\tablebases\dtz6`
-
-    It is recommended to store .rtbw files on an SSD. There is no loss in storing
-    the .rtbz files on a regular HD. It is recommended to verify all md5 checksums
-    of the downloaded tablebase files (`md5sum -c checksum.md5`) as corruption will
-    lead to engine crashes.
-
-  * #### SyzygyProbeDepth
-    Minimum remaining search depth for which a position is probed. Set this option
-    to a higher value to probe less agressively if you experience too much slowdown
-    (in terms of nps) due to TB probing.
-
-  * #### Syzygy50MoveRule
-    Disable to let fifty-move rule draws detected by Syzygy tablebase probes count
-    as wins or losses. This is useful for ICCF correspondence games.
-
-  * #### SyzygyProbeLimit
-    Limit Syzygy tablebase probing to positions with at most this many pieces left
-    (including kings and pawns).
-
-
-## What to expect from Syzygybases?
-
-If the engine is searching a position that is not in the tablebases (e.g.
-a position with 8 pieces), it will access the tablebases during the search.
-If the engine reports a very large score (typically 153.xx), this means
-that it has found a winning line into a tablebase position.
-
-If the engine is given a position to search that is in the tablebases, it
-will use the tablebases at the beginning of the search to preselect all
-good moves, i.e. all moves that preserve the win or preserve the draw while
-taking into account the 50-move rule.
-It will then perform a search only on those moves. **The engine will not move
-immediately**, unless there is only a single good move. **The engine likely
-will not report a mate score even if the position is known to be won.**
-
-It is therefore clear that this behaviour is not identical to what one might
-be used to with Nalimov tablebases. There are technical reasons for this
-difference, the main technical reason being that Nalimov tablebases use the
-DTM metric (distance-to-mate), while Syzygybases use a variation of the
-DTZ metric (distance-to-zero, zero meaning any move that resets the 50-move
-counter). This special metric is one of the reasons that Syzygybases are
-more compact than Nalimov tablebases, while still storing all information
-needed for optimal play and in addition being able to take into account
-the 50-move rule.
-
-
-## Compiling Stockfish yourself from the sources
-
-On Unix-like systems, it should be possible to compile Stockfish
-directly from the source code with the included Makefile.
-
-Stockfish has support for 32 or 64-bit CPUs, the hardware POPCNT
-instruction, big-endian machines such as Power PC, and other platforms.
-
-In general it is recommended to run `make help` to see a list of make
-targets with corresponding descriptions. When not using the Makefile to
-compile (for instance with Microsoft MSVC) you need to manually
-set/unset some switches in the compiler command line; see file *types.h*
-for a quick reference.
-
-When reporting an issue or a bug, please tell us which version and
-compiler you used to create your executable. These informations can
-be found by typing the following commands in a console:
-
-```
-    ./stockfish
-    compiler
-```
-
-## Understanding the code base and participating in the project
-
-Stockfish's improvement over the last couple of years has been a great
-community effort. There are a few ways to help contribute to its growth.
-
-### Donating hardware
-
-Improving Stockfish requires a massive amount of testing. You can donate
-your hardware resources by installing the [Fishtest Worker](https://github.com/glinscott/fishtest/wiki/Running-the-worker:-overview)
-and view the current tests on [Fishtest](https://tests.stockfishchess.org/tests).
-
-### Improving the code
-
-If you want to help improve the code, there are several valuable resources:
-
-* [In this wiki,](https://www.chessprogramming.org) many techniques used in
-Stockfish are explained with a lot of background information.
-
-* [The section on Stockfish](https://www.chessprogramming.org/Stockfish)
-describes many features and techniques used by Stockfish. However, it is
-generic rather than being focused on Stockfish's precise implementation.
-Nevertheless, a helpful resource.
-
-* The latest source can always be found on [GitHub](https://github.com/official-stockfish/Stockfish).
-Discussions about Stockfish take place in the [FishCooking](https://groups.google.com/forum/#!forum/fishcooking)
-group and engine testing is done on [Fishtest](https://tests.stockfishchess.org/tests).
-If you want to help improve Stockfish, please read this [guideline](https://github.com/glinscott/fishtest/wiki/Creating-my-first-test)
-first, where the basics of Stockfish development are explained.
-
-
-## Terms of use
-
-Stockfish is free, and distributed under the **GNU General Public License version 3**
-(GPL v3). Essentially, this means that you are free to do almost exactly
-what you want with the program, including distributing it among your
-friends, making it available for download from your web site, selling
-it (either by itself or as part of some bigger software package), or
-using it as the starting point for a software project of your own.
-
-The only real limitation is that whenever you distribute Stockfish in
-some way, you must always include the full source code, or a pointer
-to where the source code can be found. If you make any changes to the
-source code, these changes must also be made available under the GPL.
-
-For full details, read the copy of the GPL v3 found in the file named
-*Copying.txt*.

Top CPU Contributors.txt

@@ -1,154 +1,205 @@
-Contributors with >10,000 CPU hours as of January 7, 2020
+Contributors to Fishtest with >10,000 CPU hours, as of Jun 29, 2021.
 Thank you!
 
-Username                  CPU Hours   Games played
+Username                 CPU Hours       Games played
---------------------------------------------------
+-----------------------------------------------------
-noobpwnftw                  9305707      695548021
+noobpwnftw                27649494         1834734733
-mlang                        780050       61648867
+mlang                      1426107           89454622
-dew                          621626       43921547
+dew                        1380910           82831648
-mibere                       524702       42238645
+mibere                      703840           46867607
-crunchy                      354587       27344275
+grandphish2                 692707           41737913
-cw                           354495       27274181
+tvijlbrief                  669642           42371594
-fastgm                       332801       22804359
+JojoM                       597778           35297180
-JojoM                        295750       20437451
+TueRens                     519226           31823562
-CSU_Dynasty                  262015       21828122
+cw                          458421           30307421
-Fisherman                    232181       18939229
+fastgm                      439667           25950040
-ctoks                        218866       17622052
+gvreuls                     436599           28177460
-glinscott                    201989       13780820
+crunchy                     427035           27344275
-tvijlbrief                   201204       15337115
+CSU_Dynasty                 374765           25106278
-velislav                     188630       14348485
+Fisherman                   326901           21822979
-gvreuls                      187164       15149976
+ctoks                       325477           21767943
-bking_US                     180289       11876016
+velislav                    295343           18844324
-nordlandia                   172076       13467830
+linrock                     292789           10624427
-leszek                       157152       11443978
+bcross                      278584           19488961
-Thanar                       148021       12365359
+okrout                      262818           13803272
-spams                        141975       10319326
+pemo                        245982           11376085
-drabel                       138073       11121749
+glinscott                   217799           13780820
-vdv                          137850        9394330
+leszek                      212346           12959025
-mgrabiak                     133578       10454324
+nordlandia                  211692           13484886
-TueRens                      132485       10878471
+bking_US                    198894           11876016
-bcross                       129683       11557084
+drabel                      196463           13450602
-marrco                       126078        9356740
+robal                       195473           12375650
-sqrt2                        125830        9724586
+mgrabiak                    187226           12016564
-robal                        122873        9593418
+Dantist                     183202           10990484
-vdbergh                      120766        8926915
+Thanar                      179852           12365359
-malala                       115926        8002293
+vdv                         175274            9889046
-CoffeeOne                    114241        5004100
+spams                       157128           10319326
-dsmith                       113189        7570238
+marrco                      150295            9402141
-BrunoBanani                  104644        7436849
+sqrt2                       147963            9724586
-Data                          92328        8220352
+mhoram                      141278            8901241
-mhoram                        89333        6695109
+CoffeeOne                   137100            5024116
-davar                         87924        7009424
+vdbergh                     137041            8926915
-xoto                          81094        6869316
+malala                      136182            8002293
-ElbertoOne                    80899        7023771
+xoto                        133702            9156676
-grandphish2                   78067        6160199
+davar                       122092            7960001
-brabos                        77212        6186135
+dsmith                      122059            7570238
-psk                           75733        5984901
+Data                        113305            8220352
-BRAVONE                       73875        5054681
+BrunoBanani                 112960            7436849
-sunu                          70771        5597972
+MaZePallas                  102823            6633619
-sterni1971                    70605        5590573
+sterni1971                  100532            5880772
-MaZePallas                    66886        5188978
+ElbertoOne                   99028            7023771
-Vizvezdenec                   63708        4967313
+brabos                       92118            6186135
-nssy                          63462        5259388
+oz                           92100            6486640
-jromang                       61634        4940891
+psk                          89957            5984901
-teddybaer                     61231        5407666
+amicic                       89156            5392305
-Pking_cda                     60099        5293873
+sunu                         88851            6028873
-solarlight                    57469        5028306
+Vizvezdenec                  83761            5344740
-dv8silencer                   56913        3883992
+0x3C33                       82614            5271253
-tinker                        54936        4086118
+BRAVONE                      81239            5054681
-renouve                       49732        3501516
+racerschmacer                80899            5759262
-Freja                         49543        3733019
+cuistot                      80300            4606144
-robnjr                        46972        4053117
+nssy                         76497            5259388
-rap                           46563        3219146
+teddybaer                    75125            5407666
-Bobo1239                      46036        3817196
+Pking_cda                    73776            5293873
-ttruscott                     45304        3649765
+jromang                      72192            5057715
-racerschmacer                 44881        3975413
+solarlight                   70517            5028306
-finfish                       44764        3370515
+dv8silencer                  70287            3883992
-eva42                         41783        3599691
+Bobo1239                     68515            4652287
-biffhero                      40263        3111352
+manap                        66273            4121774
-bigpen0r                      39817        3291647
+skiminki                     65088            4023328
-mhunt                         38871        2691355
+tinker                       64333            4268790
-ronaldjerum                   38820        3240695
+sschnee                      60767            3500800
-Antihistamine                 38785        2761312
+qurashee                     57344            3168264
-pb00067                       38038        3086320
+robnjr                       57262            4053117
-speedycpu                     37591        3003273
+Freja                        56938            3733019
-rkl                           37207        3289580
+ttruscott                    56010            3680085
-VoyagerOne                    37050        3441673
+rkl                          55132            4164467
-jbwiebe                       35320        2805433
+renouve                      53811            3501516
-cuistot                       34191        2146279
+finfish                      51360            3370515
-homyur                        33927        2850481
+eva42                        51272            3599691
-manap                         32873        2327384
+rap                          49985            3219146
-gri                           32538        2515779
+pb00067                      49727            3298270
-oryx                          31267        2899051
+ronaldjerum                  47654            3240695
-EthanOConnor                  30959        2090311
+bigpen0r                     47653            3335327
-SC                            30832        2730764
+eastorwest                   47585            3221629
-csnodgrass                    29505        2688994
+biffhero                     46564            3111352
-jmdana                        29458        2205261
+VoyagerOne                   45476            3452465
-strelock                      28219        2067805
+yurikvelo                    44834            3034550
-jkiiski                       27832        1904470
+speedycpu                    43842            3003273
-Pyafue                        27533        1902349
+jbwiebe                      43305            2805433
-Garf                          27515        2747562
+Spprtr                       42279            2680153
-eastorwest                    27421        2317535
+DesolatedDodo                42007            2447516
-slakovv                       26903        2021889
+Antihistamine                41788            2761312
-Prcuvu                        24835        2170122
+mhunt                        41735            2691355
-anst                          24714        2190091
+homyur                       39893            2850481
-hyperbolic.tom                24319        2017394
+gri                          39871            2515779
-Patrick_G                     23687        1801617
+Fifis                        38776            2529121
-Sharaf_DG                     22896        1786697
+oryx                         38724            2966648
-nabildanial                   22195        1519409
+SC                           37290            2731014
-chriswk                       21931        1868317
+csnodgrass                   36207            2688994
-achambord                     21665        1767323
+jmdana                       36157            2210661
-Zirie                         20887        1472937
+strelock                     34716            2074055
-team-oh                       20217        1636708
+rpngn                        33951            2057395
-Isidor                        20096        1680691
+Garf                         33922            2751802
-ncfish1                       19931        1520927
+EthanOConnor                 33370            2090311
-nesoneg                       19875        1463031
+slakovv                      32915            2021889
-Spprtr                        19853        1548165
+manapbk                      30987            1810399
-JanErik                       19849        1703875
+Prcuvu                       30377            2170122
-agg177                        19478        1395014
+anst                         30301            2190091
-SFTUser                       19231        1567999
+jkiiski                      30136            1904470
-xor12                         19017        1680165
+hyperbolic.tom               29840            2017394
-sg4032                        18431        1641865
+Pyafue                       29650            1902349
-rstoesser                     18118        1293588
+Wolfgang                     29260            1658936
-MazeOfGalious                 17917        1629593
+zeryl                        28156            1579911
-j3corre                       17743         941444
+OuaisBla                     27636            1578800
-cisco2015                     17725        1690126
+DMBK                         27051            1999456
-ianh2105                      17706        1632562
+chriswk                      26902            1868317
-dex                           17678        1467203
+achambord                    26582            1767323
-jundery                       17194        1115855
+Patrick_G                    26276            1801617
-iisiraider                    17019        1101015
+yorkman                      26193            1992080
-horst.prack                   17012        1465656
+SFTUser                      25182            1675689
-Adrian.Schmidt123             16563        1281436
+nabildanial                  24942            1519409
-purplefishies                 16342        1092533
+Sharaf_DG                    24765            1786697
-wei                           16274        1745989
+ncfish1                      24411            1520927
-ville                         16144        1384026
+rodneyc                      24227            1409514
-eudhan                        15712        1283717
+agg177                       23890            1395014
-OuaisBla                      15581         972000
+JanErik                      23408            1703875
-DragonLord                    15559        1162790
+Isidor                       23388            1680691
-dju                           14716         875569
+Norabor                      23164            1591830
-chris                         14479        1487385
+cisco2015                    22897            1762669
-0xB00B1ES                     14079        1001120
+Zirie                        22542            1472937
-OssumOpossum                  13776        1007129
+team-oh                      22272            1636708
-enedene                       13460         905279
+MazeOfGalious                21978            1629593
-bpfliegel                     13346         884523
+sg4032                       21947            1643265
-Ente                          13198        1156722
+ianh2105                     21725            1632562
-IgorLeMasson                  13087        1147232
+xor12                        21628            1680365
-jpulman                       13000         870599
+dex                          21612            1467203
-ako027ako                     12775        1173203
+nesoneg                      21494            1463031
-Nikolay.IT                    12352        1068349
+sphinx                       21211            1384728
-Andrew Grant                  12327         895539
+jjoshua2                     21001            1423089
-joster                        12008         950160
+horst.prack                  20878            1465656
-AdrianSA                      11996         804972
+Ente                         20865            1477066
-Nesa92                        11455        1111993
+0xB00B1ES                    20590            1208666
-fatmurphy                     11345         853210
+j3corre                      20405             941444
-Dark_wizzie                   11108        1007152
+Adrian.Schmidt123            20316            1281436
-modolief                      10869         896470
+wei                          19973            1745989
-mschmidt                      10757         803401
+MaxKlaxxMiner                19850            1009176
-infinity                      10594         727027
+rstoesser                    19569            1293588
-mabichito                     10524         749391
+gopeto                       19491            1174952
-Thomas A. Anderson            10474         732094
+eudhan                       19274            1283717
-thijsk                        10431         719357
+jundery                      18445            1115855
-Flopzee                       10339         894821
+megaman7de                   18377            1067540
-crocogoat                     10104        1013854
+iisiraider                   18247            1101015
-SapphireBrand                 10104         969604
+ville                        17883            1384026
-stocky                        10017         699440
+chris                        17698            1487385
+purplefishies                17595            1092533
+dju                          17353             978595
+DragonLord                   17014            1162790
+IgorLeMasson                 16064            1147232
+ako027ako                    15671            1173203
+chuckstablers                15289             891576
+Nikolay.IT                   15154            1068349
+Andrew Grant                 15114             895539
+OssumOpossum                 14857            1007129
+Karby                        14808             867120
+enedene                      14476             905279
+bpfliegel                    14298             884523
+mpx86                        14019             759568
+jpulman                      13982             870599
+crocogoat                    13803            1117422
+joster                       13794             950160
+Nesa92                       13786            1114691
+Hjax                         13535             915487
+jsys14                       13459             785000
+Dark_wizzie                  13422            1007152
+mabichito                    12903             749391
+thijsk                       12886             722107
+AdrianSA                     12860             804972
+Flopzee                      12698             894821
+fatmurphy                    12547             853210
+Rudolphous                   12520             832340
+scuzzi                       12511             845761
+SapphireBrand                12416             969604
+modolief                     12386             896470
+Machariel                    12335             810784
+pgontarz                     12151             848794
+stocky                       11954             699440
+mschmidt                     11941             803401
+Maxim                        11543             836024
+infinity                     11470             727027
+torbjo                       11395             729145
+Thomas A. Anderson           11372             732094
+savage84                     11358             670860
+d64                          11263             789184
+MooTheCow                    11237             720174
+snicolet                     11106             869170
+ali-al-zhrani                11086             767926
+AndreasKrug                  10875             887457
+pirt                         10806             836519
+basepi                       10637             744851
+michaelrpg                   10508             739039
+dzjp                         10343             732529
+aga                          10302             622975
+ols                          10259             570669
+lbraesch                     10252             647825
+FormazChar                   10059             757283

appveyor.yml

@@ -4,10 +4,9 @@ clone_depth: 50
 branches:
   only:
     - master
-    - appveyor
 
 # Operating system (build VM template)
-os: Visual Studio 2017
+os: Visual Studio 2019
 
 # Build platform, i.e. x86, x64, AnyCPU. This setting is optional.
 platform:
@@ -36,8 +35,11 @@ before_build:
       $src = $src.Replace("\", "/")
 
       # Build CMakeLists.txt
-      $t = 'cmake_minimum_required(VERSION 3.8)',
+      $t = 'cmake_minimum_required(VERSION 3.17)',
            'project(Stockfish)',
+           'set(CMAKE_CXX_STANDARD 17)',
+           'set(CMAKE_CXX_STANDARD_REQUIRED ON)',
+           'set (CMAKE_CXX_EXTENSIONS OFF)',
            'set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR}/src)',
            'set(source_files', $src, ')',
            'add_executable(stockfish ${source_files})'
@@ -51,13 +53,28 @@ before_build:
       $b = git log HEAD | sls "\b[Bb]ench[ :]+[0-9]{7}" | select -first 1
       $bench = $b -match '\D+(\d+)' | % { $matches[1] }
       Write-Host "Reference bench:" $bench
-      $g = "Visual Studio 15 2017"
+      $g = "Visual Studio 16 2019"
-      If (${env:PLATFORM} -eq 'x64') { $g = $g + ' Win64' }
+      If (${env:PLATFORM} -eq 'x64') { $a = "x64" }
-      cmake -G "${g}" .
+      If (${env:PLATFORM} -eq 'x86') { $a = "Win32" }
-      Write-Host "Generated files for: " $g
+      cmake -G "${g}" -A ${a} .
+      Write-Host "Generated files for: " $g $a
 
 build_script:
   - cmake --build . --config %CONFIGURATION% -- /verbosity:minimal
+  - ps: |
+      # Download default NNUE net from fishtest
+      $nnuenet = Get-Content -Path src\evaluate.h | Select-String -CaseSensitive -Pattern "EvalFileDefaultName" | Select-String -CaseSensitive -Pattern "nn-[a-z0-9]{12}.nnue"
+      $dummy = $nnuenet -match "(?<nnuenet>nn-[a-z0-9]{12}.nnue)"
+      $nnuenet = $Matches.nnuenet
+      Write-Host "Default net:" $nnuenet
+      $nnuedownloadurl = "https://tests.stockfishchess.org/api/nn/$nnuenet"
+      $nnuefilepath = "src\${env:CONFIGURATION}\$nnuenet"
+      if (Test-Path -Path $nnuefilepath) {
+            Write-Host "Already available."
+      } else {
+            Write-Host "Downloading $nnuedownloadurl to $nnuefilepath"
+            Invoke-WebRequest -Uri $nnuedownloadurl -OutFile $nnuefilepath
+      }
 
 before_test:
   - cd src/%CONFIGURATION%

src/Makefile

@@ -1,7 +1,5 @@
 # Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-# Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+# Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-# Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-# Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 #
 # Stockfish is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -33,12 +31,21 @@ PREFIX = /usr/local
 BINDIR = $(PREFIX)/bin
 
 ### Built-in benchmark for pgo-builds
-PGOBENCH = ./$(EXE) bench
+ifeq ($(SDE_PATH),)
+	PGOBENCH = ./$(EXE) bench
+else
+	PGOBENCH = $(SDE_PATH) -- ./$(EXE) bench
+endif
 
-### Object files
+### Source and object files
-OBJS = benchmark.o bitbase.o bitboard.o endgame.o evaluate.o main.o \
+SRCS = benchmark.cpp bitbase.cpp bitboard.cpp endgame.cpp evaluate.cpp main.cpp \
-	material.o misc.o movegen.o movepick.o pawns.o position.o psqt.o \
+	material.cpp misc.cpp movegen.cpp movepick.cpp pawns.cpp position.cpp psqt.cpp \
-	search.o thread.o timeman.o tt.o uci.o ucioption.o syzygy/tbprobe.o
+	search.cpp thread.cpp timeman.cpp tt.cpp uci.cpp ucioption.cpp tune.cpp syzygy/tbprobe.cpp \
+	nnue/evaluate_nnue.cpp nnue/features/half_ka_v2.cpp
+
+OBJS = $(notdir $(SRCS:.cpp=.o))
+
+VPATH = syzygy:nnue:nnue/features
 
 ### Establish the operating system name
 KERNEL = $(shell uname -s)
@@ -50,105 +57,266 @@ endif
 ### Section 2. High-level Configuration
 ### ==========================================================================
 #
-# flag                --- Comp switch --- Description
+# flag                --- Comp switch      --- Description
 # ----------------------------------------------------------------------------
 #
 # debug = yes/no      --- -DNDEBUG         --- Enable/Disable debug mode
-# sanitize = undefined/thread/no (-fsanitize )
+# sanitize = none/<sanitizer> ... (-fsanitize )
 #                     --- ( undefined )    --- enable undefined behavior checks
-#                     --- ( thread    )    --- enable threading error  checks
+#                     --- ( thread    )    --- enable threading error checks
+#                     --- ( address   )    --- enable memory access checks
+#                     --- ...etc...        --- see compiler documentation for supported sanitizers
 # optimize = yes/no   --- (-O3/-fast etc.) --- Enable/Disable optimizations
 # arch = (name)       --- (-arch)          --- Target architecture
 # bits = 64/32        --- -DIS_64BIT       --- 64-/32-bit operating system
 # prefetch = yes/no   --- -DUSE_PREFETCH   --- Use prefetch asm-instruction
 # popcnt = yes/no     --- -DUSE_POPCNT     --- Use popcnt asm-instruction
-# sse = yes/no        --- -msse            --- Use Intel Streaming SIMD Extensions
 # pext = yes/no       --- -DUSE_PEXT       --- Use pext x86_64 asm-instruction
+# sse = yes/no        --- -msse            --- Use Intel Streaming SIMD Extensions
+# mmx = yes/no        --- -mmmx            --- Use Intel MMX instructions
+# sse2 = yes/no       --- -msse2           --- Use Intel Streaming SIMD Extensions 2
+# ssse3 = yes/no      --- -mssse3          --- Use Intel Supplemental Streaming SIMD Extensions 3
+# sse41 = yes/no      --- -msse4.1         --- Use Intel Streaming SIMD Extensions 4.1
+# avx2 = yes/no       --- -mavx2           --- Use Intel Advanced Vector Extensions 2
+# avx512 = yes/no     --- -mavx512bw       --- Use Intel Advanced Vector Extensions 512
+# vnni256 = yes/no    --- -mavx512vnni     --- Use Intel Vector Neural Network Instructions 256
+# vnni512 = yes/no    --- -mavx512vnni     --- Use Intel Vector Neural Network Instructions 512
+# neon = yes/no       --- -DUSE_NEON       --- Use ARM SIMD architecture
 #
 # Note that Makefile is space sensitive, so when adding new architectures
 # or modifying existing flags, you have to make sure there are no extra spaces
 # at the end of the line for flag values.
+#
+# Example of use for these flags:
+# make build ARCH=x86-64-avx512 debug=on sanitize="address undefined"
+
 
 ### 2.1. General and architecture defaults
+
+ifeq ($(ARCH),)
+   ARCH = x86-64-modern
+   help_skip_sanity = yes
+endif
+# explicitly check for the list of supported architectures (as listed with make help),
+# the user can override with `make ARCH=x86-32-vnni256 SUPPORTED_ARCH=true`
+ifeq ($(ARCH), $(filter $(ARCH), \
+                 x86-64-vnni512 x86-64-vnni256 x86-64-avx512 x86-64-bmi2 x86-64-avx2 \
+                 x86-64-sse41-popcnt x86-64-modern x86-64-ssse3 x86-64-sse3-popcnt \
+                 x86-64 x86-32-sse41-popcnt x86-32-sse2 x86-32 ppc-64 ppc-32 e2k \
+                 armv7 armv7-neon armv8 apple-silicon general-64 general-32))
+   SUPPORTED_ARCH=true
+else
+   SUPPORTED_ARCH=false
+endif
+
 optimize = yes
 debug = no
-sanitize = no
+sanitize = none
-bits = 32
+bits = 64
 prefetch = no
 popcnt = no
-sse = no
 pext = no
+sse = no
+mmx = no
+sse2 = no
+ssse3 = no
+sse41 = no
+avx2 = no
+avx512 = no
+vnni256 = no
+vnni512 = no
+neon = no
+STRIP = strip
 
 ### 2.2 Architecture specific
 
+ifeq ($(findstring x86,$(ARCH)),x86)
+
+# x86-32/64
+
+ifeq ($(findstring x86-32,$(ARCH)),x86-32)
+	arch = i386
+	bits = 32
+	sse = yes
+	mmx = yes
+else
+	arch = x86_64
+	sse = yes
+	sse2 = yes
+endif
+
+ifeq ($(findstring -sse,$(ARCH)),-sse)
+	sse = yes
+endif
+
+ifeq ($(findstring -popcnt,$(ARCH)),-popcnt)
+	popcnt = yes
+endif
+
+ifeq ($(findstring -mmx,$(ARCH)),-mmx)
+	mmx = yes
+endif
+
+ifeq ($(findstring -sse2,$(ARCH)),-sse2)
+	sse = yes
+	sse2 = yes
+endif
+
+ifeq ($(findstring -ssse3,$(ARCH)),-ssse3)
+	sse = yes
+	sse2 = yes
+	ssse3 = yes
+endif
+
+ifeq ($(findstring -sse41,$(ARCH)),-sse41)
+	sse = yes
+	sse2 = yes
+	ssse3 = yes
+	sse41 = yes
+endif
+
+ifeq ($(findstring -modern,$(ARCH)),-modern)
+	popcnt = yes
+	sse = yes
+	sse2 = yes
+	ssse3 = yes
+	sse41 = yes
+endif
+
+ifeq ($(findstring -avx2,$(ARCH)),-avx2)
+	popcnt = yes
+	sse = yes
+	sse2 = yes
+	ssse3 = yes
+	sse41 = yes
+	avx2 = yes
+endif
+
+ifeq ($(findstring -bmi2,$(ARCH)),-bmi2)
+	popcnt = yes
+	sse = yes
+	sse2 = yes
+	ssse3 = yes
+	sse41 = yes
+	avx2 = yes
+	pext = yes
+endif
+
+ifeq ($(findstring -avx512,$(ARCH)),-avx512)
+	popcnt = yes
+	sse = yes
+	sse2 = yes
+	ssse3 = yes
+	sse41 = yes
+	avx2 = yes
+	pext = yes
+	avx512 = yes
+endif
+
+ifeq ($(findstring -vnni256,$(ARCH)),-vnni256)
+	popcnt = yes
+	sse = yes
+	sse2 = yes
+	ssse3 = yes
+	sse41 = yes
+	avx2 = yes
+	pext = yes
+	vnni256 = yes
+endif
+
+ifeq ($(findstring -vnni512,$(ARCH)),-vnni512)
+	popcnt = yes
+	sse = yes
+	sse2 = yes
+	ssse3 = yes
+	sse41 = yes
+	avx2 = yes
+	pext = yes
+	avx512 = yes
+	vnni512 = yes
+endif
+
+ifeq ($(sse),yes)
+	prefetch = yes
+endif
+
+# 64-bit pext is not available on x86-32
+ifeq ($(bits),32)
+	pext = no
+endif
+
+else
+
+# all other architectures
+
 ifeq ($(ARCH),general-32)
 	arch = any
-endif
+	bits = 32
-
-ifeq ($(ARCH),x86-32-old)
-	arch = i386
-endif
-
-ifeq ($(ARCH),x86-32)
-	arch = i386
-	prefetch = yes
-	sse = yes
 endif
 
 ifeq ($(ARCH),general-64)
 	arch = any
-	bits = 64
-endif
-
-ifeq ($(ARCH),x86-64)
-	arch = x86_64
-	bits = 64
-	prefetch = yes
-	sse = yes
-endif
-
-ifeq ($(ARCH),x86-64-modern)
-	arch = x86_64
-	bits = 64
-	prefetch = yes
-	popcnt = yes
-	sse = yes
-endif
-
-ifeq ($(ARCH),x86-64-bmi2)
-	arch = x86_64
-	bits = 64
-	prefetch = yes
-	popcnt = yes
-	sse = yes
-	pext = yes
 endif
 
 ifeq ($(ARCH),armv7)
 	arch = armv7
 	prefetch = yes
+	bits = 32
+endif
+
+ifeq ($(ARCH),armv7-neon)
+	arch = armv7
+	prefetch = yes
+	popcnt = yes
+	neon = yes
+	bits = 32
+endif
+
+ifeq ($(ARCH),armv8)
+	arch = armv8
+	prefetch = yes
+	popcnt = yes
+	neon = yes
+endif
+
+ifeq ($(ARCH),apple-silicon)
+	arch = arm64
+	prefetch = yes
+	popcnt = yes
+	neon = yes
 endif
 
 ifeq ($(ARCH),ppc-32)
 	arch = ppc
+	bits = 32
 endif
 
 ifeq ($(ARCH),ppc-64)
 	arch = ppc64
-	bits = 64
 	popcnt = yes
 	prefetch = yes
 endif
 
+ifeq ($(findstring e2k,$(ARCH)),e2k)
+	arch = e2k
+	mmx = yes
+	bits = 64
+	sse = yes
+	sse2 = yes
+	ssse3 = yes
+	sse41 = yes
+	popcnt = yes
+endif
+
+endif
 
 ### ==========================================================================
-### Section 3. Low-level configuration
+### Section 3. Low-level Configuration
 ### ==========================================================================
 
 ### 3.1 Selecting compiler (default = gcc)
-
+CXXFLAGS += -Wall -Wcast-qual -fno-exceptions -std=c++17 $(EXTRACXXFLAGS)
-CXXFLAGS += -Wall -Wcast-qual -fno-exceptions -std=c++11 $(EXTRACXXFLAGS)
+DEPENDFLAGS += -std=c++17
-DEPENDFLAGS += -std=c++11
 LDFLAGS += $(EXTRALDFLAGS)
 
 ifeq ($(COMP),)
@@ -160,7 +328,7 @@ ifeq ($(COMP),gcc)
 	CXX=g++
 	CXXFLAGS += -pedantic -Wextra -Wshadow
 
-	ifeq ($(ARCH),armv7)
+	ifeq ($(arch),$(filter $(arch),armv7 armv8))
 		ifeq ($(OS),Android)
 			CXXFLAGS += -m$(bits)
 			LDFLAGS += -m$(bits)
@@ -170,6 +338,10 @@ ifeq ($(COMP),gcc)
 		LDFLAGS += -m$(bits)
 	endif
 
+	ifeq ($(arch),$(filter $(arch),armv7))
+		LDFLAGS += -latomic
+	endif
+
 	ifneq ($(KERNEL),Darwin)
 	   LDFLAGS += -Wl,--no-as-needed
 	endif
@@ -213,11 +385,13 @@ ifeq ($(COMP),clang)
 
 	ifneq ($(KERNEL),Darwin)
 	ifneq ($(KERNEL),OpenBSD)
+	ifneq ($(KERNEL),FreeBSD)
 		LDFLAGS += -latomic
 	endif
 	endif
+	endif
 
-	ifeq ($(ARCH),armv7)
+	ifeq ($(arch),$(filter $(arch),armv7 armv8))
 		ifeq ($(OS),Android)
 			CXXFLAGS += -m$(bits)
 			LDFLAGS += -m$(bits)
@@ -228,23 +402,40 @@ ifeq ($(COMP),clang)
 	endif
 endif
 
+ifeq ($(KERNEL),Darwin)
+	CXXFLAGS += -arch $(arch) -mmacosx-version-min=10.14
+	LDFLAGS += -arch $(arch) -mmacosx-version-min=10.14
+	XCRUN = xcrun
+endif
+
+# To cross-compile for Android, NDK version r21 or later is recommended.
+# In earlier NDK versions, you'll need to pass -fno-addrsig if using GNU binutils.
+# Currently we don't know how to make PGO builds with the NDK yet.
+ifeq ($(COMP),ndk)
+	CXXFLAGS += -stdlib=libc++ -fPIE
+	comp=clang
+	ifeq ($(arch),armv7)
+		CXX=armv7a-linux-androideabi16-clang++
+		CXXFLAGS += -mthumb -march=armv7-a -mfloat-abi=softfp -mfpu=neon
+		STRIP=arm-linux-androideabi-strip
+	endif
+	ifeq ($(arch),armv8)
+		CXX=aarch64-linux-android21-clang++
+		STRIP=aarch64-linux-android-strip
+	endif
+	LDFLAGS += -static-libstdc++ -pie -lm -latomic
+endif
+
 ifeq ($(comp),icc)
 	profile_make = icc-profile-make
 	profile_use = icc-profile-use
-else
+else ifeq ($(comp),clang)
-ifeq ($(comp),clang)
 	profile_make = clang-profile-make
 	profile_use = clang-profile-use
 else
 	profile_make = gcc-profile-make
 	profile_use = gcc-profile-use
 endif
-endif
-
-ifeq ($(KERNEL),Darwin)
-	CXXFLAGS += -arch $(arch) -mmacosx-version-min=10.9
-	LDFLAGS += -arch $(arch) -mmacosx-version-min=10.9
-endif
 
 ### Travis CI script uses COMPILER to overwrite CXX
 ifdef COMPILER
@@ -256,13 +447,26 @@ ifdef COMPCXX
 	CXX=$(COMPCXX)
 endif
 
+### Sometimes gcc is really clang
+ifeq ($(COMP),gcc)
+	gccversion = $(shell $(CXX) --version)
+	gccisclang = $(findstring clang,$(gccversion))
+	ifneq ($(gccisclang),)
+		profile_make = clang-profile-make
+		profile_use = clang-profile-use
+	endif
+endif
+
 ### On mingw use Windows threads, otherwise POSIX
 ifneq ($(comp),mingw)
+	CXXFLAGS += -DUSE_PTHREADS
 	# On Android Bionic's C library comes with its own pthread implementation bundled in
 	ifneq ($(OS),Android)
 		# Haiku has pthreads in its libroot, so only link it in on other platforms
 		ifneq ($(KERNEL),Haiku)
-			LDFLAGS += -lpthread
+			ifneq ($(COMP),ndk)
+				LDFLAGS += -lpthread
+			endif
 		endif
 	endif
 endif
@@ -275,9 +479,9 @@ else
 endif
 
 ### 3.2.2 Debugging with undefined behavior sanitizers
-ifneq ($(sanitize),no)
+ifneq ($(sanitize),none)
-        CXXFLAGS += -g3 -fsanitize=$(sanitize) -fuse-ld=gold
+        CXXFLAGS += -g3 $(addprefix -fsanitize=,$(sanitize))
-        LDFLAGS += -fsanitize=$(sanitize) -fuse-ld=gold
+        LDFLAGS += $(addprefix -fsanitize=,$(sanitize))
 endif
 
 ### 3.3 Optimization
@@ -296,6 +500,10 @@ ifeq ($(optimize),yes)
 			CXXFLAGS += -mdynamic-no-pic
 		endif
 	endif
+
+	ifeq ($(comp),clang)
+		CXXFLAGS += -fexperimental-new-pass-manager
+	endif
 endif
 
 ### 3.4 Bits
@@ -307,7 +515,6 @@ endif
 ifeq ($(prefetch),yes)
 	ifeq ($(sse),yes)
 		CXXFLAGS += -msse
-		DEPENDFLAGS += -msse
 	endif
 else
 	CXXFLAGS += -DNO_PREFETCH
@@ -315,7 +522,7 @@ endif
 
 ### 3.6 popcnt
 ifeq ($(popcnt),yes)
-	ifeq ($(arch),ppc64)
+	ifeq ($(arch),$(filter $(arch),ppc64 armv7 armv8 arm64))
 		CXXFLAGS += -DUSE_POPCNT
 	else ifeq ($(comp),icc)
 		CXXFLAGS += -msse3 -DUSE_POPCNT
@@ -324,28 +531,120 @@ ifeq ($(popcnt),yes)
 	endif
 endif
 
+ifeq ($(avx2),yes)
+	CXXFLAGS += -DUSE_AVX2
+	ifeq ($(comp),$(filter $(comp),gcc clang mingw))
+		CXXFLAGS += -mavx2
+	endif
+endif
+
+ifeq ($(avx512),yes)
+	CXXFLAGS += -DUSE_AVX512
+	ifeq ($(comp),$(filter $(comp),gcc clang mingw))
+		CXXFLAGS += -mavx512f -mavx512bw
+	endif
+endif
+
+ifeq ($(vnni256),yes)
+	CXXFLAGS += -DUSE_VNNI
+	ifeq ($(comp),$(filter $(comp),gcc clang mingw))
+		CXXFLAGS += -mavx512f -mavx512bw -mavx512vnni -mavx512dq -mavx512vl -mprefer-vector-width=256
+	endif
+endif
+
+ifeq ($(vnni512),yes)
+	CXXFLAGS += -DUSE_VNNI
+	ifeq ($(comp),$(filter $(comp),gcc clang mingw))
+		CXXFLAGS += -mavx512vnni -mavx512dq -mavx512vl
+	endif
+endif
+
+ifeq ($(sse41),yes)
+	CXXFLAGS += -DUSE_SSE41
+	ifeq ($(comp),$(filter $(comp),gcc clang mingw))
+		CXXFLAGS += -msse4.1
+	endif
+endif
+
+ifeq ($(ssse3),yes)
+	CXXFLAGS += -DUSE_SSSE3
+	ifeq ($(comp),$(filter $(comp),gcc clang mingw))
+		CXXFLAGS += -mssse3
+	endif
+endif
+
+ifeq ($(sse2),yes)
+	CXXFLAGS += -DUSE_SSE2
+	ifeq ($(comp),$(filter $(comp),gcc clang mingw))
+		CXXFLAGS += -msse2
+	endif
+endif
+
+ifeq ($(mmx),yes)
+	CXXFLAGS += -DUSE_MMX
+	ifeq ($(comp),$(filter $(comp),gcc clang mingw))
+		CXXFLAGS += -mmmx
+	endif
+endif
+
+ifeq ($(neon),yes)
+	CXXFLAGS += -DUSE_NEON
+	ifeq ($(KERNEL),Linux)
+	ifneq ($(COMP),ndk)
+	ifneq ($(arch),armv8)
+		CXXFLAGS += -mfpu=neon
+	endif
+	endif
+	endif
+endif
+
 ### 3.7 pext
 ifeq ($(pext),yes)
 	CXXFLAGS += -DUSE_PEXT
 	ifeq ($(comp),$(filter $(comp),gcc clang mingw))
-		CXXFLAGS += -msse4 -mbmi2
+		CXXFLAGS += -mbmi2
 	endif
 endif
 
-### 3.8 Link Time Optimization, it works since gcc 4.5 but not on mingw under Windows.
+### 3.8 Link Time Optimization
 ### This is a mix of compile and link time options because the lto link phase
 ### needs access to the optimization flags.
 ifeq ($(optimize),yes)
 ifeq ($(debug), no)
-	ifeq ($(comp),$(filter $(comp),gcc clang))
+	ifeq ($(comp),clang)
+		CXXFLAGS += -flto
+		ifneq ($(findstring MINGW,$(KERNEL)),)
+			CXXFLAGS += -fuse-ld=lld
+		else ifneq ($(findstring MSYS,$(KERNEL)),)
+			CXXFLAGS += -fuse-ld=lld
+		endif
+		LDFLAGS += $(CXXFLAGS)
+
+# GCC and CLANG use different methods for parallelizing LTO and CLANG pretends to be
+# GCC on some systems.
+	else ifeq ($(comp),gcc)
+	ifeq ($(gccisclang),)
+		CXXFLAGS += -flto
+		LDFLAGS += $(CXXFLAGS) -flto=jobserver
+		ifneq ($(findstring MINGW,$(KERNEL)),)
+			LDFLAGS += -save-temps
+		else ifneq ($(findstring MSYS,$(KERNEL)),)
+			LDFLAGS += -save-temps
+		endif
+	else
 		CXXFLAGS += -flto
 		LDFLAGS += $(CXXFLAGS)
 	endif
 
-	ifeq ($(comp),mingw)
+# To use LTO and static linking on windows, the tool chain requires a recent gcc:
+# gcc version 10.1 in msys2 or TDM-GCC version 9.2 are known to work, older might not.
+# So, only enable it for a cross from Linux by default.
+	else ifeq ($(comp),mingw)
 	ifeq ($(KERNEL),Linux)
+	ifneq ($(arch),i386)
 		CXXFLAGS += -flto
-		LDFLAGS += $(CXXFLAGS)
+		LDFLAGS += $(CXXFLAGS) -flto=jobserver
+	endif
 	endif
 	endif
 endif
@@ -358,10 +657,10 @@ ifeq ($(OS), Android)
 	LDFLAGS += -fPIE -pie
 endif
 
+### ==========================================================================
+### Section 4. Public Targets
+### ==========================================================================
 
-### ==========================================================================
-### Section 4. Public targets
-### ==========================================================================
 
 help:
 	@echo ""
@@ -371,22 +670,36 @@ help:
 	@echo ""
 	@echo "Supported targets:"
 	@echo ""
+	@echo "help                    > Display architecture details"
 	@echo "build                   > Standard build"
-	@echo "profile-build           > PGO build"
+	@echo "net                     > Download the default nnue net"
+	@echo "profile-build           > Faster build (with profile-guided optimization)"
 	@echo "strip                   > Strip executable"
 	@echo "install                 > Install executable"
 	@echo "clean                   > Clean up"
 	@echo ""
 	@echo "Supported archs:"
 	@echo ""
-	@echo "x86-64-bmi2             > x86 64-bit with pext support (also enables SSE4)"
+	@echo "x86-64-vnni512          > x86 64-bit with vnni support 512bit wide"
-	@echo "x86-64-modern           > x86 64-bit with popcnt support (also enables SSE3)"
+	@echo "x86-64-vnni256          > x86 64-bit with vnni support 256bit wide"
-	@echo "x86-64                  > x86 64-bit generic"
+	@echo "x86-64-avx512           > x86 64-bit with avx512 support"
-	@echo "x86-32                  > x86 32-bit (also enables SSE)"
+	@echo "x86-64-bmi2             > x86 64-bit with bmi2 support"
-	@echo "x86-32-old              > x86 32-bit fall back for old hardware"
+	@echo "x86-64-avx2             > x86 64-bit with avx2 support"
+	@echo "x86-64-sse41-popcnt     > x86 64-bit with sse41 and popcnt support"
+	@echo "x86-64-modern           > common modern CPU, currently x86-64-sse41-popcnt"
+	@echo "x86-64-ssse3            > x86 64-bit with ssse3 support"
+	@echo "x86-64-sse3-popcnt      > x86 64-bit with sse3 and popcnt support"
+	@echo "x86-64                  > x86 64-bit generic (with sse2 support)"
+	@echo "x86-32-sse41-popcnt     > x86 32-bit with sse41 and popcnt support"
+	@echo "x86-32-sse2             > x86 32-bit with sse2 support"
+	@echo "x86-32                  > x86 32-bit generic (with mmx and sse support)"
 	@echo "ppc-64                  > PPC 64-bit"
 	@echo "ppc-32                  > PPC 32-bit"
 	@echo "armv7                   > ARMv7 32-bit"
+	@echo "armv7-neon              > ARMv7 32-bit with popcnt and neon"
+	@echo "armv8                   > ARMv8 64-bit with popcnt and neon"
+	@echo "e2k                     > Elbrus 2000"
+	@echo "apple-silicon           > Apple silicon ARM64"
 	@echo "general-64              > unspecified 64-bit"
 	@echo "general-32              > unspecified 32-bit"
 	@echo ""
@@ -396,27 +709,37 @@ help:
 	@echo "mingw                   > Gnu compiler with MinGW under Windows"
 	@echo "clang                   > LLVM Clang compiler"
 	@echo "icc                     > Intel compiler"
+	@echo "ndk                     > Google NDK to cross-compile for Android"
 	@echo ""
 	@echo "Simple examples. If you don't know what to do, you likely want to run: "
 	@echo ""
-	@echo "make build ARCH=x86-64    (This is for 64-bit systems)"
+	@echo "make -j build ARCH=x86-64  (A portable, slow compile for 64-bit systems)"
-	@echo "make build ARCH=x86-32    (This is for 32-bit systems)"
+	@echo "make -j build ARCH=x86-32  (A portable, slow compile for 32-bit systems)"
 	@echo ""
-	@echo "Advanced examples, for experienced users: "
+	@echo "Advanced examples, for experienced users looking for performance: "
 	@echo ""
-	@echo "make build ARCH=x86-64 COMP=clang"
+	@echo "make    help  ARCH=x86-64-bmi2"
-	@echo "make profile-build ARCH=x86-64-bmi2 COMP=gcc COMPCXX=g++-4.8"
+	@echo "make -j profile-build ARCH=x86-64-bmi2 COMP=gcc COMPCXX=g++-9.0"
+	@echo "make -j build ARCH=x86-64-ssse3 COMP=clang"
 	@echo ""
+	@echo "-------------------------------"
+ifeq ($(SUPPORTED_ARCH)$(help_skip_sanity), true)
+	@echo "The selected architecture $(ARCH) will enable the following configuration: "
+	@$(MAKE) ARCH=$(ARCH) COMP=$(COMP) config-sanity
+else
+	@echo "Specify a supported architecture with the ARCH option for more details"
+	@echo ""
+endif
 
 
-.PHONY: help build profile-build strip install clean objclean profileclean help \
+.PHONY: help build profile-build strip install clean net objclean profileclean \
         config-sanity icc-profile-use icc-profile-make gcc-profile-use gcc-profile-make \
         clang-profile-use clang-profile-make
 
-build: config-sanity
+build: net config-sanity
 	$(MAKE) ARCH=$(ARCH) COMP=$(COMP) all
 
-profile-build: config-sanity objclean profileclean
+profile-build: net config-sanity objclean profileclean
 	@echo ""
 	@echo "Step 1/4. Building instrumented executable ..."
 	$(MAKE) ARCH=$(ARCH) COMP=$(COMP) $(profile_make)
@@ -432,37 +755,64 @@ profile-build: config-sanity objclean profileclean
 	$(MAKE) ARCH=$(ARCH) COMP=$(COMP) profileclean
 
 strip:
-	strip $(EXE)
+	$(STRIP) $(EXE)
 
 install:
 	-mkdir -p -m 755 $(BINDIR)
 	-cp $(EXE) $(BINDIR)
 	-strip $(BINDIR)/$(EXE)
 
-#clean all
+# clean all
 clean: objclean profileclean
 	@rm -f .depend *~ core
 
+# evaluation network (nnue)
+net:
+	$(eval nnuenet := $(shell grep EvalFileDefaultName evaluate.h | grep define | sed 's/.*\(nn-[a-z0-9]\{12\}.nnue\).*/\1/'))
+	@echo "Default net: $(nnuenet)"
+	$(eval nnuedownloadurl := https://tests.stockfishchess.org/api/nn/$(nnuenet))
+	$(eval curl_or_wget := $(shell if hash curl 2>/dev/null; then echo "curl -skL"; elif hash wget 2>/dev/null; then echo "wget -qO-"; fi))
+	@if test -f "$(nnuenet)"; then \
+            echo "Already available."; \
+         else \
+            if [ "x$(curl_or_wget)" = "x" ]; then \
+               echo "Automatic download failed: neither curl nor wget is installed. Install one of these tools or download the net manually"; exit 1; \
+            else \
+               echo "Downloading $(nnuedownloadurl)"; $(curl_or_wget) $(nnuedownloadurl) > $(nnuenet);\
+            fi; \
+        fi;
+	$(eval shasum_command := $(shell if hash shasum 2>/dev/null; then echo "shasum -a 256 "; elif hash sha256sum 2>/dev/null; then echo "sha256sum "; fi))
+	@if [ "x$(shasum_command)" != "x" ]; then \
+	    if [ "$(nnuenet)" != "nn-"`$(shasum_command) $(nnuenet) | cut -c1-12`".nnue" ]; then \
+                echo "Failed download or $(nnuenet) corrupted, please delete!"; exit 1; \
+            fi \
+         else \
+            echo "shasum / sha256sum not found, skipping net validation"; \
+        fi
+
 # clean binaries and objects
 objclean:
-	@rm -f $(EXE) *.o ./syzygy/*.o
+	@rm -f $(EXE) *.o ./syzygy/*.o ./nnue/*.o ./nnue/features/*.o
 
 # clean auxiliary profiling files
 profileclean:
 	@rm -rf profdir
-	@rm -f bench.txt *.gcda ./syzygy/*.gcda *.gcno ./syzygy/*.gcno
+	@rm -f bench.txt *.gcda *.gcno ./syzygy/*.gcda ./nnue/*.gcda ./nnue/features/*.gcda *.s
 	@rm -f stockfish.profdata *.profraw
+	@rm -f stockfish.exe.lto_wrapper_args
+	@rm -f stockfish.exe.ltrans.out
+	@rm -f ./-lstdc++.res
 
 default:
 	help
 
 ### ==========================================================================
-### Section 5. Private targets
+### Section 5. Private Targets
 ### ==========================================================================
 
 all: $(EXE) .depend
 
-config-sanity:
+config-sanity: net
 	@echo ""
 	@echo "Config:"
 	@echo "debug: '$(debug)'"
@@ -474,8 +824,17 @@ config-sanity:
 	@echo "os: '$(OS)'"
 	@echo "prefetch: '$(prefetch)'"
 	@echo "popcnt: '$(popcnt)'"
-	@echo "sse: '$(sse)'"
 	@echo "pext: '$(pext)'"
+	@echo "sse: '$(sse)'"
+	@echo "mmx: '$(mmx)'"
+	@echo "sse2: '$(sse2)'"
+	@echo "ssse3: '$(ssse3)'"
+	@echo "sse41: '$(sse41)'"
+	@echo "avx2: '$(avx2)'"
+	@echo "avx512: '$(avx512)'"
+	@echo "vnni256: '$(vnni256)'"
+	@echo "vnni512: '$(vnni512)'"
+	@echo "neon: '$(neon)'"
 	@echo ""
 	@echo "Flags:"
 	@echo "CXX: $(CXX)"
@@ -485,19 +844,30 @@ config-sanity:
 	@echo "Testing config sanity. If this fails, try 'make help' ..."
 	@echo ""
 	@test "$(debug)" = "yes" || test "$(debug)" = "no"
-	@test "$(sanitize)" = "undefined" || test "$(sanitize)" = "thread" || test "$(sanitize)" = "address" || test "$(sanitize)" = "no"
 	@test "$(optimize)" = "yes" || test "$(optimize)" = "no"
+	@test "$(SUPPORTED_ARCH)" = "true"
 	@test "$(arch)" = "any" || test "$(arch)" = "x86_64" || test "$(arch)" = "i386" || \
-	 test "$(arch)" = "ppc64" || test "$(arch)" = "ppc" || test "$(arch)" = "armv7"
+	 test "$(arch)" = "ppc64" || test "$(arch)" = "ppc" || test "$(arch)" = "e2k" || \
+	 test "$(arch)" = "armv7" || test "$(arch)" = "armv8" || test "$(arch)" = "arm64"
 	@test "$(bits)" = "32" || test "$(bits)" = "64"
 	@test "$(prefetch)" = "yes" || test "$(prefetch)" = "no"
 	@test "$(popcnt)" = "yes" || test "$(popcnt)" = "no"
-	@test "$(sse)" = "yes" || test "$(sse)" = "no"
 	@test "$(pext)" = "yes" || test "$(pext)" = "no"
-	@test "$(comp)" = "gcc" || test "$(comp)" = "icc" || test "$(comp)" = "mingw" || test "$(comp)" = "clang"
+	@test "$(sse)" = "yes" || test "$(sse)" = "no"
+	@test "$(mmx)" = "yes" || test "$(mmx)" = "no"
+	@test "$(sse2)" = "yes" || test "$(sse2)" = "no"
+	@test "$(ssse3)" = "yes" || test "$(ssse3)" = "no"
+	@test "$(sse41)" = "yes" || test "$(sse41)" = "no"
+	@test "$(avx2)" = "yes" || test "$(avx2)" = "no"
+	@test "$(avx512)" = "yes" || test "$(avx512)" = "no"
+	@test "$(vnni256)" = "yes" || test "$(vnni256)" = "no"
+	@test "$(vnni512)" = "yes" || test "$(vnni512)" = "no"
+	@test "$(neon)" = "yes" || test "$(neon)" = "no"
+	@test "$(comp)" = "gcc" || test "$(comp)" = "icc" || test "$(comp)" = "mingw" || test "$(comp)" = "clang" \
+	|| test "$(comp)" = "armv7a-linux-androideabi16-clang"  || test "$(comp)" = "aarch64-linux-android21-clang"
 
 $(EXE): $(OBJS)
-	$(CXX) -o $@ $(OBJS) $(LDFLAGS)
+	+$(CXX) -o $@ $(OBJS) $(LDFLAGS)
 
 clang-profile-make:
 	$(MAKE) ARCH=$(ARCH) COMP=$(COMP) \
@@ -506,21 +876,22 @@ clang-profile-make:
 	all
 
 clang-profile-use:
-	llvm-profdata merge -output=stockfish.profdata *.profraw
+	$(XCRUN) llvm-profdata merge -output=stockfish.profdata *.profraw
 	$(MAKE) ARCH=$(ARCH) COMP=$(COMP) \
 	EXTRACXXFLAGS='-fprofile-instr-use=stockfish.profdata' \
 	EXTRALDFLAGS='-fprofile-use ' \
 	all
 
 gcc-profile-make:
+	@mkdir -p profdir
 	$(MAKE) ARCH=$(ARCH) COMP=$(COMP) \
-	EXTRACXXFLAGS='-fprofile-generate' \
+	EXTRACXXFLAGS='-fprofile-generate=profdir' \
 	EXTRALDFLAGS='-lgcov' \
 	all
 
 gcc-profile-use:
 	$(MAKE) ARCH=$(ARCH) COMP=$(COMP) \
-	EXTRACXXFLAGS='-fprofile-use -fno-peel-loops -fno-tracer' \
+	EXTRACXXFLAGS='-fprofile-use=profdir -fno-peel-loops -fno-tracer' \
 	EXTRALDFLAGS='-lgcov' \
 	all
 
@@ -536,7 +907,6 @@ icc-profile-use:
 	all
 
 .depend:
-	-@$(CXX) $(DEPENDFLAGS) -MM $(OBJS:.o=.cpp) > $@ 2> /dev/null
+	-@$(CXX) $(DEPENDFLAGS) -MM $(SRCS) > $@ 2> /dev/null
 
 -include .depend
-

src/benchmark.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -65,6 +63,7 @@ const vector<string> Defaults = {
   "4rrk1/1p1nq3/p7/2p1P1pp/3P2bp/3Q1Bn1/PPPB4/1K2R1NR w - - 40 21",
   "r3k2r/3nnpbp/q2pp1p1/p7/Pp1PPPP1/4BNN1/1P5P/R2Q1RK1 w kq - 0 16",
   "3Qb1k1/1r2ppb1/pN1n2q1/Pp1Pp1Pr/4P2p/4BP2/4B1R1/1R5K b - - 11 40",
+  "4k3/3q1r2/1N2r1b1/3ppN2/2nPP3/1B1R2n1/2R1Q3/3K4 w - - 5 1",
 
   // 5-man positions
   "8/8/8/8/5kp1/P7/8/1K1N4 w - - 0 1",     // Kc2 - mate
@@ -87,17 +86,20 @@ const vector<string> Defaults = {
 
   // Chess 960
   "setoption name UCI_Chess960 value true",
-  "bbqnnrkr/pppppppp/8/8/8/8/PPPPPPPP/BBQNNRKR w KQkq - 0 1 moves g2g3 d7d5 d2d4 c8h3 c1g5 e8d6 g5e7 f7f6",
+  "bbqnnrkr/pppppppp/8/8/8/8/PPPPPPPP/BBQNNRKR w HFhf - 0 1 moves g2g3 d7d5 d2d4 c8h3 c1g5 e8d6 g5e7 f7f6",
   "setoption name UCI_Chess960 value false"
 };
 
 } // namespace
 
+namespace Stockfish {
+
 /// setup_bench() builds a list of UCI commands to be run by bench. There
 /// are five parameters: TT size in MB, number of search threads that
 /// should be used, the limit value spent for each position, a file name
-/// where to look for positions in FEN format and the type of the limit:
+/// where to look for positions in FEN format, the type of the limit:
-/// depth, perft, nodes and movetime (in millisecs).
+/// depth, perft, nodes and movetime (in millisecs), and evaluation type
+/// mixed (default), classical, NNUE.
 ///
 /// bench -> search default positions up to depth 13
 /// bench 64 1 15 -> search default positions up to depth 15 (TT = 64MB)
@@ -116,6 +118,7 @@ vector<string> setup_bench(const Position& current, istream& is) {
   string limit     = (is >> token) ? token : "13";
   string fenFile   = (is >> token) ? token : "default";
   string limitType = (is >> token) ? token : "depth";
+  string evalType  = (is >> token) ? token : "mixed";
 
   go = limitType == "eval" ? "eval" : "go " + limitType + " " + limit;
 
@@ -147,14 +150,25 @@ vector<string> setup_bench(const Position& current, istream& is) {
   list.emplace_back("setoption name Hash value " + ttSize);
   list.emplace_back("ucinewgame");
 
+  size_t posCounter = 0;
+
   for (const string& fen : fens)
       if (fen.find("setoption") != string::npos)
           list.emplace_back(fen);
       else
       {
+          if (evalType == "classical" || (evalType == "mixed" && posCounter % 2 == 0))
+              list.emplace_back("setoption name Use NNUE value false");
+          else if (evalType == "NNUE" || (evalType == "mixed" && posCounter % 2 != 0))
+              list.emplace_back("setoption name Use NNUE value true");
           list.emplace_back("position fen " + fen);
           list.emplace_back(go);
+          ++posCounter;
       }
 
+  list.emplace_back("setoption name Use NNUE value true");
+
   return list;
 }
+
+} // namespace Stockfish

src/bitbase.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -19,20 +17,21 @@
 */
 
 #include <cassert>
-#include <numeric>
 #include <vector>
+#include <bitset>
 
 #include "bitboard.h"
 #include "types.h"
 
+namespace Stockfish {
+
 namespace {
 
   // There are 24 possible pawn squares: files A to D and ranks from 2 to 7.
   // Positions with the pawn on files E to H will be mirrored before probing.
   constexpr unsigned MAX_INDEX = 2*24*64*64; // stm * psq * wksq * bksq = 196608
 
-  // Each uint32_t stores results of 32 positions, one per bit
+  std::bitset<MAX_INDEX> KPKBitbase;
-  uint32_t KPKBitbase[MAX_INDEX / 32];
 
   // A KPK bitbase index is an integer in [0, IndexMax] range
   //
@@ -43,8 +42,8 @@ namespace {
   // bit    12: side to move (WHITE or BLACK)
   // bit 13-14: white pawn file (from FILE_A to FILE_D)
   // bit 15-17: white pawn RANK_7 - rank (from RANK_7 - RANK_7 to RANK_7 - RANK_2)
-  unsigned index(Color us, Square bksq, Square wksq, Square psq) {
+  unsigned index(Color stm, Square bksq, Square wksq, Square psq) {
-    return int(wksq) | (bksq << 6) | (us << 12) | (file_of(psq) << 13) | ((RANK_7 - rank_of(psq)) << 15);
+    return int(wksq) | (bksq << 6) | (stm << 12) | (file_of(psq) << 13) | ((RANK_7 - rank_of(psq)) << 15);
   }
 
   enum Result {
@@ -60,25 +59,20 @@ namespace {
     KPKPosition() = default;
     explicit KPKPosition(unsigned idx);
     operator Result() const { return result; }
-    Result classify(const std::vector<KPKPosition>& db)
+    Result classify(const std::vector<KPKPosition>& db);
-    { return us == WHITE ? classify<WHITE>(db) : classify<BLACK>(db); }
 
-    template<Color Us> Result classify(const std::vector<KPKPosition>& db);
+    Color stm;
-
-    Color us;
     Square ksq[COLOR_NB], psq;
     Result result;
   };
 
 } // namespace
 
-
+bool Bitbases::probe(Square wksq, Square wpsq, Square bksq, Color stm) {
-bool Bitbases::probe(Square wksq, Square wpsq, Square bksq, Color us) {
 
   assert(file_of(wpsq) <= FILE_D);
 
-  unsigned idx = index(us, bksq, wksq, wpsq);
+  return KPKBitbase[index(stm, bksq, wksq, wpsq)];
-  return KPKBitbase[idx / 32] & (1 << (idx & 0x1F));
 }
 
 
@@ -97,41 +91,40 @@ void Bitbases::init() {
       for (repeat = idx = 0; idx < MAX_INDEX; ++idx)
           repeat |= (db[idx] == UNKNOWN && db[idx].classify(db) != UNKNOWN);
 
-  // Map 32 results into one KPKBitbase[] entry
+  // Fill the bitbase with the decisive results
   for (idx = 0; idx < MAX_INDEX; ++idx)
       if (db[idx] == WIN)
-          KPKBitbase[idx / 32] |= 1 << (idx & 0x1F);
+          KPKBitbase.set(idx);
 }
 
-
 namespace {
 
   KPKPosition::KPKPosition(unsigned idx) {
 
     ksq[WHITE] = Square((idx >>  0) & 0x3F);
     ksq[BLACK] = Square((idx >>  6) & 0x3F);
-    us         = Color ((idx >> 12) & 0x01);
+    stm        = Color ((idx >> 12) & 0x01);
     psq        = make_square(File((idx >> 13) & 0x3), Rank(RANK_7 - ((idx >> 15) & 0x7)));
 
-    // Check if two pieces are on the same square or if a king can be captured
+    // Invalid if two pieces are on the same square or if a king can be captured
     if (   distance(ksq[WHITE], ksq[BLACK]) <= 1
         || ksq[WHITE] == psq
         || ksq[BLACK] == psq
-        || (us == WHITE && (PawnAttacks[WHITE][psq] & ksq[BLACK])))
+        || (stm == WHITE && (pawn_attacks_bb(WHITE, psq) & ksq[BLACK])))
         result = INVALID;
 
-    // Immediate win if a pawn can be promoted without getting captured
+    // Win if the pawn can be promoted without getting captured
-    else if (   us == WHITE
+    else if (   stm == WHITE
              && rank_of(psq) == RANK_7
-             && ksq[us] != psq + NORTH
+             && ksq[WHITE] != psq + NORTH
-             && (    distance(ksq[~us], psq + NORTH) > 1
+             && (    distance(ksq[BLACK], psq + NORTH) > 1
-                 || (PseudoAttacks[KING][ksq[us]] & (psq + NORTH))))
+                 || (distance(ksq[WHITE], psq + NORTH) == 1)))
         result = WIN;
 
-    // Immediate draw if it is a stalemate or a king captures undefended pawn
+    // Draw if it is stalemate or the black king can capture the pawn
-    else if (   us == BLACK
+    else if (   stm == BLACK
-             && (  !(PseudoAttacks[KING][ksq[us]] & ~(PseudoAttacks[KING][ksq[~us]] | PawnAttacks[~us][psq]))
+             && (  !(attacks_bb<KING>(ksq[BLACK]) & ~(attacks_bb<KING>(ksq[WHITE]) | pawn_attacks_bb(WHITE, psq)))
-                 || (PseudoAttacks[KING][ksq[us]] & psq & ~PseudoAttacks[KING][ksq[~us]])))
+                 || (attacks_bb<KING>(ksq[BLACK]) & ~attacks_bb<KING>(ksq[WHITE]) & psq)))
         result = DRAW;
 
     // Position will be classified later
@@ -139,7 +132,6 @@ namespace {
         result = UNKNOWN;
   }
 
-  template<Color Us>
   Result KPKPosition::classify(const std::vector<KPKPosition>& db) {
 
     // White to move: If one move leads to a position classified as WIN, the result
@@ -151,30 +143,30 @@ namespace {
     // of the current position is DRAW. If all moves lead to positions classified
     // as WIN, the position is classified as WIN, otherwise the current position is
     // classified as UNKNOWN.
-
+    const Result Good = (stm == WHITE ? WIN   : DRAW);
-    constexpr Color  Them = (Us == WHITE ? BLACK : WHITE);
+    const Result Bad  = (stm == WHITE ? DRAW  : WIN);
-    constexpr Result Good = (Us == WHITE ? WIN   : DRAW);
-    constexpr Result Bad  = (Us == WHITE ? DRAW  : WIN);
 
     Result r = INVALID;
-    Bitboard b = PseudoAttacks[KING][ksq[Us]];
+    Bitboard b = attacks_bb<KING>(ksq[stm]);
 
     while (b)
-        r |= Us == WHITE ? db[index(Them, ksq[Them]  , pop_lsb(&b), psq)]
+        r |= stm == WHITE ? db[index(BLACK, ksq[BLACK], pop_lsb(b), psq)]
-                         : db[index(Them, pop_lsb(&b), ksq[Them]  , psq)];
+                          : db[index(WHITE, pop_lsb(b), ksq[WHITE], psq)];
 
-    if (Us == WHITE)
+    if (stm == WHITE)
     {
         if (rank_of(psq) < RANK_7)      // Single push
-            r |= db[index(Them, ksq[Them], ksq[Us], psq + NORTH)];
+            r |= db[index(BLACK, ksq[BLACK], ksq[WHITE], psq + NORTH)];
 
         if (   rank_of(psq) == RANK_2   // Double push
-            && psq + NORTH != ksq[Us]
+            && psq + NORTH != ksq[WHITE]
-            && psq + NORTH != ksq[Them])
+            && psq + NORTH != ksq[BLACK])
-            r |= db[index(Them, ksq[Them], ksq[Us], psq + NORTH + NORTH)];
+            r |= db[index(BLACK, ksq[BLACK], ksq[WHITE], psq + NORTH + NORTH)];
     }
 
     return result = r & Good  ? Good  : r & UNKNOWN ? UNKNOWN : Bad;
   }
 
 } // namespace
+
+} // namespace Stockfish

src/bitboard.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -24,11 +22,14 @@
 #include "bitboard.h"
 #include "misc.h"
 
+namespace Stockfish {
+
 uint8_t PopCnt16[1 << 16];
 uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
 
 Bitboard SquareBB[SQUARE_NB];
 Bitboard LineBB[SQUARE_NB][SQUARE_NB];
+Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
 Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
 Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
 
@@ -40,14 +41,23 @@ namespace {
   Bitboard RookTable[0x19000];  // To store rook attacks
   Bitboard BishopTable[0x1480]; // To store bishop attacks
 
-  void init_magics(Bitboard table[], Magic magics[], Direction directions[]);
+  void init_magics(PieceType pt, Bitboard table[], Magic magics[]);
+
+}
+
+/// safe_destination() returns the bitboard of target square for the given step
+/// from the given square. If the step is off the board, returns empty bitboard.
+
+inline Bitboard safe_destination(Square s, int step) {
+    Square to = Square(s + step);
+    return is_ok(to) && distance(s, to) <= 2 ? square_bb(to) : Bitboard(0);
 }
 
 
 /// Bitboards::pretty() returns an ASCII representation of a bitboard suitable
 /// to be printed to standard output. Useful for debugging.
 
-const std::string Bitboards::pretty(Bitboard b) {
+std::string Bitboards::pretty(Bitboard b) {
 
   std::string s = "+---+---+---+---+---+---+---+---+\n";
 
@@ -56,8 +66,9 @@ const std::string Bitboards::pretty(Bitboard b) {
       for (File f = FILE_A; f <= FILE_H; ++f)
           s += b & make_square(f, r) ? "| X " : "|   ";
 
-      s += "|\n+---+---+---+---+---+---+---+---+\n";
+      s += "| " + std::to_string(1 + r) + "\n+---+---+---+---+---+---+---+---+\n";
   }
+  s += "  a   b   c   d   e   f   g   h\n";
 
   return s;
 }
@@ -69,7 +80,7 @@ const std::string Bitboards::pretty(Bitboard b) {
 void Bitboards::init() {
 
   for (unsigned i = 0; i < (1 << 16); ++i)
-      PopCnt16[i] = std::bitset<16>(i).count();
+      PopCnt16[i] = uint8_t(std::bitset<16>(i).count());
 
   for (Square s = SQ_A1; s <= SQ_H8; ++s)
       SquareBB[s] = (1ULL << s);
@@ -78,65 +89,52 @@ void Bitboards::init() {
       for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
           SquareDistance[s1][s2] = std::max(distance<File>(s1, s2), distance<Rank>(s1, s2));
 
-  for (Square s = SQ_A1; s <= SQ_H8; ++s)
+  init_magics(ROOK, RookTable, RookMagics);
-  {
+  init_magics(BISHOP, BishopTable, BishopMagics);
-      PawnAttacks[WHITE][s] = pawn_attacks_bb<WHITE>(square_bb(s));
-      PawnAttacks[BLACK][s] = pawn_attacks_bb<BLACK>(square_bb(s));
-  }
-
-  // Helper returning the target bitboard of a step from a square
-  auto landing_square_bb = [&](Square s, int step)
-  {
-      Square to = Square(s + step);
-      return is_ok(to) && distance(s, to) <= 2 ? square_bb(to) : Bitboard(0);
-  };
-
-  for (Square s = SQ_A1; s <= SQ_H8; ++s)
-  {
-      for (int step : {-9, -8, -7, -1, 1, 7, 8, 9} )
-         PseudoAttacks[KING][s] |= landing_square_bb(s, step);
-
-      for (int step : {-17, -15, -10, -6, 6, 10, 15, 17} )
-         PseudoAttacks[KNIGHT][s] |= landing_square_bb(s, step);
-  }
-
-  Direction RookDirections[] = { NORTH, EAST, SOUTH, WEST };
-  Direction BishopDirections[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST };
-
-  init_magics(RookTable, RookMagics, RookDirections);
-  init_magics(BishopTable, BishopMagics, BishopDirections);
 
   for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
   {
+      PawnAttacks[WHITE][s1] = pawn_attacks_bb<WHITE>(square_bb(s1));
+      PawnAttacks[BLACK][s1] = pawn_attacks_bb<BLACK>(square_bb(s1));
+
+      for (int step : {-9, -8, -7, -1, 1, 7, 8, 9} )
+         PseudoAttacks[KING][s1] |= safe_destination(s1, step);
+
+      for (int step : {-17, -15, -10, -6, 6, 10, 15, 17} )
+         PseudoAttacks[KNIGHT][s1] |= safe_destination(s1, step);
+
       PseudoAttacks[QUEEN][s1]  = PseudoAttacks[BISHOP][s1] = attacks_bb<BISHOP>(s1, 0);
       PseudoAttacks[QUEEN][s1] |= PseudoAttacks[  ROOK][s1] = attacks_bb<  ROOK>(s1, 0);
 
       for (PieceType pt : { BISHOP, ROOK })
           for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
+          {
               if (PseudoAttacks[pt][s1] & s2)
-                  LineBB[s1][s2] = (attacks_bb(pt, s1, 0) & attacks_bb(pt, s2, 0)) | s1 | s2;
+              {
+                  LineBB[s1][s2]    = (attacks_bb(pt, s1, 0) & attacks_bb(pt, s2, 0)) | s1 | s2;
+                  BetweenBB[s1][s2] = (attacks_bb(pt, s1, square_bb(s2)) & attacks_bb(pt, s2, square_bb(s1)));
+              }
+              BetweenBB[s1][s2] |= s2;
+          }
   }
 }
 
-
 namespace {
 
-  Bitboard sliding_attack(Direction directions[], Square sq, Bitboard occupied) {
+  Bitboard sliding_attack(PieceType pt, Square sq, Bitboard occupied) {
 
-    Bitboard attack = 0;
+    Bitboard attacks = 0;
+    Direction   RookDirections[4] = {NORTH, SOUTH, EAST, WEST};
+    Direction BishopDirections[4] = {NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST};
 
-    for (int i = 0; i < 4; ++i)
+    for (Direction d : (pt == ROOK ? RookDirections : BishopDirections))
-        for (Square s = sq + directions[i];
+    {
-             is_ok(s) && distance(s, s - directions[i]) == 1;
+        Square s = sq;
-             s += directions[i])
+        while (safe_destination(s, d) && !(occupied & s))
-        {
+            attacks |= (s += d);
-            attack |= s;
+    }
 
-            if (occupied & s)
+    return attacks;
-                break;
-        }
-
-    return attack;
   }
 
 
@@ -145,7 +143,7 @@ namespace {
   // www.chessprogramming.org/Magic_Bitboards. In particular, here we use the so
   // called "fancy" approach.
 
-  void init_magics(Bitboard table[], Magic magics[], Direction directions[]) {
+  void init_magics(PieceType pt, Bitboard table[], Magic magics[]) {
 
     // Optimal PRNG seeds to pick the correct magics in the shortest time
     int seeds[][RANK_NB] = { { 8977, 44560, 54343, 38998,  5731, 95205, 104912, 17020 },
@@ -165,7 +163,7 @@ namespace {
         // the number of 1s of the mask. Hence we deduce the size of the shift to
         // apply to the 64 or 32 bits word to get the index.
         Magic& m = magics[s];
-        m.mask  = sliding_attack(directions, s, 0) & ~edges;
+        m.mask  = sliding_attack(pt, s, 0) & ~edges;
         m.shift = (Is64Bit ? 64 : 32) - popcount(m.mask);
 
         // Set the offset for the attacks table of the square. We have individual
@@ -177,7 +175,7 @@ namespace {
         b = size = 0;
         do {
             occupancy[size] = b;
-            reference[size] = sliding_attack(directions, s, b);
+            reference[size] = sliding_attack(pt, s, b);
 
             if (HasPext)
                 m.attacks[pext(b, m.mask)] = reference[size];
@@ -220,3 +218,5 @@ namespace {
     }
   }
 }
+
+} // namespace Stockfish

src/bitboard.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -25,19 +23,21 @@
 
 #include "types.h"
 
+namespace Stockfish {
+
 namespace Bitbases {
 
 void init();
 bool probe(Square wksq, Square wpsq, Square bksq, Color us);
 
-}
+} // namespace Stockfish::Bitbases
 
 namespace Bitboards {
 
 void init();
-const std::string pretty(Bitboard b);
+std::string pretty(Bitboard b);
 
-}
+} // namespace Stockfish::Bitboards
 
 constexpr Bitboard AllSquares = ~Bitboard(0);
 constexpr Bitboard DarkSquares = 0xAA55AA55AA55AA55ULL;
@@ -75,6 +75,7 @@ extern uint8_t PopCnt16[1 << 16];
 extern uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
 
 extern Bitboard SquareBB[SQUARE_NB];
+extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
 extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
 extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
 extern Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
@@ -106,10 +107,11 @@ extern Magic RookMagics[SQUARE_NB];
 extern Magic BishopMagics[SQUARE_NB];
 
 inline Bitboard square_bb(Square s) {
-  assert(s >= SQ_A1 && s <= SQ_H8);
+  assert(is_ok(s));
   return SquareBB[s];
 }
 
+
 /// Overloads of bitwise operators between a Bitboard and a Square for testing
 /// whether a given bit is set in a bitboard, and for setting and clearing bits.
 
@@ -123,38 +125,39 @@ inline Bitboard  operator&(Square s, Bitboard b) { return b & s; }
 inline Bitboard  operator|(Square s, Bitboard b) { return b | s; }
 inline Bitboard  operator^(Square s, Bitboard b) { return b ^ s; }
 
-inline Bitboard  operator|(Square s, Square s2) { return square_bb(s) | square_bb(s2); }
+inline Bitboard  operator|(Square s1, Square s2) { return square_bb(s1) | s2; }
 
 constexpr bool more_than_one(Bitboard b) {
   return b & (b - 1);
 }
 
-inline bool opposite_colors(Square s1, Square s2) {
+
-  return bool(DarkSquares & s1) != bool(DarkSquares & s2);
+constexpr bool opposite_colors(Square s1, Square s2) {
+  return (s1 + rank_of(s1) + s2 + rank_of(s2)) & 1;
 }
 
 
 /// rank_bb() and file_bb() return a bitboard representing all the squares on
 /// the given file or rank.
 
-inline Bitboard rank_bb(Rank r) {
+constexpr Bitboard rank_bb(Rank r) {
   return Rank1BB << (8 * r);
 }
 
-inline Bitboard rank_bb(Square s) {
+constexpr Bitboard rank_bb(Square s) {
   return rank_bb(rank_of(s));
 }
 
-inline Bitboard file_bb(File f) {
+constexpr Bitboard file_bb(File f) {
   return FileABB << f;
 }
 
-inline Bitboard file_bb(Square s) {
+constexpr Bitboard file_bb(Square s) {
   return file_bb(file_of(s));
 }
 
 
-/// shift() moves a bitboard one step along direction D
+/// shift() moves a bitboard one or two steps as specified by the direction D
 
 template<Direction D>
 constexpr Bitboard shift(Bitboard b) {
@@ -176,6 +179,12 @@ constexpr Bitboard pawn_attacks_bb(Bitboard b) {
                     : shift<SOUTH_WEST>(b) | shift<SOUTH_EAST>(b);
 }
 
+inline Bitboard pawn_attacks_bb(Color c, Square s) {
+
+  assert(is_ok(s));
+  return PawnAttacks[c][s];
+}
+
 
 /// pawn_double_attacks_bb() returns the squares doubly attacked by pawns of the
 /// given color from the squares in the given bitboard.
@@ -188,45 +197,65 @@ constexpr Bitboard pawn_double_attacks_bb(Bitboard b) {
 
 
 /// adjacent_files_bb() returns a bitboard representing all the squares on the
-/// adjacent files of the given one.
+/// adjacent files of a given square.
 
-inline Bitboard adjacent_files_bb(Square s) {
+constexpr Bitboard adjacent_files_bb(Square s) {
   return shift<EAST>(file_bb(s)) | shift<WEST>(file_bb(s));
 }
 
 
-/// between_bb() returns squares that are linearly between the given squares
+/// line_bb() returns a bitboard representing an entire line (from board edge
-/// If the given squares are not on a same file/rank/diagonal, return 0.
+/// to board edge) that intersects the two given squares. If the given squares
+/// are not on a same file/rank/diagonal, the function returns 0. For instance,
+/// line_bb(SQ_C4, SQ_F7) will return a bitboard with the A2-G8 diagonal.
 
-inline Bitboard between_bb(Square s1, Square s2) {
+inline Bitboard line_bb(Square s1, Square s2) {
-  return LineBB[s1][s2] & ( (AllSquares << (s1 +  (s1 < s2)))
+
-                           ^(AllSquares << (s2 + !(s1 < s2))));
+  assert(is_ok(s1) && is_ok(s2));
+
+  return LineBB[s1][s2];
 }
 
 
-/// forward_ranks_bb() returns a bitboard representing the squares on the ranks
+/// between_bb(s1, s2) returns a bitboard representing the squares in the semi-open
-/// in front of the given one, from the point of view of the given color. For instance,
+/// segment between the squares s1 and s2 (excluding s1 but including s2). If the
+/// given squares are not on a same file/rank/diagonal, it returns s2. For instance,
+/// between_bb(SQ_C4, SQ_F7) will return a bitboard with squares D5, E6 and F7, but
+/// between_bb(SQ_E6, SQ_F8) will return a bitboard with the square F8. This trick
+/// allows to generate non-king evasion moves faster: the defending piece must either
+/// interpose itself to cover the check or capture the checking piece.
+
+inline Bitboard between_bb(Square s1, Square s2) {
+
+  assert(is_ok(s1) && is_ok(s2));
+
+  return BetweenBB[s1][s2];
+}
+
+
+/// forward_ranks_bb() returns a bitboard representing the squares on the ranks in
+/// front of the given one, from the point of view of the given color. For instance,
 /// forward_ranks_bb(BLACK, SQ_D3) will return the 16 squares on ranks 1 and 2.
 
-inline Bitboard forward_ranks_bb(Color c, Square s) {
+constexpr Bitboard forward_ranks_bb(Color c, Square s) {
-  return c == WHITE ? ~Rank1BB << 8 * (rank_of(s) - RANK_1)
+  return c == WHITE ? ~Rank1BB << 8 * relative_rank(WHITE, s)
-                    : ~Rank8BB >> 8 * (RANK_8 - rank_of(s));
+                    : ~Rank8BB >> 8 * relative_rank(BLACK, s);
 }
 
 
 /// forward_file_bb() returns a bitboard representing all the squares along the
 /// line in front of the given one, from the point of view of the given color.
 
-inline Bitboard forward_file_bb(Color c, Square s) {
+constexpr Bitboard forward_file_bb(Color c, Square s) {
   return forward_ranks_bb(c, s) & file_bb(s);
 }
 
 
 /// pawn_attack_span() returns a bitboard representing all the squares that can
-/// be attacked by a pawn of the given color when it moves along its file,
+/// be attacked by a pawn of the given color when it moves along its file, starting
-/// starting from the given square.
+/// from the given square.
 
-inline Bitboard pawn_attack_span(Color c, Square s) {
+constexpr Bitboard pawn_attack_span(Color c, Square s) {
   return forward_ranks_bb(c, s) & adjacent_files_bb(s);
 }
 
@@ -234,8 +263,8 @@ inline Bitboard pawn_attack_span(Color c, Square s) {
 /// passed_pawn_span() returns a bitboard which can be used to test if a pawn of
 /// the given color and on the given square is a passed pawn.
 
-inline Bitboard passed_pawn_span(Color c, Square s) {
+constexpr Bitboard passed_pawn_span(Color c, Square s) {
-  return forward_ranks_bb(c, s) & (adjacent_files_bb(s) | file_bb(s));
+  return pawn_attack_span(c, s) | forward_file_bb(c, s);
 }
 
 
@@ -243,7 +272,7 @@ inline Bitboard passed_pawn_span(Color c, Square s) {
 /// straight or on a diagonal line.
 
 inline bool aligned(Square s1, Square s2, Square s3) {
-  return LineBB[s1][s2] & s3;
+  return line_bb(s1, s2) & s3;
 }
 
 
@@ -255,23 +284,43 @@ template<> inline int distance<File>(Square x, Square y) { return std::abs(file_
 template<> inline int distance<Rank>(Square x, Square y) { return std::abs(rank_of(x) - rank_of(y)); }
 template<> inline int distance<Square>(Square x, Square y) { return SquareDistance[x][y]; }
 
-template<class T> constexpr const T& clamp(const T& v, const T& lo, const T&  hi) {
+inline int edge_distance(File f) { return std::min(f, File(FILE_H - f)); }
-  return v < lo ? lo : v > hi ? hi : v;
+inline int edge_distance(Rank r) { return std::min(r, Rank(RANK_8 - r)); }
+
+
+/// attacks_bb(Square) returns the pseudo attacks of the give piece type
+/// assuming an empty board.
+
+template<PieceType Pt>
+inline Bitboard attacks_bb(Square s) {
+
+  assert((Pt != PAWN) && (is_ok(s)));
+
+  return PseudoAttacks[Pt][s];
 }
 
-/// attacks_bb() returns a bitboard representing all the squares attacked by a
+
-/// piece of type Pt (bishop or rook) placed on 's'.
+/// attacks_bb(Square, Bitboard) returns the attacks by the given piece
+/// assuming the board is occupied according to the passed Bitboard.
+/// Sliding piece attacks do not continue passed an occupied square.
 
 template<PieceType Pt>
 inline Bitboard attacks_bb(Square s, Bitboard occupied) {
 
-  const Magic& m = Pt == ROOK ? RookMagics[s] : BishopMagics[s];
+  assert((Pt != PAWN) && (is_ok(s)));
-  return m.attacks[m.index(occupied)];
+
+  switch (Pt)
+  {
+  case BISHOP: return BishopMagics[s].attacks[BishopMagics[s].index(occupied)];
+  case ROOK  : return   RookMagics[s].attacks[  RookMagics[s].index(occupied)];
+  case QUEEN : return attacks_bb<BISHOP>(s, occupied) | attacks_bb<ROOK>(s, occupied);
+  default    : return PseudoAttacks[Pt][s];
+  }
 }
 
 inline Bitboard attacks_bb(PieceType pt, Square s, Bitboard occupied) {
 
-  assert(pt != PAWN);
+  assert((pt != PAWN) && (is_ok(s)));
 
   switch (pt)
   {
@@ -372,19 +421,31 @@ inline Square msb(Bitboard b) {
 
 #endif
 
+/// least_significant_square_bb() returns the bitboard of the least significant
+/// square of a non-zero bitboard. It is equivalent to square_bb(lsb(bb)).
+
+inline Bitboard least_significant_square_bb(Bitboard b) {
+  assert(b);
+  return b & -b;
+}
 
 /// pop_lsb() finds and clears the least significant bit in a non-zero bitboard
 
-inline Square pop_lsb(Bitboard* b) {
+inline Square pop_lsb(Bitboard& b) {
-  const Square s = lsb(*b);
+  assert(b);
-  *b &= *b - 1;
+  const Square s = lsb(b);
+  b &= b - 1;
   return s;
 }
 
 
-/// frontmost_sq() returns the most advanced square for the given color
+/// frontmost_sq() returns the most advanced square for the given color,
+/// requires a non-zero bitboard.
 inline Square frontmost_sq(Color c, Bitboard b) {
+  assert(b);
   return c == WHITE ? msb(b) : lsb(b);
 }
 
+} // namespace Stockfish
+
 #endif // #ifndef BITBOARD_H_INCLUDED

src/endgame.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -24,42 +22,27 @@
 #include "endgame.h"
 #include "movegen.h"
 
-using std::string;
+namespace Stockfish {
 
 namespace {
 
-  // Table used to drive the king towards the edge of the board
+  // Used to drive the king towards the edge of the board
   // in KX vs K and KQ vs KR endgames.
-  constexpr int PushToEdges[SQUARE_NB] = {
+  // Values range from 27 (center squares) to 90 (in the corners)
-    100, 90, 80, 70, 70, 80, 90, 100,
+  inline int push_to_edge(Square s) {
-     90, 70, 60, 50, 50, 60, 70,  90,
+      int rd = edge_distance(rank_of(s)), fd = edge_distance(file_of(s));
-     80, 60, 40, 30, 30, 40, 60,  80,
+      return 90 - (7 * fd * fd / 2 + 7 * rd * rd / 2);
-     70, 50, 30, 20, 20, 30, 50,  70,
+  }
-     70, 50, 30, 20, 20, 30, 50,  70,
-     80, 60, 40, 30, 30, 40, 60,  80,
-     90, 70, 60, 50, 50, 60, 70,  90,
-    100, 90, 80, 70, 70, 80, 90, 100
-  };
 
-  // Table used to drive the king towards a corner square of the
+  // Used to drive the king towards A1H8 corners in KBN vs K endgames.
-  // right color in KBN vs K endgames.
+  // Values range from 0 on A8H1 diagonal to 7 in A1H8 corners
-  constexpr int PushToCorners[SQUARE_NB] = {
+  inline int push_to_corner(Square s) {
-     6400, 6080, 5760, 5440, 5120, 4800, 4480, 4160,
+      return abs(7 - rank_of(s) - file_of(s));
-     6080, 5760, 5440, 5120, 4800, 4480, 4160, 4480,
+  }
-     5760, 5440, 4960, 4480, 4480, 4000, 4480, 4800,
-     5440, 5120, 4480, 3840, 3520, 4480, 4800, 5120,
-     5120, 4800, 4480, 3520, 3840, 4480, 5120, 5440,
-     4800, 4480, 4000, 4480, 4480, 4960, 5440, 5760,
-     4480, 4160, 4480, 4800, 5120, 5440, 5760, 6080,
-     4160, 4480, 4800, 5120, 5440, 5760, 6080, 6400
-  };
 
-  // Tables used to drive a piece towards or away from another piece
+  // Drive a piece close to or away from another piece
-  constexpr int PushClose[8] = { 0, 0, 100, 80, 60, 40, 20, 10 };
+  inline int push_close(Square s1, Square s2) { return 140 - 20 * distance(s1, s2); }
-  constexpr int PushAway [8] = { 0, 5, 20, 40, 60, 80, 90, 100 };
+  inline int push_away(Square s1, Square s2) { return 120 - push_close(s1, s2); }
-
-  // Pawn Rank based scaling factors used in KRPPKRP endgame
-  constexpr int KRPPKRPScaleFactors[RANK_NB] = { 0, 9, 10, 14, 21, 44, 0, 0 };
 
 #ifndef NDEBUG
   bool verify_material(const Position& pos, Color c, Value npm, int pawnsCnt) {
@@ -74,9 +57,9 @@ namespace {
     assert(pos.count<PAWN>(strongSide) == 1);
 
     if (file_of(pos.square<PAWN>(strongSide)) >= FILE_E)
-        sq = Square(int(sq) ^ 7); // Mirror SQ_H1 -> SQ_A1
+        sq = flip_file(sq);
 
-    return strongSide == WHITE ? sq : ~sq;
+    return strongSide == WHITE ? sq : flip_rank(sq);
   }
 
 } // namespace
@@ -98,8 +81,6 @@ namespace Endgames {
     add<KQKR>("KQKR");
     add<KNNKP>("KNNKP");
 
-    add<KNPK>("KNPK");
-    add<KNPKB>("KNPKB");
     add<KRPKR>("KRPKR");
     add<KRPKB>("KRPKB");
     add<KBPKB>("KBPKB");
@@ -124,20 +105,20 @@ Value Endgame<KXK>::operator()(const Position& pos) const {
   if (pos.side_to_move() == weakSide && !MoveList<LEGAL>(pos).size())
       return VALUE_DRAW;
 
-  Square winnerKSq = pos.square<KING>(strongSide);
+  Square strongKing = pos.square<KING>(strongSide);
-  Square loserKSq = pos.square<KING>(weakSide);
+  Square weakKing   = pos.square<KING>(weakSide);
 
   Value result =  pos.non_pawn_material(strongSide)
                 + pos.count<PAWN>(strongSide) * PawnValueEg
-                + PushToEdges[loserKSq]
+                + push_to_edge(weakKing)
-                + PushClose[distance(winnerKSq, loserKSq)];
+                + push_close(strongKing, weakKing);
 
   if (   pos.count<QUEEN>(strongSide)
       || pos.count<ROOK>(strongSide)
       ||(pos.count<BISHOP>(strongSide) && pos.count<KNIGHT>(strongSide))
       || (   (pos.pieces(strongSide, BISHOP) & ~DarkSquares)
           && (pos.pieces(strongSide, BISHOP) &  DarkSquares)))
-      result = std::min(result + VALUE_KNOWN_WIN, VALUE_MATE_IN_MAX_PLY - 1);
+      result = std::min(result + VALUE_KNOWN_WIN, VALUE_TB_WIN_IN_MAX_PLY - 1);
 
   return strongSide == pos.side_to_move() ? result : -result;
 }
@@ -151,18 +132,18 @@ Value Endgame<KBNK>::operator()(const Position& pos) const {
   assert(verify_material(pos, strongSide, KnightValueMg + BishopValueMg, 0));
   assert(verify_material(pos, weakSide, VALUE_ZERO, 0));
 
-  Square winnerKSq = pos.square<KING>(strongSide);
+  Square strongKing   = pos.square<KING>(strongSide);
-  Square loserKSq = pos.square<KING>(weakSide);
+  Square strongBishop = pos.square<BISHOP>(strongSide);
-  Square bishopSq = pos.square<BISHOP>(strongSide);
+  Square weakKing     = pos.square<KING>(weakSide);
 
   // If our bishop does not attack A1/H8, we flip the enemy king square
   // to drive to opposite corners (A8/H1).
 
-  Value result =  VALUE_KNOWN_WIN
+  Value result =  (VALUE_KNOWN_WIN + 3520)
-                + PushClose[distance(winnerKSq, loserKSq)]
+                + push_close(strongKing, weakKing)
-                + PushToCorners[opposite_colors(bishopSq, SQ_A1) ? ~loserKSq : loserKSq];
+                + 420 * push_to_corner(opposite_colors(strongBishop, SQ_A1) ? flip_file(weakKing) : weakKing);
 
-  assert(abs(result) < VALUE_MATE_IN_MAX_PLY);
+  assert(abs(result) < VALUE_TB_WIN_IN_MAX_PLY);
   return strongSide == pos.side_to_move() ? result : -result;
 }
 
@@ -175,16 +156,16 @@ Value Endgame<KPK>::operator()(const Position& pos) const {
   assert(verify_material(pos, weakSide, VALUE_ZERO, 0));
 
   // Assume strongSide is white and the pawn is on files A-D
-  Square wksq = normalize(pos, strongSide, pos.square<KING>(strongSide));
+  Square strongKing = normalize(pos, strongSide, pos.square<KING>(strongSide));
-  Square bksq = normalize(pos, strongSide, pos.square<KING>(weakSide));
+  Square strongPawn = normalize(pos, strongSide, pos.square<PAWN>(strongSide));
-  Square psq  = normalize(pos, strongSide, pos.square<PAWN>(strongSide));
+  Square weakKing   = normalize(pos, strongSide, pos.square<KING>(weakSide));
 
   Color us = strongSide == pos.side_to_move() ? WHITE : BLACK;
 
-  if (!Bitbases::probe(wksq, psq, bksq, us))
+  if (!Bitbases::probe(strongKing, strongPawn, weakKing, us))
       return VALUE_DRAW;
 
-  Value result = VALUE_KNOWN_WIN + PawnValueEg + Value(rank_of(psq));
+  Value result = VALUE_KNOWN_WIN + PawnValueEg + Value(rank_of(strongPawn));
 
   return strongSide == pos.side_to_move() ? result : -result;
 }
@@ -200,36 +181,35 @@ Value Endgame<KRKP>::operator()(const Position& pos) const {
   assert(verify_material(pos, strongSide, RookValueMg, 0));
   assert(verify_material(pos, weakSide, VALUE_ZERO, 1));
 
-  Square wksq = relative_square(strongSide, pos.square<KING>(strongSide));
+  Square strongKing = pos.square<KING>(strongSide);
-  Square bksq = relative_square(strongSide, pos.square<KING>(weakSide));
+  Square weakKing   = pos.square<KING>(weakSide);
-  Square rsq  = relative_square(strongSide, pos.square<ROOK>(strongSide));
+  Square strongRook = pos.square<ROOK>(strongSide);
-  Square psq  = relative_square(strongSide, pos.square<PAWN>(weakSide));
+  Square weakPawn   = pos.square<PAWN>(weakSide);
-
+  Square queeningSquare = make_square(file_of(weakPawn), relative_rank(weakSide, RANK_8));
-  Square queeningSq = make_square(file_of(psq), RANK_1);
   Value result;
 
   // If the stronger side's king is in front of the pawn, it's a win
-  if (forward_file_bb(WHITE, wksq) & psq)
+  if (forward_file_bb(strongSide, strongKing) & weakPawn)
-      result = RookValueEg - distance(wksq, psq);
+      result = RookValueEg - distance(strongKing, weakPawn);
 
   // If the weaker side's king is too far from the pawn and the rook,
   // it's a win.
-  else if (   distance(bksq, psq) >= 3 + (pos.side_to_move() == weakSide)
+  else if (   distance(weakKing, weakPawn) >= 3 + (pos.side_to_move() == weakSide)
-           && distance(bksq, rsq) >= 3)
+           && distance(weakKing, strongRook) >= 3)
-      result = RookValueEg - distance(wksq, psq);
+      result = RookValueEg - distance(strongKing, weakPawn);
 
   // If the pawn is far advanced and supported by the defending king,
   // the position is drawish
-  else if (   rank_of(bksq) <= RANK_3
+  else if (   relative_rank(strongSide, weakKing) <= RANK_3
-           && distance(bksq, psq) == 1
+           && distance(weakKing, weakPawn) == 1
-           && rank_of(wksq) >= RANK_4
+           && relative_rank(strongSide, strongKing) >= RANK_4
-           && distance(wksq, psq) > 2 + (pos.side_to_move() == strongSide))
+           && distance(strongKing, weakPawn) > 2 + (pos.side_to_move() == strongSide))
-      result = Value(80) - 8 * distance(wksq, psq);
+      result = Value(80) - 8 * distance(strongKing, weakPawn);
 
   else
-      result =  Value(200) - 8 * (  distance(wksq, psq + SOUTH)
+      result =  Value(200) - 8 * (  distance(strongKing, weakPawn + pawn_push(weakSide))
-                                  - distance(bksq, psq + SOUTH)
+                                  - distance(weakKing, weakPawn + pawn_push(weakSide))
-                                  - distance(psq, queeningSq));
+                                  - distance(weakPawn, queeningSquare));
 
   return strongSide == pos.side_to_move() ? result : -result;
 }
@@ -243,7 +223,7 @@ Value Endgame<KRKB>::operator()(const Position& pos) const {
   assert(verify_material(pos, strongSide, RookValueMg, 0));
   assert(verify_material(pos, weakSide, BishopValueMg, 0));
 
-  Value result = Value(PushToEdges[pos.square<KING>(weakSide)]);
+  Value result = Value(push_to_edge(pos.square<KING>(weakSide)));
   return strongSide == pos.side_to_move() ? result : -result;
 }
 
@@ -256,9 +236,9 @@ Value Endgame<KRKN>::operator()(const Position& pos) const {
   assert(verify_material(pos, strongSide, RookValueMg, 0));
   assert(verify_material(pos, weakSide, KnightValueMg, 0));
 
-  Square bksq = pos.square<KING>(weakSide);
+  Square weakKing   = pos.square<KING>(weakSide);
-  Square bnsq = pos.square<KNIGHT>(weakSide);
+  Square weakKnight = pos.square<KNIGHT>(weakSide);
-  Value result = Value(PushToEdges[bksq] + PushAway[distance(bksq, bnsq)]);
+  Value result = Value(push_to_edge(weakKing) + push_away(weakKing, weakKnight));
   return strongSide == pos.side_to_move() ? result : -result;
 }
 
@@ -273,22 +253,22 @@ Value Endgame<KQKP>::operator()(const Position& pos) const {
   assert(verify_material(pos, strongSide, QueenValueMg, 0));
   assert(verify_material(pos, weakSide, VALUE_ZERO, 1));
 
-  Square winnerKSq = pos.square<KING>(strongSide);
+  Square strongKing = pos.square<KING>(strongSide);
-  Square loserKSq = pos.square<KING>(weakSide);
+  Square weakKing   = pos.square<KING>(weakSide);
-  Square pawnSq = pos.square<PAWN>(weakSide);
+  Square weakPawn   = pos.square<PAWN>(weakSide);
 
-  Value result = Value(PushClose[distance(winnerKSq, loserKSq)]);
+  Value result = Value(push_close(strongKing, weakKing));
 
-  if (   relative_rank(weakSide, pawnSq) != RANK_7
+  if (   relative_rank(weakSide, weakPawn) != RANK_7
-      || distance(loserKSq, pawnSq) != 1
+      || distance(weakKing, weakPawn) != 1
-      || !((FileABB | FileCBB | FileFBB | FileHBB) & pawnSq))
+      || ((FileBBB | FileDBB | FileEBB | FileGBB) & weakPawn))
       result += QueenValueEg - PawnValueEg;
 
   return strongSide == pos.side_to_move() ? result : -result;
 }
 
 
-/// KQ vs KR.  This is almost identical to KX vs K:  We give the attacking
+/// KQ vs KR. This is almost identical to KX vs K: we give the attacking
 /// king a bonus for having the kings close together, and for forcing the
 /// defending king towards the edge. If we also take care to avoid null move for
 /// the defending side in the search, this is usually sufficient to win KQ vs KR.
@@ -298,28 +278,32 @@ Value Endgame<KQKR>::operator()(const Position& pos) const {
   assert(verify_material(pos, strongSide, QueenValueMg, 0));
   assert(verify_material(pos, weakSide, RookValueMg, 0));
 
-  Square winnerKSq = pos.square<KING>(strongSide);
+  Square strongKing = pos.square<KING>(strongSide);
-  Square loserKSq = pos.square<KING>(weakSide);
+  Square weakKing   = pos.square<KING>(weakSide);
 
   Value result =  QueenValueEg
                 - RookValueEg
-                + PushToEdges[loserKSq]
+                + push_to_edge(weakKing)
-                + PushClose[distance(winnerKSq, loserKSq)];
+                + push_close(strongKing, weakKing);
 
   return strongSide == pos.side_to_move() ? result : -result;
 }
 
 
-/// KNN vs KP. Simply push the opposing king to the corner
+/// KNN vs KP. Very drawish, but there are some mate opportunities if we can
+/// press the weakSide King to a corner before the pawn advances too much.
 template<>
 Value Endgame<KNNKP>::operator()(const Position& pos) const {
 
   assert(verify_material(pos, strongSide, 2 * KnightValueMg, 0));
   assert(verify_material(pos, weakSide, VALUE_ZERO, 1));
 
-  Value result =  2 * KnightValueEg
+  Square weakKing = pos.square<KING>(weakSide);
-                - PawnValueEg
+  Square weakPawn = pos.square<PAWN>(weakSide);
-                + PushToEdges[pos.square<KING>(weakSide)];
+
+  Value result =      PawnValueEg
+               +  2 * push_to_edge(weakKing)
+               - 10 * relative_rank(weakSide, weakPawn);
 
   return strongSide == pos.side_to_move() ? result : -result;
 }
@@ -342,51 +326,47 @@ ScaleFactor Endgame<KBPsK>::operator()(const Position& pos) const {
   // No assertions about the material of weakSide, because we want draws to
   // be detected even when the weaker side has some pawns.
 
-  Bitboard pawns = pos.pieces(strongSide, PAWN);
+  Bitboard strongPawns = pos.pieces(strongSide, PAWN);
-  File pawnsFile = file_of(lsb(pawns));
+  Bitboard allPawns = pos.pieces(PAWN);
 
-  // All pawns are on a single rook file?
+  Square strongBishop = pos.square<BISHOP>(strongSide);
-  if (    (pawnsFile == FILE_A || pawnsFile == FILE_H)
+  Square weakKing = pos.square<KING>(weakSide);
-      && !(pawns & ~file_bb(pawnsFile)))
+  Square strongKing = pos.square<KING>(strongSide);
+
+  // All strongSide pawns are on a single rook file?
+  if (!(strongPawns & ~FileABB) || !(strongPawns & ~FileHBB))
   {
-      Square bishopSq = pos.square<BISHOP>(strongSide);
+      Square queeningSquare = relative_square(strongSide, make_square(file_of(lsb(strongPawns)), RANK_8));
-      Square queeningSq = relative_square(strongSide, make_square(pawnsFile, RANK_8));
-      Square kingSq = pos.square<KING>(weakSide);
 
-      if (   opposite_colors(queeningSq, bishopSq)
+      if (   opposite_colors(queeningSquare, strongBishop)
-          && distance(queeningSq, kingSq) <= 1)
+          && distance(queeningSquare, weakKing) <= 1)
           return SCALE_FACTOR_DRAW;
   }
 
   // If all the pawns are on the same B or G file, then it's potentially a draw
-  if (    (pawnsFile == FILE_B || pawnsFile == FILE_G)
+  if ((!(allPawns & ~FileBBB) || !(allPawns & ~FileGBB))
-      && !(pos.pieces(PAWN) & ~file_bb(pawnsFile))
       && pos.non_pawn_material(weakSide) == 0
       && pos.count<PAWN>(weakSide) >= 1)
   {
-      // Get weakSide pawn that is closest to the home rank
+      // Get the least advanced weakSide pawn
-      Square weakPawnSq = frontmost_sq(strongSide, pos.pieces(weakSide, PAWN));
+      Square weakPawn = frontmost_sq(strongSide, pos.pieces(weakSide, PAWN));
-
-      Square strongKingSq = pos.square<KING>(strongSide);
-      Square weakKingSq = pos.square<KING>(weakSide);
-      Square bishopSq = pos.square<BISHOP>(strongSide);
 
       // There's potential for a draw if our pawn is blocked on the 7th rank,
-      // the bishop cannot attack it or they only have one pawn left
+      // the bishop cannot attack it or they only have one pawn left.
-      if (   relative_rank(strongSide, weakPawnSq) == RANK_7
+      if (   relative_rank(strongSide, weakPawn) == RANK_7
-          && (pos.pieces(strongSide, PAWN) & (weakPawnSq + pawn_push(weakSide)))
+          && (strongPawns & (weakPawn + pawn_push(weakSide)))
-          && (opposite_colors(bishopSq, weakPawnSq) || pos.count<PAWN>(strongSide) == 1))
+          && (opposite_colors(strongBishop, weakPawn) || !more_than_one(strongPawns)))
       {
-          int strongKingDist = distance(weakPawnSq, strongKingSq);
+          int strongKingDist = distance(weakPawn, strongKing);
-          int weakKingDist = distance(weakPawnSq, weakKingSq);
+          int weakKingDist = distance(weakPawn, weakKing);
 
           // It's a draw if the weak king is on its back two ranks, within 2
           // squares of the blocking pawn and the strong king is not
           // closer. (I think this rule only fails in practically
           // unreachable positions such as 5k1K/6p1/6P1/8/8/3B4/8/8 w
           // and positions where qsearch will immediately correct the
-          // problem such as 8/4k1p1/6P1/1K6/3B4/8/8/8 w)
+          // problem such as 8/4k1p1/6P1/1K6/3B4/8/8/8 w).
-          if (   relative_rank(strongSide, weakKingSq) >= RANK_7
+          if (   relative_rank(strongSide, weakKing) >= RANK_7
               && weakKingDist <= 2
               && weakKingDist <= strongKingDist)
               return SCALE_FACTOR_DRAW;
@@ -406,15 +386,16 @@ ScaleFactor Endgame<KQKRPs>::operator()(const Position& pos) const {
   assert(pos.count<ROOK>(weakSide) == 1);
   assert(pos.count<PAWN>(weakSide) >= 1);
 
-  Square kingSq = pos.square<KING>(weakSide);
+  Square strongKing = pos.square<KING>(strongSide);
-  Square rsq = pos.square<ROOK>(weakSide);
+  Square weakKing   = pos.square<KING>(weakSide);
+  Square weakRook   = pos.square<ROOK>(weakSide);
 
-  if (    relative_rank(weakSide, kingSq) <= RANK_2
+  if (    relative_rank(weakSide,   weakKing) <= RANK_2
-      &&  relative_rank(weakSide, pos.square<KING>(strongSide)) >= RANK_4
+      &&  relative_rank(weakSide, strongKing) >= RANK_4
-      &&  relative_rank(weakSide, rsq) == RANK_3
+      &&  relative_rank(weakSide,   weakRook) == RANK_3
       && (  pos.pieces(weakSide, PAWN)
-          & pos.attacks_from<KING>(kingSq)
+          & attacks_bb<KING>(weakKing)
-          & pos.attacks_from<PAWN>(rsq, strongSide)))
+          & pawn_attacks_bb(strongSide, weakRook)))
           return SCALE_FACTOR_DRAW;
 
   return SCALE_FACTOR_NONE;
@@ -434,89 +415,89 @@ ScaleFactor Endgame<KRPKR>::operator()(const Position& pos) const {
   assert(verify_material(pos, weakSide,   RookValueMg, 0));
 
   // Assume strongSide is white and the pawn is on files A-D
-  Square wksq = normalize(pos, strongSide, pos.square<KING>(strongSide));
+  Square strongKing = normalize(pos, strongSide, pos.square<KING>(strongSide));
-  Square bksq = normalize(pos, strongSide, pos.square<KING>(weakSide));
+  Square strongRook = normalize(pos, strongSide, pos.square<ROOK>(strongSide));
-  Square wrsq = normalize(pos, strongSide, pos.square<ROOK>(strongSide));
+  Square strongPawn = normalize(pos, strongSide, pos.square<PAWN>(strongSide));
-  Square wpsq = normalize(pos, strongSide, pos.square<PAWN>(strongSide));
+  Square weakKing = normalize(pos, strongSide, pos.square<KING>(weakSide));
-  Square brsq = normalize(pos, strongSide, pos.square<ROOK>(weakSide));
+  Square weakRook = normalize(pos, strongSide, pos.square<ROOK>(weakSide));
 
-  File f = file_of(wpsq);
+  File pawnFile = file_of(strongPawn);
-  Rank r = rank_of(wpsq);
+  Rank pawnRank = rank_of(strongPawn);
-  Square queeningSq = make_square(f, RANK_8);
+  Square queeningSquare = make_square(pawnFile, RANK_8);
   int tempo = (pos.side_to_move() == strongSide);
 
   // If the pawn is not too far advanced and the defending king defends the
   // queening square, use the third-rank defence.
-  if (   r <= RANK_5
+  if (   pawnRank <= RANK_5
-      && distance(bksq, queeningSq) <= 1
+      && distance(weakKing, queeningSquare) <= 1
-      && wksq <= SQ_H5
+      && strongKing <= SQ_H5
-      && (rank_of(brsq) == RANK_6 || (r <= RANK_3 && rank_of(wrsq) != RANK_6)))
+      && (rank_of(weakRook) == RANK_6 || (pawnRank <= RANK_3 && rank_of(strongRook) != RANK_6)))
       return SCALE_FACTOR_DRAW;
 
   // The defending side saves a draw by checking from behind in case the pawn
   // has advanced to the 6th rank with the king behind.
-  if (   r == RANK_6
+  if (   pawnRank == RANK_6
-      && distance(bksq, queeningSq) <= 1
+      && distance(weakKing, queeningSquare) <= 1
-      && rank_of(wksq) + tempo <= RANK_6
+      && rank_of(strongKing) + tempo <= RANK_6
-      && (rank_of(brsq) == RANK_1 || (!tempo && distance<File>(brsq, wpsq) >= 3)))
+      && (rank_of(weakRook) == RANK_1 || (!tempo && distance<File>(weakRook, strongPawn) >= 3)))
       return SCALE_FACTOR_DRAW;
 
-  if (   r >= RANK_6
+  if (   pawnRank >= RANK_6
-      && bksq == queeningSq
+      && weakKing == queeningSquare
-      && rank_of(brsq) == RANK_1
+      && rank_of(weakRook) == RANK_1
-      && (!tempo || distance(wksq, wpsq) >= 2))
+      && (!tempo || distance(strongKing, strongPawn) >= 2))
       return SCALE_FACTOR_DRAW;
 
   // White pawn on a7 and rook on a8 is a draw if black's king is on g7 or h7
   // and the black rook is behind the pawn.
-  if (   wpsq == SQ_A7
+  if (   strongPawn == SQ_A7
-      && wrsq == SQ_A8
+      && strongRook == SQ_A8
-      && (bksq == SQ_H7 || bksq == SQ_G7)
+      && (weakKing == SQ_H7 || weakKing == SQ_G7)
-      && file_of(brsq) == FILE_A
+      && file_of(weakRook) == FILE_A
-      && (rank_of(brsq) <= RANK_3 || file_of(wksq) >= FILE_D || rank_of(wksq) <= RANK_5))
+      && (rank_of(weakRook) <= RANK_3 || file_of(strongKing) >= FILE_D || rank_of(strongKing) <= RANK_5))
       return SCALE_FACTOR_DRAW;
 
   // If the defending king blocks the pawn and the attacking king is too far
   // away, it's a draw.
-  if (   r <= RANK_5
+  if (   pawnRank <= RANK_5
-      && bksq == wpsq + NORTH
+      && weakKing == strongPawn + NORTH
-      && distance(wksq, wpsq) - tempo >= 2
+      && distance(strongKing, strongPawn) - tempo >= 2
-      && distance(wksq, brsq) - tempo >= 2)
+      && distance(strongKing, weakRook) - tempo >= 2)
       return SCALE_FACTOR_DRAW;
 
   // Pawn on the 7th rank supported by the rook from behind usually wins if the
   // attacking king is closer to the queening square than the defending king,
   // and the defending king cannot gain tempi by threatening the attacking rook.
-  if (   r == RANK_7
+  if (   pawnRank == RANK_7
-      && f != FILE_A
+      && pawnFile != FILE_A
-      && file_of(wrsq) == f
+      && file_of(strongRook) == pawnFile
-      && wrsq != queeningSq
+      && strongRook != queeningSquare
-      && (distance(wksq, queeningSq) < distance(bksq, queeningSq) - 2 + tempo)
+      && (distance(strongKing, queeningSquare) < distance(weakKing, queeningSquare) - 2 + tempo)
-      && (distance(wksq, queeningSq) < distance(bksq, wrsq) + tempo))
+      && (distance(strongKing, queeningSquare) < distance(weakKing, strongRook) + tempo))
-      return ScaleFactor(SCALE_FACTOR_MAX - 2 * distance(wksq, queeningSq));
+      return ScaleFactor(SCALE_FACTOR_MAX - 2 * distance(strongKing, queeningSquare));
 
   // Similar to the above, but with the pawn further back
-  if (   f != FILE_A
+  if (   pawnFile != FILE_A
-      && file_of(wrsq) == f
+      && file_of(strongRook) == pawnFile
-      && wrsq < wpsq
+      && strongRook < strongPawn
-      && (distance(wksq, queeningSq) < distance(bksq, queeningSq) - 2 + tempo)
+      && (distance(strongKing, queeningSquare) < distance(weakKing, queeningSquare) - 2 + tempo)
-      && (distance(wksq, wpsq + NORTH) < distance(bksq, wpsq + NORTH) - 2 + tempo)
+      && (distance(strongKing, strongPawn + NORTH) < distance(weakKing, strongPawn + NORTH) - 2 + tempo)
-      && (  distance(bksq, wrsq) + tempo >= 3
+      && (  distance(weakKing, strongRook) + tempo >= 3
-          || (    distance(wksq, queeningSq) < distance(bksq, wrsq) + tempo
+          || (    distance(strongKing, queeningSquare) < distance(weakKing, strongRook) + tempo
-              && (distance(wksq, wpsq + NORTH) < distance(bksq, wrsq) + tempo))))
+              && (distance(strongKing, strongPawn + NORTH) < distance(weakKing, strongPawn) + tempo))))
       return ScaleFactor(  SCALE_FACTOR_MAX
-                         - 8 * distance(wpsq, queeningSq)
+                         - 8 * distance(strongPawn, queeningSquare)
-                         - 2 * distance(wksq, queeningSq));
+                         - 2 * distance(strongKing, queeningSquare));
 
   // If the pawn is not far advanced and the defending king is somewhere in
   // the pawn's path, it's probably a draw.
-  if (r <= RANK_4 && bksq > wpsq)
+  if (pawnRank <= RANK_4 && weakKing > strongPawn)
   {
-      if (file_of(bksq) == file_of(wpsq))
+      if (file_of(weakKing) == file_of(strongPawn))
           return ScaleFactor(10);
-      if (   distance<File>(bksq, wpsq) == 1
+      if (   distance<File>(weakKing, strongPawn) == 1
-          && distance(wksq, bksq) > 2)
+          && distance(strongKing, weakKing) > 2)
-          return ScaleFactor(24 - 2 * distance(wksq, bksq));
+          return ScaleFactor(24 - 2 * distance(strongKing, weakKing));
   }
   return SCALE_FACTOR_NONE;
 }
@@ -530,10 +511,11 @@ ScaleFactor Endgame<KRPKB>::operator()(const Position& pos) const {
   // Test for a rook pawn
   if (pos.pieces(PAWN) & (FileABB | FileHBB))
   {
-      Square ksq = pos.square<KING>(weakSide);
+      Square weakKing = pos.square<KING>(weakSide);
-      Square bsq = pos.square<BISHOP>(weakSide);
+      Square weakBishop = pos.square<BISHOP>(weakSide);
-      Square psq = pos.square<PAWN>(strongSide);
+      Square strongKing = pos.square<KING>(strongSide);
-      Rank rk = relative_rank(strongSide, psq);
+      Square strongPawn = pos.square<PAWN>(strongSide);
+      Rank pawnRank = relative_rank(strongSide, strongPawn);
       Direction push = pawn_push(strongSide);
 
       // If the pawn is on the 5th rank and the pawn (currently) is on
@@ -541,11 +523,11 @@ ScaleFactor Endgame<KRPKB>::operator()(const Position& pos) const {
       // a fortress. Depending on the king position give a moderate
       // reduction or a stronger one if the defending king is near the
       // corner but not trapped there.
-      if (rk == RANK_5 && !opposite_colors(bsq, psq))
+      if (pawnRank == RANK_5 && !opposite_colors(weakBishop, strongPawn))
       {
-          int d = distance(psq + 3 * push, ksq);
+          int d = distance(strongPawn + 3 * push, weakKing);
 
-          if (d <= 2 && !(d == 0 && ksq == pos.square<KING>(strongSide) + 2 * push))
+          if (d <= 2 && !(d == 0 && weakKing == strongKing + 2 * push))
               return ScaleFactor(24);
           else
               return ScaleFactor(48);
@@ -555,10 +537,10 @@ ScaleFactor Endgame<KRPKB>::operator()(const Position& pos) const {
       // it's drawn if the bishop attacks the square in front of the
       // pawn from a reasonable distance and the defending king is near
       // the corner
-      if (   rk == RANK_6
+      if (   pawnRank == RANK_6
-          && distance(psq + 2 * push, ksq) <= 1
+          && distance(strongPawn + 2 * push, weakKing) <= 1
-          && (PseudoAttacks[BISHOP][bsq] & (psq + push))
+          && (attacks_bb<BISHOP>(weakBishop) & (strongPawn + push))
-          && distance<File>(bsq, psq) >= 2)
+          && distance<File>(weakBishop, strongPawn) >= 2)
           return ScaleFactor(8);
   }
 
@@ -573,28 +555,28 @@ ScaleFactor Endgame<KRPPKRP>::operator()(const Position& pos) const {
   assert(verify_material(pos, strongSide, RookValueMg, 2));
   assert(verify_material(pos, weakSide,   RookValueMg, 1));
 
-  Square wpsq1 = pos.squares<PAWN>(strongSide)[0];
+  Square strongPawn1 = lsb(pos.pieces(strongSide, PAWN));
-  Square wpsq2 = pos.squares<PAWN>(strongSide)[1];
+  Square strongPawn2 = msb(pos.pieces(strongSide, PAWN));
-  Square bksq = pos.square<KING>(weakSide);
+  Square weakKing = pos.square<KING>(weakSide);
 
   // Does the stronger side have a passed pawn?
-  if (pos.pawn_passed(strongSide, wpsq1) || pos.pawn_passed(strongSide, wpsq2))
+  if (pos.pawn_passed(strongSide, strongPawn1) || pos.pawn_passed(strongSide, strongPawn2))
       return SCALE_FACTOR_NONE;
 
-  Rank r = std::max(relative_rank(strongSide, wpsq1), relative_rank(strongSide, wpsq2));
+  Rank pawnRank = std::max(relative_rank(strongSide, strongPawn1), relative_rank(strongSide, strongPawn2));
 
-  if (   distance<File>(bksq, wpsq1) <= 1
+  if (   distance<File>(weakKing, strongPawn1) <= 1
-      && distance<File>(bksq, wpsq2) <= 1
+      && distance<File>(weakKing, strongPawn2) <= 1
-      && relative_rank(strongSide, bksq) > r)
+      && relative_rank(strongSide, weakKing) > pawnRank)
   {
-      assert(r > RANK_1 && r < RANK_7);
+      assert(pawnRank > RANK_1 && pawnRank < RANK_7);
-      return ScaleFactor(KRPPKRPScaleFactors[r]);
+      return ScaleFactor(7 * pawnRank);
   }
   return SCALE_FACTOR_NONE;
 }
 
 
-/// K and two or more pawns vs K. There is just a single rule here: If all pawns
+/// K and two or more pawns vs K. There is just a single rule here: if all pawns
 /// are on the same rook file and are blocked by the defending king, it's a draw.
 template<>
 ScaleFactor Endgame<KPsK>::operator()(const Position& pos) const {
@@ -603,14 +585,12 @@ ScaleFactor Endgame<KPsK>::operator()(const Position& pos) const {
   assert(pos.count<PAWN>(strongSide) >= 2);
   assert(verify_material(pos, weakSide, VALUE_ZERO, 0));
 
-  Square ksq = pos.square<KING>(weakSide);
+  Square weakKing = pos.square<KING>(weakSide);
-  Bitboard pawns = pos.pieces(strongSide, PAWN);
+  Bitboard strongPawns = pos.pieces(strongSide, PAWN);
 
-  // If all pawns are ahead of the king, on a single rook file and
+  // If all pawns are ahead of the king on a single rook file, it's a draw.
-  // the king is within one file of the pawns, it's a draw.
+  if (   !(strongPawns & ~(FileABB | FileHBB))
-  if (   !(pawns & ~forward_ranks_bb(weakSide, ksq))
+      && !(strongPawns & ~passed_pawn_span(weakSide, weakKing)))
-      && !((pawns & ~FileABB) && (pawns & ~FileHBB))
-      &&  distance<File>(ksq, lsb(pawns)) <= 1)
       return SCALE_FACTOR_DRAW;
 
   return SCALE_FACTOR_NONE;
@@ -627,20 +607,19 @@ ScaleFactor Endgame<KBPKB>::operator()(const Position& pos) const {
   assert(verify_material(pos, strongSide, BishopValueMg, 1));
   assert(verify_material(pos, weakSide,   BishopValueMg, 0));
 
-  Square pawnSq = pos.square<PAWN>(strongSide);
+  Square strongPawn = pos.square<PAWN>(strongSide);
-  Square strongBishopSq = pos.square<BISHOP>(strongSide);
+  Square strongBishop = pos.square<BISHOP>(strongSide);
-  Square weakBishopSq = pos.square<BISHOP>(weakSide);
+  Square weakBishop = pos.square<BISHOP>(weakSide);
-  Square weakKingSq = pos.square<KING>(weakSide);
+  Square weakKing = pos.square<KING>(weakSide);
 
   // Case 1: Defending king blocks the pawn, and cannot be driven away
-  if (   file_of(weakKingSq) == file_of(pawnSq)
+  if (   (forward_file_bb(strongSide, strongPawn) & weakKing)
-      && relative_rank(strongSide, pawnSq) < relative_rank(strongSide, weakKingSq)
+      && (   opposite_colors(weakKing, strongBishop)
-      && (   opposite_colors(weakKingSq, strongBishopSq)
+          || relative_rank(strongSide, weakKing) <= RANK_6))
-          || relative_rank(strongSide, weakKingSq) <= RANK_6))
       return SCALE_FACTOR_DRAW;
 
   // Case 2: Opposite colored bishops
-  if (opposite_colors(strongBishopSq, weakBishopSq))
+  if (opposite_colors(strongBishop, weakBishop))
       return SCALE_FACTOR_DRAW;
 
   return SCALE_FACTOR_NONE;
@@ -654,36 +633,36 @@ ScaleFactor Endgame<KBPPKB>::operator()(const Position& pos) const {
   assert(verify_material(pos, strongSide, BishopValueMg, 2));
   assert(verify_material(pos, weakSide,   BishopValueMg, 0));
 
-  Square wbsq = pos.square<BISHOP>(strongSide);
+  Square strongBishop = pos.square<BISHOP>(strongSide);
-  Square bbsq = pos.square<BISHOP>(weakSide);
+  Square weakBishop   = pos.square<BISHOP>(weakSide);
 
-  if (!opposite_colors(wbsq, bbsq))
+  if (!opposite_colors(strongBishop, weakBishop))
       return SCALE_FACTOR_NONE;
 
-  Square ksq = pos.square<KING>(weakSide);
+  Square weakKing = pos.square<KING>(weakSide);
-  Square psq1 = pos.squares<PAWN>(strongSide)[0];
+  Square strongPawn1 = lsb(pos.pieces(strongSide, PAWN));
-  Square psq2 = pos.squares<PAWN>(strongSide)[1];
+  Square strongPawn2 = msb(pos.pieces(strongSide, PAWN));
   Square blockSq1, blockSq2;
 
-  if (relative_rank(strongSide, psq1) > relative_rank(strongSide, psq2))
+  if (relative_rank(strongSide, strongPawn1) > relative_rank(strongSide, strongPawn2))
   {
-      blockSq1 = psq1 + pawn_push(strongSide);
+      blockSq1 = strongPawn1 + pawn_push(strongSide);
-      blockSq2 = make_square(file_of(psq2), rank_of(psq1));
+      blockSq2 = make_square(file_of(strongPawn2), rank_of(strongPawn1));
   }
   else
   {
-      blockSq1 = psq2 + pawn_push(strongSide);
+      blockSq1 = strongPawn2 + pawn_push(strongSide);
-      blockSq2 = make_square(file_of(psq1), rank_of(psq2));
+      blockSq2 = make_square(file_of(strongPawn1), rank_of(strongPawn2));
   }
 
-  switch (distance<File>(psq1, psq2))
+  switch (distance<File>(strongPawn1, strongPawn2))
   {
   case 0:
     // Both pawns are on the same file. It's an easy draw if the defender firmly
     // controls some square in the frontmost pawn's path.
-    if (   file_of(ksq) == file_of(blockSq1)
+    if (   file_of(weakKing) == file_of(blockSq1)
-        && relative_rank(strongSide, ksq) >= relative_rank(strongSide, blockSq1)
+        && relative_rank(strongSide, weakKing) >= relative_rank(strongSide, blockSq1)
-        && opposite_colors(ksq, wbsq))
+        && opposite_colors(weakKing, strongBishop))
         return SCALE_FACTOR_DRAW;
     else
         return SCALE_FACTOR_NONE;
@@ -692,17 +671,17 @@ ScaleFactor Endgame<KBPPKB>::operator()(const Position& pos) const {
     // Pawns on adjacent files. It's a draw if the defender firmly controls the
     // square in front of the frontmost pawn's path, and the square diagonally
     // behind this square on the file of the other pawn.
-    if (   ksq == blockSq1
+    if (   weakKing == blockSq1
-        && opposite_colors(ksq, wbsq)
+        && opposite_colors(weakKing, strongBishop)
-        && (   bbsq == blockSq2
+        && (   weakBishop == blockSq2
-            || (pos.attacks_from<BISHOP>(blockSq2) & pos.pieces(weakSide, BISHOP))
+            || (attacks_bb<BISHOP>(blockSq2, pos.pieces()) & pos.pieces(weakSide, BISHOP))
-            || distance<Rank>(psq1, psq2) >= 2))
+            || distance<Rank>(strongPawn1, strongPawn2) >= 2))
         return SCALE_FACTOR_DRAW;
 
-    else if (   ksq == blockSq2
+    else if (   weakKing == blockSq2
-             && opposite_colors(ksq, wbsq)
+             && opposite_colors(weakKing, strongBishop)
-             && (   bbsq == blockSq1
+             && (   weakBishop == blockSq1
-                 || (pos.attacks_from<BISHOP>(blockSq1) & pos.pieces(weakSide, BISHOP))))
+                 || (attacks_bb<BISHOP>(blockSq1, pos.pieces()) & pos.pieces(weakSide, BISHOP))))
         return SCALE_FACTOR_DRAW;
     else
         return SCALE_FACTOR_NONE;
@@ -714,7 +693,7 @@ ScaleFactor Endgame<KBPPKB>::operator()(const Position& pos) const {
 }
 
 
-/// KBP vs KN. There is a single rule: If the defending king is somewhere along
+/// KBP vs KN. There is a single rule: if the defending king is somewhere along
 /// the path of the pawn, and the square of the king is not of the same color as
 /// the stronger side's bishop, it's a draw.
 template<>
@@ -723,62 +702,22 @@ ScaleFactor Endgame<KBPKN>::operator()(const Position& pos) const {
   assert(verify_material(pos, strongSide, BishopValueMg, 1));
   assert(verify_material(pos, weakSide, KnightValueMg, 0));
 
-  Square pawnSq = pos.square<PAWN>(strongSide);
+  Square strongPawn = pos.square<PAWN>(strongSide);
-  Square strongBishopSq = pos.square<BISHOP>(strongSide);
+  Square strongBishop = pos.square<BISHOP>(strongSide);
-  Square weakKingSq = pos.square<KING>(weakSide);
+  Square weakKing = pos.square<KING>(weakSide);
 
-  if (   file_of(weakKingSq) == file_of(pawnSq)
+  if (   file_of(weakKing) == file_of(strongPawn)
-      && relative_rank(strongSide, pawnSq) < relative_rank(strongSide, weakKingSq)
+      && relative_rank(strongSide, strongPawn) < relative_rank(strongSide, weakKing)
-      && (   opposite_colors(weakKingSq, strongBishopSq)
+      && (   opposite_colors(weakKing, strongBishop)
-          || relative_rank(strongSide, weakKingSq) <= RANK_6))
+          || relative_rank(strongSide, weakKing) <= RANK_6))
       return SCALE_FACTOR_DRAW;
 
   return SCALE_FACTOR_NONE;
 }
 
 
-/// KNP vs K. There is a single rule: if the pawn is a rook pawn on the 7th rank
-/// and the defending king prevents the pawn from advancing, the position is drawn.
-template<>
-ScaleFactor Endgame<KNPK>::operator()(const Position& pos) const {
-
-  assert(verify_material(pos, strongSide, KnightValueMg, 1));
-  assert(verify_material(pos, weakSide, VALUE_ZERO, 0));
-
-  // Assume strongSide is white and the pawn is on files A-D
-  Square pawnSq     = normalize(pos, strongSide, pos.square<PAWN>(strongSide));
-  Square weakKingSq = normalize(pos, strongSide, pos.square<KING>(weakSide));
-
-  if (pawnSq == SQ_A7 && distance(SQ_A8, weakKingSq) <= 1)
-      return SCALE_FACTOR_DRAW;
-
-  return SCALE_FACTOR_NONE;
-}
-
-
-/// KNP vs KB. If knight can block bishop from taking pawn, it's a win.
-/// Otherwise the position is drawn.
-template<>
-ScaleFactor Endgame<KNPKB>::operator()(const Position& pos) const {
-
-  assert(verify_material(pos, strongSide, KnightValueMg, 1));
-  assert(verify_material(pos, weakSide, BishopValueMg, 0));
-
-  Square pawnSq = pos.square<PAWN>(strongSide);
-  Square bishopSq = pos.square<BISHOP>(weakSide);
-  Square weakKingSq = pos.square<KING>(weakSide);
-
-  // King needs to get close to promoting pawn to prevent knight from blocking.
-  // Rules for this are very tricky, so just approximate.
-  if (forward_file_bb(strongSide, pawnSq) & pos.attacks_from<BISHOP>(bishopSq))
-      return ScaleFactor(distance(weakKingSq, pawnSq));
-
-  return SCALE_FACTOR_NONE;
-}
-
-
 /// KP vs KP. This is done by removing the weakest side's pawn and probing the
-/// KP vs K bitbase: If the weakest side has a draw without the pawn, it probably
+/// KP vs K bitbase: if the weakest side has a draw without the pawn, it probably
 /// has at least a draw with the pawn as well. The exception is when the stronger
 /// side's pawn is far advanced and not on a rook file; in this case it is often
 /// possible to win (e.g. 8/4k3/3p4/3P4/6K1/8/8/8 w - - 0 1).
@@ -789,18 +728,20 @@ ScaleFactor Endgame<KPKP>::operator()(const Position& pos) const {
   assert(verify_material(pos, weakSide,   VALUE_ZERO, 1));
 
   // Assume strongSide is white and the pawn is on files A-D
-  Square wksq = normalize(pos, strongSide, pos.square<KING>(strongSide));
+  Square strongKing = normalize(pos, strongSide, pos.square<KING>(strongSide));
-  Square bksq = normalize(pos, strongSide, pos.square<KING>(weakSide));
+  Square weakKing   = normalize(pos, strongSide, pos.square<KING>(weakSide));
-  Square psq  = normalize(pos, strongSide, pos.square<PAWN>(strongSide));
+  Square strongPawn = normalize(pos, strongSide, pos.square<PAWN>(strongSide));
 
   Color us = strongSide == pos.side_to_move() ? WHITE : BLACK;
 
   // If the pawn has advanced to the fifth rank or further, and is not a
   // rook pawn, it's too dangerous to assume that it's at least a draw.
-  if (rank_of(psq) >= RANK_5 && file_of(psq) != FILE_A)
+  if (rank_of(strongPawn) >= RANK_5 && file_of(strongPawn) != FILE_A)
       return SCALE_FACTOR_NONE;
 
   // Probe the KPK bitbase with the weakest side's pawn removed. If it's a draw,
   // it's probably at least a draw even with the pawn.
-  return Bitbases::probe(wksq, psq, bksq, us) ? SCALE_FACTOR_NONE : SCALE_FACTOR_DRAW;
+  return Bitbases::probe(strongKing, strongPawn, weakKing, us) ? SCALE_FACTOR_NONE : SCALE_FACTOR_DRAW;
 }
+
+} // namespace Stockfish

src/endgame.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -21,15 +19,16 @@
 #ifndef ENDGAME_H_INCLUDED
 #define ENDGAME_H_INCLUDED
 
-#include <unordered_map>
 #include <memory>
 #include <string>
 #include <type_traits>
+#include <unordered_map>
 #include <utility>
 
 #include "position.h"
 #include "types.h"
 
+namespace Stockfish {
 
 /// EndgameCode lists all supported endgame functions by corresponding codes
 
@@ -57,8 +56,6 @@ enum EndgameCode {
   KBPKB,   // KBP vs KB
   KBPPKB,  // KBPP vs KB
   KBPKN,   // KBP vs KN
-  KNPK,    // KNP vs K
-  KNPKB,   // KNP vs KB
   KPKP     // KP vs KP
 };
 
@@ -124,4 +121,6 @@ namespace Endgames {
   }
 }
 
+} // namespace Stockfish
+
 #endif // #ifndef ENDGAME_H_INCLUDED

src/evaluate.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -22,18 +20,43 @@
 #define EVALUATE_H_INCLUDED
 
 #include <string>
+#include <optional>
 
 #include "types.h"
 
+namespace Stockfish {
+
 class Position;
 
 namespace Eval {
 
-constexpr Value Tempo = Value(28); // Must be visible to search
+  std::string trace(Position& pos);
+  Value evaluate(const Position& pos);
 
-std::string trace(const Position& pos);
+  extern bool useNNUE;
+  extern std::string eval_file_loaded;
 
-Value evaluate(const Position& pos);
+  // The default net name MUST follow the format nn-[SHA256 first 12 digits].nnue
-}
+  // for the build process (profile-build and fishtest) to work. Do not change the
+  // name of the macro, as it is used in the Makefile.
+  #define EvalFileDefaultName   "nn-3475407dc199.nnue"
+
+  namespace NNUE {
+
+    std::string trace(Position& pos);
+    Value evaluate(const Position& pos, bool adjusted = false);
+
+    void init();
+    void verify();
+
+    bool load_eval(std::string name, std::istream& stream);
+    bool save_eval(std::ostream& stream);
+    bool save_eval(const std::optional<std::string>& filename);
+
+  } // namespace NNUE
+
+} // namespace Eval
+
+} // namespace Stockfish
 
 #endif // #ifndef EVALUATE_H_INCLUDED

src/incbin/UNLICENCE

@@ -0,0 +1,26 @@
+The file "incbin.h" is free and unencumbered software released into
+the public domain by Dale Weiler, see:
+   <https://github.com/graphitemaster/incbin>
+
+Anyone is free to copy, modify, publish, use, compile, sell, or
+distribute this software, either in source code form or as a compiled
+binary, for any purpose, commercial or non-commercial, and by any
+means.
+
+In jurisdictions that recognize copyright laws, the author or authors
+of this software dedicate any and all copyright interest in the
+software to the public domain. We make this dedication for the benefit
+of the public at large and to the detriment of our heirs and
+successors. We intend this dedication to be an overt act of
+relinquishment in perpetuity of all present and future rights to this
+software under copyright law.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+For more information, please refer to <http://unlicense.org/>

src/incbin/incbin.h

@@ -0,0 +1,368 @@
+/**
+ * @file incbin.h
+ * @author Dale Weiler
+ * @brief Utility for including binary files
+ *
+ * Facilities for including binary files into the current translation unit and
+ * making use from them externally in other translation units.
+ */
+#ifndef INCBIN_HDR
+#define INCBIN_HDR
+#include <limits.h>
+#if   defined(__AVX512BW__) || \
+      defined(__AVX512CD__) || \
+      defined(__AVX512DQ__) || \
+      defined(__AVX512ER__) || \
+      defined(__AVX512PF__) || \
+      defined(__AVX512VL__) || \
+      defined(__AVX512F__)
+# define INCBIN_ALIGNMENT_INDEX 6
+#elif defined(__AVX__)      || \
+      defined(__AVX2__)
+# define INCBIN_ALIGNMENT_INDEX 5
+#elif defined(__SSE__)      || \
+      defined(__SSE2__)     || \
+      defined(__SSE3__)     || \
+      defined(__SSSE3__)    || \
+      defined(__SSE4_1__)   || \
+      defined(__SSE4_2__)   || \
+      defined(__neon__)
+# define INCBIN_ALIGNMENT_INDEX 4
+#elif ULONG_MAX != 0xffffffffu
+# define INCBIN_ALIGNMENT_INDEX 3
+# else
+# define INCBIN_ALIGNMENT_INDEX 2
+#endif
+
+/* Lookup table of (1 << n) where `n' is `INCBIN_ALIGNMENT_INDEX' */
+#define INCBIN_ALIGN_SHIFT_0 1
+#define INCBIN_ALIGN_SHIFT_1 2
+#define INCBIN_ALIGN_SHIFT_2 4
+#define INCBIN_ALIGN_SHIFT_3 8
+#define INCBIN_ALIGN_SHIFT_4 16
+#define INCBIN_ALIGN_SHIFT_5 32
+#define INCBIN_ALIGN_SHIFT_6 64
+
+/* Actual alignment value */
+#define INCBIN_ALIGNMENT \
+    INCBIN_CONCATENATE( \
+        INCBIN_CONCATENATE(INCBIN_ALIGN_SHIFT, _), \
+        INCBIN_ALIGNMENT_INDEX)
+
+/* Stringize */
+#define INCBIN_STR(X) \
+    #X
+#define INCBIN_STRINGIZE(X) \
+    INCBIN_STR(X)
+/* Concatenate */
+#define INCBIN_CAT(X, Y) \
+    X ## Y
+#define INCBIN_CONCATENATE(X, Y) \
+    INCBIN_CAT(X, Y)
+/* Deferred macro expansion */
+#define INCBIN_EVAL(X) \
+    X
+#define INCBIN_INVOKE(N, ...) \
+    INCBIN_EVAL(N(__VA_ARGS__))
+
+/* Green Hills uses a different directive for including binary data */
+#if defined(__ghs__)
+#  if (__ghs_asm == 2)
+#    define INCBIN_MACRO ".file"
+/* Or consider the ".myrawdata" entry in the ld file */
+#  else
+#    define INCBIN_MACRO "\tINCBIN"
+#  endif
+#else
+#  define INCBIN_MACRO ".incbin"
+#endif
+
+#ifndef _MSC_VER
+#  define INCBIN_ALIGN \
+    __attribute__((aligned(INCBIN_ALIGNMENT)))
+#else
+#  define INCBIN_ALIGN __declspec(align(INCBIN_ALIGNMENT))
+#endif
+
+#if defined(__arm__) || /* GNU C and RealView */ \
+    defined(__arm) || /* Diab */ \
+    defined(_ARM) /* ImageCraft */
+#  define INCBIN_ARM
+#endif
+
+#ifdef __GNUC__
+/* Utilize .balign where supported */
+#  define INCBIN_ALIGN_HOST ".balign " INCBIN_STRINGIZE(INCBIN_ALIGNMENT) "\n"
+#  define INCBIN_ALIGN_BYTE ".balign 1\n"
+#elif defined(INCBIN_ARM)
+/*
+ * On arm assemblers, the alignment value is calculated as (1 << n) where `n' is
+ * the shift count. This is the value passed to `.align'
+ */
+#  define INCBIN_ALIGN_HOST ".align " INCBIN_STRINGIZE(INCBIN_ALIGNMENT_INDEX) "\n"
+#  define INCBIN_ALIGN_BYTE ".align 0\n"
+#else
+/* We assume other inline assembler's treat `.align' as `.balign' */
+#  define INCBIN_ALIGN_HOST ".align " INCBIN_STRINGIZE(INCBIN_ALIGNMENT) "\n"
+#  define INCBIN_ALIGN_BYTE ".align 1\n"
+#endif
+
+/* INCBIN_CONST is used by incbin.c generated files */
+#if defined(__cplusplus)
+#  define INCBIN_EXTERNAL extern "C"
+#  define INCBIN_CONST    extern const
+#else
+#  define INCBIN_EXTERNAL extern
+#  define INCBIN_CONST    const
+#endif
+
+/**
+ * @brief Optionally override the linker section into which data is emitted.
+ *
+ * @warning If you use this facility, you'll have to deal with platform-specific linker output
+ * section naming on your own
+ *
+ * Overriding the default linker output section, e.g for esp8266/Arduino:
+ * @code
+ * #define INCBIN_OUTPUT_SECTION ".irom.text"
+ * #include "incbin.h"
+ * INCBIN(Foo, "foo.txt");
+ * // Data is emitted into program memory that never gets copied to RAM
+ * @endcode
+ */
+#if !defined(INCBIN_OUTPUT_SECTION)
+#  if defined(__APPLE__)
+#    define INCBIN_OUTPUT_SECTION         ".const_data"
+#  else
+#    define INCBIN_OUTPUT_SECTION         ".rodata"
+#  endif
+#endif
+
+#if defined(__APPLE__)
+/* The directives are different for Apple branded compilers */
+#  define INCBIN_SECTION         INCBIN_OUTPUT_SECTION "\n"
+#  define INCBIN_GLOBAL(NAME)    ".globl " INCBIN_MANGLE INCBIN_STRINGIZE(INCBIN_PREFIX) #NAME "\n"
+#  define INCBIN_INT             ".long "
+#  define INCBIN_MANGLE          "_"
+#  define INCBIN_BYTE            ".byte "
+#  define INCBIN_TYPE(...)
+#else
+#  define INCBIN_SECTION         ".section " INCBIN_OUTPUT_SECTION "\n"
+#  define INCBIN_GLOBAL(NAME)    ".global " INCBIN_STRINGIZE(INCBIN_PREFIX) #NAME "\n"
+#  if defined(__ghs__)
+#    define INCBIN_INT           ".word "
+#  else
+#    define INCBIN_INT           ".int "
+#  endif
+#  if defined(__USER_LABEL_PREFIX__)
+#    define INCBIN_MANGLE        INCBIN_STRINGIZE(__USER_LABEL_PREFIX__)
+#  else
+#    define INCBIN_MANGLE        ""
+#  endif
+#  if defined(INCBIN_ARM)
+/* On arm assemblers, `@' is used as a line comment token */
+#    define INCBIN_TYPE(NAME)    ".type " INCBIN_STRINGIZE(INCBIN_PREFIX) #NAME ", %object\n"
+#  elif defined(__MINGW32__) || defined(__MINGW64__)
+/* Mingw doesn't support this directive either */
+#    define INCBIN_TYPE(NAME)
+#  else
+/* It's safe to use `@' on other architectures */
+#    define INCBIN_TYPE(NAME)    ".type " INCBIN_STRINGIZE(INCBIN_PREFIX) #NAME ", @object\n"
+#  endif
+#  define INCBIN_BYTE            ".byte "
+#endif
+
+/* List of style types used for symbol names */
+#define INCBIN_STYLE_CAMEL 0
+#define INCBIN_STYLE_SNAKE 1
+
+/**
+ * @brief Specify the prefix to use for symbol names.
+ *
+ * By default this is `g', producing symbols of the form:
+ * @code
+ * #include "incbin.h"
+ * INCBIN(Foo, "foo.txt");
+ *
+ * // Now you have the following symbols:
+ * // const unsigned char gFooData[];
+ * // const unsigned char *const gFooEnd;
+ * // const unsigned int gFooSize;
+ * @endcode
+ *
+ * If however you specify a prefix before including: e.g:
+ * @code
+ * #define INCBIN_PREFIX incbin
+ * #include "incbin.h"
+ * INCBIN(Foo, "foo.txt");
+ *
+ * // Now you have the following symbols instead:
+ * // const unsigned char incbinFooData[];
+ * // const unsigned char *const incbinFooEnd;
+ * // const unsigned int incbinFooSize;
+ * @endcode
+ */
+#if !defined(INCBIN_PREFIX)
+#  define INCBIN_PREFIX g
+#endif
+
+/**
+ * @brief Specify the style used for symbol names.
+ *
+ * Possible options are
+ * - INCBIN_STYLE_CAMEL "CamelCase"
+ * - INCBIN_STYLE_SNAKE "snake_case"
+ *
+ * Default option is *INCBIN_STYLE_CAMEL* producing symbols of the form:
+ * @code
+ * #include "incbin.h"
+ * INCBIN(Foo, "foo.txt");
+ *
+ * // Now you have the following symbols:
+ * // const unsigned char <prefix>FooData[];
+ * // const unsigned char *const <prefix>FooEnd;
+ * // const unsigned int <prefix>FooSize;
+ * @endcode
+ *
+ * If however you specify a style before including: e.g:
+ * @code
+ * #define INCBIN_STYLE INCBIN_STYLE_SNAKE
+ * #include "incbin.h"
+ * INCBIN(foo, "foo.txt");
+ *
+ * // Now you have the following symbols:
+ * // const unsigned char <prefix>foo_data[];
+ * // const unsigned char *const <prefix>foo_end;
+ * // const unsigned int <prefix>foo_size;
+ * @endcode
+ */
+#if !defined(INCBIN_STYLE)
+#  define INCBIN_STYLE INCBIN_STYLE_CAMEL
+#endif
+
+/* Style lookup tables */
+#define INCBIN_STYLE_0_DATA Data
+#define INCBIN_STYLE_0_END End
+#define INCBIN_STYLE_0_SIZE Size
+#define INCBIN_STYLE_1_DATA _data
+#define INCBIN_STYLE_1_END _end
+#define INCBIN_STYLE_1_SIZE _size
+
+/* Style lookup: returning identifier */
+#define INCBIN_STYLE_IDENT(TYPE) \
+    INCBIN_CONCATENATE( \
+        INCBIN_STYLE_, \
+        INCBIN_CONCATENATE( \
+            INCBIN_EVAL(INCBIN_STYLE), \
+            INCBIN_CONCATENATE(_, TYPE)))
+
+/* Style lookup: returning string literal */
+#define INCBIN_STYLE_STRING(TYPE) \
+    INCBIN_STRINGIZE( \
+        INCBIN_STYLE_IDENT(TYPE)) \
+
+/* Generate the global labels by indirectly invoking the macro with our style
+ * type and concatenating the name against them. */
+#define INCBIN_GLOBAL_LABELS(NAME, TYPE) \
+    INCBIN_INVOKE( \
+        INCBIN_GLOBAL, \
+        INCBIN_CONCATENATE( \
+            NAME, \
+            INCBIN_INVOKE( \
+                INCBIN_STYLE_IDENT, \
+                TYPE))) \
+    INCBIN_INVOKE( \
+        INCBIN_TYPE, \
+        INCBIN_CONCATENATE( \
+            NAME, \
+            INCBIN_INVOKE( \
+                INCBIN_STYLE_IDENT, \
+                TYPE)))
+
+/**
+ * @brief Externally reference binary data included in another translation unit.
+ *
+ * Produces three external symbols that reference the binary data included in
+ * another translation unit.
+ *
+ * The symbol names are a concatenation of `INCBIN_PREFIX' before *NAME*; with
+ * "Data", as well as "End" and "Size" after. An example is provided below.
+ *
+ * @param NAME The name given for the binary data
+ *
+ * @code
+ * INCBIN_EXTERN(Foo);
+ *
+ * // Now you have the following symbols:
+ * // extern const unsigned char <prefix>FooData[];
+ * // extern const unsigned char *const <prefix>FooEnd;
+ * // extern const unsigned int <prefix>FooSize;
+ * @endcode
+ */
+#define INCBIN_EXTERN(NAME) \
+    INCBIN_EXTERNAL const INCBIN_ALIGN unsigned char \
+        INCBIN_CONCATENATE( \
+            INCBIN_CONCATENATE(INCBIN_PREFIX, NAME), \
+            INCBIN_STYLE_IDENT(DATA))[]; \
+    INCBIN_EXTERNAL const INCBIN_ALIGN unsigned char *const \
+    INCBIN_CONCATENATE( \
+        INCBIN_CONCATENATE(INCBIN_PREFIX, NAME), \
+        INCBIN_STYLE_IDENT(END)); \
+    INCBIN_EXTERNAL const unsigned int \
+        INCBIN_CONCATENATE( \
+            INCBIN_CONCATENATE(INCBIN_PREFIX, NAME), \
+            INCBIN_STYLE_IDENT(SIZE))
+
+/**
+ * @brief Include a binary file into the current translation unit.
+ *
+ * Includes a binary file into the current translation unit, producing three symbols
+ * for objects that encode the data and size respectively.
+ *
+ * The symbol names are a concatenation of `INCBIN_PREFIX' before *NAME*; with
+ * "Data", as well as "End" and "Size" after. An example is provided below.
+ *
+ * @param NAME The name to associate with this binary data (as an identifier.)
+ * @param FILENAME The file to include (as a string literal.)
+ *
+ * @code
+ * INCBIN(Icon, "icon.png");
+ *
+ * // Now you have the following symbols:
+ * // const unsigned char <prefix>IconData[];
+ * // const unsigned char *const <prefix>IconEnd;
+ * // const unsigned int <prefix>IconSize;
+ * @endcode
+ *
+ * @warning This must be used in global scope
+ * @warning The identifiers may be different if INCBIN_STYLE is not default
+ *
+ * To externally reference the data included by this in another translation unit
+ * please @see INCBIN_EXTERN.
+ */
+#ifdef _MSC_VER
+#define INCBIN(NAME, FILENAME) \
+    INCBIN_EXTERN(NAME)
+#else
+#define INCBIN(NAME, FILENAME) \
+    __asm__(INCBIN_SECTION \
+            INCBIN_GLOBAL_LABELS(NAME, DATA) \
+            INCBIN_ALIGN_HOST \
+            INCBIN_MANGLE INCBIN_STRINGIZE(INCBIN_PREFIX) #NAME INCBIN_STYLE_STRING(DATA) ":\n" \
+            INCBIN_MACRO " \"" FILENAME "\"\n" \
+            INCBIN_GLOBAL_LABELS(NAME, END) \
+            INCBIN_ALIGN_BYTE \
+            INCBIN_MANGLE INCBIN_STRINGIZE(INCBIN_PREFIX) #NAME INCBIN_STYLE_STRING(END) ":\n" \
+                INCBIN_BYTE "1\n" \
+            INCBIN_GLOBAL_LABELS(NAME, SIZE) \
+            INCBIN_ALIGN_HOST \
+            INCBIN_MANGLE INCBIN_STRINGIZE(INCBIN_PREFIX) #NAME INCBIN_STYLE_STRING(SIZE) ":\n" \
+                INCBIN_INT INCBIN_MANGLE INCBIN_STRINGIZE(INCBIN_PREFIX) #NAME INCBIN_STYLE_STRING(END) " - " \
+                           INCBIN_MANGLE INCBIN_STRINGIZE(INCBIN_PREFIX) #NAME INCBIN_STYLE_STRING(DATA) "\n" \
+            INCBIN_ALIGN_HOST \
+            ".text\n" \
+    ); \
+    INCBIN_EXTERN(NAME)
+
+#endif
+#endif

src/main.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -21,30 +19,32 @@
 #include <iostream>
 
 #include "bitboard.h"
+#include "endgame.h"
 #include "position.h"
+#include "psqt.h"
 #include "search.h"
+#include "syzygy/tbprobe.h"
 #include "thread.h"
 #include "tt.h"
 #include "uci.h"
-#include "endgame.h"
-#include "syzygy/tbprobe.h"
 
-namespace PSQT {
+using namespace Stockfish;
-  void init();
-}
 
 int main(int argc, char* argv[]) {
 
   std::cout << engine_info() << std::endl;
 
+  CommandLine::init(argc, argv);
   UCI::init(Options);
+  Tune::init();
   PSQT::init();
   Bitboards::init();
   Position::init();
   Bitbases::init();
   Endgames::init();
-  Threads.set(Options["Threads"]);
+  Threads.set(size_t(Options["Threads"]));
   Search::clear(); // After threads are up
+  Eval::NNUE::init();
 
   UCI::loop(argc, argv);
 

src/material.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -26,32 +24,39 @@
 
 using namespace std;
 
+namespace Stockfish {
+
 namespace {
+  #define S(mg, eg) make_score(mg, eg)
 
   // Polynomial material imbalance parameters
 
-  constexpr int QuadraticOurs[][PIECE_TYPE_NB] = {
+  // One Score parameter for each pair (our piece, another of our pieces)
-    //            OUR PIECES
+  constexpr Score QuadraticOurs[][PIECE_TYPE_NB] = {
-    // pair pawn knight bishop rook queen
+    // OUR PIECE 2
-    {1438                               }, // Bishop pair
+    // bishop pair    pawn         knight       bishop       rook           queen
-    {  40,   38                         }, // Pawn
+    {S(1419, 1455)                                                                  }, // Bishop pair
-    {  32,  255, -62                    }, // Knight      OUR PIECES
+    {S( 101,   28), S( 37,  39)                                                     }, // Pawn
-    {   0,  104,   4,    0              }, // Bishop
+    {S(  57,   64), S(249, 187), S(-49, -62)                                        }, // Knight      OUR PIECE 1
-    { -26,   -2,  47,   105,  -208      }, // Rook
+    {S(   0,    0), S(118, 137), S( 10,  27), S(  0,   0)                           }, // Bishop
-    {-189,   24, 117,   133,  -134, -6  }  // Queen
+    {S( -63,  -68), S( -5,   3), S(100,  81), S(132, 118), S(-246, -244)            }, // Rook
+    {S(-210, -211), S( 37,  14), S(147, 141), S(161, 105), S(-158, -174), S(-9,-31) }  // Queen
   };
 
-  constexpr int QuadraticTheirs[][PIECE_TYPE_NB] = {
+  // One Score parameter for each pair (our piece, their piece)
-    //           THEIR PIECES
+  constexpr Score QuadraticTheirs[][PIECE_TYPE_NB] = {
-    // pair pawn knight bishop rook queen
+    // THEIR PIECE
-    {   0                               }, // Bishop pair
+    // bishop pair   pawn         knight       bishop       rook         queen
-    {  36,    0                         }, // Pawn
+    {                                                                               }, // Bishop pair
-    {   9,   63,   0                    }, // Knight      OUR PIECES
+    {S(  33,  30)                                                                   }, // Pawn
-    {  59,   65,  42,     0             }, // Bishop
+    {S(  46,  18), S(106,  84)                                                      }, // Knight      OUR PIECE
-    {  46,   39,  24,   -24,    0       }, // Rook
+    {S(  75,  35), S( 59,  44), S( 60,  15)                                         }, // Bishop
-    {  97,  100, -42,   137,  268,    0 }  // Queen
+    {S(  26,  35), S(  6,  22), S( 38,  39), S(-12,  -2)                            }, // Rook
+    {S(  97,  93), S(100, 163), S(-58, -91), S(112, 192), S(276, 225)               }  // Queen
   };
 
+  #undef S
+
   // Endgame evaluation and scaling functions are accessed directly and not through
   // the function maps because they correspond to more than one material hash key.
   Endgame<KXK>    EvaluateKXK[] = { Endgame<KXK>(WHITE),    Endgame<KXK>(BLACK) };
@@ -69,7 +74,7 @@ namespace {
 
   bool is_KBPsK(const Position& pos, Color us) {
     return   pos.non_pawn_material(us) == BishopValueMg
-          && pos.count<PAWN  >(us) >= 1;
+          && pos.count<PAWN>(us) >= 1;
   }
 
   bool is_KQKRPs(const Position& pos, Color us) {
@@ -79,14 +84,16 @@ namespace {
           && pos.count<PAWN>(~us) >= 1;
   }
 
+
   /// imbalance() calculates the imbalance by comparing the piece count of each
   /// piece type for both colors.
+
   template<Color Us>
-  int imbalance(const int pieceCount[][PIECE_TYPE_NB]) {
+  Score imbalance(const int pieceCount[][PIECE_TYPE_NB]) {
 
-    constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
+    constexpr Color Them = ~Us;
 
-    int bonus = 0;
+    Score bonus = SCORE_ZERO;
 
     // Second-degree polynomial material imbalance, by Tord Romstad
     for (int pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; ++pt1)
@@ -94,9 +101,9 @@ namespace {
         if (!pieceCount[Us][pt1])
             continue;
 
-        int v = 0;
+        int v = QuadraticOurs[pt1][pt1] * pieceCount[Us][pt1];
 
-        for (int pt2 = NO_PIECE_TYPE; pt2 <= pt1; ++pt2)
+        for (int pt2 = NO_PIECE_TYPE; pt2 < pt1; ++pt2)
             v +=  QuadraticOurs[pt1][pt2] * pieceCount[Us][pt2]
                 + QuadraticTheirs[pt1][pt2] * pieceCount[Them][pt2];
 
@@ -110,6 +117,7 @@ namespace {
 
 namespace Material {
 
+
 /// Material::probe() looks up the current position's material configuration in
 /// the material hash table. It returns a pointer to the Entry if the position
 /// is found. Otherwise a new Entry is computed and stored there, so we don't
@@ -129,7 +137,7 @@ Entry* probe(const Position& pos) {
 
   Value npm_w = pos.non_pawn_material(WHITE);
   Value npm_b = pos.non_pawn_material(BLACK);
-  Value npm   = clamp(npm_w + npm_b, EndgameLimit, MidgameLimit);
+  Value npm   = std::clamp(npm_w + npm_b, EndgameLimit, MidgameLimit);
 
   // Map total non-pawn material into [PHASE_ENDGAME, PHASE_MIDGAME]
   e->gamePhase = Phase(((npm - EndgameLimit) * PHASE_MIDGAME) / (MidgameLimit - EndgameLimit));
@@ -212,8 +220,10 @@ Entry* probe(const Position& pos) {
   { pos.count<BISHOP>(BLACK) > 1, pos.count<PAWN>(BLACK), pos.count<KNIGHT>(BLACK),
     pos.count<BISHOP>(BLACK)    , pos.count<ROOK>(BLACK), pos.count<QUEEN >(BLACK) } };
 
-  e->value = int16_t((imbalance<WHITE>(pieceCount) - imbalance<BLACK>(pieceCount)) / 16);
+  e->score = (imbalance<WHITE>(pieceCount) - imbalance<BLACK>(pieceCount)) / 16;
   return e;
 }
 
 } // namespace Material
+
+} // namespace Stockfish

src/material.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -26,7 +24,7 @@
 #include "position.h"
 #include "types.h"
 
-namespace Material {
+namespace Stockfish::Material {
 
 /// Material::Entry contains various information about a material configuration.
 /// It contains a material imbalance evaluation, a function pointer to a special
@@ -39,12 +37,12 @@ namespace Material {
 
 struct Entry {
 
-  Score imbalance() const { return make_score(value, value); }
+  Score imbalance() const { return score; }
-  Phase game_phase() const { return gamePhase; }
+  Phase game_phase() const { return (Phase)gamePhase; }
   bool specialized_eval_exists() const { return evaluationFunction != nullptr; }
   Value evaluate(const Position& pos) const { return (*evaluationFunction)(pos); }
 
-  // scale_factor takes a position and a color as input and returns a scale factor
+  // scale_factor() takes a position and a color as input and returns a scale factor
   // for the given color. We have to provide the position in addition to the color
   // because the scale factor may also be a function which should be applied to
   // the position. For instance, in KBP vs K endgames, the scaling function looks
@@ -59,15 +57,15 @@ struct Entry {
   const EndgameBase<Value>* evaluationFunction;
   const EndgameBase<ScaleFactor>* scalingFunction[COLOR_NB]; // Could be one for each
                                                              // side (e.g. KPKP, KBPsK)
-  int16_t value;
+  Score score;
+  int16_t gamePhase;
   uint8_t factor[COLOR_NB];
-  Phase gamePhase;
 };
 
 typedef HashTable<Entry, 8192> Table;
 
 Entry* probe(const Position& pos);
 
-} // namespace Material
+} // namespace Stockfish::Material
 
 #endif // #ifndef MATERIAL_H_INCLUDED

src/misc.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -46,17 +44,30 @@ typedef bool(*fun3_t)(HANDLE, CONST GROUP_AFFINITY*, PGROUP_AFFINITY);
 #include <iostream>
 #include <sstream>
 #include <vector>
+#include <cstdlib>
+
+#if defined(__linux__) && !defined(__ANDROID__)
+#include <stdlib.h>
+#include <sys/mman.h>
+#endif
+
+#if defined(__APPLE__) || defined(__ANDROID__) || defined(__OpenBSD__) || (defined(__GLIBCXX__) && !defined(_GLIBCXX_HAVE_ALIGNED_ALLOC) && !defined(_WIN32)) || defined(__e2k__)
+#define POSIXALIGNEDALLOC
+#include <stdlib.h>
+#endif
 
 #include "misc.h"
 #include "thread.h"
 
 using namespace std;
 
+namespace Stockfish {
+
 namespace {
 
 /// Version number. If Version is left empty, then compile date in the format
 /// DD-MM-YY and show in engine_info.
-const string Version = "11";
+const string Version = "14";
 
 /// Our fancy logging facility. The trick here is to replace cin.rdbuf() and
 /// cout.rdbuf() with two Tie objects that tie cin and cout to a file stream. We
@@ -123,12 +134,13 @@ public:
 
 } // namespace
 
+
 /// engine_info() returns the full name of the current Stockfish version. This
 /// will be either "Stockfish <Tag> DD-MM-YY" (where DD-MM-YY is the date when
 /// the program was compiled) or "Stockfish <Version>", depending on whether
 /// Version is empty.
 
-const string engine_info(bool to_uci) {
+string engine_info(bool to_uci) {
 
   const string months("Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec");
   string month, day, year;
@@ -142,10 +154,8 @@ const string engine_info(bool to_uci) {
       ss << setw(2) << day << setw(2) << (1 + months.find(month) / 4) << year.substr(2);
   }
 
-  ss << (Is64Bit ? " 64" : "")
+  ss << (to_uci  ? "\nid author ": " by ")
-     << (HasPext ? " BMI2" : (HasPopCnt ? " POPCNT" : ""))
+     << "the Stockfish developers (see AUTHORS file)";
-     << (to_uci  ? "\nid author ": " by ")
-     << "T. Romstad, M. Costalba, J. Kiiski, G. Linscott";
 
   return ss.str();
 }
@@ -153,11 +163,11 @@ const string engine_info(bool to_uci) {
 
 /// compiler_info() returns a string trying to describe the compiler we use
 
-const std::string compiler_info() {
+std::string compiler_info() {
 
-  #define STRINGIFY2(x) #x
+  #define stringify2(x) #x
-  #define STRINGIFY(x) STRINGIFY2(x)
+  #define stringify(x) stringify2(x)
-  #define VER_STRING(major, minor, patch) STRINGIFY(major) "." STRINGIFY(minor) "." STRINGIFY(patch)
+  #define make_version_string(major, minor, patch) stringify(major) "." stringify(minor) "." stringify(patch)
 
 /// Predefined macros hell:
 ///
@@ -171,26 +181,38 @@ const std::string compiler_info() {
 
   #ifdef __clang__
      compiler += "clang++ ";
-     compiler += VER_STRING(__clang_major__, __clang_minor__, __clang_patchlevel__);
+     compiler += make_version_string(__clang_major__, __clang_minor__, __clang_patchlevel__);
   #elif __INTEL_COMPILER
      compiler += "Intel compiler ";
      compiler += "(version ";
-     compiler += STRINGIFY(__INTEL_COMPILER) " update " STRINGIFY(__INTEL_COMPILER_UPDATE);
+     compiler += stringify(__INTEL_COMPILER) " update " stringify(__INTEL_COMPILER_UPDATE);
      compiler += ")";
   #elif _MSC_VER
      compiler += "MSVC ";
      compiler += "(version ";
-     compiler += STRINGIFY(_MSC_FULL_VER) "." STRINGIFY(_MSC_BUILD);
+     compiler += stringify(_MSC_FULL_VER) "." stringify(_MSC_BUILD);
+     compiler += ")";
+  #elif defined(__e2k__) && defined(__LCC__)
+    #define dot_ver2(n) \
+      compiler += (char)'.'; \
+      compiler += (char)('0' + (n) / 10); \
+      compiler += (char)('0' + (n) % 10);
+
+     compiler += "MCST LCC ";
+     compiler += "(version ";
+     compiler += std::to_string(__LCC__ / 100);
+     dot_ver2(__LCC__ % 100)
+     dot_ver2(__LCC_MINOR__)
      compiler += ")";
   #elif __GNUC__
      compiler += "g++ (GNUC) ";
-     compiler += VER_STRING(__GNUC__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__);
+     compiler += make_version_string(__GNUC__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__);
   #else
      compiler += "Unknown compiler ";
      compiler += "(unknown version)";
   #endif
 
-  #if defined(__APPLE__) 
+  #if defined(__APPLE__)
      compiler += " on Apple";
   #elif defined(__CYGWIN__)
      compiler += " on Cygwin";
@@ -210,7 +232,40 @@ const std::string compiler_info() {
      compiler += " on unknown system";
   #endif
 
-  compiler += "\n __VERSION__ macro expands to: ";
+  compiler += "\nCompilation settings include: ";
+  compiler += (Is64Bit ? " 64bit" : " 32bit");
+  #if defined(USE_VNNI)
+    compiler += " VNNI";
+  #endif
+  #if defined(USE_AVX512)
+    compiler += " AVX512";
+  #endif
+  compiler += (HasPext ? " BMI2" : "");
+  #if defined(USE_AVX2)
+    compiler += " AVX2";
+  #endif
+  #if defined(USE_SSE41)
+    compiler += " SSE41";
+  #endif
+  #if defined(USE_SSSE3)
+    compiler += " SSSE3";
+  #endif
+  #if defined(USE_SSE2)
+    compiler += " SSE2";
+  #endif
+  compiler += (HasPopCnt ? " POPCNT" : "");
+  #if defined(USE_MMX)
+    compiler += " MMX";
+  #endif
+  #if defined(USE_NEON)
+    compiler += " NEON";
+  #endif
+
+  #if !defined(NDEBUG)
+    compiler += " DEBUG";
+  #endif
+
+  compiler += "\n__VERSION__ macro expands to: ";
   #ifdef __VERSION__
      compiler += __VERSION__;
   #else
@@ -288,6 +343,148 @@ void prefetch(void* addr) {
 
 #endif
 
+
+/// std_aligned_alloc() is our wrapper for systems where the c++17 implementation
+/// does not guarantee the availability of aligned_alloc(). Memory allocated with
+/// std_aligned_alloc() must be freed with std_aligned_free().
+
+void* std_aligned_alloc(size_t alignment, size_t size) {
+
+#if defined(POSIXALIGNEDALLOC)
+  void *mem;
+  return posix_memalign(&mem, alignment, size) ? nullptr : mem;
+#elif defined(_WIN32)
+  return _mm_malloc(size, alignment);
+#else
+  return std::aligned_alloc(alignment, size);
+#endif
+}
+
+void std_aligned_free(void* ptr) {
+
+#if defined(POSIXALIGNEDALLOC)
+  free(ptr);
+#elif defined(_WIN32)
+  _mm_free(ptr);
+#else
+  free(ptr);
+#endif
+}
+
+/// aligned_large_pages_alloc() will return suitably aligned memory, if possible using large pages.
+
+#if defined(_WIN32)
+
+static void* aligned_large_pages_alloc_windows(size_t allocSize) {
+
+  #if !defined(_WIN64)
+    return nullptr;
+  #else
+
+  HANDLE hProcessToken { };
+  LUID luid { };
+  void* mem = nullptr;
+
+  const size_t largePageSize = GetLargePageMinimum();
+  if (!largePageSize)
+      return nullptr;
+
+  // We need SeLockMemoryPrivilege, so try to enable it for the process
+  if (!OpenProcessToken(GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY, &hProcessToken))
+      return nullptr;
+
+  if (LookupPrivilegeValue(NULL, SE_LOCK_MEMORY_NAME, &luid))
+  {
+      TOKEN_PRIVILEGES tp { };
+      TOKEN_PRIVILEGES prevTp { };
+      DWORD prevTpLen = 0;
+
+      tp.PrivilegeCount = 1;
+      tp.Privileges[0].Luid = luid;
+      tp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
+
+      // Try to enable SeLockMemoryPrivilege. Note that even if AdjustTokenPrivileges() succeeds,
+      // we still need to query GetLastError() to ensure that the privileges were actually obtained.
+      if (AdjustTokenPrivileges(
+              hProcessToken, FALSE, &tp, sizeof(TOKEN_PRIVILEGES), &prevTp, &prevTpLen) &&
+          GetLastError() == ERROR_SUCCESS)
+      {
+          // Round up size to full pages and allocate
+          allocSize = (allocSize + largePageSize - 1) & ~size_t(largePageSize - 1);
+          mem = VirtualAlloc(
+              NULL, allocSize, MEM_RESERVE | MEM_COMMIT | MEM_LARGE_PAGES, PAGE_READWRITE);
+
+          // Privilege no longer needed, restore previous state
+          AdjustTokenPrivileges(hProcessToken, FALSE, &prevTp, 0, NULL, NULL);
+      }
+  }
+
+  CloseHandle(hProcessToken);
+
+  return mem;
+
+  #endif
+}
+
+void* aligned_large_pages_alloc(size_t allocSize) {
+
+  // Try to allocate large pages
+  void* mem = aligned_large_pages_alloc_windows(allocSize);
+
+  // Fall back to regular, page aligned, allocation if necessary
+  if (!mem)
+      mem = VirtualAlloc(NULL, allocSize, MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
+
+  return mem;
+}
+
+#else
+
+void* aligned_large_pages_alloc(size_t allocSize) {
+
+#if defined(__linux__)
+  constexpr size_t alignment = 2 * 1024 * 1024; // assumed 2MB page size
+#else
+  constexpr size_t alignment = 4096; // assumed small page size
+#endif
+
+  // round up to multiples of alignment
+  size_t size = ((allocSize + alignment - 1) / alignment) * alignment;
+  void *mem = std_aligned_alloc(alignment, size);
+#if defined(MADV_HUGEPAGE)
+  madvise(mem, size, MADV_HUGEPAGE);
+#endif
+  return mem;
+}
+
+#endif
+
+
+/// aligned_large_pages_free() will free the previously allocated ttmem
+
+#if defined(_WIN32)
+
+void aligned_large_pages_free(void* mem) {
+
+  if (mem && !VirtualFree(mem, 0, MEM_RELEASE))
+  {
+      DWORD err = GetLastError();
+      std::cerr << "Failed to free large page memory. Error code: 0x"
+                << std::hex << err
+                << std::dec << std::endl;
+      exit(EXIT_FAILURE);
+  }
+}
+
+#else
+
+void aligned_large_pages_free(void *mem) {
+  std_aligned_free(mem);
+}
+
+#endif
+
+
 namespace WinProcGroup {
 
 #ifndef _WIN32
@@ -393,3 +590,62 @@ void bindThisThread(size_t idx) {
 #endif
 
 } // namespace WinProcGroup
+
+#ifdef _WIN32
+#include <direct.h>
+#define GETCWD _getcwd
+#else
+#include <unistd.h>
+#define GETCWD getcwd
+#endif
+
+namespace CommandLine {
+
+string argv0;            // path+name of the executable binary, as given by argv[0]
+string binaryDirectory;  // path of the executable directory
+string workingDirectory; // path of the working directory
+
+void init(int argc, char* argv[]) {
+    (void)argc;
+    string pathSeparator;
+
+    // extract the path+name of the executable binary
+    argv0 = argv[0];
+
+#ifdef _WIN32
+    pathSeparator = "\\";
+  #ifdef _MSC_VER
+    // Under windows argv[0] may not have the extension. Also _get_pgmptr() had
+    // issues in some windows 10 versions, so check returned values carefully.
+    char* pgmptr = nullptr;
+    if (!_get_pgmptr(&pgmptr) && pgmptr != nullptr && *pgmptr)
+        argv0 = pgmptr;
+  #endif
+#else
+    pathSeparator = "/";
+#endif
+
+    // extract the working directory
+    workingDirectory = "";
+    char buff[40000];
+    char* cwd = GETCWD(buff, 40000);
+    if (cwd)
+        workingDirectory = cwd;
+
+    // extract the binary directory path from argv0
+    binaryDirectory = argv0;
+    size_t pos = binaryDirectory.find_last_of("\\/");
+    if (pos == std::string::npos)
+        binaryDirectory = "." + pathSeparator;
+    else
+        binaryDirectory.resize(pos + 1);
+
+    // pattern replacement: "./" at the start of path is replaced by the working directory
+    if (binaryDirectory.find("." + pathSeparator) == 0)
+        binaryDirectory.replace(0, 1, workingDirectory);
+}
+
+
+} // namespace CommandLine
+
+} // namespace Stockfish

src/misc.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -26,13 +24,20 @@
 #include <ostream>
 #include <string>
 #include <vector>
+#include <cstdint>
 
 #include "types.h"
 
-const std::string engine_info(bool to_uci = false);
+namespace Stockfish {
-const std::string compiler_info();
+
+std::string engine_info(bool to_uci = false);
+std::string compiler_info();
 void prefetch(void* addr);
 void start_logger(const std::string& fname);
+void* std_aligned_alloc(size_t alignment, size_t size);
+void std_aligned_free(void* ptr);
+void* aligned_large_pages_alloc(size_t size); // memory aligned by page size, min alignment: 4096 bytes
+void aligned_large_pages_free(void* mem); // nop if mem == nullptr
 
 void dbg_hit_on(bool b);
 void dbg_hit_on(bool c, bool b);
@@ -40,9 +45,7 @@ void dbg_mean_of(int v);
 void dbg_print();
 
 typedef std::chrono::milliseconds::rep TimePoint; // A value in milliseconds
-
 static_assert(sizeof(TimePoint) == sizeof(int64_t), "TimePoint should be 64 bits");
-
 inline TimePoint now() {
   return std::chrono::duration_cast<std::chrono::milliseconds>
         (std::chrono::steady_clock::now().time_since_epoch()).count();
@@ -64,6 +67,67 @@ std::ostream& operator<<(std::ostream&, SyncCout);
 #define sync_endl std::endl << IO_UNLOCK
 
 
+// align_ptr_up() : get the first aligned element of an array.
+// ptr must point to an array of size at least `sizeof(T) * N + alignment` bytes,
+// where N is the number of elements in the array.
+template <uintptr_t Alignment, typename T>
+T* align_ptr_up(T* ptr)
+{
+  static_assert(alignof(T) < Alignment);
+
+  const uintptr_t ptrint = reinterpret_cast<uintptr_t>(reinterpret_cast<char*>(ptr));
+  return reinterpret_cast<T*>(reinterpret_cast<char*>((ptrint + (Alignment - 1)) / Alignment * Alignment));
+}
+
+
+// IsLittleEndian : true if and only if the binary is compiled on a little endian machine
+static inline const union { uint32_t i; char c[4]; } Le = { 0x01020304 };
+static inline const bool IsLittleEndian = (Le.c[0] == 4);
+
+
+template <typename T>
+class ValueListInserter {
+public:
+  ValueListInserter(T* v, std::size_t& s) :
+    values(v),
+    size(&s)
+  {
+  }
+
+  void push_back(const T& value) { values[(*size)++] = value; }
+private:
+  T* values;
+  std::size_t* size;
+};
+
+template <typename T, std::size_t MaxSize>
+class ValueList {
+
+public:
+  std::size_t size() const { return size_; }
+  void resize(std::size_t newSize) { size_ = newSize; }
+  void push_back(const T& value) { values_[size_++] = value; }
+  T& operator[](std::size_t index) { return values_[index]; }
+  T* begin() { return values_; }
+  T* end() { return values_ + size_; }
+  const T& operator[](std::size_t index) const { return values_[index]; }
+  const T* begin() const { return values_; }
+  const T* end() const { return values_ + size_; }
+  operator ValueListInserter<T>() { return ValueListInserter(values_, size_); }
+
+  void swap(ValueList& other) {
+    const std::size_t maxSize = std::max(size_, other.size_);
+    for (std::size_t i = 0; i < maxSize; ++i) {
+      std::swap(values_[i], other.values_[i]);
+    }
+    std::swap(size_, other.size_);
+  }
+
+private:
+  T values_[MaxSize];
+  std::size_t size_ = 0;
+};
+
 /// xorshift64star Pseudo-Random Number Generator
 /// This class is based on original code written and dedicated
 /// to the public domain by Sebastiano Vigna (2014).
@@ -100,6 +164,19 @@ public:
   { return T(rand64() & rand64() & rand64()); }
 };
 
+inline uint64_t mul_hi64(uint64_t a, uint64_t b) {
+#if defined(__GNUC__) && defined(IS_64BIT)
+    __extension__ typedef unsigned __int128 uint128;
+    return ((uint128)a * (uint128)b) >> 64;
+#else
+    uint64_t aL = (uint32_t)a, aH = a >> 32;
+    uint64_t bL = (uint32_t)b, bH = b >> 32;
+    uint64_t c1 = (aL * bL) >> 32;
+    uint64_t c2 = aH * bL + c1;
+    uint64_t c3 = aL * bH + (uint32_t)c2;
+    return aH * bH + (c2 >> 32) + (c3 >> 32);
+#endif
+}
 
 /// Under Windows it is not possible for a process to run on more than one
 /// logical processor group. This usually means to be limited to use max 64
@@ -111,4 +188,13 @@ namespace WinProcGroup {
   void bindThisThread(size_t idx);
 }
 
+namespace CommandLine {
+  void init(int argc, char* argv[]);
+
+  extern std::string binaryDirectory;  // path of the executable directory
+  extern std::string workingDirectory; // path of the working directory
+}
+
+} // namespace Stockfish
+
 #endif // #ifndef MISC_H_INCLUDED

src/movegen.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -23,10 +21,12 @@
 #include "movegen.h"
 #include "position.h"
 
+namespace Stockfish {
+
 namespace {
 
   template<GenType Type, Direction D>
-  ExtMove* make_promotions(ExtMove* moveList, Square to, Square ksq) {
+  ExtMove* make_promotions(ExtMove* moveList, Square to) {
 
     if (Type == CAPTURES || Type == EVASIONS || Type == NON_EVASIONS)
         *moveList++ = make<PROMOTION>(to - D, to, QUEEN);
@@ -38,13 +38,6 @@ namespace {
         *moveList++ = make<PROMOTION>(to - D, to, KNIGHT);
     }
 
-    // Knight promotion is the only promotion that can give a direct check
-    // that's not already included in the queen promotion.
-    if (Type == QUIET_CHECKS && (PseudoAttacks[KNIGHT][to] & ksq))
-        *moveList++ = make<PROMOTION>(to - D, to, KNIGHT);
-    else
-        (void)ksq; // Silence a warning under MSVC
-
     return moveList;
   }
 
@@ -52,28 +45,23 @@ namespace {
   template<Color Us, GenType Type>
   ExtMove* generate_pawn_moves(const Position& pos, ExtMove* moveList, Bitboard target) {
 
-    // Compute some compile time parameters relative to the white side
+    constexpr Color     Them     = ~Us;
-    constexpr Color     Them     = (Us == WHITE ? BLACK      : WHITE);
     constexpr Bitboard  TRank7BB = (Us == WHITE ? Rank7BB    : Rank2BB);
     constexpr Bitboard  TRank3BB = (Us == WHITE ? Rank3BB    : Rank6BB);
     constexpr Direction Up       = pawn_push(Us);
     constexpr Direction UpRight  = (Us == WHITE ? NORTH_EAST : SOUTH_WEST);
     constexpr Direction UpLeft   = (Us == WHITE ? NORTH_WEST : SOUTH_EAST);
 
-    const Square ksq = pos.square<KING>(Them);
+    const Bitboard emptySquares = Type == QUIETS || Type == QUIET_CHECKS ? target : ~pos.pieces();
-    Bitboard emptySquares;
+    const Bitboard enemies      = Type == EVASIONS ? pos.checkers()
+                                : Type == CAPTURES ? target : pos.pieces(Them);
 
     Bitboard pawnsOn7    = pos.pieces(Us, PAWN) &  TRank7BB;
     Bitboard pawnsNotOn7 = pos.pieces(Us, PAWN) & ~TRank7BB;
 
-    Bitboard enemies = (Type == EVASIONS ? pos.pieces(Them) & target:
-                        Type == CAPTURES ? target : pos.pieces(Them));
-
     // Single and double pawn pushes, no promotions
     if (Type != CAPTURES)
     {
-        emptySquares = (Type == QUIETS || Type == QUIET_CHECKS ? target : ~pos.pieces());
-
         Bitboard b1 = shift<Up>(pawnsNotOn7)   & emptySquares;
         Bitboard b2 = shift<Up>(b1 & TRank3BB) & emptySquares;
 
@@ -85,33 +73,24 @@ namespace {
 
         if (Type == QUIET_CHECKS)
         {
-            b1 &= pos.attacks_from<PAWN>(ksq, Them);
+            // To make a quiet check, you either make a direct check by pushing a pawn
-            b2 &= pos.attacks_from<PAWN>(ksq, Them);
+            // or push a blocker pawn that is not on the same file as the enemy king.
-
+            // Discovered check promotion has been already generated amongst the captures.
-            // Add pawn pushes which give discovered check. This is possible only
+            Square ksq = pos.square<KING>(Them);
-            // if the pawn is not on the same file as the enemy king, because we
+            Bitboard dcCandidatePawns = pos.blockers_for_king(Them) & ~file_bb(ksq);
-            // don't generate captures. Note that a possible discovery check
+            b1 &= pawn_attacks_bb(Them, ksq) | shift<   Up>(dcCandidatePawns);
-            // promotion has been already generated amongst the captures.
+            b2 &= pawn_attacks_bb(Them, ksq) | shift<Up+Up>(dcCandidatePawns);
-            Bitboard dcCandidateQuiets = pos.blockers_for_king(Them) & pawnsNotOn7;
-            if (dcCandidateQuiets)
-            {
-                Bitboard dc1 = shift<Up>(dcCandidateQuiets) & emptySquares & ~file_bb(ksq);
-                Bitboard dc2 = shift<Up>(dc1 & TRank3BB) & emptySquares;
-
-                b1 |= dc1;
-                b2 |= dc2;
-            }
         }
 
         while (b1)
         {
-            Square to = pop_lsb(&b1);
+            Square to = pop_lsb(b1);
             *moveList++ = make_move(to - Up, to);
         }
 
         while (b2)
         {
-            Square to = pop_lsb(&b2);
+            Square to = pop_lsb(b2);
             *moveList++ = make_move(to - Up - Up, to);
         }
     }
@@ -119,27 +98,24 @@ namespace {
     // Promotions and underpromotions
     if (pawnsOn7)
     {
-        if (Type == CAPTURES)
-            emptySquares = ~pos.pieces();
-
-        if (Type == EVASIONS)
-            emptySquares &= target;
-
         Bitboard b1 = shift<UpRight>(pawnsOn7) & enemies;
         Bitboard b2 = shift<UpLeft >(pawnsOn7) & enemies;
         Bitboard b3 = shift<Up     >(pawnsOn7) & emptySquares;
 
+        if (Type == EVASIONS)
+            b3 &= target;
+
         while (b1)
-            moveList = make_promotions<Type, UpRight>(moveList, pop_lsb(&b1), ksq);
+            moveList = make_promotions<Type, UpRight>(moveList, pop_lsb(b1));
 
         while (b2)
-            moveList = make_promotions<Type, UpLeft >(moveList, pop_lsb(&b2), ksq);
+            moveList = make_promotions<Type, UpLeft >(moveList, pop_lsb(b2));
 
         while (b3)
-            moveList = make_promotions<Type, Up     >(moveList, pop_lsb(&b3), ksq);
+            moveList = make_promotions<Type, Up     >(moveList, pop_lsb(b3));
     }
 
-    // Standard and en-passant captures
+    // Standard and en passant captures
     if (Type == CAPTURES || Type == EVASIONS || Type == NON_EVASIONS)
     {
         Bitboard b1 = shift<UpRight>(pawnsNotOn7) & enemies;
@@ -147,13 +123,13 @@ namespace {
 
         while (b1)
         {
-            Square to = pop_lsb(&b1);
+            Square to = pop_lsb(b1);
             *moveList++ = make_move(to - UpRight, to);
         }
 
         while (b2)
         {
-            Square to = pop_lsb(&b2);
+            Square to = pop_lsb(b2);
             *moveList++ = make_move(to - UpLeft, to);
         }
 
@@ -161,18 +137,16 @@ namespace {
         {
             assert(rank_of(pos.ep_square()) == relative_rank(Us, RANK_6));
 
-            // An en passant capture can be an evasion only if the checking piece
+            // An en passant capture cannot resolve a discovered check
-            // is the double pushed pawn and so is in the target. Otherwise this
+            if (Type == EVASIONS && (target & (pos.ep_square() + Up)))
-            // is a discovery check and we are forced to do otherwise.
-            if (Type == EVASIONS && !(target & (pos.ep_square() - Up)))
                 return moveList;
 
-            b1 = pawnsNotOn7 & pos.attacks_from<PAWN>(pos.ep_square(), Them);
+            b1 = pawnsNotOn7 & pawn_attacks_bb(Them, pos.ep_square());
 
             assert(b1);
 
             while (b1)
-                *moveList++ = make<ENPASSANT>(pop_lsb(&b1), pos.ep_square());
+                *moveList++ = make<EN_PASSANT>(pop_lsb(b1), pos.ep_square());
         }
     }
 
@@ -180,33 +154,24 @@ namespace {
   }
 
 
-  template<PieceType Pt, bool Checks>
+  template<Color Us, PieceType Pt, bool Checks>
-  ExtMove* generate_moves(const Position& pos, ExtMove* moveList, Color us,
+  ExtMove* generate_moves(const Position& pos, ExtMove* moveList, Bitboard target) {
-                          Bitboard target) {
 
     static_assert(Pt != KING && Pt != PAWN, "Unsupported piece type in generate_moves()");
 
-    const Square* pl = pos.squares<Pt>(us);
+    Bitboard bb = pos.pieces(Us, Pt);
 
-    for (Square from = *pl; from != SQ_NONE; from = *++pl)
+    while (bb)
     {
-        if (Checks)
+        Square from = pop_lsb(bb);
-        {
+        Bitboard b = attacks_bb<Pt>(from, pos.pieces()) & target;
-            if (    (Pt == BISHOP || Pt == ROOK || Pt == QUEEN)
-                && !(PseudoAttacks[Pt][from] & target & pos.check_squares(Pt)))
-                continue;
 
-            if (pos.blockers_for_king(~us) & from)
+        // To check, you either move freely a blocker or make a direct check.
-                continue;
+        if (Checks && (Pt == QUEEN || !(pos.blockers_for_king(~Us) & from)))
-        }
-
-        Bitboard b = pos.attacks_from<Pt>(from) & target;
-
-        if (Checks)
             b &= pos.check_squares(Pt);
 
         while (b)
-            *moveList++ = make_move(from, pop_lsb(&b));
+            *moveList++ = make_move(from, pop_lsb(b));
     }
 
     return moveList;
@@ -214,33 +179,42 @@ namespace {
 
 
   template<Color Us, GenType Type>
-  ExtMove* generate_all(const Position& pos, ExtMove* moveList, Bitboard target) {
+  ExtMove* generate_all(const Position& pos, ExtMove* moveList) {
 
-    constexpr CastlingRights OO  = Us & KING_SIDE;
+    static_assert(Type != LEGAL, "Unsupported type in generate_all()");
-    constexpr CastlingRights OOO = Us & QUEEN_SIDE;
-    constexpr bool Checks = Type == QUIET_CHECKS; // Reduce template instantations
 
-    moveList = generate_pawn_moves<Us, Type>(pos, moveList, target);
+    constexpr bool Checks = Type == QUIET_CHECKS; // Reduce template instantiations
-    moveList = generate_moves<KNIGHT, Checks>(pos, moveList, Us, target);
+    const Square ksq = pos.square<KING>(Us);
-    moveList = generate_moves<BISHOP, Checks>(pos, moveList, Us, target);
+    Bitboard target;
-    moveList = generate_moves<  ROOK, Checks>(pos, moveList, Us, target);
-    moveList = generate_moves< QUEEN, Checks>(pos, moveList, Us, target);
 
-    if (Type != QUIET_CHECKS && Type != EVASIONS)
+    // Skip generating non-king moves when in double check
+    if (Type != EVASIONS || !more_than_one(pos.checkers()))
     {
-        Square ksq = pos.square<KING>(Us);
+        target = Type == EVASIONS     ?  between_bb(ksq, lsb(pos.checkers()))
-        Bitboard b = pos.attacks_from<KING>(ksq) & target;
+               : Type == NON_EVASIONS ? ~pos.pieces( Us)
+               : Type == CAPTURES     ?  pos.pieces(~Us)
+                                      : ~pos.pieces(   ); // QUIETS || QUIET_CHECKS
+
+        moveList = generate_pawn_moves<Us, Type>(pos, moveList, target);
+        moveList = generate_moves<Us, KNIGHT, Checks>(pos, moveList, target);
+        moveList = generate_moves<Us, BISHOP, Checks>(pos, moveList, target);
+        moveList = generate_moves<Us,   ROOK, Checks>(pos, moveList, target);
+        moveList = generate_moves<Us,  QUEEN, Checks>(pos, moveList, target);
+    }
+
+    if (!Checks || pos.blockers_for_king(~Us) & ksq)
+    {
+        Bitboard b = attacks_bb<KING>(ksq) & (Type == EVASIONS ? ~pos.pieces(Us) : target);
+        if (Checks)
+            b &= ~attacks_bb<QUEEN>(pos.square<KING>(~Us));
+
         while (b)
-            *moveList++ = make_move(ksq, pop_lsb(&b));
+            *moveList++ = make_move(ksq, pop_lsb(b));
 
-        if (Type != CAPTURES && pos.can_castle(CastlingRights(OO | OOO)))
+        if ((Type == QUIETS || Type == NON_EVASIONS) && pos.can_castle(Us & ANY_CASTLING))
-        {
+            for (CastlingRights cr : { Us & KING_SIDE, Us & QUEEN_SIDE } )
-            if (!pos.castling_impeded(OO) && pos.can_castle(OO))
+                if (!pos.castling_impeded(cr) && pos.can_castle(cr))
-                *moveList++ = make<CASTLING>(ksq, pos.castling_rook_square(OO));
+                    *moveList++ = make<CASTLING>(ksq, pos.castling_rook_square(cr));
-
-            if (!pos.castling_impeded(OOO) && pos.can_castle(OOO))
-                *moveList++ = make<CASTLING>(ksq, pos.castling_rook_square(OOO));
-        }
     }
 
     return moveList;
@@ -249,8 +223,10 @@ namespace {
 } // namespace
 
 
-/// <CAPTURES>     Generates all pseudo-legal captures and queen promotions
+/// <CAPTURES>     Generates all pseudo-legal captures plus queen promotions
 /// <QUIETS>       Generates all pseudo-legal non-captures and underpromotions
+/// <EVASIONS>     Generates all pseudo-legal check evasions when the side to move is in check
+/// <QUIET_CHECKS> Generates all pseudo-legal non-captures giving check, except castling and promotions
 /// <NON_EVASIONS> Generates all pseudo-legal captures and non-captures
 ///
 /// Returns a pointer to the end of the move list.
@@ -258,95 +234,23 @@ namespace {
 template<GenType Type>
 ExtMove* generate(const Position& pos, ExtMove* moveList) {
 
-  static_assert(Type == CAPTURES || Type == QUIETS || Type == NON_EVASIONS, "Unsupported type in generate()");
+  static_assert(Type != LEGAL, "Unsupported type in generate()");
-  assert(!pos.checkers());
+  assert((Type == EVASIONS) == (bool)pos.checkers());
 
   Color us = pos.side_to_move();
 
-  Bitboard target =  Type == CAPTURES     ?  pos.pieces(~us)
+  return us == WHITE ? generate_all<WHITE, Type>(pos, moveList)
-                   : Type == QUIETS       ? ~pos.pieces()
+                     : generate_all<BLACK, Type>(pos, moveList);
-                   : Type == NON_EVASIONS ? ~pos.pieces(us) : 0;
-
-  return us == WHITE ? generate_all<WHITE, Type>(pos, moveList, target)
-                     : generate_all<BLACK, Type>(pos, moveList, target);
 }
 
 // Explicit template instantiations
 template ExtMove* generate<CAPTURES>(const Position&, ExtMove*);
 template ExtMove* generate<QUIETS>(const Position&, ExtMove*);
+template ExtMove* generate<EVASIONS>(const Position&, ExtMove*);
+template ExtMove* generate<QUIET_CHECKS>(const Position&, ExtMove*);
 template ExtMove* generate<NON_EVASIONS>(const Position&, ExtMove*);
 
 
-/// generate<QUIET_CHECKS> generates all pseudo-legal non-captures and knight
-/// underpromotions that give check. Returns a pointer to the end of the move list.
-template<>
-ExtMove* generate<QUIET_CHECKS>(const Position& pos, ExtMove* moveList) {
-
-  assert(!pos.checkers());
-
-  Color us = pos.side_to_move();
-  Bitboard dc = pos.blockers_for_king(~us) & pos.pieces(us);
-
-  while (dc)
-  {
-     Square from = pop_lsb(&dc);
-     PieceType pt = type_of(pos.piece_on(from));
-
-     if (pt == PAWN)
-         continue; // Will be generated together with direct checks
-
-     Bitboard b = pos.attacks_from(pt, from) & ~pos.pieces();
-
-     if (pt == KING)
-         b &= ~PseudoAttacks[QUEEN][pos.square<KING>(~us)];
-
-     while (b)
-         *moveList++ = make_move(from, pop_lsb(&b));
-  }
-
-  return us == WHITE ? generate_all<WHITE, QUIET_CHECKS>(pos, moveList, ~pos.pieces())
-                     : generate_all<BLACK, QUIET_CHECKS>(pos, moveList, ~pos.pieces());
-}
-
-
-/// generate<EVASIONS> generates all pseudo-legal check evasions when the side
-/// to move is in check. Returns a pointer to the end of the move list.
-template<>
-ExtMove* generate<EVASIONS>(const Position& pos, ExtMove* moveList) {
-
-  assert(pos.checkers());
-
-  Color us = pos.side_to_move();
-  Square ksq = pos.square<KING>(us);
-  Bitboard sliderAttacks = 0;
-  Bitboard sliders = pos.checkers() & ~pos.pieces(KNIGHT, PAWN);
-
-  // Find all the squares attacked by slider checkers. We will remove them from
-  // the king evasions in order to skip known illegal moves, which avoids any
-  // useless legality checks later on.
-  while (sliders)
-  {
-      Square checksq = pop_lsb(&sliders);
-      sliderAttacks |= LineBB[checksq][ksq] ^ checksq;
-  }
-
-  // Generate evasions for king, capture and non capture moves
-  Bitboard b = pos.attacks_from<KING>(ksq) & ~pos.pieces(us) & ~sliderAttacks;
-  while (b)
-      *moveList++ = make_move(ksq, pop_lsb(&b));
-
-  if (more_than_one(pos.checkers()))
-      return moveList; // Double check, only a king move can save the day
-
-  // Generate blocking evasions or captures of the checking piece
-  Square checksq = lsb(pos.checkers());
-  Bitboard target = between_bb(checksq, ksq) | checksq;
-
-  return us == WHITE ? generate_all<WHITE, EVASIONS>(pos, moveList, target)
-                     : generate_all<BLACK, EVASIONS>(pos, moveList, target);
-}
-
-
 /// generate<LEGAL> generates all the legal moves in the given position
 
 template<>
@@ -360,7 +264,7 @@ ExtMove* generate<LEGAL>(const Position& pos, ExtMove* moveList) {
   moveList = pos.checkers() ? generate<EVASIONS    >(pos, moveList)
                             : generate<NON_EVASIONS>(pos, moveList);
   while (cur != moveList)
-      if (   (pinned || from_sq(*cur) == ksq || type_of(*cur) == ENPASSANT)
+      if (  ((pinned && pinned & from_sq(*cur)) || from_sq(*cur) == ksq || type_of(*cur) == EN_PASSANT)
           && !pos.legal(*cur))
           *cur = (--moveList)->move;
       else
@@ -368,3 +272,5 @@ ExtMove* generate<LEGAL>(const Position& pos, ExtMove* moveList) {
 
   return moveList;
 }
+
+} // namespace Stockfish

src/movegen.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -25,6 +23,8 @@
 
 #include "types.h"
 
+namespace Stockfish {
+
 class Position;
 
 enum GenType {
@@ -72,4 +72,6 @@ private:
   ExtMove moveList[MAX_MOVES], *last;
 };
 
+} // namespace Stockfish
+
 #endif // #ifndef MOVEGEN_H_INCLUDED

src/movepick.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -22,6 +20,8 @@
 
 #include "movepick.h"
 
+namespace Stockfish {
+
 namespace {
 
   enum Stages {
@@ -56,45 +56,40 @@ namespace {
 /// ordering is at the current node.
 
 /// MovePicker constructor for the main search
-MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh,
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh, const LowPlyHistory* lp,
-                       const CapturePieceToHistory* cph, const PieceToHistory** ch, Move cm, Move* killers)
+                       const CapturePieceToHistory* cph, const PieceToHistory** ch, Move cm, const Move* killers, int pl)
-           : pos(p), mainHistory(mh), captureHistory(cph), continuationHistory(ch),
+           : pos(p), mainHistory(mh), lowPlyHistory(lp), captureHistory(cph), continuationHistory(ch),
-             refutations{{killers[0], 0}, {killers[1], 0}, {cm, 0}}, depth(d) {
+             ttMove(ttm), refutations{{killers[0], 0}, {killers[1], 0}, {cm, 0}}, depth(d), ply(pl) {
 
   assert(d > 0);
 
-  stage = pos.checkers() ? EVASION_TT : MAIN_TT;
+  stage = (pos.checkers() ? EVASION_TT : MAIN_TT) +
-  ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE;
+          !(ttm && pos.pseudo_legal(ttm));
-  stage += (ttMove == MOVE_NONE);
 }
 
 /// MovePicker constructor for quiescence search
 MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh,
                        const CapturePieceToHistory* cph, const PieceToHistory** ch, Square rs)
-           : pos(p), mainHistory(mh), captureHistory(cph), continuationHistory(ch), recaptureSquare(rs), depth(d) {
+           : pos(p), mainHistory(mh), captureHistory(cph), continuationHistory(ch), ttMove(ttm), recaptureSquare(rs), depth(d) {
 
   assert(d <= 0);
 
-  stage = pos.checkers() ? EVASION_TT : QSEARCH_TT;
+  stage = (pos.checkers() ? EVASION_TT : QSEARCH_TT) +
-  ttMove =   ttm
+          !(   ttm
-          && (depth > DEPTH_QS_RECAPTURES || to_sq(ttm) == recaptureSquare)
+            && (pos.checkers() || depth > DEPTH_QS_RECAPTURES || to_sq(ttm) == recaptureSquare)
-          && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE;
+            && pos.pseudo_legal(ttm));
-  stage += (ttMove == MOVE_NONE);
 }
 
 /// MovePicker constructor for ProbCut: we generate captures with SEE greater
 /// than or equal to the given threshold.
 MovePicker::MovePicker(const Position& p, Move ttm, Value th, const CapturePieceToHistory* cph)
-           : pos(p), captureHistory(cph), threshold(th) {
+           : pos(p), captureHistory(cph), ttMove(ttm), threshold(th) {
 
   assert(!pos.checkers());
 
-  stage = PROBCUT_TT;
+  stage = PROBCUT_TT + !(ttm && pos.capture(ttm)
-  ttMove =   ttm
+                             && pos.pseudo_legal(ttm)
-          && pos.capture(ttm)
+                             && pos.see_ge(ttm, threshold));
-          && pos.pseudo_legal(ttm)
-          && pos.see_ge(ttm, threshold) ? ttm : MOVE_NONE;
-  stage += (ttMove == MOVE_NONE);
 }
 
 /// MovePicker::score() assigns a numerical value to each move in a list, used
@@ -106,16 +101,17 @@ void MovePicker::score() {
   static_assert(Type == CAPTURES || Type == QUIETS || Type == EVASIONS, "Wrong type");
 
   for (auto& m : *this)
-      if (Type == CAPTURES)
+      if constexpr (Type == CAPTURES)
           m.value =  int(PieceValue[MG][pos.piece_on(to_sq(m))]) * 6
                    + (*captureHistory)[pos.moved_piece(m)][to_sq(m)][type_of(pos.piece_on(to_sq(m)))];
 
-      else if (Type == QUIETS)
+      else if constexpr (Type == QUIETS)
           m.value =      (*mainHistory)[pos.side_to_move()][from_to(m)]
                    + 2 * (*continuationHistory[0])[pos.moved_piece(m)][to_sq(m)]
-                   + 2 * (*continuationHistory[1])[pos.moved_piece(m)][to_sq(m)]
+                   +     (*continuationHistory[1])[pos.moved_piece(m)][to_sq(m)]
-                   + 2 * (*continuationHistory[3])[pos.moved_piece(m)][to_sq(m)]
+                   +     (*continuationHistory[3])[pos.moved_piece(m)][to_sq(m)]
-                   +     (*continuationHistory[5])[pos.moved_piece(m)][to_sq(m)];
+                   +     (*continuationHistory[5])[pos.moved_piece(m)][to_sq(m)]
+                   + (ply < MAX_LPH ? std::min(4, depth / 3) * (*lowPlyHistory)[ply][from_to(m)] : 0);
 
       else // Type == EVASIONS
       {
@@ -123,8 +119,8 @@ void MovePicker::score() {
               m.value =  PieceValue[MG][pos.piece_on(to_sq(m))]
                        - Value(type_of(pos.moved_piece(m)));
           else
-              m.value =  (*mainHistory)[pos.side_to_move()][from_to(m)]
+              m.value =      (*mainHistory)[pos.side_to_move()][from_to(m)]
-                       + (*continuationHistory[0])[pos.moved_piece(m)][to_sq(m)]
+                       + 2 * (*continuationHistory[0])[pos.moved_piece(m)][to_sq(m)]
                        - (1 << 28);
       }
 }
@@ -148,7 +144,7 @@ Move MovePicker::select(Pred filter) {
 }
 
 /// MovePicker::next_move() is the most important method of the MovePicker class. It
-/// returns a new pseudo legal move every time it is called until there are no more
+/// returns a new pseudo-legal move every time it is called until there are no more
 /// moves left, picking the move with the highest score from a list of generated moves.
 Move MovePicker::next_move(bool skipQuiets) {
 
@@ -174,7 +170,7 @@ top:
 
   case GOOD_CAPTURE:
       if (select<Best>([&](){
-                       return pos.see_ge(*cur, Value(-55 * cur->value / 1024)) ?
+                       return pos.see_ge(*cur, Value(-69 * cur->value / 1024)) ?
                               // Move losing capture to endBadCaptures to be tried later
                               true : (*endBadCaptures++ = *cur, false); }))
           return *(cur - 1);
@@ -189,7 +185,7 @@ top:
           --endMoves;
 
       ++stage;
-      /* fallthrough */
+      [[fallthrough]];
 
   case REFUTATION:
       if (select<Next>([&](){ return    *cur != MOVE_NONE
@@ -197,7 +193,7 @@ top:
                                     &&  pos.pseudo_legal(*cur); }))
           return *(cur - 1);
       ++stage;
-      /* fallthrough */
+      [[fallthrough]];
 
   case QUIET_INIT:
       if (!skipQuiets)
@@ -210,7 +206,7 @@ top:
       }
 
       ++stage;
-      /* fallthrough */
+      [[fallthrough]];
 
   case QUIET:
       if (   !skipQuiets
@@ -224,7 +220,7 @@ top:
       endMoves = endBadCaptures;
 
       ++stage;
-      /* fallthrough */
+      [[fallthrough]];
 
   case BAD_CAPTURE:
       return select<Next>([](){ return true; });
@@ -235,7 +231,7 @@ top:
 
       score<EVASIONS>();
       ++stage;
-      /* fallthrough */
+      [[fallthrough]];
 
   case EVASION:
       return select<Best>([](){ return true; });
@@ -253,14 +249,14 @@ top:
           return MOVE_NONE;
 
       ++stage;
-      /* fallthrough */
+      [[fallthrough]];
 
   case QCHECK_INIT:
       cur = moves;
       endMoves = generate<QUIET_CHECKS>(pos, cur);
 
       ++stage;
-      /* fallthrough */
+      [[fallthrough]];
 
   case QCHECK:
       return select<Next>([](){ return true; });
@@ -269,3 +265,5 @@ top:
   assert(false);
   return MOVE_NONE; // Silence warning
 }
+
+} // namespace Stockfish

src/movepick.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -29,6 +27,8 @@
 #include "position.h"
 #include "types.h"
 
+namespace Stockfish {
+
 /// StatsEntry stores the stat table value. It is usually a number but could
 /// be a move or even a nested history. We use a class instead of naked value
 /// to directly call history update operator<<() on the entry so to use stats
@@ -86,7 +86,13 @@ enum StatsType { NoCaptures, Captures };
 /// unsuccessful during the current search, and is used for reduction and move
 /// ordering decisions. It uses 2 tables (one for each color) indexed by
 /// the move's from and to squares, see www.chessprogramming.org/Butterfly_Boards
-typedef Stats<int16_t, 10692, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyHistory;
+typedef Stats<int16_t, 13365, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyHistory;
+
+/// At higher depths LowPlyHistory records successful quiet moves near the root
+/// and quiet moves which are/were in the PV (ttPv). It is cleared with each new
+/// search and filled during iterative deepening.
+constexpr int MAX_LPH = 4;
+typedef Stats<int16_t, 10692, MAX_LPH, int(SQUARE_NB) * int(SQUARE_NB)> LowPlyHistory;
 
 /// CounterMoveHistory stores counter moves indexed by [piece][to] of the previous
 /// move, see www.chessprogramming.org/Countermove_Heuristic
@@ -104,12 +110,12 @@ typedef Stats<int16_t, 29952, PIECE_NB, SQUARE_NB> PieceToHistory;
 typedef Stats<PieceToHistory, NOT_USED, PIECE_NB, SQUARE_NB> ContinuationHistory;
 
 
-/// MovePicker class is used to pick one pseudo legal move at a time from the
+/// MovePicker class is used to pick one pseudo-legal move at a time from the
 /// current position. The most important method is next_move(), which returns a
-/// new pseudo legal move each time it is called, until there are no moves left,
+/// new pseudo-legal move each time it is called, until there are no moves left,
-/// when MOVE_NONE is returned. In order to improve the efficiency of the alpha
+/// when MOVE_NONE is returned. In order to improve the efficiency of the
-/// beta algorithm, MovePicker attempts to return the moves which are most likely
+/// alpha-beta algorithm, MovePicker attempts to return the moves which are most
-/// to get a cut-off first.
+/// likely to get a cut-off first.
 class MovePicker {
 
   enum PickType { Next, Best };
@@ -123,10 +129,12 @@ public:
                                            const PieceToHistory**,
                                            Square);
   MovePicker(const Position&, Move, Depth, const ButterflyHistory*,
+                                           const LowPlyHistory*,
                                            const CapturePieceToHistory*,
                                            const PieceToHistory**,
                                            Move,
-                                           Move*);
+                                           const Move*,
+                                           int);
   Move next_move(bool skipQuiets = false);
 
 private:
@@ -137,6 +145,7 @@ private:
 
   const Position& pos;
   const ButterflyHistory* mainHistory;
+  const LowPlyHistory* lowPlyHistory;
   const CapturePieceToHistory* captureHistory;
   const PieceToHistory** continuationHistory;
   Move ttMove;
@@ -145,7 +154,10 @@ private:
   Square recaptureSquare;
   Value threshold;
   Depth depth;
+  int ply;
   ExtMove moves[MAX_MOVES];
 };
 
+} // namespace Stockfish
+
 #endif // #ifndef MOVEPICK_H_INCLUDED

src/nnue/evaluate_nnue.cpp

@@ -0,0 +1,443 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+// Code for calculating NNUE evaluation function
+
+#include <iostream>
+#include <set>
+#include <sstream>
+#include <iomanip>
+#include <fstream>
+
+#include "../evaluate.h"
+#include "../position.h"
+#include "../misc.h"
+#include "../uci.h"
+#include "../types.h"
+
+#include "evaluate_nnue.h"
+
+namespace Stockfish::Eval::NNUE {
+
+  // Input feature converter
+  LargePagePtr<FeatureTransformer> featureTransformer;
+
+  // Evaluation function
+  AlignedPtr<Network> network[LayerStacks];
+
+  // Evaluation function file name
+  std::string fileName;
+  std::string netDescription;
+
+  namespace Detail {
+
+  // Initialize the evaluation function parameters
+  template <typename T>
+  void initialize(AlignedPtr<T>& pointer) {
+
+    pointer.reset(reinterpret_cast<T*>(std_aligned_alloc(alignof(T), sizeof(T))));
+    std::memset(pointer.get(), 0, sizeof(T));
+  }
+
+  template <typename T>
+  void initialize(LargePagePtr<T>& pointer) {
+
+    static_assert(alignof(T) <= 4096, "aligned_large_pages_alloc() may fail for such a big alignment requirement of T");
+    pointer.reset(reinterpret_cast<T*>(aligned_large_pages_alloc(sizeof(T))));
+    std::memset(pointer.get(), 0, sizeof(T));
+  }
+
+  // Read evaluation function parameters
+  template <typename T>
+  bool read_parameters(std::istream& stream, T& reference) {
+
+    std::uint32_t header;
+    header = read_little_endian<std::uint32_t>(stream);
+    if (!stream || header != T::get_hash_value()) return false;
+    return reference.read_parameters(stream);
+  }
+
+  // Write evaluation function parameters
+  template <typename T>
+  bool write_parameters(std::ostream& stream, const T& reference) {
+
+    write_little_endian<std::uint32_t>(stream, T::get_hash_value());
+    return reference.write_parameters(stream);
+  }
+
+  }  // namespace Detail
+
+  // Initialize the evaluation function parameters
+  void initialize() {
+
+    Detail::initialize(featureTransformer);
+    for (std::size_t i = 0; i < LayerStacks; ++i)
+      Detail::initialize(network[i]);
+  }
+
+  // Read network header
+  bool read_header(std::istream& stream, std::uint32_t* hashValue, std::string* desc)
+  {
+    std::uint32_t version, size;
+
+    version     = read_little_endian<std::uint32_t>(stream);
+    *hashValue  = read_little_endian<std::uint32_t>(stream);
+    size        = read_little_endian<std::uint32_t>(stream);
+    if (!stream || version != Version) return false;
+    desc->resize(size);
+    stream.read(&(*desc)[0], size);
+    return !stream.fail();
+  }
+
+  // Write network header
+  bool write_header(std::ostream& stream, std::uint32_t hashValue, const std::string& desc)
+  {
+    write_little_endian<std::uint32_t>(stream, Version);
+    write_little_endian<std::uint32_t>(stream, hashValue);
+    write_little_endian<std::uint32_t>(stream, desc.size());
+    stream.write(&desc[0], desc.size());
+    return !stream.fail();
+  }
+
+  // Read network parameters
+  bool read_parameters(std::istream& stream) {
+
+    std::uint32_t hashValue;
+    if (!read_header(stream, &hashValue, &netDescription)) return false;
+    if (hashValue != HashValue) return false;
+    if (!Detail::read_parameters(stream, *featureTransformer)) return false;
+    for (std::size_t i = 0; i < LayerStacks; ++i)
+      if (!Detail::read_parameters(stream, *(network[i]))) return false;
+    return stream && stream.peek() == std::ios::traits_type::eof();
+  }
+
+  // Write network parameters
+  bool write_parameters(std::ostream& stream) {
+
+    if (!write_header(stream, HashValue, netDescription)) return false;
+    if (!Detail::write_parameters(stream, *featureTransformer)) return false;
+    for (std::size_t i = 0; i < LayerStacks; ++i)
+      if (!Detail::write_parameters(stream, *(network[i]))) return false;
+    return (bool)stream;
+  }
+
+  // Evaluation function. Perform differential calculation.
+  Value evaluate(const Position& pos, bool adjusted) {
+
+    // We manually align the arrays on the stack because with gcc < 9.3
+    // overaligning stack variables with alignas() doesn't work correctly.
+
+    constexpr uint64_t alignment = CacheLineSize;
+
+#if defined(ALIGNAS_ON_STACK_VARIABLES_BROKEN)
+    TransformedFeatureType transformedFeaturesUnaligned[
+      FeatureTransformer::BufferSize + alignment / sizeof(TransformedFeatureType)];
+    char bufferUnaligned[Network::BufferSize + alignment];
+
+    auto* transformedFeatures = align_ptr_up<alignment>(&transformedFeaturesUnaligned[0]);
+    auto* buffer = align_ptr_up<alignment>(&bufferUnaligned[0]);
+#else
+    alignas(alignment)
+      TransformedFeatureType transformedFeatures[FeatureTransformer::BufferSize];
+    alignas(alignment) char buffer[Network::BufferSize];
+#endif
+
+    ASSERT_ALIGNED(transformedFeatures, alignment);
+    ASSERT_ALIGNED(buffer, alignment);
+
+    const std::size_t bucket = (pos.count<ALL_PIECES>() - 1) / 4;
+    const auto psqt = featureTransformer->transform(pos, transformedFeatures, bucket);
+    const auto output = network[bucket]->propagate(transformedFeatures, buffer);
+
+    int materialist = psqt;
+    int positional  = output[0];
+
+    int delta_npm = abs(pos.non_pawn_material(WHITE) - pos.non_pawn_material(BLACK));
+    int entertainment = (adjusted && delta_npm <= BishopValueMg - KnightValueMg ? 7 : 0);
+
+    int A = 128 - entertainment;
+    int B = 128 + entertainment;
+
+    int sum = (A * materialist + B * positional) / 128;
+
+    return static_cast<Value>( sum / OutputScale );
+  }
+
+  struct NnueEvalTrace {
+    static_assert(LayerStacks == PSQTBuckets);
+
+    Value psqt[LayerStacks];
+    Value positional[LayerStacks];
+    std::size_t correctBucket;
+  };
+
+  static NnueEvalTrace trace_evaluate(const Position& pos) {
+
+    // We manually align the arrays on the stack because with gcc < 9.3
+    // overaligning stack variables with alignas() doesn't work correctly.
+
+    constexpr uint64_t alignment = CacheLineSize;
+
+#if defined(ALIGNAS_ON_STACK_VARIABLES_BROKEN)
+    TransformedFeatureType transformedFeaturesUnaligned[
+      FeatureTransformer::BufferSize + alignment / sizeof(TransformedFeatureType)];
+    char bufferUnaligned[Network::BufferSize + alignment];
+
+    auto* transformedFeatures = align_ptr_up<alignment>(&transformedFeaturesUnaligned[0]);
+    auto* buffer = align_ptr_up<alignment>(&bufferUnaligned[0]);
+#else
+    alignas(alignment)
+      TransformedFeatureType transformedFeatures[FeatureTransformer::BufferSize];
+    alignas(alignment) char buffer[Network::BufferSize];
+#endif
+
+    ASSERT_ALIGNED(transformedFeatures, alignment);
+    ASSERT_ALIGNED(buffer, alignment);
+
+    NnueEvalTrace t{};
+    t.correctBucket = (pos.count<ALL_PIECES>() - 1) / 4;
+    for (std::size_t bucket = 0; bucket < LayerStacks; ++bucket) {
+      const auto psqt = featureTransformer->transform(pos, transformedFeatures, bucket);
+      const auto output = network[bucket]->propagate(transformedFeatures, buffer);
+
+      int materialist = psqt;
+      int positional  = output[0];
+
+      t.psqt[bucket] = static_cast<Value>( materialist / OutputScale );
+      t.positional[bucket] = static_cast<Value>( positional / OutputScale );
+    }
+
+    return t;
+  }
+
+  static const std::string PieceToChar(" PNBRQK  pnbrqk");
+
+  // Requires the buffer to have capacity for at least 5 values
+  static void format_cp_compact(Value v, char* buffer) {
+
+    buffer[0] = (v < 0 ? '-' : v > 0 ? '+' : ' ');
+
+    int cp = std::abs(100 * v / PawnValueEg);
+
+    if (cp >= 10000)
+    {
+      buffer[1] = '0' + cp / 10000; cp %= 10000;
+      buffer[2] = '0' + cp / 1000; cp %= 1000;
+      buffer[3] = '0' + cp / 100; cp %= 100;
+      buffer[4] = ' ';
+    }
+    else if (cp >= 1000)
+    {
+      buffer[1] = '0' + cp / 1000; cp %= 1000;
+      buffer[2] = '0' + cp / 100; cp %= 100;
+      buffer[3] = '.';
+      buffer[4] = '0' + cp / 10;
+    }
+    else
+    {
+      buffer[1] = '0' + cp / 100; cp %= 100;
+      buffer[2] = '.';
+      buffer[3] = '0' + cp / 10; cp %= 10;
+      buffer[4] = '0' + cp / 1;
+    }
+  }
+
+  // Requires the buffer to have capacity for at least 7 values
+  static void format_cp_aligned_dot(Value v, char* buffer) {
+    buffer[0] = (v < 0 ? '-' : v > 0 ? '+' : ' ');
+
+    int cp = std::abs(100 * v / PawnValueEg);
+
+    if (cp >= 10000)
+    {
+      buffer[1] = '0' + cp / 10000; cp %= 10000;
+      buffer[2] = '0' + cp / 1000; cp %= 1000;
+      buffer[3] = '0' + cp / 100; cp %= 100;
+      buffer[4] = '.';
+      buffer[5] = '0' + cp / 10; cp %= 10;
+      buffer[6] = '0' + cp;
+    }
+    else if (cp >= 1000)
+    {
+      buffer[1] = ' ';
+      buffer[2] = '0' + cp / 1000; cp %= 1000;
+      buffer[3] = '0' + cp / 100; cp %= 100;
+      buffer[4] = '.';
+      buffer[5] = '0' + cp / 10; cp %= 10;
+      buffer[6] = '0' + cp;
+    }
+    else
+    {
+      buffer[1] = ' ';
+      buffer[2] = ' ';
+      buffer[3] = '0' + cp / 100; cp %= 100;
+      buffer[4] = '.';
+      buffer[5] = '0' + cp / 10; cp %= 10;
+      buffer[6] = '0' + cp / 1;
+    }
+  }
+
+
+  // trace() returns a string with the value of each piece on a board,
+  // and a table for (PSQT, Layers) values bucket by bucket.
+
+  std::string trace(Position& pos) {
+
+    std::stringstream ss;
+
+    char board[3*8+1][8*8+2];
+    std::memset(board, ' ', sizeof(board));
+    for (int row = 0; row < 3*8+1; ++row)
+      board[row][8*8+1] = '\0';
+
+    // A lambda to output one box of the board
+    auto writeSquare = [&board](File file, Rank rank, Piece pc, Value value) {
+
+      const int x = ((int)file) * 8;
+      const int y = (7 - (int)rank) * 3;
+      for (int i = 1; i < 8; ++i)
+         board[y][x+i] = board[y+3][x+i] = '-';
+      for (int i = 1; i < 3; ++i)
+         board[y+i][x] = board[y+i][x+8] = '|';
+      board[y][x] = board[y][x+8] = board[y+3][x+8] = board[y+3][x] = '+';
+      if (pc != NO_PIECE)
+        board[y+1][x+4] = PieceToChar[pc];
+      if (value != VALUE_NONE)
+        format_cp_compact(value, &board[y+2][x+2]);
+    };
+
+    // We estimate the value of each piece by doing a differential evaluation from
+    // the current base eval, simulating the removal of the piece from its square.
+    Value base = evaluate(pos);
+    base = pos.side_to_move() == WHITE ? base : -base;
+
+    for (File f = FILE_A; f <= FILE_H; ++f)
+      for (Rank r = RANK_1; r <= RANK_8; ++r)
+      {
+        Square sq = make_square(f, r);
+        Piece pc = pos.piece_on(sq);
+        Value v = VALUE_NONE;
+
+        if (pc != NO_PIECE && type_of(pc) != KING)
+        {
+          auto st = pos.state();
+
+          pos.remove_piece(sq);
+          st->accumulator.computed[WHITE] = false;
+          st->accumulator.computed[BLACK] = false;
+
+          Value eval = evaluate(pos);
+          eval = pos.side_to_move() == WHITE ? eval : -eval;
+          v = base - eval;
+
+          pos.put_piece(pc, sq);
+          st->accumulator.computed[WHITE] = false;
+          st->accumulator.computed[BLACK] = false;
+        }
+
+        writeSquare(f, r, pc, v);
+      }
+
+    ss << " NNUE derived piece values:\n";
+    for (int row = 0; row < 3*8+1; ++row)
+        ss << board[row] << '\n';
+    ss << '\n';
+
+    auto t = trace_evaluate(pos);
+
+    ss << " NNUE network contributions "
+       << (pos.side_to_move() == WHITE ? "(White to move)" : "(Black to move)") << std::endl
+       << "+------------+------------+------------+------------+\n"
+       << "|   Bucket   |  Material  | Positional |   Total    |\n"
+       << "|            |   (PSQT)   |  (Layers)  |            |\n"
+       << "+------------+------------+------------+------------+\n";
+
+    for (std::size_t bucket = 0; bucket < LayerStacks; ++bucket)
+    {
+      char buffer[3][8];
+      std::memset(buffer, '\0', sizeof(buffer));
+
+      format_cp_aligned_dot(t.psqt[bucket], buffer[0]);
+      format_cp_aligned_dot(t.positional[bucket], buffer[1]);
+      format_cp_aligned_dot(t.psqt[bucket] + t.positional[bucket], buffer[2]);
+
+      ss <<  "|  " << bucket    << "        "
+         << " |  " << buffer[0] << "  "
+         << " |  " << buffer[1] << "  "
+         << " |  " << buffer[2] << "  "
+         << " |";
+      if (bucket == t.correctBucket)
+          ss << " <-- this bucket is used";
+      ss << '\n';
+    }
+
+    ss << "+------------+------------+------------+------------+\n";
+
+    return ss.str();
+  }
+
+
+  // Load eval, from a file stream or a memory stream
+  bool load_eval(std::string name, std::istream& stream) {
+
+    initialize();
+    fileName = name;
+    return read_parameters(stream);
+  }
+
+  // Save eval, to a file stream or a memory stream
+  bool save_eval(std::ostream& stream) {
+
+    if (fileName.empty())
+      return false;
+
+    return write_parameters(stream);
+  }
+
+  /// Save eval, to a file given by its name
+  bool save_eval(const std::optional<std::string>& filename) {
+
+    std::string actualFilename;
+    std::string msg;
+
+    if (filename.has_value())
+        actualFilename = filename.value();
+    else
+    {
+        if (eval_file_loaded != EvalFileDefaultName)
+        {
+             msg = "Failed to export a net. A non-embedded net can only be saved if the filename is specified";
+
+             sync_cout << msg << sync_endl;
+             return false;
+        }
+        actualFilename = EvalFileDefaultName;
+    }
+
+    std::ofstream stream(actualFilename, std::ios_base::binary);
+    bool saved = save_eval(stream);
+
+    msg = saved ? "Network saved successfully to " + actualFilename
+                : "Failed to export a net";
+
+    sync_cout << msg << sync_endl;
+    return saved;
+  }
+
+
+} // namespace Stockfish::Eval::NNUE

src/nnue/evaluate_nnue.h

@@ -0,0 +1,59 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+// header used in NNUE evaluation function
+
+#ifndef NNUE_EVALUATE_NNUE_H_INCLUDED
+#define NNUE_EVALUATE_NNUE_H_INCLUDED
+
+#include "nnue_feature_transformer.h"
+
+#include <memory>
+
+namespace Stockfish::Eval::NNUE {
+
+  // Hash value of evaluation function structure
+  constexpr std::uint32_t HashValue =
+      FeatureTransformer::get_hash_value() ^ Network::get_hash_value();
+
+  // Deleter for automating release of memory area
+  template <typename T>
+  struct AlignedDeleter {
+    void operator()(T* ptr) const {
+      ptr->~T();
+      std_aligned_free(ptr);
+    }
+  };
+
+  template <typename T>
+  struct LargePageDeleter {
+    void operator()(T* ptr) const {
+      ptr->~T();
+      aligned_large_pages_free(ptr);
+    }
+  };
+
+  template <typename T>
+  using AlignedPtr = std::unique_ptr<T, AlignedDeleter<T>>;
+
+  template <typename T>
+  using LargePagePtr = std::unique_ptr<T, LargePageDeleter<T>>;
+
+}  // namespace Stockfish::Eval::NNUE
+
+#endif // #ifndef NNUE_EVALUATE_NNUE_H_INCLUDED

src/nnue/features/half_ka_v2.cpp

@@ -0,0 +1,85 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+//Definition of input features HalfKAv2 of NNUE evaluation function
+
+#include "half_ka_v2.h"
+
+#include "../../position.h"
+
+namespace Stockfish::Eval::NNUE::Features {
+
+  // Orient a square according to perspective (rotates by 180 for black)
+  inline Square HalfKAv2::orient(Color perspective, Square s) {
+    return Square(int(s) ^ (bool(perspective) * 56));
+  }
+
+  // Index of a feature for a given king position and another piece on some square
+  inline IndexType HalfKAv2::make_index(Color perspective, Square s, Piece pc, Square ksq) {
+    return IndexType(orient(perspective, s) + PieceSquareIndex[perspective][pc] + PS_NB * ksq);
+  }
+
+  // Get a list of indices for active features
+  void HalfKAv2::append_active_indices(
+    const Position& pos,
+    Color perspective,
+    ValueListInserter<IndexType> active
+  ) {
+    Square ksq = orient(perspective, pos.square<KING>(perspective));
+    Bitboard bb = pos.pieces();
+    while (bb)
+    {
+      Square s = pop_lsb(bb);
+      active.push_back(make_index(perspective, s, pos.piece_on(s), ksq));
+    }
+  }
+
+
+  // append_changed_indices() : get a list of indices for recently changed features
+
+  void HalfKAv2::append_changed_indices(
+    Square ksq,
+    StateInfo* st,
+    Color perspective,
+    ValueListInserter<IndexType> removed,
+    ValueListInserter<IndexType> added
+  ) {
+    const auto& dp = st->dirtyPiece;
+    Square oriented_ksq = orient(perspective, ksq);
+    for (int i = 0; i < dp.dirty_num; ++i) {
+      Piece pc = dp.piece[i];
+      if (dp.from[i] != SQ_NONE)
+        removed.push_back(make_index(perspective, dp.from[i], pc, oriented_ksq));
+      if (dp.to[i] != SQ_NONE)
+        added.push_back(make_index(perspective, dp.to[i], pc, oriented_ksq));
+    }
+  }
+
+  int HalfKAv2::update_cost(StateInfo* st) {
+    return st->dirtyPiece.dirty_num;
+  }
+
+  int HalfKAv2::refresh_cost(const Position& pos) {
+    return pos.count<ALL_PIECES>();
+  }
+
+  bool HalfKAv2::requires_refresh(StateInfo* st, Color perspective) {
+    return st->dirtyPiece.piece[0] == make_piece(perspective, KING);
+  }
+
+}  // namespace Stockfish::Eval::NNUE::Features

src/nnue/features/half_ka_v2.h

@@ -0,0 +1,111 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+//Definition of input features HalfKP of NNUE evaluation function
+
+#ifndef NNUE_FEATURES_HALF_KA_V2_H_INCLUDED
+#define NNUE_FEATURES_HALF_KA_V2_H_INCLUDED
+
+#include "../nnue_common.h"
+
+#include "../../evaluate.h"
+#include "../../misc.h"
+
+namespace Stockfish {
+  struct StateInfo;
+}
+
+namespace Stockfish::Eval::NNUE::Features {
+
+  // Feature HalfKAv2: Combination of the position of own king
+  // and the position of pieces
+  class HalfKAv2 {
+
+    // unique number for each piece type on each square
+    enum {
+      PS_NONE     =  0,
+      PS_W_PAWN   =  0,
+      PS_B_PAWN   =  1 * SQUARE_NB,
+      PS_W_KNIGHT =  2 * SQUARE_NB,
+      PS_B_KNIGHT =  3 * SQUARE_NB,
+      PS_W_BISHOP =  4 * SQUARE_NB,
+      PS_B_BISHOP =  5 * SQUARE_NB,
+      PS_W_ROOK   =  6 * SQUARE_NB,
+      PS_B_ROOK   =  7 * SQUARE_NB,
+      PS_W_QUEEN  =  8 * SQUARE_NB,
+      PS_B_QUEEN  =  9 * SQUARE_NB,
+      PS_KING     =  10 * SQUARE_NB,
+      PS_NB = 11 * SQUARE_NB
+    };
+
+    static constexpr IndexType PieceSquareIndex[COLOR_NB][PIECE_NB] = {
+      // convention: W - us, B - them
+      // viewed from other side, W and B are reversed
+      { PS_NONE, PS_W_PAWN, PS_W_KNIGHT, PS_W_BISHOP, PS_W_ROOK, PS_W_QUEEN, PS_KING, PS_NONE,
+        PS_NONE, PS_B_PAWN, PS_B_KNIGHT, PS_B_BISHOP, PS_B_ROOK, PS_B_QUEEN, PS_KING, PS_NONE },
+      { PS_NONE, PS_B_PAWN, PS_B_KNIGHT, PS_B_BISHOP, PS_B_ROOK, PS_B_QUEEN, PS_KING, PS_NONE,
+        PS_NONE, PS_W_PAWN, PS_W_KNIGHT, PS_W_BISHOP, PS_W_ROOK, PS_W_QUEEN, PS_KING, PS_NONE }
+    };
+
+    // Orient a square according to perspective (rotates by 180 for black)
+    static Square orient(Color perspective, Square s);
+
+    // Index of a feature for a given king position and another piece on some square
+    static IndexType make_index(Color perspective, Square s, Piece pc, Square ksq);
+
+   public:
+    // Feature name
+    static constexpr const char* Name = "HalfKAv2(Friend)";
+
+    // Hash value embedded in the evaluation file
+    static constexpr std::uint32_t HashValue = 0x5f234cb8u;
+
+    // Number of feature dimensions
+    static constexpr IndexType Dimensions =
+        static_cast<IndexType>(SQUARE_NB) * static_cast<IndexType>(PS_NB);
+
+    // Maximum number of simultaneously active features.
+    static constexpr IndexType MaxActiveDimensions = 32;
+
+    // Get a list of indices for active features
+    static void append_active_indices(
+      const Position& pos,
+      Color perspective,
+      ValueListInserter<IndexType> active);
+
+    // Get a list of indices for recently changed features
+    static void append_changed_indices(
+      Square ksq,
+      StateInfo* st,
+      Color perspective,
+      ValueListInserter<IndexType> removed,
+      ValueListInserter<IndexType> added);
+
+    // Returns the cost of updating one perspective, the most costly one.
+    // Assumes no refresh needed.
+    static int update_cost(StateInfo* st);
+    static int refresh_cost(const Position& pos);
+
+    // Returns whether the change stored in this StateInfo means that
+    // a full accumulator refresh is required.
+    static bool requires_refresh(StateInfo* st, Color perspective);
+  };
+
+}  // namespace Stockfish::Eval::NNUE::Features
+
+#endif // #ifndef NNUE_FEATURES_HALF_KA_V2_H_INCLUDED

src/nnue/layers/affine_transform.h

@@ -0,0 +1,435 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+// Definition of layer AffineTransform of NNUE evaluation function
+
+#ifndef NNUE_LAYERS_AFFINE_TRANSFORM_H_INCLUDED
+#define NNUE_LAYERS_AFFINE_TRANSFORM_H_INCLUDED
+
+#include <iostream>
+#include "../nnue_common.h"
+
+namespace Stockfish::Eval::NNUE::Layers {
+
+  // Affine transformation layer
+  template <typename PreviousLayer, IndexType OutDims>
+  class AffineTransform {
+   public:
+    // Input/output type
+    using InputType = typename PreviousLayer::OutputType;
+    using OutputType = std::int32_t;
+    static_assert(std::is_same<InputType, std::uint8_t>::value, "");
+
+    // Number of input/output dimensions
+    static constexpr IndexType InputDimensions =
+        PreviousLayer::OutputDimensions;
+    static constexpr IndexType OutputDimensions = OutDims;
+    static constexpr IndexType PaddedInputDimensions =
+        ceil_to_multiple<IndexType>(InputDimensions, MaxSimdWidth);
+#if defined (USE_AVX512)
+    static constexpr const IndexType OutputSimdWidth = SimdWidth / 2;
+#elif defined (USE_SSSE3)
+    static constexpr const IndexType OutputSimdWidth = SimdWidth / 4;
+#endif
+
+    // Size of forward propagation buffer used in this layer
+    static constexpr std::size_t SelfBufferSize =
+        ceil_to_multiple(OutputDimensions * sizeof(OutputType), CacheLineSize);
+
+    // Size of the forward propagation buffer used from the input layer to this layer
+    static constexpr std::size_t BufferSize =
+        PreviousLayer::BufferSize + SelfBufferSize;
+
+    // Hash value embedded in the evaluation file
+    static constexpr std::uint32_t get_hash_value() {
+      std::uint32_t hashValue = 0xCC03DAE4u;
+      hashValue += OutputDimensions;
+      hashValue ^= PreviousLayer::get_hash_value() >> 1;
+      hashValue ^= PreviousLayer::get_hash_value() << 31;
+      return hashValue;
+    }
+
+    // Read network parameters
+    bool read_parameters(std::istream& stream) {
+      if (!previousLayer.read_parameters(stream)) return false;
+      for (std::size_t i = 0; i < OutputDimensions; ++i)
+        biases[i] = read_little_endian<BiasType>(stream);
+      for (std::size_t i = 0; i < OutputDimensions * PaddedInputDimensions; ++i)
+#if !defined (USE_SSSE3)
+        weights[i] = read_little_endian<WeightType>(stream);
+#else
+        weights[
+          (i / 4) % (PaddedInputDimensions / 4) * OutputDimensions * 4 +
+          i / PaddedInputDimensions * 4 +
+          i % 4
+        ] = read_little_endian<WeightType>(stream);
+#endif
+
+      return !stream.fail();
+    }
+
+    // Write network parameters
+    bool write_parameters(std::ostream& stream) const {
+      if (!previousLayer.write_parameters(stream)) return false;
+      for (std::size_t i = 0; i < OutputDimensions; ++i)
+          write_little_endian<BiasType>(stream, biases[i]);
+#if !defined (USE_SSSE3)
+      for (std::size_t i = 0; i < OutputDimensions * PaddedInputDimensions; ++i)
+          write_little_endian<WeightType>(stream, weights[i]);
+#else
+      std::unique_ptr<WeightType[]> unscrambledWeights = std::make_unique<WeightType[]>(OutputDimensions * PaddedInputDimensions);
+      for (std::size_t i = 0; i < OutputDimensions * PaddedInputDimensions; ++i) {
+          unscrambledWeights[i] =
+              weights[
+                (i / 4) % (PaddedInputDimensions / 4) * OutputDimensions * 4 +
+                i / PaddedInputDimensions * 4 +
+                i % 4
+              ];
+      }
+
+      for (std::size_t i = 0; i < OutputDimensions * PaddedInputDimensions; ++i)
+          write_little_endian<WeightType>(stream, unscrambledWeights[i]);
+#endif
+
+      return !stream.fail();
+    }
+
+    // Forward propagation
+    const OutputType* propagate(
+        const TransformedFeatureType* transformedFeatures, char* buffer) const {
+      const auto input = previousLayer.propagate(
+          transformedFeatures, buffer + SelfBufferSize);
+
+#if defined (USE_AVX512)
+
+      [[maybe_unused]] const __m512i Ones512 = _mm512_set1_epi16(1);
+
+      [[maybe_unused]] auto m512_hadd = [](__m512i sum, int bias) -> int {
+        return _mm512_reduce_add_epi32(sum) + bias;
+      };
+
+      [[maybe_unused]] auto m512_add_dpbusd_epi32 = [=](__m512i& acc, __m512i a, __m512i b) {
+#if defined (USE_VNNI)
+        acc = _mm512_dpbusd_epi32(acc, a, b);
+#else
+        __m512i product0 = _mm512_maddubs_epi16(a, b);
+        product0 = _mm512_madd_epi16(product0, Ones512);
+        acc = _mm512_add_epi32(acc, product0);
+#endif
+      };
+
+      [[maybe_unused]] auto m512_add_dpbusd_epi32x4 = [=](__m512i& acc, __m512i a0, __m512i b0, __m512i a1, __m512i b1,
+                                                                        __m512i a2, __m512i b2, __m512i a3, __m512i b3) {
+#if defined (USE_VNNI)
+        acc = _mm512_dpbusd_epi32(acc, a0, b0);
+        acc = _mm512_dpbusd_epi32(acc, a1, b1);
+        acc = _mm512_dpbusd_epi32(acc, a2, b2);
+        acc = _mm512_dpbusd_epi32(acc, a3, b3);
+#else
+        __m512i product0 = _mm512_maddubs_epi16(a0, b0);
+        __m512i product1 = _mm512_maddubs_epi16(a1, b1);
+        __m512i product2 = _mm512_maddubs_epi16(a2, b2);
+        __m512i product3 = _mm512_maddubs_epi16(a3, b3);
+        product0 = _mm512_adds_epi16(product0, product1);
+        product0 = _mm512_madd_epi16(product0, Ones512);
+        product2 = _mm512_adds_epi16(product2, product3);
+        product2 = _mm512_madd_epi16(product2, Ones512);
+        acc = _mm512_add_epi32(acc, _mm512_add_epi32(product0, product2));
+#endif
+      };
+
+#endif
+#if defined (USE_AVX2)
+
+      [[maybe_unused]] const __m256i Ones256 = _mm256_set1_epi16(1);
+
+      [[maybe_unused]] auto m256_hadd = [](__m256i sum, int bias) -> int {
+        __m128i sum128 = _mm_add_epi32(_mm256_castsi256_si128(sum), _mm256_extracti128_si256(sum, 1));
+        sum128 = _mm_add_epi32(sum128, _mm_shuffle_epi32(sum128, _MM_PERM_BADC));
+        sum128 = _mm_add_epi32(sum128, _mm_shuffle_epi32(sum128, _MM_PERM_CDAB));
+        return _mm_cvtsi128_si32(sum128) + bias;
+      };
+
+      [[maybe_unused]] auto m256_add_dpbusd_epi32 = [=](__m256i& acc, __m256i a, __m256i b) {
+#if defined (USE_VNNI)
+        acc = _mm256_dpbusd_epi32(acc, a, b);
+#else
+        __m256i product0 = _mm256_maddubs_epi16(a, b);
+        product0 = _mm256_madd_epi16(product0, Ones256);
+        acc = _mm256_add_epi32(acc, product0);
+#endif
+      };
+
+      [[maybe_unused]] auto m256_add_dpbusd_epi32x4 = [=](__m256i& acc, __m256i a0, __m256i b0, __m256i a1, __m256i b1,
+                                                                        __m256i a2, __m256i b2, __m256i a3, __m256i b3) {
+#if defined (USE_VNNI)
+        acc = _mm256_dpbusd_epi32(acc, a0, b0);
+        acc = _mm256_dpbusd_epi32(acc, a1, b1);
+        acc = _mm256_dpbusd_epi32(acc, a2, b2);
+        acc = _mm256_dpbusd_epi32(acc, a3, b3);
+#else
+        __m256i product0 = _mm256_maddubs_epi16(a0, b0);
+        __m256i product1 = _mm256_maddubs_epi16(a1, b1);
+        __m256i product2 = _mm256_maddubs_epi16(a2, b2);
+        __m256i product3 = _mm256_maddubs_epi16(a3, b3);
+        product0 = _mm256_adds_epi16(product0, product1);
+        product0 = _mm256_madd_epi16(product0, Ones256);
+        product2 = _mm256_adds_epi16(product2, product3);
+        product2 = _mm256_madd_epi16(product2, Ones256);
+        acc = _mm256_add_epi32(acc, _mm256_add_epi32(product0, product2));
+#endif
+      };
+
+#endif
+#if defined (USE_SSSE3)
+
+      [[maybe_unused]] const __m128i Ones128 = _mm_set1_epi16(1);
+
+      [[maybe_unused]] auto m128_hadd = [](__m128i sum, int bias) -> int {
+        sum = _mm_add_epi32(sum, _mm_shuffle_epi32(sum, 0x4E)); //_MM_PERM_BADC
+        sum = _mm_add_epi32(sum, _mm_shuffle_epi32(sum, 0xB1)); //_MM_PERM_CDAB
+        return _mm_cvtsi128_si32(sum) + bias;
+      };
+
+      [[maybe_unused]] auto m128_add_dpbusd_epi32 = [=](__m128i& acc, __m128i a, __m128i b) {
+        __m128i product0 = _mm_maddubs_epi16(a, b);
+        product0 = _mm_madd_epi16(product0, Ones128);
+        acc = _mm_add_epi32(acc, product0);
+      };
+
+      [[maybe_unused]] auto m128_add_dpbusd_epi32x4 = [=](__m128i& acc, __m128i a0, __m128i b0, __m128i a1, __m128i b1,
+                                                                        __m128i a2, __m128i b2, __m128i a3, __m128i b3) {
+        __m128i product0 = _mm_maddubs_epi16(a0, b0);
+        __m128i product1 = _mm_maddubs_epi16(a1, b1);
+        __m128i product2 = _mm_maddubs_epi16(a2, b2);
+        __m128i product3 = _mm_maddubs_epi16(a3, b3);
+        product0 = _mm_adds_epi16(product0, product1);
+        product0 = _mm_madd_epi16(product0, Ones128);
+        product2 = _mm_adds_epi16(product2, product3);
+        product2 = _mm_madd_epi16(product2, Ones128);
+        acc = _mm_add_epi32(acc, _mm_add_epi32(product0, product2));
+      };
+
+#endif
+
+#if defined (USE_AVX512)
+      using vec_t = __m512i;
+      #define vec_setzero _mm512_setzero_si512
+      #define vec_set_32 _mm512_set1_epi32
+      auto& vec_add_dpbusd_32 = m512_add_dpbusd_epi32;
+      auto& vec_add_dpbusd_32x4 = m512_add_dpbusd_epi32x4;
+      auto& vec_hadd = m512_hadd;
+#elif defined (USE_AVX2)
+      using vec_t = __m256i;
+      #define vec_setzero _mm256_setzero_si256
+      #define vec_set_32 _mm256_set1_epi32
+      auto& vec_add_dpbusd_32 = m256_add_dpbusd_epi32;
+      auto& vec_add_dpbusd_32x4 = m256_add_dpbusd_epi32x4;
+      auto& vec_hadd = m256_hadd;
+#elif defined (USE_SSSE3)
+      using vec_t = __m128i;
+      #define vec_setzero _mm_setzero_si128
+      #define vec_set_32 _mm_set1_epi32
+      auto& vec_add_dpbusd_32 = m128_add_dpbusd_epi32;
+      auto& vec_add_dpbusd_32x4 = m128_add_dpbusd_epi32x4;
+      auto& vec_hadd = m128_hadd;
+#endif
+
+#if defined (USE_SSSE3)
+      // Different layout, we process 4 inputs at a time, always.
+      static_assert(InputDimensions % 4 == 0);
+
+      const auto output = reinterpret_cast<OutputType*>(buffer);
+      const auto inputVector = reinterpret_cast<const vec_t*>(input);
+
+      static_assert(OutputDimensions % OutputSimdWidth == 0 || OutputDimensions == 1);
+
+      // OutputDimensions is either 1 or a multiple of SimdWidth
+      // because then it is also an input dimension.
+      if constexpr (OutputDimensions % OutputSimdWidth == 0)
+      {
+          constexpr IndexType NumChunks = InputDimensions / 4;
+
+          const auto input32 = reinterpret_cast<const std::int32_t*>(input);
+          vec_t* outptr = reinterpret_cast<vec_t*>(output);
+          std::memcpy(output, biases, OutputDimensions * sizeof(OutputType));
+
+          for (int i = 0; i < (int)NumChunks - 3; i += 4)
+          {
+              const vec_t in0 = vec_set_32(input32[i + 0]);
+              const vec_t in1 = vec_set_32(input32[i + 1]);
+              const vec_t in2 = vec_set_32(input32[i + 2]);
+              const vec_t in3 = vec_set_32(input32[i + 3]);
+              const auto col0 = reinterpret_cast<const vec_t*>(&weights[(i + 0) * OutputDimensions * 4]);
+              const auto col1 = reinterpret_cast<const vec_t*>(&weights[(i + 1) * OutputDimensions * 4]);
+              const auto col2 = reinterpret_cast<const vec_t*>(&weights[(i + 2) * OutputDimensions * 4]);
+              const auto col3 = reinterpret_cast<const vec_t*>(&weights[(i + 3) * OutputDimensions * 4]);
+              for (int j = 0; j * OutputSimdWidth < OutputDimensions; ++j)
+                  vec_add_dpbusd_32x4(outptr[j], in0, col0[j], in1, col1[j], in2, col2[j], in3, col3[j]);
+          }
+      }
+      else if constexpr (OutputDimensions == 1)
+      {
+#if defined (USE_AVX512)
+          if constexpr (PaddedInputDimensions % (SimdWidth * 2) != 0)
+          {
+              constexpr IndexType NumChunks = PaddedInputDimensions / SimdWidth;
+              const auto inputVector256 = reinterpret_cast<const __m256i*>(input);
+
+              __m256i sum0 = _mm256_setzero_si256();
+              const auto row0 = reinterpret_cast<const __m256i*>(&weights[0]);
+
+              for (int j = 0; j < (int)NumChunks; ++j)
+              {
+                  const __m256i in = inputVector256[j];
+                  m256_add_dpbusd_epi32(sum0, in, row0[j]);
+              }
+              output[0] = m256_hadd(sum0, biases[0]);
+          }
+          else
+#endif
+          {
+#if defined (USE_AVX512)
+              constexpr IndexType NumChunks = PaddedInputDimensions / (SimdWidth * 2);
+#else
+              constexpr IndexType NumChunks = PaddedInputDimensions / SimdWidth;
+#endif
+              vec_t sum0 = vec_setzero();
+              const auto row0 = reinterpret_cast<const vec_t*>(&weights[0]);
+
+              for (int j = 0; j < (int)NumChunks; ++j)
+              {
+                  const vec_t in = inputVector[j];
+                  vec_add_dpbusd_32(sum0, in, row0[j]);
+              }
+              output[0] = vec_hadd(sum0, biases[0]);
+          }
+      }
+
+#else
+
+// Use old implementation for the other architectures.
+
+      auto output = reinterpret_cast<OutputType*>(buffer);
+
+#if defined(USE_SSE2)
+      // At least a multiple of 16, with SSE2.
+      static_assert(InputDimensions % SimdWidth == 0);
+      constexpr IndexType NumChunks = InputDimensions / SimdWidth;
+      const __m128i Zeros = _mm_setzero_si128();
+      const auto inputVector = reinterpret_cast<const __m128i*>(input);
+
+#elif defined(USE_MMX)
+      static_assert(InputDimensions % SimdWidth == 0);
+      constexpr IndexType NumChunks = InputDimensions / SimdWidth;
+      const __m64 Zeros = _mm_setzero_si64();
+      const auto inputVector = reinterpret_cast<const __m64*>(input);
+
+#elif defined(USE_NEON)
+      static_assert(InputDimensions % SimdWidth == 0);
+      constexpr IndexType NumChunks = InputDimensions / SimdWidth;
+      const auto inputVector = reinterpret_cast<const int8x8_t*>(input);
+#endif
+
+      for (IndexType i = 0; i < OutputDimensions; ++i) {
+        const IndexType offset = i * PaddedInputDimensions;
+
+#if defined(USE_SSE2)
+        __m128i sumLo = _mm_cvtsi32_si128(biases[i]);
+        __m128i sumHi = Zeros;
+        const auto row = reinterpret_cast<const __m128i*>(&weights[offset]);
+        for (IndexType j = 0; j < NumChunks; ++j) {
+          __m128i row_j = _mm_load_si128(&row[j]);
+          __m128i input_j = _mm_load_si128(&inputVector[j]);
+          __m128i extendedRowLo = _mm_srai_epi16(_mm_unpacklo_epi8(row_j, row_j), 8);
+          __m128i extendedRowHi = _mm_srai_epi16(_mm_unpackhi_epi8(row_j, row_j), 8);
+          __m128i extendedInputLo = _mm_unpacklo_epi8(input_j, Zeros);
+          __m128i extendedInputHi = _mm_unpackhi_epi8(input_j, Zeros);
+          __m128i productLo = _mm_madd_epi16(extendedRowLo, extendedInputLo);
+          __m128i productHi = _mm_madd_epi16(extendedRowHi, extendedInputHi);
+          sumLo = _mm_add_epi32(sumLo, productLo);
+          sumHi = _mm_add_epi32(sumHi, productHi);
+        }
+        __m128i sum = _mm_add_epi32(sumLo, sumHi);
+        __m128i sumHigh_64 = _mm_shuffle_epi32(sum, _MM_SHUFFLE(1, 0, 3, 2));
+        sum = _mm_add_epi32(sum, sumHigh_64);
+        __m128i sum_second_32 = _mm_shufflelo_epi16(sum, _MM_SHUFFLE(1, 0, 3, 2));
+        sum = _mm_add_epi32(sum, sum_second_32);
+        output[i] = _mm_cvtsi128_si32(sum);
+
+#elif defined(USE_MMX)
+        __m64 sumLo = _mm_cvtsi32_si64(biases[i]);
+        __m64 sumHi = Zeros;
+        const auto row = reinterpret_cast<const __m64*>(&weights[offset]);
+        for (IndexType j = 0; j < NumChunks; ++j) {
+          __m64 row_j = row[j];
+          __m64 input_j = inputVector[j];
+          __m64 extendedRowLo = _mm_srai_pi16(_mm_unpacklo_pi8(row_j, row_j), 8);
+          __m64 extendedRowHi = _mm_srai_pi16(_mm_unpackhi_pi8(row_j, row_j), 8);
+          __m64 extendedInputLo = _mm_unpacklo_pi8(input_j, Zeros);
+          __m64 extendedInputHi = _mm_unpackhi_pi8(input_j, Zeros);
+          __m64 productLo = _mm_madd_pi16(extendedRowLo, extendedInputLo);
+          __m64 productHi = _mm_madd_pi16(extendedRowHi, extendedInputHi);
+          sumLo = _mm_add_pi32(sumLo, productLo);
+          sumHi = _mm_add_pi32(sumHi, productHi);
+        }
+        __m64 sum = _mm_add_pi32(sumLo, sumHi);
+        sum = _mm_add_pi32(sum, _mm_unpackhi_pi32(sum, sum));
+        output[i] = _mm_cvtsi64_si32(sum);
+
+#elif defined(USE_NEON)
+        int32x4_t sum = {biases[i]};
+        const auto row = reinterpret_cast<const int8x8_t*>(&weights[offset]);
+        for (IndexType j = 0; j < NumChunks; ++j) {
+          int16x8_t product = vmull_s8(inputVector[j * 2], row[j * 2]);
+          product = vmlal_s8(product, inputVector[j * 2 + 1], row[j * 2 + 1]);
+          sum = vpadalq_s16(sum, product);
+        }
+        output[i] = sum[0] + sum[1] + sum[2] + sum[3];
+
+#else
+        OutputType sum = biases[i];
+        for (IndexType j = 0; j < InputDimensions; ++j) {
+          sum += weights[offset + j] * input[j];
+        }
+        output[i] = sum;
+#endif
+
+      }
+#if defined(USE_MMX)
+      _mm_empty();
+#endif
+
+#endif
+
+      return output;
+    }
+
+   private:
+    using BiasType = OutputType;
+    using WeightType = std::int8_t;
+
+    PreviousLayer previousLayer;
+
+    alignas(CacheLineSize) BiasType biases[OutputDimensions];
+    alignas(CacheLineSize) WeightType weights[OutputDimensions * PaddedInputDimensions];
+  };
+
+}  // namespace Stockfish::Eval::NNUE::Layers
+
+#endif // #ifndef NNUE_LAYERS_AFFINE_TRANSFORM_H_INCLUDED

src/nnue/layers/clipped_relu.h

@@ -0,0 +1,191 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+// Definition of layer ClippedReLU of NNUE evaluation function
+
+#ifndef NNUE_LAYERS_CLIPPED_RELU_H_INCLUDED
+#define NNUE_LAYERS_CLIPPED_RELU_H_INCLUDED
+
+#include "../nnue_common.h"
+
+namespace Stockfish::Eval::NNUE::Layers {
+
+  // Clipped ReLU
+  template <typename PreviousLayer>
+  class ClippedReLU {
+   public:
+    // Input/output type
+    using InputType = typename PreviousLayer::OutputType;
+    using OutputType = std::uint8_t;
+    static_assert(std::is_same<InputType, std::int32_t>::value, "");
+
+    // Number of input/output dimensions
+    static constexpr IndexType InputDimensions =
+        PreviousLayer::OutputDimensions;
+    static constexpr IndexType OutputDimensions = InputDimensions;
+
+    // Size of forward propagation buffer used in this layer
+    static constexpr std::size_t SelfBufferSize =
+        ceil_to_multiple(OutputDimensions * sizeof(OutputType), CacheLineSize);
+
+    // Size of the forward propagation buffer used from the input layer to this layer
+    static constexpr std::size_t BufferSize =
+        PreviousLayer::BufferSize + SelfBufferSize;
+
+    // Hash value embedded in the evaluation file
+    static constexpr std::uint32_t get_hash_value() {
+      std::uint32_t hashValue = 0x538D24C7u;
+      hashValue += PreviousLayer::get_hash_value();
+      return hashValue;
+    }
+
+    // Read network parameters
+    bool read_parameters(std::istream& stream) {
+      return previousLayer.read_parameters(stream);
+    }
+
+    // Write network parameters
+    bool write_parameters(std::ostream& stream) const {
+      return previousLayer.write_parameters(stream);
+    }
+
+    // Forward propagation
+    const OutputType* propagate(
+        const TransformedFeatureType* transformedFeatures, char* buffer) const {
+      const auto input = previousLayer.propagate(
+          transformedFeatures, buffer + SelfBufferSize);
+      const auto output = reinterpret_cast<OutputType*>(buffer);
+
+  #if defined(USE_AVX2)
+      if constexpr (InputDimensions % SimdWidth == 0) {
+        constexpr IndexType NumChunks = InputDimensions / SimdWidth;
+        const __m256i Zero = _mm256_setzero_si256();
+        const __m256i Offsets = _mm256_set_epi32(7, 3, 6, 2, 5, 1, 4, 0);
+        const auto in = reinterpret_cast<const __m256i*>(input);
+        const auto out = reinterpret_cast<__m256i*>(output);
+        for (IndexType i = 0; i < NumChunks; ++i) {
+          const __m256i words0 = _mm256_srai_epi16(_mm256_packs_epi32(
+              _mm256_load_si256(&in[i * 4 + 0]),
+              _mm256_load_si256(&in[i * 4 + 1])), WeightScaleBits);
+          const __m256i words1 = _mm256_srai_epi16(_mm256_packs_epi32(
+              _mm256_load_si256(&in[i * 4 + 2]),
+              _mm256_load_si256(&in[i * 4 + 3])), WeightScaleBits);
+          _mm256_store_si256(&out[i], _mm256_permutevar8x32_epi32(_mm256_max_epi8(
+              _mm256_packs_epi16(words0, words1), Zero), Offsets));
+        }
+      } else {
+        constexpr IndexType NumChunks = InputDimensions / (SimdWidth / 2);
+        const __m128i Zero = _mm_setzero_si128();
+        const auto in = reinterpret_cast<const __m128i*>(input);
+        const auto out = reinterpret_cast<__m128i*>(output);
+        for (IndexType i = 0; i < NumChunks; ++i) {
+          const __m128i words0 = _mm_srai_epi16(_mm_packs_epi32(
+              _mm_load_si128(&in[i * 4 + 0]),
+              _mm_load_si128(&in[i * 4 + 1])), WeightScaleBits);
+          const __m128i words1 = _mm_srai_epi16(_mm_packs_epi32(
+              _mm_load_si128(&in[i * 4 + 2]),
+              _mm_load_si128(&in[i * 4 + 3])), WeightScaleBits);
+          const __m128i packedbytes = _mm_packs_epi16(words0, words1);
+          _mm_store_si128(&out[i], _mm_max_epi8(packedbytes, Zero));
+        }
+      }
+      constexpr IndexType Start =
+        InputDimensions % SimdWidth == 0
+        ? InputDimensions / SimdWidth * SimdWidth
+        : InputDimensions / (SimdWidth / 2) * (SimdWidth / 2);
+
+  #elif defined(USE_SSE2)
+      constexpr IndexType NumChunks = InputDimensions / SimdWidth;
+
+  #ifdef USE_SSE41
+      const __m128i Zero = _mm_setzero_si128();
+  #else
+      const __m128i k0x80s = _mm_set1_epi8(-128);
+  #endif
+
+      const auto in = reinterpret_cast<const __m128i*>(input);
+      const auto out = reinterpret_cast<__m128i*>(output);
+      for (IndexType i = 0; i < NumChunks; ++i) {
+        const __m128i words0 = _mm_srai_epi16(_mm_packs_epi32(
+            _mm_load_si128(&in[i * 4 + 0]),
+            _mm_load_si128(&in[i * 4 + 1])), WeightScaleBits);
+        const __m128i words1 = _mm_srai_epi16(_mm_packs_epi32(
+            _mm_load_si128(&in[i * 4 + 2]),
+            _mm_load_si128(&in[i * 4 + 3])), WeightScaleBits);
+        const __m128i packedbytes = _mm_packs_epi16(words0, words1);
+        _mm_store_si128(&out[i],
+
+  #ifdef USE_SSE41
+          _mm_max_epi8(packedbytes, Zero)
+  #else
+          _mm_subs_epi8(_mm_adds_epi8(packedbytes, k0x80s), k0x80s)
+  #endif
+
+        );
+      }
+      constexpr IndexType Start = NumChunks * SimdWidth;
+
+  #elif defined(USE_MMX)
+      constexpr IndexType NumChunks = InputDimensions / SimdWidth;
+      const __m64 k0x80s = _mm_set1_pi8(-128);
+      const auto in = reinterpret_cast<const __m64*>(input);
+      const auto out = reinterpret_cast<__m64*>(output);
+      for (IndexType i = 0; i < NumChunks; ++i) {
+        const __m64 words0 = _mm_srai_pi16(
+            _mm_packs_pi32(in[i * 4 + 0], in[i * 4 + 1]),
+            WeightScaleBits);
+        const __m64 words1 = _mm_srai_pi16(
+            _mm_packs_pi32(in[i * 4 + 2], in[i * 4 + 3]),
+            WeightScaleBits);
+        const __m64 packedbytes = _mm_packs_pi16(words0, words1);
+        out[i] = _mm_subs_pi8(_mm_adds_pi8(packedbytes, k0x80s), k0x80s);
+      }
+      _mm_empty();
+      constexpr IndexType Start = NumChunks * SimdWidth;
+
+  #elif defined(USE_NEON)
+      constexpr IndexType NumChunks = InputDimensions / (SimdWidth / 2);
+      const int8x8_t Zero = {0};
+      const auto in = reinterpret_cast<const int32x4_t*>(input);
+      const auto out = reinterpret_cast<int8x8_t*>(output);
+      for (IndexType i = 0; i < NumChunks; ++i) {
+        int16x8_t shifted;
+        const auto pack = reinterpret_cast<int16x4_t*>(&shifted);
+        pack[0] = vqshrn_n_s32(in[i * 2 + 0], WeightScaleBits);
+        pack[1] = vqshrn_n_s32(in[i * 2 + 1], WeightScaleBits);
+        out[i] = vmax_s8(vqmovn_s16(shifted), Zero);
+      }
+      constexpr IndexType Start = NumChunks * (SimdWidth / 2);
+  #else
+      constexpr IndexType Start = 0;
+  #endif
+
+      for (IndexType i = Start; i < InputDimensions; ++i) {
+        output[i] = static_cast<OutputType>(
+            std::max(0, std::min(127, input[i] >> WeightScaleBits)));
+      }
+      return output;
+    }
+
+   private:
+    PreviousLayer previousLayer;
+  };
+
+}  // namespace Stockfish::Eval::NNUE::Layers
+
+#endif // NNUE_LAYERS_CLIPPED_RELU_H_INCLUDED

src/nnue/layers/input_slice.h

@@ -0,0 +1,73 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+// NNUE evaluation function layer InputSlice definition
+
+#ifndef NNUE_LAYERS_INPUT_SLICE_H_INCLUDED
+#define NNUE_LAYERS_INPUT_SLICE_H_INCLUDED
+
+#include "../nnue_common.h"
+
+namespace Stockfish::Eval::NNUE::Layers {
+
+// Input layer
+template <IndexType OutDims, IndexType Offset = 0>
+class InputSlice {
+ public:
+  // Need to maintain alignment
+  static_assert(Offset % MaxSimdWidth == 0, "");
+
+  // Output type
+  using OutputType = TransformedFeatureType;
+
+  // Output dimensionality
+  static constexpr IndexType OutputDimensions = OutDims;
+
+  // Size of forward propagation buffer used from the input layer to this layer
+  static constexpr std::size_t BufferSize = 0;
+
+  // Hash value embedded in the evaluation file
+  static constexpr std::uint32_t get_hash_value() {
+    std::uint32_t hashValue = 0xEC42E90Du;
+    hashValue ^= OutputDimensions ^ (Offset << 10);
+    return hashValue;
+  }
+
+  // Read network parameters
+  bool read_parameters(std::istream& /*stream*/) {
+    return true;
+  }
+
+  // Write network parameters
+  bool write_parameters(std::ostream& /*stream*/) const {
+    return true;
+  }
+
+  // Forward propagation
+  const OutputType* propagate(
+      const TransformedFeatureType* transformedFeatures,
+      char* /*buffer*/) const {
+    return transformedFeatures + Offset;
+  }
+
+ private:
+};
+
+}  // namespace Stockfish::Eval::NNUE::Layers
+
+#endif // #ifndef NNUE_LAYERS_INPUT_SLICE_H_INCLUDED

src/nnue/nnue_accumulator.h

@@ -0,0 +1,37 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+// Class for difference calculation of NNUE evaluation function
+
+#ifndef NNUE_ACCUMULATOR_H_INCLUDED
+#define NNUE_ACCUMULATOR_H_INCLUDED
+
+#include "nnue_architecture.h"
+
+namespace Stockfish::Eval::NNUE {
+
+  // Class that holds the result of affine transformation of input features
+  struct alignas(CacheLineSize) Accumulator {
+    std::int16_t accumulation[2][TransformedFeatureDimensions];
+    std::int32_t psqtAccumulation[2][PSQTBuckets];
+    bool computed[2];
+  };
+
+}  // namespace Stockfish::Eval::NNUE
+
+#endif // NNUE_ACCUMULATOR_H_INCLUDED

src/nnue/nnue_architecture.h

@@ -0,0 +1,60 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+// Input features and network structure used in NNUE evaluation function
+
+#ifndef NNUE_ARCHITECTURE_H_INCLUDED
+#define NNUE_ARCHITECTURE_H_INCLUDED
+
+#include "nnue_common.h"
+
+#include "features/half_ka_v2.h"
+
+#include "layers/input_slice.h"
+#include "layers/affine_transform.h"
+#include "layers/clipped_relu.h"
+
+namespace Stockfish::Eval::NNUE {
+
+  // Input features used in evaluation function
+  using FeatureSet = Features::HalfKAv2;
+
+  // Number of input feature dimensions after conversion
+  constexpr IndexType TransformedFeatureDimensions = 512;
+  constexpr IndexType PSQTBuckets = 8;
+  constexpr IndexType LayerStacks = 8;
+
+  namespace Layers {
+
+    // Define network structure
+    using InputLayer = InputSlice<TransformedFeatureDimensions * 2>;
+    using HiddenLayer1 = ClippedReLU<AffineTransform<InputLayer, 16>>;
+    using HiddenLayer2 = ClippedReLU<AffineTransform<HiddenLayer1, 32>>;
+    using OutputLayer = AffineTransform<HiddenLayer2, 1>;
+
+  }  // namespace Layers
+
+  using Network = Layers::OutputLayer;
+
+  static_assert(TransformedFeatureDimensions % MaxSimdWidth == 0, "");
+  static_assert(Network::OutputDimensions == 1, "");
+  static_assert(std::is_same<Network::OutputType, std::int32_t>::value, "");
+
+}  // namespace Stockfish::Eval::NNUE
+
+#endif // #ifndef NNUE_ARCHITECTURE_H_INCLUDED

src/nnue/nnue_common.h

@@ -0,0 +1,164 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+// Constants used in NNUE evaluation function
+
+#ifndef NNUE_COMMON_H_INCLUDED
+#define NNUE_COMMON_H_INCLUDED
+
+#include <cstring>
+#include <iostream>
+
+#include "../misc.h"  // for IsLittleEndian
+
+#if defined(USE_AVX2)
+#include <immintrin.h>
+
+#elif defined(USE_SSE41)
+#include <smmintrin.h>
+
+#elif defined(USE_SSSE3)
+#include <tmmintrin.h>
+
+#elif defined(USE_SSE2)
+#include <emmintrin.h>
+
+#elif defined(USE_MMX)
+#include <mmintrin.h>
+
+#elif defined(USE_NEON)
+#include <arm_neon.h>
+#endif
+
+namespace Stockfish::Eval::NNUE {
+
+  // Version of the evaluation file
+  constexpr std::uint32_t Version = 0x7AF32F20u;
+
+  // Constant used in evaluation value calculation
+  constexpr int OutputScale = 16;
+  constexpr int WeightScaleBits = 6;
+
+  // Size of cache line (in bytes)
+  constexpr std::size_t CacheLineSize = 64;
+
+  // SIMD width (in bytes)
+  #if defined(USE_AVX2)
+  constexpr std::size_t SimdWidth = 32;
+
+  #elif defined(USE_SSE2)
+  constexpr std::size_t SimdWidth = 16;
+
+  #elif defined(USE_MMX)
+  constexpr std::size_t SimdWidth = 8;
+
+  #elif defined(USE_NEON)
+  constexpr std::size_t SimdWidth = 16;
+  #endif
+
+  constexpr std::size_t MaxSimdWidth = 32;
+
+  // Type of input feature after conversion
+  using TransformedFeatureType = std::uint8_t;
+  using IndexType = std::uint32_t;
+
+  // Round n up to be a multiple of base
+  template <typename IntType>
+  constexpr IntType ceil_to_multiple(IntType n, IntType base) {
+      return (n + base - 1) / base * base;
+  }
+
+  // read_little_endian() is our utility to read an integer (signed or unsigned, any size)
+  // from a stream in little-endian order. We swap the byte order after the read if
+  // necessary to return a result with the byte ordering of the compiling machine.
+  template <typename IntType>
+  inline IntType read_little_endian(std::istream& stream) {
+      IntType result;
+
+      if (IsLittleEndian)
+          stream.read(reinterpret_cast<char*>(&result), sizeof(IntType));
+      else
+      {
+          std::uint8_t u[sizeof(IntType)];
+          typename std::make_unsigned<IntType>::type v = 0;
+
+          stream.read(reinterpret_cast<char*>(u), sizeof(IntType));
+          for (std::size_t i = 0; i < sizeof(IntType); ++i)
+              v = (v << 8) | u[sizeof(IntType) - i - 1];
+
+          std::memcpy(&result, &v, sizeof(IntType));
+      }
+
+      return result;
+  }
+
+  // write_little_endian() is our utility to write an integer (signed or unsigned, any size)
+  // to a stream in little-endian order. We swap the byte order before the write if
+  // necessary to always write in little endian order, independantly of the byte
+  // ordering of the compiling machine.
+  template <typename IntType>
+  inline void write_little_endian(std::ostream& stream, IntType value) {
+
+      if (IsLittleEndian)
+          stream.write(reinterpret_cast<const char*>(&value), sizeof(IntType));
+      else
+      {
+          std::uint8_t u[sizeof(IntType)];
+          typename std::make_unsigned<IntType>::type v = value;
+
+          std::size_t i = 0;
+          // if constexpr to silence the warning about shift by 8
+          if constexpr (sizeof(IntType) > 1)
+          {
+            for (; i + 1 < sizeof(IntType); ++i)
+            {
+                u[i] = v;
+                v >>= 8;
+            }
+          }
+          u[i] = v;
+
+          stream.write(reinterpret_cast<char*>(u), sizeof(IntType));
+      }
+  }
+
+  // read_little_endian(s, out, N) : read integers in bulk from a little indian stream.
+  // This reads N integers from stream s and put them in array out.
+  template <typename IntType>
+  inline void read_little_endian(std::istream& stream, IntType* out, std::size_t count) {
+      if (IsLittleEndian)
+          stream.read(reinterpret_cast<char*>(out), sizeof(IntType) * count);
+      else
+          for (std::size_t i = 0; i < count; ++i)
+              out[i] = read_little_endian<IntType>(stream);
+  }
+
+  // write_little_endian(s, values, N) : write integers in bulk to a little indian stream.
+  // This takes N integers from array values and writes them on stream s.
+  template <typename IntType>
+  inline void write_little_endian(std::ostream& stream, const IntType* values, std::size_t count) {
+      if (IsLittleEndian)
+          stream.write(reinterpret_cast<const char*>(values), sizeof(IntType) * count);
+      else
+          for (std::size_t i = 0; i < count; ++i)
+              write_little_endian<IntType>(stream, values[i]);
+  }
+
+}  // namespace Stockfish::Eval::NNUE
+
+#endif // #ifndef NNUE_COMMON_H_INCLUDED

src/nnue/nnue_feature_transformer.h

@@ -0,0 +1,615 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+// A class that converts the input features of the NNUE evaluation function
+
+#ifndef NNUE_FEATURE_TRANSFORMER_H_INCLUDED
+#define NNUE_FEATURE_TRANSFORMER_H_INCLUDED
+
+#include "nnue_common.h"
+#include "nnue_architecture.h"
+
+#include <cstring> // std::memset()
+
+namespace Stockfish::Eval::NNUE {
+
+  using BiasType       = std::int16_t;
+  using WeightType     = std::int16_t;
+  using PSQTWeightType = std::int32_t;
+
+  // If vector instructions are enabled, we update and refresh the
+  // accumulator tile by tile such that each tile fits in the CPU's
+  // vector registers.
+  #define VECTOR
+
+  static_assert(PSQTBuckets % 8 == 0,
+    "Per feature PSQT values cannot be processed at granularity lower than 8 at a time.");
+
+  #ifdef USE_AVX512
+  typedef __m512i vec_t;
+  typedef __m256i psqt_vec_t;
+  #define vec_load(a) _mm512_load_si512(a)
+  #define vec_store(a,b) _mm512_store_si512(a,b)
+  #define vec_add_16(a,b) _mm512_add_epi16(a,b)
+  #define vec_sub_16(a,b) _mm512_sub_epi16(a,b)
+  #define vec_load_psqt(a) _mm256_load_si256(a)
+  #define vec_store_psqt(a,b) _mm256_store_si256(a,b)
+  #define vec_add_psqt_32(a,b) _mm256_add_epi32(a,b)
+  #define vec_sub_psqt_32(a,b) _mm256_sub_epi32(a,b)
+  #define vec_zero_psqt() _mm256_setzero_si256()
+  #define NumRegistersSIMD 32
+
+  #elif USE_AVX2
+  typedef __m256i vec_t;
+  typedef __m256i psqt_vec_t;
+  #define vec_load(a) _mm256_load_si256(a)
+  #define vec_store(a,b) _mm256_store_si256(a,b)
+  #define vec_add_16(a,b) _mm256_add_epi16(a,b)
+  #define vec_sub_16(a,b) _mm256_sub_epi16(a,b)
+  #define vec_load_psqt(a) _mm256_load_si256(a)
+  #define vec_store_psqt(a,b) _mm256_store_si256(a,b)
+  #define vec_add_psqt_32(a,b) _mm256_add_epi32(a,b)
+  #define vec_sub_psqt_32(a,b) _mm256_sub_epi32(a,b)
+  #define vec_zero_psqt() _mm256_setzero_si256()
+  #define NumRegistersSIMD 16
+
+  #elif USE_SSE2
+  typedef __m128i vec_t;
+  typedef __m128i psqt_vec_t;
+  #define vec_load(a) (*(a))
+  #define vec_store(a,b) *(a)=(b)
+  #define vec_add_16(a,b) _mm_add_epi16(a,b)
+  #define vec_sub_16(a,b) _mm_sub_epi16(a,b)
+  #define vec_load_psqt(a) (*(a))
+  #define vec_store_psqt(a,b) *(a)=(b)
+  #define vec_add_psqt_32(a,b) _mm_add_epi32(a,b)
+  #define vec_sub_psqt_32(a,b) _mm_sub_epi32(a,b)
+  #define vec_zero_psqt() _mm_setzero_si128()
+  #define NumRegistersSIMD (Is64Bit ? 16 : 8)
+
+  #elif USE_MMX
+  typedef __m64 vec_t;
+  typedef __m64 psqt_vec_t;
+  #define vec_load(a) (*(a))
+  #define vec_store(a,b) *(a)=(b)
+  #define vec_add_16(a,b) _mm_add_pi16(a,b)
+  #define vec_sub_16(a,b) _mm_sub_pi16(a,b)
+  #define vec_load_psqt(a) (*(a))
+  #define vec_store_psqt(a,b) *(a)=(b)
+  #define vec_add_psqt_32(a,b) _mm_add_pi32(a,b)
+  #define vec_sub_psqt_32(a,b) _mm_sub_pi32(a,b)
+  #define vec_zero_psqt() _mm_setzero_si64()
+  #define NumRegistersSIMD 8
+
+  #elif USE_NEON
+  typedef int16x8_t vec_t;
+  typedef int32x4_t psqt_vec_t;
+  #define vec_load(a) (*(a))
+  #define vec_store(a,b) *(a)=(b)
+  #define vec_add_16(a,b) vaddq_s16(a,b)
+  #define vec_sub_16(a,b) vsubq_s16(a,b)
+  #define vec_load_psqt(a) (*(a))
+  #define vec_store_psqt(a,b) *(a)=(b)
+  #define vec_add_psqt_32(a,b) vaddq_s32(a,b)
+  #define vec_sub_psqt_32(a,b) vsubq_s32(a,b)
+  #define vec_zero_psqt() psqt_vec_t{0}
+  #define NumRegistersSIMD 16
+
+  #else
+  #undef VECTOR
+
+  #endif
+
+
+  #ifdef VECTOR
+
+      // Compute optimal SIMD register count for feature transformer accumulation.
+
+      // We use __m* types as template arguments, which causes GCC to emit warnings
+      // about losing some attribute information. This is irrelevant to us as we
+      // only take their size, so the following pragma are harmless.
+      #pragma GCC diagnostic push
+      #pragma GCC diagnostic ignored "-Wignored-attributes"
+
+      template <typename SIMDRegisterType,
+                typename LaneType,
+                int      NumLanes,
+                int      MaxRegisters>
+      static constexpr int BestRegisterCount()
+      {
+          #define RegisterSize  sizeof(SIMDRegisterType)
+          #define LaneSize      sizeof(LaneType)
+
+          static_assert(RegisterSize >= LaneSize);
+          static_assert(MaxRegisters <= NumRegistersSIMD);
+          static_assert(MaxRegisters > 0);
+          static_assert(NumRegistersSIMD > 0);
+          static_assert(RegisterSize % LaneSize == 0);
+          static_assert((NumLanes * LaneSize) % RegisterSize == 0);
+
+          const int ideal = (NumLanes * LaneSize) / RegisterSize;
+          if (ideal <= MaxRegisters)
+            return ideal;
+
+          // Look for the largest divisor of the ideal register count that is smaller than MaxRegisters
+          for (int divisor = MaxRegisters; divisor > 1; --divisor)
+            if (ideal % divisor == 0)
+              return divisor;
+
+          return 1;
+      }
+
+      static constexpr int NumRegs     = BestRegisterCount<vec_t, WeightType, TransformedFeatureDimensions, NumRegistersSIMD>();
+      static constexpr int NumPsqtRegs = BestRegisterCount<psqt_vec_t, PSQTWeightType, PSQTBuckets, NumRegistersSIMD>();
+
+      #pragma GCC diagnostic pop
+
+  #endif
+
+
+
+  // Input feature converter
+  class FeatureTransformer {
+
+   private:
+    // Number of output dimensions for one side
+    static constexpr IndexType HalfDimensions = TransformedFeatureDimensions;
+
+    #ifdef VECTOR
+    static constexpr IndexType TileHeight = NumRegs * sizeof(vec_t) / 2;
+    static constexpr IndexType PsqtTileHeight = NumPsqtRegs * sizeof(psqt_vec_t) / 4;
+    static_assert(HalfDimensions % TileHeight == 0, "TileHeight must divide HalfDimensions");
+    static_assert(PSQTBuckets % PsqtTileHeight == 0, "PsqtTileHeight must divide PSQTBuckets");
+    #endif
+
+   public:
+    // Output type
+    using OutputType = TransformedFeatureType;
+
+    // Number of input/output dimensions
+    static constexpr IndexType InputDimensions = FeatureSet::Dimensions;
+    static constexpr IndexType OutputDimensions = HalfDimensions * 2;
+
+    // Size of forward propagation buffer
+    static constexpr std::size_t BufferSize =
+        OutputDimensions * sizeof(OutputType);
+
+    // Hash value embedded in the evaluation file
+    static constexpr std::uint32_t get_hash_value() {
+      return FeatureSet::HashValue ^ OutputDimensions;
+    }
+
+    // Read network parameters
+    bool read_parameters(std::istream& stream) {
+
+      read_little_endian<BiasType      >(stream, biases     , HalfDimensions                  );
+      read_little_endian<WeightType    >(stream, weights    , HalfDimensions * InputDimensions);
+      read_little_endian<PSQTWeightType>(stream, psqtWeights, PSQTBuckets    * InputDimensions);
+
+      return !stream.fail();
+    }
+
+    // Write network parameters
+    bool write_parameters(std::ostream& stream) const {
+
+      write_little_endian<BiasType      >(stream, biases     , HalfDimensions                  );
+      write_little_endian<WeightType    >(stream, weights    , HalfDimensions * InputDimensions);
+      write_little_endian<PSQTWeightType>(stream, psqtWeights, PSQTBuckets    * InputDimensions);
+
+      return !stream.fail();
+    }
+
+    // Convert input features
+    std::int32_t transform(const Position& pos, OutputType* output, int bucket) const {
+      update_accumulator(pos, WHITE);
+      update_accumulator(pos, BLACK);
+
+      const Color perspectives[2] = {pos.side_to_move(), ~pos.side_to_move()};
+      const auto& accumulation = pos.state()->accumulator.accumulation;
+      const auto& psqtAccumulation = pos.state()->accumulator.psqtAccumulation;
+
+      const auto psqt = (
+            psqtAccumulation[perspectives[0]][bucket]
+          - psqtAccumulation[perspectives[1]][bucket]
+        ) / 2;
+
+
+  #if defined(USE_AVX512)
+
+      constexpr IndexType NumChunks = HalfDimensions / (SimdWidth * 2);
+      static_assert(HalfDimensions % (SimdWidth * 2) == 0);
+      const __m512i Control = _mm512_setr_epi64(0, 2, 4, 6, 1, 3, 5, 7);
+      const __m512i Zero = _mm512_setzero_si512();
+
+      for (IndexType p = 0; p < 2; ++p)
+      {
+          const IndexType offset = HalfDimensions * p;
+          auto out = reinterpret_cast<__m512i*>(&output[offset]);
+          for (IndexType j = 0; j < NumChunks; ++j)
+          {
+              __m512i sum0 = _mm512_load_si512(&reinterpret_cast<const __m512i*>
+                                              (accumulation[perspectives[p]])[j * 2 + 0]);
+              __m512i sum1 = _mm512_load_si512(&reinterpret_cast<const __m512i*>
+                                              (accumulation[perspectives[p]])[j * 2 + 1]);
+
+              _mm512_store_si512(&out[j], _mm512_permutexvar_epi64(Control,
+                                 _mm512_max_epi8(_mm512_packs_epi16(sum0, sum1), Zero)));
+          }
+      }
+      return psqt;
+
+  #elif defined(USE_AVX2)
+
+      constexpr IndexType NumChunks = HalfDimensions / SimdWidth;
+      constexpr int Control = 0b11011000;
+      const __m256i Zero = _mm256_setzero_si256();
+
+      for (IndexType p = 0; p < 2; ++p)
+      {
+          const IndexType offset = HalfDimensions * p;
+          auto out = reinterpret_cast<__m256i*>(&output[offset]);
+          for (IndexType j = 0; j < NumChunks; ++j)
+          {
+              __m256i sum0 = _mm256_load_si256(&reinterpret_cast<const __m256i*>
+                                              (accumulation[perspectives[p]])[j * 2 + 0]);
+              __m256i sum1 = _mm256_load_si256(&reinterpret_cast<const __m256i*>
+                                              (accumulation[perspectives[p]])[j * 2 + 1]);
+
+              _mm256_store_si256(&out[j], _mm256_permute4x64_epi64(
+                                 _mm256_max_epi8(_mm256_packs_epi16(sum0, sum1), Zero), Control));
+          }
+      }
+      return psqt;
+
+  #elif defined(USE_SSE2)
+
+      #ifdef USE_SSE41
+      constexpr IndexType NumChunks = HalfDimensions / SimdWidth;
+      const __m128i Zero = _mm_setzero_si128();
+      #else
+      constexpr IndexType NumChunks = HalfDimensions / SimdWidth;
+      const __m128i k0x80s = _mm_set1_epi8(-128);
+      #endif
+
+      for (IndexType p = 0; p < 2; ++p)
+      {
+          const IndexType offset = HalfDimensions * p;
+          auto out = reinterpret_cast<__m128i*>(&output[offset]);
+          for (IndexType j = 0; j < NumChunks; ++j)
+          {
+              __m128i sum0 = _mm_load_si128(&reinterpret_cast<const __m128i*>
+                                           (accumulation[perspectives[p]])[j * 2 + 0]);
+              __m128i sum1 = _mm_load_si128(&reinterpret_cast<const __m128i*>
+                                           (accumulation[perspectives[p]])[j * 2 + 1]);
+              const __m128i packedbytes = _mm_packs_epi16(sum0, sum1);
+
+              #ifdef USE_SSE41
+              _mm_store_si128(&out[j], _mm_max_epi8(packedbytes, Zero));
+              #else
+              _mm_store_si128(&out[j], _mm_subs_epi8(_mm_adds_epi8(packedbytes, k0x80s), k0x80s));
+              #endif
+          }
+      }
+      return psqt;
+
+  #elif defined(USE_MMX)
+
+      constexpr IndexType NumChunks = HalfDimensions / SimdWidth;
+      const __m64 k0x80s = _mm_set1_pi8(-128);
+
+      for (IndexType p = 0; p < 2; ++p)
+      {
+          const IndexType offset = HalfDimensions * p;
+          auto out = reinterpret_cast<__m64*>(&output[offset]);
+          for (IndexType j = 0; j < NumChunks; ++j)
+          {
+              __m64 sum0 = *(&reinterpret_cast<const __m64*>(accumulation[perspectives[p]])[j * 2 + 0]);
+              __m64 sum1 = *(&reinterpret_cast<const __m64*>(accumulation[perspectives[p]])[j * 2 + 1]);
+              const __m64 packedbytes = _mm_packs_pi16(sum0, sum1);
+              out[j] = _mm_subs_pi8(_mm_adds_pi8(packedbytes, k0x80s), k0x80s);
+          }
+      }
+      _mm_empty();
+      return psqt;
+
+  #elif defined(USE_NEON)
+
+      constexpr IndexType NumChunks = HalfDimensions / (SimdWidth / 2);
+      const int8x8_t Zero = {0};
+
+      for (IndexType p = 0; p < 2; ++p)
+      {
+          const IndexType offset = HalfDimensions * p;
+          const auto out = reinterpret_cast<int8x8_t*>(&output[offset]);
+          for (IndexType j = 0; j < NumChunks; ++j)
+          {
+              int16x8_t sum = reinterpret_cast<const int16x8_t*>(accumulation[perspectives[p]])[j];
+              out[j] = vmax_s8(vqmovn_s16(sum), Zero);
+          }
+      }
+      return psqt;
+
+  #else
+
+      for (IndexType p = 0; p < 2; ++p)
+      {
+          const IndexType offset = HalfDimensions * p;
+          for (IndexType j = 0; j < HalfDimensions; ++j)
+          {
+              BiasType sum = accumulation[perspectives[p]][j];
+              output[offset + j] = static_cast<OutputType>(std::max<int>(0, std::min<int>(127, sum)));
+          }
+      }
+      return psqt;
+
+  #endif
+
+   } // end of function transform()
+
+
+
+   private:
+    void update_accumulator(const Position& pos, const Color perspective) const {
+
+      // The size must be enough to contain the largest possible update.
+      // That might depend on the feature set and generally relies on the
+      // feature set's update cost calculation to be correct and never
+      // allow updates with more added/removed features than MaxActiveDimensions.
+      using IndexList = ValueList<IndexType, FeatureSet::MaxActiveDimensions>;
+
+  #ifdef VECTOR
+      // Gcc-10.2 unnecessarily spills AVX2 registers if this array
+      // is defined in the VECTOR code below, once in each branch
+      vec_t acc[NumRegs];
+      psqt_vec_t psqt[NumPsqtRegs];
+  #endif
+
+      // Look for a usable accumulator of an earlier position. We keep track
+      // of the estimated gain in terms of features to be added/subtracted.
+      StateInfo *st = pos.state(), *next = nullptr;
+      int gain = FeatureSet::refresh_cost(pos);
+      while (st->previous && !st->accumulator.computed[perspective])
+      {
+        // This governs when a full feature refresh is needed and how many
+        // updates are better than just one full refresh.
+        if (   FeatureSet::requires_refresh(st, perspective)
+            || (gain -= FeatureSet::update_cost(st) + 1) < 0)
+          break;
+        next = st;
+        st = st->previous;
+      }
+
+      if (st->accumulator.computed[perspective])
+      {
+        if (next == nullptr)
+          return;
+
+        // Update incrementally in two steps. First, we update the "next"
+        // accumulator. Then, we update the current accumulator (pos.state()).
+
+        // Gather all features to be updated.
+        const Square ksq = pos.square<KING>(perspective);
+        IndexList removed[2], added[2];
+        FeatureSet::append_changed_indices(
+          ksq, next, perspective, removed[0], added[0]);
+        for (StateInfo *st2 = pos.state(); st2 != next; st2 = st2->previous)
+          FeatureSet::append_changed_indices(
+            ksq, st2, perspective, removed[1], added[1]);
+
+        // Mark the accumulators as computed.
+        next->accumulator.computed[perspective] = true;
+        pos.state()->accumulator.computed[perspective] = true;
+
+        // Now update the accumulators listed in states_to_update[], where the last element is a sentinel.
+        StateInfo *states_to_update[3] =
+          { next, next == pos.state() ? nullptr : pos.state(), nullptr };
+  #ifdef VECTOR
+        for (IndexType j = 0; j < HalfDimensions / TileHeight; ++j)
+        {
+          // Load accumulator
+          auto accTile = reinterpret_cast<vec_t*>(
+            &st->accumulator.accumulation[perspective][j * TileHeight]);
+          for (IndexType k = 0; k < NumRegs; ++k)
+            acc[k] = vec_load(&accTile[k]);
+
+          for (IndexType i = 0; states_to_update[i]; ++i)
+          {
+            // Difference calculation for the deactivated features
+            for (const auto index : removed[i])
+            {
+              const IndexType offset = HalfDimensions * index + j * TileHeight;
+              auto column = reinterpret_cast<const vec_t*>(&weights[offset]);
+              for (IndexType k = 0; k < NumRegs; ++k)
+                acc[k] = vec_sub_16(acc[k], column[k]);
+            }
+
+            // Difference calculation for the activated features
+            for (const auto index : added[i])
+            {
+              const IndexType offset = HalfDimensions * index + j * TileHeight;
+              auto column = reinterpret_cast<const vec_t*>(&weights[offset]);
+              for (IndexType k = 0; k < NumRegs; ++k)
+                acc[k] = vec_add_16(acc[k], column[k]);
+            }
+
+            // Store accumulator
+            accTile = reinterpret_cast<vec_t*>(
+              &states_to_update[i]->accumulator.accumulation[perspective][j * TileHeight]);
+            for (IndexType k = 0; k < NumRegs; ++k)
+              vec_store(&accTile[k], acc[k]);
+          }
+        }
+
+        for (IndexType j = 0; j < PSQTBuckets / PsqtTileHeight; ++j)
+        {
+          // Load accumulator
+          auto accTilePsqt = reinterpret_cast<psqt_vec_t*>(
+            &st->accumulator.psqtAccumulation[perspective][j * PsqtTileHeight]);
+          for (std::size_t k = 0; k < NumPsqtRegs; ++k)
+            psqt[k] = vec_load_psqt(&accTilePsqt[k]);
+
+          for (IndexType i = 0; states_to_update[i]; ++i)
+          {
+            // Difference calculation for the deactivated features
+            for (const auto index : removed[i])
+            {
+              const IndexType offset = PSQTBuckets * index + j * PsqtTileHeight;
+              auto columnPsqt = reinterpret_cast<const psqt_vec_t*>(&psqtWeights[offset]);
+              for (std::size_t k = 0; k < NumPsqtRegs; ++k)
+                psqt[k] = vec_sub_psqt_32(psqt[k], columnPsqt[k]);
+            }
+
+            // Difference calculation for the activated features
+            for (const auto index : added[i])
+            {
+              const IndexType offset = PSQTBuckets * index + j * PsqtTileHeight;
+              auto columnPsqt = reinterpret_cast<const psqt_vec_t*>(&psqtWeights[offset]);
+              for (std::size_t k = 0; k < NumPsqtRegs; ++k)
+                psqt[k] = vec_add_psqt_32(psqt[k], columnPsqt[k]);
+            }
+
+            // Store accumulator
+            accTilePsqt = reinterpret_cast<psqt_vec_t*>(
+              &states_to_update[i]->accumulator.psqtAccumulation[perspective][j * PsqtTileHeight]);
+            for (std::size_t k = 0; k < NumPsqtRegs; ++k)
+              vec_store_psqt(&accTilePsqt[k], psqt[k]);
+          }
+        }
+
+  #else
+        for (IndexType i = 0; states_to_update[i]; ++i)
+        {
+          std::memcpy(states_to_update[i]->accumulator.accumulation[perspective],
+              st->accumulator.accumulation[perspective],
+              HalfDimensions * sizeof(BiasType));
+
+          for (std::size_t k = 0; k < PSQTBuckets; ++k)
+            states_to_update[i]->accumulator.psqtAccumulation[perspective][k] = st->accumulator.psqtAccumulation[perspective][k];
+
+          st = states_to_update[i];
+
+          // Difference calculation for the deactivated features
+          for (const auto index : removed[i])
+          {
+            const IndexType offset = HalfDimensions * index;
+
+            for (IndexType j = 0; j < HalfDimensions; ++j)
+              st->accumulator.accumulation[perspective][j] -= weights[offset + j];
+
+            for (std::size_t k = 0; k < PSQTBuckets; ++k)
+              st->accumulator.psqtAccumulation[perspective][k] -= psqtWeights[index * PSQTBuckets + k];
+          }
+
+          // Difference calculation for the activated features
+          for (const auto index : added[i])
+          {
+            const IndexType offset = HalfDimensions * index;
+
+            for (IndexType j = 0; j < HalfDimensions; ++j)
+              st->accumulator.accumulation[perspective][j] += weights[offset + j];
+
+            for (std::size_t k = 0; k < PSQTBuckets; ++k)
+              st->accumulator.psqtAccumulation[perspective][k] += psqtWeights[index * PSQTBuckets + k];
+          }
+        }
+  #endif
+      }
+      else
+      {
+        // Refresh the accumulator
+        auto& accumulator = pos.state()->accumulator;
+        accumulator.computed[perspective] = true;
+        IndexList active;
+        FeatureSet::append_active_indices(pos, perspective, active);
+
+  #ifdef VECTOR
+        for (IndexType j = 0; j < HalfDimensions / TileHeight; ++j)
+        {
+          auto biasesTile = reinterpret_cast<const vec_t*>(
+              &biases[j * TileHeight]);
+          for (IndexType k = 0; k < NumRegs; ++k)
+            acc[k] = biasesTile[k];
+
+          for (const auto index : active)
+          {
+            const IndexType offset = HalfDimensions * index + j * TileHeight;
+            auto column = reinterpret_cast<const vec_t*>(&weights[offset]);
+
+            for (unsigned k = 0; k < NumRegs; ++k)
+              acc[k] = vec_add_16(acc[k], column[k]);
+          }
+
+          auto accTile = reinterpret_cast<vec_t*>(
+              &accumulator.accumulation[perspective][j * TileHeight]);
+          for (unsigned k = 0; k < NumRegs; k++)
+            vec_store(&accTile[k], acc[k]);
+        }
+
+        for (IndexType j = 0; j < PSQTBuckets / PsqtTileHeight; ++j)
+        {
+          for (std::size_t k = 0; k < NumPsqtRegs; ++k)
+            psqt[k] = vec_zero_psqt();
+
+          for (const auto index : active)
+          {
+            const IndexType offset = PSQTBuckets * index + j * PsqtTileHeight;
+            auto columnPsqt = reinterpret_cast<const psqt_vec_t*>(&psqtWeights[offset]);
+
+            for (std::size_t k = 0; k < NumPsqtRegs; ++k)
+              psqt[k] = vec_add_psqt_32(psqt[k], columnPsqt[k]);
+          }
+
+          auto accTilePsqt = reinterpret_cast<psqt_vec_t*>(
+            &accumulator.psqtAccumulation[perspective][j * PsqtTileHeight]);
+          for (std::size_t k = 0; k < NumPsqtRegs; ++k)
+            vec_store_psqt(&accTilePsqt[k], psqt[k]);
+        }
+
+  #else
+        std::memcpy(accumulator.accumulation[perspective], biases,
+            HalfDimensions * sizeof(BiasType));
+
+        for (std::size_t k = 0; k < PSQTBuckets; ++k)
+          accumulator.psqtAccumulation[perspective][k] = 0;
+
+        for (const auto index : active)
+        {
+          const IndexType offset = HalfDimensions * index;
+
+          for (IndexType j = 0; j < HalfDimensions; ++j)
+            accumulator.accumulation[perspective][j] += weights[offset + j];
+
+          for (std::size_t k = 0; k < PSQTBuckets; ++k)
+            accumulator.psqtAccumulation[perspective][k] += psqtWeights[index * PSQTBuckets + k];
+        }
+  #endif
+      }
+
+  #if defined(USE_MMX)
+      _mm_empty();
+  #endif
+    }
+
+    alignas(CacheLineSize) BiasType biases[HalfDimensions];
+    alignas(CacheLineSize) WeightType weights[HalfDimensions * InputDimensions];
+    alignas(CacheLineSize) PSQTWeightType psqtWeights[InputDimensions * PSQTBuckets];
+  };
+
+}  // namespace Stockfish::Eval::NNUE
+
+#endif // #ifndef NNUE_FEATURE_TRANSFORMER_H_INCLUDED

src/pawns.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -26,29 +24,38 @@
 #include "position.h"
 #include "thread.h"
 
+namespace Stockfish {
+
 namespace {
 
   #define V Value
   #define S(mg, eg) make_score(mg, eg)
 
   // Pawn penalties
-  constexpr Score Backward      = S( 9, 24);
+  constexpr Score Backward      = S( 9, 22);
-  constexpr Score BlockedStorm  = S(82, 82);
+  constexpr Score Doubled       = S(13, 51);
-  constexpr Score Doubled       = S(11, 56);
+  constexpr Score DoubledEarly  = S(20,  7);
-  constexpr Score Isolated      = S( 5, 15);
+  constexpr Score Isolated      = S( 3, 15);
-  constexpr Score WeakLever     = S( 0, 56);
+  constexpr Score WeakLever     = S( 4, 58);
-  constexpr Score WeakUnopposed = S(13, 27);
+  constexpr Score WeakUnopposed = S(13, 24);
+
+  // Bonus for blocked pawns at 5th or 6th rank
+  constexpr Score BlockedPawn[2] = { S(-17, -6), S(-9, 2) };
+
+  constexpr Score BlockedStorm[RANK_NB] = {
+    S(0, 0), S(0, 0), S(75, 78), S(-8, 16), S(-6, 10), S(-6, 6), S(0, 2)
+  };
 
   // Connected pawn bonus
-  constexpr int Connected[RANK_NB] = { 0, 7, 8, 12, 29, 48, 86 };
+  constexpr int Connected[RANK_NB] = { 0, 5, 7, 11, 23, 48, 87 };
 
   // Strength of pawn shelter for our king by [distance from edge][rank].
   // RANK_1 = 0 is used for files where we have no pawn, or pawn is behind our king.
   constexpr Value ShelterStrength[int(FILE_NB) / 2][RANK_NB] = {
-    { V( -6), V( 81), V( 93), V( 58), V( 39), V( 18), V(  25) },
+    { V( -5), V( 82), V( 92), V( 54), V( 36), V( 22), V(  28) },
-    { V(-43), V( 61), V( 35), V(-49), V(-29), V(-11), V( -63) },
+    { V(-44), V( 63), V( 33), V(-50), V(-30), V(-12), V( -62) },
-    { V(-10), V( 75), V( 23), V( -2), V( 32), V(  3), V( -45) },
+    { V(-11), V( 77), V( 22), V( -6), V( 31), V(  8), V( -45) },
-    { V(-39), V(-13), V(-29), V(-52), V(-48), V(-67), V(-166) }
+    { V(-39), V(-12), V(-29), V(-50), V(-43), V(-68), V(-164) }
   };
 
   // Danger of enemy pawns moving toward our king by [distance from edge][rank].
@@ -56,27 +63,40 @@ namespace {
   // is behind our king. Note that UnblockedStorm[0][1-2] accommodate opponent pawn
   // on edge, likely blocked by our king.
   constexpr Value UnblockedStorm[int(FILE_NB) / 2][RANK_NB] = {
-    { V( 85), V(-289), V(-166), V(97), V(50), V( 45), V( 50) },
+    { V( 87), V(-288), V(-168), V( 96), V( 47), V( 44), V( 46) },
-    { V( 46), V( -25), V( 122), V(45), V(37), V(-10), V( 20) },
+    { V( 42), V( -25), V( 120), V( 45), V( 34), V( -9), V( 24) },
-    { V( -6), V(  51), V( 168), V(34), V(-2), V(-22), V(-14) },
+    { V( -8), V(  51), V( 167), V( 35), V( -4), V(-16), V(-12) },
-    { V(-15), V( -11), V( 101), V( 4), V(11), V(-15), V(-29) }
+    { V(-17), V( -13), V( 100), V(  4), V(  9), V(-16), V(-31) }
   };
 
+
+  // KingOnFile[semi-open Us][semi-open Them] contains bonuses/penalties
+  // for king when the king is on a semi-open or open file.
+  constexpr Score KingOnFile[2][2] = {{ S(-21,10), S(-7, 1)  },
+                                     {  S(  0,-3), S( 9,-4) }};
+
   #undef S
   #undef V
 
+
+  /// evaluate() calculates a score for the static pawn structure of the given position.
+  /// We cannot use the location of pieces or king in this function, as the evaluation
+  /// of the pawn structure will be stored in a small cache for speed reasons, and will
+  /// be re-used even when the pieces have moved.
+
   template<Color Us>
   Score evaluate(const Position& pos, Pawns::Entry* e) {
 
-    constexpr Color     Them = (Us == WHITE ? BLACK : WHITE);
+    constexpr Color     Them = ~Us;
     constexpr Direction Up   = pawn_push(Us);
+    constexpr Direction Down = -Up;
 
     Bitboard neighbours, stoppers, support, phalanx, opposed;
     Bitboard lever, leverPush, blocked;
     Square s;
     bool backward, passed, doubled;
     Score score = SCORE_ZERO;
-    const Square* pl = pos.squares<PAWN>(Us);
+    Bitboard b = pos.pieces(Us, PAWN);
 
     Bitboard ourPawns   = pos.pieces(  Us, PAWN);
     Bitboard theirPawns = pos.pieces(Them, PAWN);
@@ -86,10 +106,13 @@ namespace {
     e->passedPawns[Us] = 0;
     e->kingSquares[Us] = SQ_NONE;
     e->pawnAttacks[Us] = e->pawnAttacksSpan[Us] = pawn_attacks_bb<Us>(ourPawns);
+    e->blockedCount += popcount(shift<Up>(ourPawns) & (theirPawns | doubleAttackThem));
 
     // Loop through all pawns of the current color and score each pawn
-    while ((s = *pl++) != SQ_NONE)
+    while (b)
     {
+        s = pop_lsb(b);
+
         assert(pos.piece_on(s) == make_piece(Us, PAWN));
 
         Rank r = relative_rank(Us, s);
@@ -98,13 +121,20 @@ namespace {
         opposed    = theirPawns & forward_file_bb(Us, s);
         blocked    = theirPawns & (s + Up);
         stoppers   = theirPawns & passed_pawn_span(Us, s);
-        lever      = theirPawns & PawnAttacks[Us][s];
+        lever      = theirPawns & pawn_attacks_bb(Us, s);
-        leverPush  = theirPawns & PawnAttacks[Us][s + Up];
+        leverPush  = theirPawns & pawn_attacks_bb(Us, s + Up);
         doubled    = ourPawns   & (s - Up);
         neighbours = ourPawns   & adjacent_files_bb(s);
         phalanx    = neighbours & rank_bb(s);
         support    = neighbours & rank_bb(s - Up);
 
+        if (doubled)
+        {
+            // Additional doubled penalty if none of their pawns is fixed
+            if (!(ourPawns & shift<Down>(theirPawns | pawn_attacks_bb<Them>(theirPawns))))
+                score -= DoubledEarly;
+        }
+
         // A pawn is backward when it is behind all pawns of the same color on
         // the adjacent files and cannot safely advance.
         backward =  !(neighbours & forward_ranks_bb(Them, s + Up))
@@ -118,12 +148,15 @@ namespace {
         // (a) there is no stoppers except some levers
         // (b) the only stoppers are the leverPush, but we outnumber them
         // (c) there is only one front stopper which can be levered.
+        //     (Refined in Evaluation::passed)
         passed =   !(stoppers ^ lever)
                 || (   !(stoppers ^ leverPush)
                     && popcount(phalanx) >= popcount(leverPush))
                 || (   stoppers == blocked && r >= RANK_5
                     && (shift<Up>(support) & ~(theirPawns | doubleAttackThem)));
 
+        passed &= !(forward_file_bb(Us, s) & ourPawns);
+
         // Passed pawns will be properly scored later in evaluation when we have
         // full attack info.
         if (passed)
@@ -133,22 +166,32 @@ namespace {
         if (support | phalanx)
         {
             int v =  Connected[r] * (2 + bool(phalanx) - bool(opposed))
-                   + 21 * popcount(support);
+                   + 22 * popcount(support);
 
             score += make_score(v, v * (r - 2) / 4);
         }
 
         else if (!neighbours)
-            score -=   Isolated
+        {
-                     + WeakUnopposed * !opposed;
+            if (     opposed
+                &&  (ourPawns & forward_file_bb(Them, s))
+                && !(theirPawns & adjacent_files_bb(s)))
+                score -= Doubled;
+            else
+                score -=  Isolated
+                        + WeakUnopposed * !opposed;
+        }
 
         else if (backward)
-            score -=   Backward
+            score -=  Backward
-                     + WeakUnopposed * !opposed;
+                    + WeakUnopposed * !opposed * bool(~(FileABB | FileHBB) & s);
 
         if (!support)
-            score -=   Doubled * doubled
+            score -=  Doubled * doubled
-                     + WeakLever * more_than_one(lever);
+                    + WeakLever * more_than_one(lever);
+
+        if (blocked && r >= RANK_5)
+            score += BlockedPawn[r - RANK_5];
     }
 
     return score;
@@ -158,6 +201,7 @@ namespace {
 
 namespace Pawns {
 
+
 /// Pawns::probe() looks up the current position's pawns configuration in
 /// the pawns hash table. It returns a pointer to the Entry if the position
 /// is found. Otherwise a new Entry is computed and stored there, so we don't
@@ -172,6 +216,7 @@ Entry* probe(const Position& pos) {
       return e;
 
   e->key = key;
+  e->blockedCount = 0;
   e->scores[WHITE] = evaluate<WHITE>(pos, e);
   e->scores[BLACK] = evaluate<BLACK>(pos, e);
 
@@ -183,17 +228,17 @@ Entry* probe(const Position& pos) {
 /// penalty for a king, looking at the king file and the two closest files.
 
 template<Color Us>
-Score Entry::evaluate_shelter(const Position& pos, Square ksq) {
+Score Entry::evaluate_shelter(const Position& pos, Square ksq) const {
 
-  constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
+  constexpr Color Them = ~Us;
 
   Bitboard b = pos.pieces(PAWN) & ~forward_ranks_bb(Them, ksq);
-  Bitboard ourPawns = b & pos.pieces(Us);
+  Bitboard ourPawns = b & pos.pieces(Us) & ~pawnAttacks[Them];
   Bitboard theirPawns = b & pos.pieces(Them);
 
   Score bonus = make_score(5, 5);
 
-  File center = clamp(file_of(ksq), FILE_B, FILE_G);
+  File center = std::clamp(file_of(ksq), FILE_B, FILE_G);
   for (File f = File(center - 1); f <= File(center + 1); ++f)
   {
       b = ourPawns & file_bb(f);
@@ -202,15 +247,18 @@ Score Entry::evaluate_shelter(const Position& pos, Square ksq) {
       b = theirPawns & file_bb(f);
       int theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0;
 
-      File d = map_to_queenside(f);
+      int d = edge_distance(f);
       bonus += make_score(ShelterStrength[d][ourRank], 0);
 
       if (ourRank && (ourRank == theirRank - 1))
-          bonus -= BlockedStorm * int(theirRank == RANK_3);
+          bonus -= BlockedStorm[theirRank];
       else
           bonus -= make_score(UnblockedStorm[d][theirRank], 0);
   }
 
+  // King On File
+  bonus -= KingOnFile[pos.is_on_semiopen_file(Us, ksq)][pos.is_on_semiopen_file(Them, ksq)];
+
   return bonus;
 }
 
@@ -238,12 +286,12 @@ Score Entry::do_king_safety(const Position& pos) {
 
   // In endgame we like to bring our king near our closest pawn
   Bitboard pawns = pos.pieces(Us, PAWN);
-  int minPawnDist = pawns ? 8 : 0;
+  int minPawnDist = 6;
 
-  if (pawns & PseudoAttacks[KING][ksq])
+  if (pawns & attacks_bb<KING>(ksq))
       minPawnDist = 1;
   else while (pawns)
-      minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(&pawns)));
+      minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(pawns)));
 
   return shelter - make_score(0, 16 * minPawnDist);
 }
@@ -253,3 +301,5 @@ template Score Entry::do_king_safety<WHITE>(const Position& pos);
 template Score Entry::do_king_safety<BLACK>(const Position& pos);
 
 } // namespace Pawns
+
+} // namespace Stockfish

src/pawns.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -25,7 +23,7 @@
 #include "position.h"
 #include "types.h"
 
-namespace Pawns {
+namespace Stockfish::Pawns {
 
 /// Pawns::Entry contains various information about a pawn structure. A lookup
 /// to the pawn hash table (performed by calling the probe function) returns a
@@ -38,6 +36,7 @@ struct Entry {
   Bitboard passed_pawns(Color c) const { return passedPawns[c]; }
   Bitboard pawn_attacks_span(Color c) const { return pawnAttacksSpan[c]; }
   int passed_count() const { return popcount(passedPawns[WHITE] | passedPawns[BLACK]); }
+  int blocked_count() const { return blockedCount; }
 
   template<Color Us>
   Score king_safety(const Position& pos) {
@@ -49,7 +48,7 @@ struct Entry {
   Score do_king_safety(const Position& pos);
 
   template<Color Us>
-  Score evaluate_shelter(const Position& pos, Square ksq);
+  Score evaluate_shelter(const Position& pos, Square ksq) const;
 
   Key key;
   Score scores[COLOR_NB];
@@ -59,12 +58,13 @@ struct Entry {
   Square kingSquares[COLOR_NB];
   Score kingSafety[COLOR_NB];
   int castlingRights[COLOR_NB];
+  int blockedCount;
 };
 
 typedef HashTable<Entry, 131072> Table;
 
 Entry* probe(const Position& pos);
 
-} // namespace Pawns
+} // namespace Stockfish::Pawns
 
 #endif // #ifndef PAWNS_H_INCLUDED

src/position.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -36,6 +34,8 @@
 
 using std::string;
 
+namespace Stockfish {
+
 namespace Zobrist {
 
   Key psq[PIECE_NB][SQUARE_NB];
@@ -64,20 +64,23 @@ std::ostream& operator<<(std::ostream& os, const Position& pos) {
       for (File f = FILE_A; f <= FILE_H; ++f)
           os << " | " << PieceToChar[pos.piece_on(make_square(f, r))];
 
-      os << " |\n +---+---+---+---+---+---+---+---+\n";
+      os << " | " << (1 + r) << "\n +---+---+---+---+---+---+---+---+\n";
   }
 
-  os << "\nFen: " << pos.fen() << "\nKey: " << std::hex << std::uppercase
+  os << "   a   b   c   d   e   f   g   h\n"
+     << "\nFen: " << pos.fen() << "\nKey: " << std::hex << std::uppercase
      << std::setfill('0') << std::setw(16) << pos.key()
      << std::setfill(' ') << std::dec << "\nCheckers: ";
 
   for (Bitboard b = pos.checkers(); b; )
-      os << UCI::square(pop_lsb(&b)) << " ";
+      os << UCI::square(pop_lsb(b)) << " ";
 
   if (    int(Tablebases::MaxCardinality) >= popcount(pos.pieces())
       && !pos.can_castle(ANY_CASTLING))
   {
       StateInfo st;
+      ASSERT_ALIGNED(&st, Eval::NNUE::CacheLineSize);
+
       Position p;
       p.set(pos.fen(), pos.is_chess960(), &st, pos.this_thread());
       Tablebases::ProbeState s1, s2;
@@ -104,8 +107,7 @@ Key cuckoo[8192];
 Move cuckooMove[8192];
 
 
-/// Position::init() initializes at startup the various arrays used to compute
+/// Position::init() initializes at startup the various arrays used to compute hash keys
-/// hash keys.
 
 void Position::init() {
 
@@ -119,15 +121,7 @@ void Position::init() {
       Zobrist::enpassant[f] = rng.rand<Key>();
 
   for (int cr = NO_CASTLING; cr <= ANY_CASTLING; ++cr)
-  {
+      Zobrist::castling[cr] = rng.rand<Key>();
-      Zobrist::castling[cr] = 0;
-      Bitboard b = cr;
-      while (b)
-      {
-          Key k = Zobrist::castling[1ULL << pop_lsb(&b)];
-          Zobrist::castling[cr] ^= k ? k : rng.rand<Key>();
-      }
-  }
 
   Zobrist::side = rng.rand<Key>();
   Zobrist::noPawns = rng.rand<Key>();
@@ -139,7 +133,7 @@ void Position::init() {
   for (Piece pc : Pieces)
       for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
           for (Square s2 = Square(s1 + 1); s2 <= SQ_H8; ++s2)
-              if (PseudoAttacks[type_of(pc)][s1] & s2)
+              if ((type_of(pc) != PAWN) && (attacks_bb(type_of(pc), s1, 0) & s2))
               {
                   Move move = make_move(s1, s2);
                   Key key = Zobrist::psq[pc][s1] ^ Zobrist::psq[pc][s2] ^ Zobrist::side;
@@ -186,9 +180,9 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th
 
    4) En passant target square (in algebraic notation). If there's no en passant
       target square, this is "-". If a pawn has just made a 2-square move, this
-      is the position "behind" the pawn. This is recorded only if there is a pawn
+      is the position "behind" the pawn. Following X-FEN standard, this is recorded only
-      in position to make an en passant capture, and if there really is a pawn
+      if there is a pawn in position to make an en passant capture, and if there really
-      that might have advanced two squares.
+      is a pawn that might have advanced two squares.
 
    5) Halfmove clock. This is the number of halfmoves since the last pawn advance
       or capture. This is used to determine if a draw can be claimed under the
@@ -205,7 +199,6 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th
 
   std::memset(this, 0, sizeof(Position));
   std::memset(si, 0, sizeof(StateInfo));
-  std::fill_n(&pieceList[0][0], sizeof(pieceList) / sizeof(Square), SQ_NONE);
   st = si;
 
   ss >> std::noskipws;
@@ -219,8 +212,7 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th
       else if (token == '/')
           sq += 2 * SOUTH;
 
-      else if ((idx = PieceToChar.find(token)) != string::npos)
+      else if ((idx = PieceToChar.find(token)) != string::npos) {
-      {
           put_piece(Piece(idx), sq);
           ++sq;
       }
@@ -259,17 +251,25 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th
       set_castling_right(c, rsq);
   }
 
-  // 4. En passant square. Ignore if no pawn capture is possible
+  // 4. En passant square.
+  // Ignore if square is invalid or not on side to move relative rank 6.
+  bool enpassant = false;
+
   if (   ((ss >> col) && (col >= 'a' && col <= 'h'))
-      && ((ss >> row) && (row == '3' || row == '6')))
+      && ((ss >> row) && (row == (sideToMove == WHITE ? '6' : '3'))))
   {
       st->epSquare = make_square(File(col - 'a'), Rank(row - '1'));
 
-      if (   !(attackers_to(st->epSquare) & pieces(sideToMove, PAWN))
+      // En passant square will be considered only if
-          || !(pieces(~sideToMove, PAWN) & (st->epSquare + pawn_push(~sideToMove))))
+      // a) side to move have a pawn threatening epSquare
-          st->epSquare = SQ_NONE;
+      // b) there is an enemy pawn in front of epSquare
+      // c) there is no piece on epSquare or behind epSquare
+      enpassant = pawn_attacks_bb(~sideToMove, st->epSquare) & pieces(sideToMove, PAWN)
+               && (pieces(~sideToMove, PAWN) & (st->epSquare + pawn_push(~sideToMove)))
+               && !(pieces() & (st->epSquare | (st->epSquare + pawn_push(sideToMove))));
   }
-  else
+
+  if (!enpassant)
       st->epSquare = SQ_NONE;
 
   // 5-6. Halfmove clock and fullmove number
@@ -305,8 +305,8 @@ void Position::set_castling_right(Color c, Square rfrom) {
   Square kto = relative_square(c, cr & KING_SIDE ? SQ_G1 : SQ_C1);
   Square rto = relative_square(c, cr & KING_SIDE ? SQ_F1 : SQ_D1);
 
-  castlingPath[cr] =   (between_bb(rfrom, rto) | between_bb(kfrom, kto) | rto | kto)
+  castlingPath[cr] =   (between_bb(rfrom, rto) | between_bb(kfrom, kto))
-                    & ~(square_bb(kfrom) | rfrom);
+                    & ~(kfrom | rfrom);
 }
 
 
@@ -319,10 +319,10 @@ void Position::set_check_info(StateInfo* si) const {
 
   Square ksq = square<KING>(~sideToMove);
 
-  si->checkSquares[PAWN]   = attacks_from<PAWN>(ksq, ~sideToMove);
+  si->checkSquares[PAWN]   = pawn_attacks_bb(~sideToMove, ksq);
-  si->checkSquares[KNIGHT] = attacks_from<KNIGHT>(ksq);
+  si->checkSquares[KNIGHT] = attacks_bb<KNIGHT>(ksq);
-  si->checkSquares[BISHOP] = attacks_from<BISHOP>(ksq);
+  si->checkSquares[BISHOP] = attacks_bb<BISHOP>(ksq, pieces());
-  si->checkSquares[ROOK]   = attacks_from<ROOK>(ksq);
+  si->checkSquares[ROOK]   = attacks_bb<ROOK>(ksq, pieces());
   si->checkSquares[QUEEN]  = si->checkSquares[BISHOP] | si->checkSquares[ROOK];
   si->checkSquares[KING]   = 0;
 }
@@ -344,7 +344,7 @@ void Position::set_state(StateInfo* si) const {
 
   for (Bitboard b = pieces(); b; )
   {
-      Square s = pop_lsb(&b);
+      Square s = pop_lsb(b);
       Piece pc = piece_on(s);
       si->key ^= Zobrist::psq[pc][s];
 
@@ -375,11 +375,13 @@ void Position::set_state(StateInfo* si) const {
 
 Position& Position::set(const string& code, Color c, StateInfo* si) {
 
-  assert(code.length() > 0 && code.length() < 8);
   assert(code[0] == 'K');
 
   string sides[] = { code.substr(code.find('K', 1)),      // Weak
-                     code.substr(0, code.find('K', 1)) }; // Strong
+                     code.substr(0, std::min(code.find('v'), code.find('K', 1))) }; // Strong
+
+  assert(sides[0].length() > 0 && sides[0].length() < 8);
+  assert(sides[1].length() > 0 && sides[1].length() < 8);
 
   std::transform(sides[c].begin(), sides[c].end(), sides[c].begin(), tolower);
 
@@ -393,7 +395,7 @@ Position& Position::set(const string& code, Color c, StateInfo* si) {
 /// Position::fen() returns a FEN representation of the position. In case of
 /// Chess960 the Shredder-FEN notation is used. This is mainly a debugging function.
 
-const string Position::fen() const {
+string Position::fen() const {
 
   int emptyCnt;
   std::ostringstream ss;
@@ -453,13 +455,13 @@ Bitboard Position::slider_blockers(Bitboard sliders, Square s, Bitboard& pinners
   pinners = 0;
 
   // Snipers are sliders that attack 's' when a piece and other snipers are removed
-  Bitboard snipers = (  (PseudoAttacks[  ROOK][s] & pieces(QUEEN, ROOK))
+  Bitboard snipers = (  (attacks_bb<  ROOK>(s) & pieces(QUEEN, ROOK))
-                      | (PseudoAttacks[BISHOP][s] & pieces(QUEEN, BISHOP))) & sliders;
+                      | (attacks_bb<BISHOP>(s) & pieces(QUEEN, BISHOP))) & sliders;
   Bitboard occupancy = pieces() ^ snipers;
 
   while (snipers)
   {
-    Square sniperSq = pop_lsb(&snipers);
+    Square sniperSq = pop_lsb(snipers);
     Bitboard b = between_bb(s, sniperSq) & occupancy;
 
     if (b && !more_than_one(b))
@@ -478,12 +480,12 @@ Bitboard Position::slider_blockers(Bitboard sliders, Square s, Bitboard& pinners
 
 Bitboard Position::attackers_to(Square s, Bitboard occupied) const {
 
-  return  (attacks_from<PAWN>(s, BLACK)    & pieces(WHITE, PAWN))
+  return  (pawn_attacks_bb(BLACK, s)       & pieces(WHITE, PAWN))
-        | (attacks_from<PAWN>(s, WHITE)    & pieces(BLACK, PAWN))
+        | (pawn_attacks_bb(WHITE, s)       & pieces(BLACK, PAWN))
-        | (attacks_from<KNIGHT>(s)         & pieces(KNIGHT))
+        | (attacks_bb<KNIGHT>(s)           & pieces(KNIGHT))
         | (attacks_bb<  ROOK>(s, occupied) & pieces(  ROOK, QUEEN))
         | (attacks_bb<BISHOP>(s, occupied) & pieces(BISHOP, QUEEN))
-        | (attacks_from<KING>(s)           & pieces(KING));
+        | (attacks_bb<KING>(s)             & pieces(KING));
 }
 
 
@@ -503,7 +505,7 @@ bool Position::legal(Move m) const {
   // En passant captures are a tricky special case. Because they are rather
   // uncommon, we do it simply by testing whether the king is attacked after
   // the move is made.
-  if (type_of(m) == ENPASSANT)
+  if (type_of(m) == EN_PASSANT)
   {
       Square ksq = square<KING>(us);
       Square capsq = to - pawn_push(us);
@@ -531,22 +533,20 @@ bool Position::legal(Move m) const {
           if (attackers_to(s) & pieces(~us))
               return false;
 
-      // In case of Chess960, verify that when moving the castling rook we do
+      // In case of Chess960, verify if the Rook blocks some checks
-      // not discover some hidden checker.
       // For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1.
-      return   !chess960
+      return !chess960 || !(blockers_for_king(us) & to_sq(m));
-            || !(attacks_bb<ROOK>(to, pieces() ^ to_sq(m)) & pieces(~us, ROOK, QUEEN));
   }
 
   // If the moving piece is a king, check whether the destination square is
   // attacked by the opponent.
   if (type_of(piece_on(from)) == KING)
-      return !(attackers_to(to) & pieces(~us));
+      return !(attackers_to(to, pieces() ^ from) & pieces(~us));
 
   // A non-king move is legal if and only if it is not pinned or it
   // is moving along the ray towards or away from the king.
-  return   !(blockers_for_king(us) & from)
+  return !(blockers_for_king(us) & from)
-        ||  aligned(from, to, square<KING>(us));
+      || aligned(from, to, square<KING>(us));
 }
 
 
@@ -562,8 +562,10 @@ bool Position::pseudo_legal(const Move m) const {
   Piece pc = moved_piece(m);
 
   // Use a slower but simpler function for uncommon cases
+  // yet we skip the legality check of MoveList<LEGAL>().
   if (type_of(m) != NORMAL)
-      return MoveList<LEGAL>(*this).contains(m);
+      return checkers() ? MoveList<    EVASIONS>(*this).contains(m)
+                        : MoveList<NON_EVASIONS>(*this).contains(m);
 
   // Is not a promotion, so promotion piece must be empty
   if (promotion_type(m) - KNIGHT != NO_PIECE_TYPE)
@@ -586,15 +588,15 @@ bool Position::pseudo_legal(const Move m) const {
       if ((Rank8BB | Rank1BB) & to)
           return false;
 
-      if (   !(attacks_from<PAWN>(from, us) & pieces(~us) & to) // Not a capture
+      if (   !(pawn_attacks_bb(us, from) & pieces(~us) & to) // Not a capture
           && !((from + pawn_push(us) == to) && empty(to))       // Not a single push
           && !(   (from + 2 * pawn_push(us) == to)              // Not a double push
-               && (rank_of(from) == relative_rank(us, RANK_2))
+               && (relative_rank(us, from) == RANK_2)
                && empty(to)
                && empty(to - pawn_push(us))))
           return false;
   }
-  else if (!(attacks_from(type_of(pc), from) & to))
+  else if (!(attacks_bb(type_of(pc), from, pieces()) & to))
       return false;
 
   // Evasions generator already takes care to avoid some kind of illegal moves
@@ -608,8 +610,8 @@ bool Position::pseudo_legal(const Move m) const {
           if (more_than_one(checkers()))
               return false;
 
-          // Our move must be a blocking evasion or a capture of the checking piece
+          // Our move must be a blocking interposition or a capture of the checking piece
-          if (!((between_bb(lsb(checkers()), square<KING>(us)) | checkers()) & to))
+          if (!(between_bb(square<KING>(us), lsb(checkers())) & to))
               return false;
       }
       // In case of king moves under check we have to remove king so as to catch
@@ -633,11 +635,11 @@ bool Position::gives_check(Move m) const {
   Square to = to_sq(m);
 
   // Is there a direct check?
-  if (st->checkSquares[type_of(piece_on(from))] & to)
+  if (check_squares(type_of(piece_on(from))) & to)
       return true;
 
   // Is there a discovered check?
-  if (   (st->blockersForKing[~sideToMove] & from)
+  if (   (blockers_for_king(~sideToMove) & from)
       && !aligned(from, to, square<KING>(~sideToMove)))
       return true;
 
@@ -653,7 +655,7 @@ bool Position::gives_check(Move m) const {
   // of direct checks and ordinary discovered check, so the only case we
   // need to handle is the unusual case of a discovered check through
   // the captured pawn.
-  case ENPASSANT:
+  case EN_PASSANT:
   {
       Square capsq = make_square(file_of(to), rank_of(from));
       Bitboard b = (pieces() ^ from ^ capsq) | to;
@@ -661,19 +663,15 @@ bool Position::gives_check(Move m) const {
       return  (attacks_bb<  ROOK>(square<KING>(~sideToMove), b) & pieces(sideToMove, QUEEN, ROOK))
             | (attacks_bb<BISHOP>(square<KING>(~sideToMove), b) & pieces(sideToMove, QUEEN, BISHOP));
   }
-  case CASTLING:
+  default: //CASTLING
   {
-      Square kfrom = from;
+      // Castling is encoded as 'king captures the rook'
-      Square rfrom = to; // Castling is encoded as 'King captures the rook'
+      Square ksq = square<KING>(~sideToMove);
-      Square kto = relative_square(sideToMove, rfrom > kfrom ? SQ_G1 : SQ_C1);
+      Square rto = relative_square(sideToMove, to > from ? SQ_F1 : SQ_D1);
-      Square rto = relative_square(sideToMove, rfrom > kfrom ? SQ_F1 : SQ_D1);
 
-      return   (PseudoAttacks[ROOK][rto] & square<KING>(~sideToMove))
+      return   (attacks_bb<ROOK>(rto) & ksq)
-            && (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & square<KING>(~sideToMove));
+            && (attacks_bb<ROOK>(rto, pieces() ^ from ^ to) & ksq);
   }
-  default:
-      assert(false);
-      return false;
   }
 }
 
@@ -703,12 +701,18 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
   ++st->rule50;
   ++st->pliesFromNull;
 
+  // Used by NNUE
+  st->accumulator.computed[WHITE] = false;
+  st->accumulator.computed[BLACK] = false;
+  auto& dp = st->dirtyPiece;
+  dp.dirty_num = 1;
+
   Color us = sideToMove;
   Color them = ~us;
   Square from = from_sq(m);
   Square to = to_sq(m);
   Piece pc = piece_on(from);
-  Piece captured = type_of(m) == ENPASSANT ? make_piece(them, PAWN) : piece_on(to);
+  Piece captured = type_of(m) == EN_PASSANT ? make_piece(them, PAWN) : piece_on(to);
 
   assert(color_of(pc) == us);
   assert(captured == NO_PIECE || color_of(captured) == (type_of(m) != CASTLING ? them : us));
@@ -734,7 +738,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
       // update non-pawn material.
       if (type_of(captured) == PAWN)
       {
-          if (type_of(m) == ENPASSANT)
+          if (type_of(m) == EN_PASSANT)
           {
               capsq -= pawn_push(us);
 
@@ -743,8 +747,6 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
               assert(relative_rank(us, to) == RANK_6);
               assert(piece_on(to) == NO_PIECE);
               assert(piece_on(capsq) == make_piece(them, PAWN));
-
-              board[capsq] = NO_PIECE; // Not done by remove_piece()
           }
 
           st->pawnKey ^= Zobrist::psq[captured][capsq];
@@ -752,8 +754,19 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
       else
           st->nonPawnMaterial[them] -= PieceValue[MG][captured];
 
+      if (Eval::useNNUE)
+      {
+          dp.dirty_num = 2;  // 1 piece moved, 1 piece captured
+          dp.piece[1] = captured;
+          dp.from[1] = capsq;
+          dp.to[1] = SQ_NONE;
+      }
+
       // Update board and piece lists
-      remove_piece(captured, capsq);
+      remove_piece(capsq);
+
+      if (type_of(m) == EN_PASSANT)
+          board[capsq] = NO_PIECE;
 
       // Update material hash key and prefetch access to materialTable
       k ^= Zobrist::psq[captured][capsq];
@@ -777,21 +790,30 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
   // Update castling rights if needed
   if (st->castlingRights && (castlingRightsMask[from] | castlingRightsMask[to]))
   {
-      int cr = castlingRightsMask[from] | castlingRightsMask[to];
+      k ^= Zobrist::castling[st->castlingRights];
-      k ^= Zobrist::castling[st->castlingRights & cr];
+      st->castlingRights &= ~(castlingRightsMask[from] | castlingRightsMask[to]);
-      st->castlingRights &= ~cr;
+      k ^= Zobrist::castling[st->castlingRights];
   }
 
   // Move the piece. The tricky Chess960 castling is handled earlier
   if (type_of(m) != CASTLING)
-      move_piece(pc, from, to);
+  {
+      if (Eval::useNNUE)
+      {
+          dp.piece[0] = pc;
+          dp.from[0] = from;
+          dp.to[0] = to;
+      }
+
+      move_piece(from, to);
+  }
 
   // If the moving piece is a pawn do some special extra work
   if (type_of(pc) == PAWN)
   {
-      // Set en-passant square if the moved pawn can be captured
+      // Set en passant square if the moved pawn can be captured
       if (   (int(to) ^ int(from)) == 16
-          && (attacks_from<PAWN>(to - pawn_push(us), us) & pieces(them, PAWN)))
+          && (pawn_attacks_bb(us, to - pawn_push(us)) & pieces(them, PAWN)))
       {
           st->epSquare = to - pawn_push(us);
           k ^= Zobrist::enpassant[file_of(st->epSquare)];
@@ -804,9 +826,19 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
           assert(relative_rank(us, to) == RANK_8);
           assert(type_of(promotion) >= KNIGHT && type_of(promotion) <= QUEEN);
 
-          remove_piece(pc, to);
+          remove_piece(to);
           put_piece(promotion, to);
 
+          if (Eval::useNNUE)
+          {
+              // Promoting pawn to SQ_NONE, promoted piece from SQ_NONE
+              dp.to[0] = SQ_NONE;
+              dp.piece[dp.dirty_num] = promotion;
+              dp.from[dp.dirty_num] = SQ_NONE;
+              dp.to[dp.dirty_num] = to;
+              dp.dirty_num++;
+          }
+
           // Update hash keys
           k ^= Zobrist::psq[pc][to] ^ Zobrist::psq[promotion][to];
           st->pawnKey ^= Zobrist::psq[pc][to];
@@ -884,7 +916,7 @@ void Position::undo_move(Move m) {
       assert(type_of(pc) == promotion_type(m));
       assert(type_of(pc) >= KNIGHT && type_of(pc) <= QUEEN);
 
-      remove_piece(pc, to);
+      remove_piece(to);
       pc = make_piece(us, PAWN);
       put_piece(pc, to);
   }
@@ -896,13 +928,13 @@ void Position::undo_move(Move m) {
   }
   else
   {
-      move_piece(pc, to, from); // Put the piece back at the source square
+      move_piece(to, from); // Put the piece back at the source square
 
       if (st->capturedPiece)
       {
           Square capsq = to;
 
-          if (type_of(m) == ENPASSANT)
+          if (type_of(m) == EN_PASSANT)
           {
               capsq -= pawn_push(us);
 
@@ -935,16 +967,28 @@ void Position::do_castling(Color us, Square from, Square& to, Square& rfrom, Squ
   rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1);
   to = relative_square(us, kingSide ? SQ_G1 : SQ_C1);
 
+  if (Do && Eval::useNNUE)
+  {
+      auto& dp = st->dirtyPiece;
+      dp.piece[0] = make_piece(us, KING);
+      dp.from[0] = from;
+      dp.to[0] = to;
+      dp.piece[1] = make_piece(us, ROOK);
+      dp.from[1] = rfrom;
+      dp.to[1] = rto;
+      dp.dirty_num = 2;
+  }
+
   // Remove both pieces first since squares could overlap in Chess960
-  remove_piece(make_piece(us, KING), Do ? from : to);
+  remove_piece(Do ? from : to);
-  remove_piece(make_piece(us, ROOK), Do ? rfrom : rto);
+  remove_piece(Do ? rfrom : rto);
-  board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do it for us
+  board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do this for us
   put_piece(make_piece(us, KING), Do ? to : from);
   put_piece(make_piece(us, ROOK), Do ? rto : rfrom);
 }
 
 
-/// Position::do(undo)_null_move() is used to do(undo) a "null move": it flips
+/// Position::do_null_move() is used to do a "null move": it flips
 /// the side to move without executing any move on the board.
 
 void Position::do_null_move(StateInfo& newSt) {
@@ -952,10 +996,16 @@ void Position::do_null_move(StateInfo& newSt) {
   assert(!checkers());
   assert(&newSt != st);
 
-  std::memcpy(&newSt, st, sizeof(StateInfo));
+  std::memcpy(&newSt, st, offsetof(StateInfo, accumulator));
+
   newSt.previous = st;
   st = &newSt;
 
+  st->dirtyPiece.dirty_num = 0;
+  st->dirtyPiece.piece[0] = NO_PIECE; // Avoid checks in UpdateAccumulator()
+  st->accumulator.computed[WHITE] = false;
+  st->accumulator.computed[BLACK] = false;
+
   if (st->epSquare != SQ_NONE)
   {
       st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
@@ -963,7 +1013,7 @@ void Position::do_null_move(StateInfo& newSt) {
   }
 
   st->key ^= Zobrist::side;
-  prefetch(TT.first_entry(st->key));
+  prefetch(TT.first_entry(key()));
 
   ++st->rule50;
   st->pliesFromNull = 0;
@@ -977,6 +1027,9 @@ void Position::do_null_move(StateInfo& newSt) {
   assert(pos_is_ok());
 }
 
+
+/// Position::undo_null_move() must be used to undo a "null move"
+
 void Position::undo_null_move() {
 
   assert(!checkers());
@@ -988,7 +1041,7 @@ void Position::undo_null_move() {
 
 /// Position::key_after() computes the new hash key after the given move. Needed
 /// for speculative prefetch. It doesn't recognize special moves like castling,
-/// en-passant and promotions.
+/// en passant and promotions.
 
 Key Position::key_after(Move m) const {
 
@@ -1013,7 +1066,7 @@ bool Position::see_ge(Move m, Value threshold) const {
 
   assert(is_ok(m));
 
-  // Only deal with normal moves, assume others pass a simple see
+  // Only deal with normal moves, assume others pass a simple SEE
   if (type_of(m) != NORMAL)
       return VALUE_ZERO >= threshold;
 
@@ -1042,10 +1095,10 @@ bool Position::see_ge(Move m, Value threshold) const {
       if (!(stmAttackers = attackers & pieces(stm)))
           break;
 
-      // Don't allow pinned pieces to attack (except the king) as long as
+      // Don't allow pinned pieces to attack as long as there are
-      // there are pinners on their original square.
+      // pinners on their original square.
-      if (st->pinners[~stm] & occupied)
+      if (pinners(~stm) & occupied)
-          stmAttackers &= ~st->blockersForKing[stm];
+          stmAttackers &= ~blockers_for_king(stm);
 
       if (!stmAttackers)
           break;
@@ -1059,7 +1112,7 @@ bool Position::see_ge(Move m, Value threshold) const {
           if ((swap = PawnValueMg - swap) < res)
               break;
 
-          occupied ^= lsb(bb);
+          occupied ^= least_significant_square_bb(bb);
           attackers |= attacks_bb<BISHOP>(to, occupied) & pieces(BISHOP, QUEEN);
       }
 
@@ -1068,7 +1121,7 @@ bool Position::see_ge(Move m, Value threshold) const {
           if ((swap = KnightValueMg - swap) < res)
               break;
 
-          occupied ^= lsb(bb);
+          occupied ^= least_significant_square_bb(bb);
       }
 
       else if ((bb = stmAttackers & pieces(BISHOP)))
@@ -1076,7 +1129,7 @@ bool Position::see_ge(Move m, Value threshold) const {
           if ((swap = BishopValueMg - swap) < res)
               break;
 
-          occupied ^= lsb(bb);
+          occupied ^= least_significant_square_bb(bb);
           attackers |= attacks_bb<BISHOP>(to, occupied) & pieces(BISHOP, QUEEN);
       }
 
@@ -1085,7 +1138,7 @@ bool Position::see_ge(Move m, Value threshold) const {
           if ((swap = RookValueMg - swap) < res)
               break;
 
-          occupied ^= lsb(bb);
+          occupied ^= least_significant_square_bb(bb);
           attackers |= attacks_bb<ROOK>(to, occupied) & pieces(ROOK, QUEEN);
       }
 
@@ -1094,7 +1147,7 @@ bool Position::see_ge(Move m, Value threshold) const {
           if ((swap = QueenValueMg - swap) < res)
               break;
 
-          occupied ^= lsb(bb);
+          occupied ^= least_significant_square_bb(bb);
           attackers |=  (attacks_bb<BISHOP>(to, occupied) & pieces(BISHOP, QUEEN))
                       | (attacks_bb<ROOK  >(to, occupied) & pieces(ROOK  , QUEEN));
       }
@@ -1108,6 +1161,7 @@ bool Position::see_ge(Move m, Value threshold) const {
   return bool(res);
 }
 
+
 /// Position::is_draw() tests whether the position is drawn by 50-move rule
 /// or by repetition. It does not detect stalemates.
 
@@ -1118,10 +1172,7 @@ bool Position::is_draw(int ply) const {
 
   // Return a draw score if a position repeats once earlier but strictly
   // after the root, or repeats twice before or at the root.
-  if (st->repetition && st->repetition < ply)
+  return st->repetition && st->repetition < ply;
-      return true;
-
-  return false;
 }
 
 
@@ -1170,7 +1221,7 @@ bool Position::has_game_cycle(int ply) const {
           Square s1 = from_sq(move);
           Square s2 = to_sq(move);
 
-          if (!(between_bb(s1, s2) & pieces()))
+          if (!((between_bb(s1, s2) ^ s2) & pieces()))
           {
               if (ply > i)
                   return true;
@@ -1267,21 +1318,17 @@ bool Position::pos_is_ok() const {
               assert(0 && "pos_is_ok: Bitboards");
 
   StateInfo si = *st;
+  ASSERT_ALIGNED(&si, Eval::NNUE::CacheLineSize);
+
   set_state(&si);
   if (std::memcmp(&si, st, sizeof(StateInfo)))
       assert(0 && "pos_is_ok: State");
 
   for (Piece pc : Pieces)
-  {
       if (   pieceCount[pc] != popcount(pieces(color_of(pc), type_of(pc)))
           || pieceCount[pc] != std::count(board, board + SQUARE_NB, pc))
           assert(0 && "pos_is_ok: Pieces");
 
-      for (int i = 0; i < pieceCount[pc]; ++i)
-          if (board[pieceList[pc][i]] != pc || index[pieceList[pc][i]] != i)
-              assert(0 && "pos_is_ok: Index");
-  }
-
   for (Color c : { WHITE, BLACK })
       for (CastlingRights cr : {c & KING_SIDE, c & QUEEN_SIDE})
       {
@@ -1296,3 +1343,5 @@ bool Position::pos_is_ok() const {
 
   return true;
 }
+
+} // namespace Stockfish

src/position.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -27,8 +25,13 @@
 #include <string>
 
 #include "bitboard.h"
+#include "evaluate.h"
+#include "psqt.h"
 #include "types.h"
 
+#include "nnue/nnue_accumulator.h"
+
+namespace Stockfish {
 
 /// StateInfo struct stores information needed to restore a Position object to
 /// its previous state when we retract a move. Whenever a move is made on the
@@ -48,14 +51,19 @@ struct StateInfo {
   // Not copied when making a move (will be recomputed anyhow)
   Key        key;
   Bitboard   checkersBB;
-  Piece      capturedPiece;
   StateInfo* previous;
   Bitboard   blockersForKing[COLOR_NB];
   Bitboard   pinners[COLOR_NB];
   Bitboard   checkSquares[PIECE_TYPE_NB];
+  Piece      capturedPiece;
   int        repetition;
+
+  // Used by NNUE
+  Eval::NNUE::Accumulator accumulator;
+  DirtyPiece dirtyPiece;
 };
 
+
 /// A list to keep track of the position states along the setup moves (from the
 /// start position to the position just before the search starts). Needed by
 /// 'draw by repetition' detection. Use a std::deque because pointers to
@@ -80,10 +88,9 @@ public:
   // FEN string input/output
   Position& set(const std::string& fenStr, bool isChess960, StateInfo* si, Thread* th);
   Position& set(const std::string& code, Color c, StateInfo* si);
-  const std::string fen() const;
+  std::string fen() const;
 
   // Position representation
-  Bitboard pieces() const;
   Bitboard pieces(PieceType pt) const;
   Bitboard pieces(PieceType pt1, PieceType pt2) const;
   Bitboard pieces(Color c) const;
@@ -94,12 +101,11 @@ public:
   bool empty(Square s) const;
   template<PieceType Pt> int count(Color c) const;
   template<PieceType Pt> int count() const;
-  template<PieceType Pt> const Square* squares(Color c) const;
   template<PieceType Pt> Square square(Color c) const;
   bool is_on_semiopen_file(Color c, Square s) const;
 
   // Castling
-  int castling_rights(Color c) const;
+  CastlingRights castling_rights(Color c) const;
   bool can_castle(CastlingRights cr) const;
   bool castling_impeded(CastlingRights cr) const;
   Square castling_rook_square(CastlingRights cr) const;
@@ -108,14 +114,11 @@ public:
   Bitboard checkers() const;
   Bitboard blockers_for_king(Color c) const;
   Bitboard check_squares(PieceType pt) const;
-  bool is_discovery_check_on_king(Color c, Move m) const;
+  Bitboard pinners(Color c) const;
 
   // Attacks to/from a given square
   Bitboard attackers_to(Square s) const;
   Bitboard attackers_to(Square s, Bitboard occupied) const;
-  Bitboard attacks_from(PieceType pt, Square s) const;
-  template<PieceType> Bitboard attacks_from(Square s) const;
-  template<PieceType> Bitboard attacks_from(Square s, Color c) const;
   Bitboard slider_blockers(Bitboard sliders, Square s, Bitboard& pinners) const;
 
   // Properties of moves
@@ -124,7 +127,6 @@ public:
   bool capture(Move m) const;
   bool capture_or_promotion(Move m) const;
   bool gives_check(Move m) const;
-  bool advanced_pawn_push(Move m) const;
   Piece moved_piece(Move m) const;
   Piece captured_piece() const;
 
@@ -166,6 +168,12 @@ public:
   bool pos_is_ok() const;
   void flip();
 
+  // Used by NNUE
+  StateInfo* state() const;
+
+  void put_piece(Piece pc, Square s);
+  void remove_piece(Square s);
+
 private:
   // Initialization helpers (used while setting up a position)
   void set_castling_right(Color c, Square rfrom);
@@ -173,9 +181,7 @@ private:
   void set_check_info(StateInfo* si) const;
 
   // Other helpers
-  void put_piece(Piece pc, Square s);
+  void move_piece(Square from, Square to);
-  void remove_piece(Piece pc, Square s);
-  void move_piece(Piece pc, Square from, Square to);
   template<bool Do>
   void do_castling(Color us, Square from, Square& to, Square& rfrom, Square& rto);
 
@@ -184,51 +190,42 @@ private:
   Bitboard byTypeBB[PIECE_TYPE_NB];
   Bitboard byColorBB[COLOR_NB];
   int pieceCount[PIECE_NB];
-  Square pieceList[PIECE_NB][16];
-  int index[SQUARE_NB];
   int castlingRightsMask[SQUARE_NB];
   Square castlingRookSquare[CASTLING_RIGHT_NB];
   Bitboard castlingPath[CASTLING_RIGHT_NB];
+  Thread* thisThread;
+  StateInfo* st;
   int gamePly;
   Color sideToMove;
   Score psq;
-  Thread* thisThread;
-  StateInfo* st;
   bool chess960;
 };
 
-namespace PSQT {
-  extern Score psq[PIECE_NB][SQUARE_NB];
-}
-
 extern std::ostream& operator<<(std::ostream& os, const Position& pos);
 
 inline Color Position::side_to_move() const {
   return sideToMove;
 }
 
-inline bool Position::empty(Square s) const {
-  return board[s] == NO_PIECE;
-}
-
 inline Piece Position::piece_on(Square s) const {
+  assert(is_ok(s));
   return board[s];
 }
 
+inline bool Position::empty(Square s) const {
+  return piece_on(s) == NO_PIECE;
+}
+
 inline Piece Position::moved_piece(Move m) const {
-  return board[from_sq(m)];
+  return piece_on(from_sq(m));
 }
 
-inline Bitboard Position::pieces() const {
+inline Bitboard Position::pieces(PieceType pt = ALL_PIECES) const {
-  return byTypeBB[ALL_PIECES];
-}
-
-inline Bitboard Position::pieces(PieceType pt) const {
   return byTypeBB[pt];
 }
 
 inline Bitboard Position::pieces(PieceType pt1, PieceType pt2) const {
-  return byTypeBB[pt1] | byTypeBB[pt2];
+  return pieces(pt1) | pieces(pt2);
 }
 
 inline Bitboard Position::pieces(Color c) const {
@@ -236,11 +233,11 @@ inline Bitboard Position::pieces(Color c) const {
 }
 
 inline Bitboard Position::pieces(Color c, PieceType pt) const {
-  return byColorBB[c] & byTypeBB[pt];
+  return pieces(c) & pieces(pt);
 }
 
 inline Bitboard Position::pieces(Color c, PieceType pt1, PieceType pt2) const {
-  return byColorBB[c] & (byTypeBB[pt1] | byTypeBB[pt2]);
+  return pieces(c) & (pieces(pt1) | pieces(pt2));
 }
 
 template<PieceType Pt> inline int Position::count(Color c) const {
@@ -248,16 +245,12 @@ template<PieceType Pt> inline int Position::count(Color c) const {
 }
 
 template<PieceType Pt> inline int Position::count() const {
-  return pieceCount[make_piece(WHITE, Pt)] + pieceCount[make_piece(BLACK, Pt)];
+  return count<Pt>(WHITE) + count<Pt>(BLACK);
-}
-
-template<PieceType Pt> inline const Square* Position::squares(Color c) const {
-  return pieceList[make_piece(c, Pt)];
 }
 
 template<PieceType Pt> inline Square Position::square(Color c) const {
-  assert(pieceCount[make_piece(c, Pt)] == 1);
+  assert(count<Pt>(c) == 1);
-  return pieceList[make_piece(c, Pt)][0];
+  return lsb(pieces(c, Pt));
 }
 
 inline Square Position::ep_square() const {
@@ -272,14 +265,14 @@ inline bool Position::can_castle(CastlingRights cr) const {
   return st->castlingRights & cr;
 }
 
-inline int Position::castling_rights(Color c) const {
+inline CastlingRights Position::castling_rights(Color c) const {
-  return st->castlingRights & (c == WHITE ? WHITE_CASTLING : BLACK_CASTLING);
+  return c & CastlingRights(st->castlingRights);
 }
 
 inline bool Position::castling_impeded(CastlingRights cr) const {
   assert(cr == WHITE_OO || cr == WHITE_OOO || cr == BLACK_OO || cr == BLACK_OOO);
 
-  return byTypeBB[ALL_PIECES] & castlingPath[cr];
+  return pieces() & castlingPath[cr];
 }
 
 inline Square Position::castling_rook_square(CastlingRights cr) const {
@@ -288,26 +281,8 @@ inline Square Position::castling_rook_square(CastlingRights cr) const {
   return castlingRookSquare[cr];
 }
 
-template<PieceType Pt>
-inline Bitboard Position::attacks_from(Square s) const {
-  static_assert(Pt != PAWN, "Pawn attacks need color");
-
-  return  Pt == BISHOP || Pt == ROOK ? attacks_bb<Pt>(s, byTypeBB[ALL_PIECES])
-        : Pt == QUEEN  ? attacks_from<ROOK>(s) | attacks_from<BISHOP>(s)
-        : PseudoAttacks[Pt][s];
-}
-
-template<>
-inline Bitboard Position::attacks_from<PAWN>(Square s, Color c) const {
-  return PawnAttacks[c][s];
-}
-
-inline Bitboard Position::attacks_from(PieceType pt, Square s) const {
-  return attacks_bb(pt, s, byTypeBB[ALL_PIECES]);
-}
-
 inline Bitboard Position::attackers_to(Square s) const {
-  return attackers_to(s, byTypeBB[ALL_PIECES]);
+  return attackers_to(s, pieces());
 }
 
 inline Bitboard Position::checkers() const {
@@ -318,29 +293,25 @@ inline Bitboard Position::blockers_for_king(Color c) const {
   return st->blockersForKing[c];
 }
 
+inline Bitboard Position::pinners(Color c) const {
+  return st->pinners[c];
+}
+
 inline Bitboard Position::check_squares(PieceType pt) const {
   return st->checkSquares[pt];
 }
 
-inline bool Position::is_discovery_check_on_king(Color c, Move m) const {
-  return st->blockersForKing[c] & from_sq(m);
-}
-
 inline bool Position::pawn_passed(Color c, Square s) const {
   return !(pieces(~c, PAWN) & passed_pawn_span(c, s));
 }
 
-inline bool Position::advanced_pawn_push(Move m) const {
-  return   type_of(moved_piece(m)) == PAWN
-        && relative_rank(sideToMove, to_sq(m)) > RANK_5;
-}
-
 inline int Position::pawns_on_same_color_squares(Color c, Square s) const {
   return popcount(pieces(c, PAWN) & ((DarkSquares & s) ? DarkSquares : ~DarkSquares));
 }
 
 inline Key Position::key() const {
-  return st->key;
+  return st->rule50 < 14 ? st->key
+                         : st->key ^ make_key((st->rule50 - 14) / 8);
 }
 
 inline Key Position::pawn_key() const {
@@ -360,7 +331,7 @@ inline Value Position::non_pawn_material(Color c) const {
 }
 
 inline Value Position::non_pawn_material() const {
-  return st->nonPawnMaterial[WHITE] + st->nonPawnMaterial[BLACK];
+  return non_pawn_material(WHITE) + non_pawn_material(BLACK);
 }
 
 inline int Position::game_ply() const {
@@ -372,8 +343,8 @@ inline int Position::rule50_count() const {
 }
 
 inline bool Position::opposite_bishops() const {
-  return   pieceCount[W_BISHOP] == 1
+  return   count<BISHOP>(WHITE) == 1
-        && pieceCount[B_BISHOP] == 1
+        && count<BISHOP>(BLACK) == 1
         && opposite_colors(square<BISHOP>(WHITE), square<BISHOP>(BLACK));
 }
 
@@ -389,7 +360,7 @@ inline bool Position::capture_or_promotion(Move m) const {
 inline bool Position::capture(Move m) const {
   assert(is_ok(m));
   // Castling is encoded as "king captures rook"
-  return (!empty(to_sq(m)) && type_of(m) != CASTLING) || type_of(m) == ENPASSANT;
+  return (!empty(to_sq(m)) && type_of(m) != CASTLING) || type_of(m) == EN_PASSANT;
 }
 
 inline Piece Position::captured_piece() const {
@@ -403,45 +374,34 @@ inline Thread* Position::this_thread() const {
 inline void Position::put_piece(Piece pc, Square s) {
 
   board[s] = pc;
-  byTypeBB[ALL_PIECES] |= s;
+  byTypeBB[ALL_PIECES] |= byTypeBB[type_of(pc)] |= s;
-  byTypeBB[type_of(pc)] |= s;
   byColorBB[color_of(pc)] |= s;
-  index[s] = pieceCount[pc]++;
+  pieceCount[pc]++;
-  pieceList[pc][index[s]] = s;
   pieceCount[make_piece(color_of(pc), ALL_PIECES)]++;
   psq += PSQT::psq[pc][s];
 }
 
-inline void Position::remove_piece(Piece pc, Square s) {
+inline void Position::remove_piece(Square s) {
 
-  // WARNING: This is not a reversible operation. If we remove a piece in
+  Piece pc = board[s];
-  // do_move() and then replace it in undo_move() we will put it at the end of
-  // the list and not in its original place, it means index[] and pieceList[]
-  // are not invariant to a do_move() + undo_move() sequence.
   byTypeBB[ALL_PIECES] ^= s;
   byTypeBB[type_of(pc)] ^= s;
   byColorBB[color_of(pc)] ^= s;
-  /* board[s] = NO_PIECE;  Not needed, overwritten by the capturing one */
+  board[s] = NO_PIECE;
-  Square lastSquare = pieceList[pc][--pieceCount[pc]];
+  pieceCount[pc]--;
-  index[lastSquare] = index[s];
-  pieceList[pc][index[lastSquare]] = lastSquare;
-  pieceList[pc][pieceCount[pc]] = SQ_NONE;
   pieceCount[make_piece(color_of(pc), ALL_PIECES)]--;
   psq -= PSQT::psq[pc][s];
 }
 
-inline void Position::move_piece(Piece pc, Square from, Square to) {
+inline void Position::move_piece(Square from, Square to) {
 
-  // index[from] is not updated and becomes stale. This works as long as index[]
+  Piece pc = board[from];
-  // is accessed just by known occupied squares.
   Bitboard fromTo = from | to;
   byTypeBB[ALL_PIECES] ^= fromTo;
   byTypeBB[type_of(pc)] ^= fromTo;
   byColorBB[color_of(pc)] ^= fromTo;
   board[from] = NO_PIECE;
   board[to] = pc;
-  index[to] = index[from];
-  pieceList[pc][index[to]] = to;
   psq += PSQT::psq[pc][to] - PSQT::psq[pc][from];
 }
 
@@ -449,4 +409,11 @@ inline void Position::do_move(Move m, StateInfo& newSt) {
   do_move(m, newSt, gives_check(m));
 }
 
+inline StateInfo* Position::state() const {
+
+  return st;
+}
+
+} // namespace Stockfish
+
 #endif // #ifndef POSITION_H_INCLUDED

src/psqt.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -18,23 +16,23 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+
+#include "psqt.h"
+
 #include <algorithm>
 
+#include "bitboard.h"
 #include "types.h"
 
-Value PieceValue[PHASE_NB][PIECE_NB] = {
+namespace Stockfish {
-  { VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg },
-  { VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg }
-};
 
-namespace PSQT {
+namespace
+{
 
-#define S(mg, eg) make_score(mg, eg)
+auto constexpr S = make_score;
 
-// Bonus[PieceType][Square / 2] contains Piece-Square scores. For each piece
+// 'Bonus' contains Piece-Square parameters.
-// type on a given square a (middlegame, endgame) score pair is assigned. Table
+// Scores are explicit for files A to D, implicitly mirrored for E to H.
-// is defined for files A..D and white side: it is symmetric for black side and
-// second half of the files.
 constexpr Score Bonus[][RANK_NB][int(FILE_NB) / 2] = {
   { },
   { },
@@ -49,14 +47,14 @@ constexpr Score Bonus[][RANK_NB][int(FILE_NB) / 2] = {
    { S(-201,-100), S(-83,-88), S(-56,-56), S(-26,-17) }
   },
   { // Bishop
-   { S(-53,-57), S( -5,-30), S( -8,-37), S(-23,-12) },
+   { S(-37,-40), S(-4 ,-21), S( -6,-26), S(-16, -8) },
-   { S(-15,-37), S(  8,-13), S( 19,-17), S(  4,  1) },
+   { S(-11,-26), S(  6, -9), S( 13,-12), S(  3,  1) },
-   { S( -7,-16), S( 21, -1), S( -5, -2), S( 17, 10) },
+   { S(-5 ,-11), S( 15, -1), S( -4, -1), S( 12,  7) },
-   { S( -5,-20), S( 11, -6), S( 25,  0), S( 39, 17) },
+   { S(-4 ,-14), S(  8, -4), S( 18,  0), S( 27, 12) },
-   { S(-12,-17), S( 29, -1), S( 22,-14), S( 31, 15) },
+   { S(-8 ,-12), S( 20, -1), S( 15,-10), S( 22, 11) },
-   { S(-16,-30), S(  6,  6), S(  1,  4), S( 11,  6) },
+   { S(-11,-21), S(  4,  4), S(  1,  3), S(  8,  4) },
-   { S(-17,-31), S(-14,-20), S(  5, -1), S(  0,  1) },
+   { S(-12,-22), S(-10,-14), S(  4, -1), S(  0,  1) },
-   { S(-48,-46), S(  1,-42), S(-14,-37), S(-23,-24) }
+   { S(-34,-32), S(  1,-29), S(-10,-26), S(-16,-17) }
   },
   { // Rook
    { S(-31, -9), S(-20,-13), S(-14,-10), S(-5, -9) },
@@ -70,13 +68,13 @@ constexpr Score Bonus[][RANK_NB][int(FILE_NB) / 2] = {
   },
   { // Queen
    { S( 3,-69), S(-5,-57), S(-5,-47), S( 4,-26) },
-   { S(-3,-55), S( 5,-31), S( 8,-22), S(12, -4) },
+   { S(-3,-54), S( 5,-31), S( 8,-22), S(12, -4) },
    { S(-3,-39), S( 6,-18), S(13, -9), S( 7,  3) },
    { S( 4,-23), S( 5, -3), S( 9, 13), S( 8, 24) },
    { S( 0,-29), S(14, -6), S(12,  9), S( 5, 21) },
-   { S(-4,-38), S(10,-18), S( 6,-12), S( 8,  1) },
+   { S(-4,-38), S(10,-18), S( 6,-11), S( 8,  1) },
    { S(-5,-50), S( 6,-27), S(10,-24), S( 8, -8) },
-   { S(-2,-75), S(-2,-52), S( 1,-43), S(-2,-36) }
+   { S(-2,-74), S(-2,-52), S( 1,-43), S(-2,-34) }
   },
   { // King
    { S(271,  1), S(327, 45), S(271, 85), S(198, 76) },
@@ -93,38 +91,41 @@ constexpr Score Bonus[][RANK_NB][int(FILE_NB) / 2] = {
 constexpr Score PBonus[RANK_NB][FILE_NB] =
   { // Pawn (asymmetric distribution)
    { },
-   { S(  3,-10), S(  3, -6), S( 10, 10), S( 19,  0), S( 16, 14), S( 19,  7), S(  7, -5), S( -5,-19) },
+   { S(  2, -8), S(  4, -6), S( 11,  9), S( 18,  5), S( 16, 16), S( 21,  6), S(  9, -6), S( -3,-18) },
-   { S( -9,-10), S(-15,-10), S( 11,-10), S( 15,  4), S( 32,  4), S( 22,  3), S(  5, -6), S(-22, -4) },
+   { S( -9, -9), S(-15, -7), S( 11,-10), S( 15,  5), S( 31,  2), S( 23,  3), S(  6, -8), S(-20, -5) },
-   { S( -8,  6), S(-23, -2), S(  6, -8), S( 20, -4), S( 40,-13), S( 17,-12), S(  4,-10), S(-12, -9) },
+   { S( -3,  7), S(-20,  1), S(  8, -8), S( 19, -2), S( 39,-14), S( 17,-13), S(  2,-11), S( -5, -6) },
-   { S( 13,  9), S(  0,  4), S(-13,  3), S(  1,-12), S( 11,-12), S( -2, -6), S(-13, 13), S(  5,  8) },
+   { S( 11, 12), S( -4,  6), S(-11,  2), S(  2, -6), S( 11, -5), S(  0, -4), S(-12, 14), S(  5,  9) },
-   { S( -5, 28), S(-12, 20), S( -7, 21), S( 22, 28), S( -8, 30), S( -5,  7), S(-15,  6), S(-18, 13) },
+   { S(  3, 27), S(-11, 18), S( -6, 19), S( 22, 29), S( -8, 30), S( -5,  9), S(-14,  8), S(-11, 14) },
-   { S( -7,  0), S(  7,-11), S( -3, 12), S(-13, 21), S(  5, 25), S(-16, 19), S( 10,  4), S( -8,  7) }
+   { S( -7, -1), S(  6,-14), S( -2, 13), S(-11, 22), S(  4, 24), S(-14, 17), S( 10,  7), S( -9,  7) }
   };
 
-#undef S
+} // namespace
+
+
+namespace PSQT
+{
 
 Score psq[PIECE_NB][SQUARE_NB];
 
-// init() initializes piece-square tables: the white halves of the tables are
+// PSQT::init() initializes piece-square tables: the white halves of the tables are
-// copied from Bonus[] adding the piece value, then the black halves of the
+// copied from Bonus[] and PBonus[], adding the piece value, then the black halves of
-// tables are initialized by flipping and changing the sign of the white scores.
+// the tables are initialized by flipping and changing the sign of the white scores.
 void init() {
 
-  for (Piece pc = W_PAWN; pc <= W_KING; ++pc)
+  for (Piece pc : {W_PAWN, W_KNIGHT, W_BISHOP, W_ROOK, W_QUEEN, W_KING})
   {
-      PieceValue[MG][~pc] = PieceValue[MG][pc];
+    Score score = make_score(PieceValue[MG][pc], PieceValue[EG][pc]);
-      PieceValue[EG][~pc] = PieceValue[EG][pc];
 
-      Score score = make_score(PieceValue[MG][pc], PieceValue[EG][pc]);
+    for (Square s = SQ_A1; s <= SQ_H8; ++s)
-
+    {
-      for (Square s = SQ_A1; s <= SQ_H8; ++s)
+      File f = File(edge_distance(file_of(s)));
-      {
+      psq[ pc][s] = score + (type_of(pc) == PAWN ? PBonus[rank_of(s)][file_of(s)]
-          File f = map_to_queenside(file_of(s));
+                                                 : Bonus[pc][rank_of(s)][f]);
-          psq[ pc][ s] = score + (type_of(pc) == PAWN ? PBonus[rank_of(s)][file_of(s)]
+      psq[~pc][flip_rank(s)] = -psq[pc][s];
-                                                      : Bonus[pc][rank_of(s)][f]);
+    }
-          psq[~pc][~s] = -psq[pc][s];
-      }
   }
 }
 
 } // namespace PSQT
+
+} // namespace Stockfish

src/psqt.h

@@ -0,0 +1,38 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+
+#ifndef PSQT_H_INCLUDED
+#define PSQT_H_INCLUDED
+
+
+#include "types.h"
+
+
+namespace Stockfish::PSQT
+{
+
+extern Score psq[PIECE_NB][SQUARE_NB];
+
+// Fill psqt array from a set of internally linked parameters
+extern void init();
+
+} // namespace Stockfish::PSQT
+
+
+#endif // PSQT_H_INCLUDED

src/search.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -27,6 +25,8 @@
 #include "movepick.h"
 #include "types.h"
 
+namespace Stockfish {
+
 class Position;
 
 namespace Search {
@@ -49,6 +49,10 @@ struct Stack {
   Value staticEval;
   int statScore;
   int moveCount;
+  bool inCheck;
+  bool ttPv;
+  bool ttHit;
+  int doubleExtensions;
 };
 
 
@@ -70,7 +74,6 @@ struct RootMove {
   Value previousScore = -VALUE_INFINITE;
   int selDepth = 0;
   int tbRank = 0;
-  int bestMoveCount = 0;
   Value tbScore;
   std::vector<Move> pv;
 };
@@ -90,7 +93,7 @@ struct LimitsType {
   }
 
   bool use_time_management() const {
-    return !(mate | movetime | depth | nodes | perft | infinite);
+    return time[WHITE] || time[BLACK];
   }
 
   std::vector<Move> searchmoves;
@@ -106,4 +109,6 @@ void clear();
 
 } // namespace Search
 
+} // namespace Stockfish
+
 #endif // #ifndef SEARCH_H_INCLUDED

src/syzygy/tbprobe.cpp

@@ -1,7 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (c) 2013 Ronald de Man
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2016-2020 Marco Costalba, Lucas Braesch
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -51,22 +50,23 @@
 #include <windows.h>
 #endif
 
-using namespace Tablebases;
+using namespace Stockfish::Tablebases;
 
-int Tablebases::MaxCardinality;
+int Stockfish::Tablebases::MaxCardinality;
+
+namespace Stockfish {
 
 namespace {
 
 constexpr int TBPIECES = 7; // Max number of supported pieces
 
 enum { BigEndian, LittleEndian };
-enum TBType { KEY, WDL, DTZ }; // Used as template parameter
+enum TBType { WDL, DTZ }; // Used as template parameter
 
 // Each table has a set of flags: all of them refer to DTZ tables, the last one to WDL tables
 enum TBFlag { STM = 1, Mapped = 2, WinPlies = 4, LossPlies = 8, Wide = 16, SingleValue = 128 };
 
 inline WDLScore operator-(WDLScore d) { return WDLScore(-int(d)); }
-inline Square operator^=(Square& s, int i) { return s = Square(int(s) ^ i); }
 inline Square operator^(Square s, int i) { return Square(int(s) ^ i); }
 
 const std::string PieceToChar = " PNBRQK  pnbrqk";
@@ -105,9 +105,6 @@ template<> inline void swap_endian<uint8_t>(uint8_t&) {}
 
 template<typename T, int LE> T number(void* addr)
 {
-    static const union { uint32_t i; char c[4]; } Le = { 0x01020304 };
-    static const bool IsLittleEndian = (Le.c[0] == 4);
-
     T v;
 
     if ((uintptr_t)addr & (alignof(T) - 1)) // Unaligned pointer (very rare)
@@ -192,7 +189,8 @@ public:
         std::stringstream ss(Paths);
         std::string path;
 
-        while (std::getline(ss, path, SepChar)) {
+        while (std::getline(ss, path, SepChar))
+        {
             fname = path + "/" + f;
             std::ifstream::open(fname);
             if (is_open())
@@ -225,7 +223,9 @@ public:
 
         *mapping = statbuf.st_size;
         *baseAddress = mmap(nullptr, statbuf.st_size, PROT_READ, MAP_SHARED, fd, 0);
+#if defined(MADV_RANDOM)
         madvise(*baseAddress, statbuf.st_size, MADV_RANDOM);
+#endif
         ::close(fd);
 
         if (*baseAddress == MAP_FAILED)
@@ -404,7 +404,17 @@ TBTable<DTZ>::TBTable(const TBTable<WDL>& wdl) : TBTable() {
 // at init time, accessed at probe time.
 class TBTables {
 
-    typedef std::tuple<Key, TBTable<WDL>*, TBTable<DTZ>*> Entry;
+    struct Entry
+    {
+        Key key;
+        TBTable<WDL>* wdl;
+        TBTable<DTZ>* dtz;
+
+        template <TBType Type>
+        TBTable<Type>* get() const {
+            return (TBTable<Type>*)(Type == WDL ? (void*)wdl : (void*)dtz);
+        }
+    };
 
     static constexpr int Size = 1 << 12; // 4K table, indexed by key's 12 lsb
     static constexpr int Overflow = 1;  // Number of elements allowed to map to the last bucket
@@ -416,12 +426,12 @@ class TBTables {
 
     void insert(Key key, TBTable<WDL>* wdl, TBTable<DTZ>* dtz) {
         uint32_t homeBucket = (uint32_t)key & (Size - 1);
-        Entry entry = std::make_tuple(key, wdl, dtz);
+        Entry entry{ key, wdl, dtz };
 
         // Ensure last element is empty to avoid overflow when looking up
         for (uint32_t bucket = homeBucket; bucket < Size + Overflow - 1; ++bucket) {
-            Key otherKey = std::get<KEY>(hashTable[bucket]);
+            Key otherKey = hashTable[bucket].key;
-            if (otherKey == key || !std::get<WDL>(hashTable[bucket])) {
+            if (otherKey == key || !hashTable[bucket].get<WDL>()) {
                 hashTable[bucket] = entry;
                 return;
             }
@@ -430,7 +440,7 @@ class TBTables {
             // insert here and search for a new spot for the other element instead.
             uint32_t otherHomeBucket = (uint32_t)otherKey & (Size - 1);
             if (otherHomeBucket > homeBucket) {
-                swap(entry, hashTable[bucket]);
+                std::swap(entry, hashTable[bucket]);
                 key = otherKey;
                 homeBucket = otherHomeBucket;
             }
@@ -443,8 +453,8 @@ public:
     template<TBType Type>
     TBTable<Type>* get(Key key) {
         for (const Entry* entry = &hashTable[(uint32_t)key & (Size - 1)]; ; ++entry) {
-            if (std::get<KEY>(*entry) == key || !std::get<Type>(*entry))
+            if (entry->key == key || !entry->get<Type>())
-                return std::get<Type>(*entry);
+                return entry->get<Type>();
         }
     }
 
@@ -521,7 +531,7 @@ int decompress_pairs(PairsData* d, uint64_t idx) {
     //       I(k) = k * d->span + d->span / 2      (1)
 
     // First step is to get the 'k' of the I(k) nearest to our idx, using definition (1)
-    uint32_t k = idx / d->span;
+    uint32_t k = uint32_t(idx / d->span);
 
     // Then we read the corresponding SparseIndex[] entry
     uint32_t block = number<uint32_t, LittleEndian>(&d->sparseIndex[k].block);
@@ -555,7 +565,8 @@ int decompress_pairs(PairsData* d, uint64_t idx) {
     int buf64Size = 64;
     Sym sym;
 
-    while (true) {
+    while (true)
+    {
         int len = 0; // This is the symbol length - d->min_sym_len
 
         // Now get the symbol length. For any symbol s64 of length l right-padded
@@ -567,7 +578,7 @@ int decompress_pairs(PairsData* d, uint64_t idx) {
         // All the symbols of a given length are consecutive integers (numerical
         // sequence property), so we can compute the offset of our symbol of
         // length len, stored at the beginning of buf64.
-        sym = (buf64 - d->base64[len]) >> (64 - len - d->minSymLen);
+        sym = Sym((buf64 - d->base64[len]) >> (64 - len - d->minSymLen));
 
         // Now add the value of the lowest symbol of length len to get our symbol
         sym += number<Sym, LittleEndian>(&d->lowestSym[len]);
@@ -593,8 +604,8 @@ int decompress_pairs(PairsData* d, uint64_t idx) {
     // We binary-search for our value recursively expanding into the left and
     // right child symbols until we reach a leaf node where symlen[sym] + 1 == 1
     // that will store the value we need.
-    while (d->symlen[sym]) {
+    while (d->symlen[sym])
-
+    {
         Sym left = d->btree[sym].get<LR::Left>();
 
         // If a symbol contains 36 sub-symbols (d->symlen[sym] + 1 = 36) and
@@ -699,14 +710,14 @@ Ret do_probe_table(const Position& pos, T* entry, WDLScore wdl, ProbeState* resu
 
         leadPawns = b = pos.pieces(color_of(pc), PAWN);
         do
-            squares[size++] = pop_lsb(&b) ^ flipSquares;
+            squares[size++] = pop_lsb(b) ^ flipSquares;
         while (b);
 
         leadPawnsCnt = size;
 
         std::swap(squares[0], *std::max_element(squares, squares + leadPawnsCnt, pawns_comp));
 
-        tbFile = map_to_queenside(file_of(squares[0]));
+        tbFile = File(edge_distance(file_of(squares[0])));
     }
 
     // DTZ tables are one-sided, i.e. they store positions only for white to
@@ -719,7 +730,7 @@ Ret do_probe_table(const Position& pos, T* entry, WDLScore wdl, ProbeState* resu
     // directly map them to the correct color and square.
     b = pos.pieces() ^ leadPawns;
     do {
-        Square s = pop_lsb(&b);
+        Square s = pop_lsb(b);
         squares[size] = s ^ flipSquares;
         pieces[size++] = Piece(pos.piece_on(s) ^ flipColor);
     } while (b);
@@ -743,14 +754,14 @@ Ret do_probe_table(const Position& pos, T* entry, WDLScore wdl, ProbeState* resu
     // the triangle A1-D1-D4.
     if (file_of(squares[0]) > FILE_D)
         for (int i = 0; i < size; ++i)
-            squares[i] ^= 7; // Horizontal flip: SQ_H1 -> SQ_A1
+            squares[i] = flip_file(squares[i]);
 
     // Encode leading pawns starting with the one with minimum MapPawns[] and
     // proceeding in ascending order.
     if (entry->hasPawns) {
         idx = LeadPawnIdx[leadPawnsCnt][squares[0]];
 
-        std::sort(squares + 1, squares + leadPawnsCnt, pawns_comp);
+        std::stable_sort(squares + 1, squares + leadPawnsCnt, pawns_comp);
 
         for (int i = 1; i < leadPawnsCnt; ++i)
             idx += Binomial[i][MapPawns[squares[i]]];
@@ -762,7 +773,7 @@ Ret do_probe_table(const Position& pos, T* entry, WDLScore wdl, ProbeState* resu
     // piece is below RANK_5.
     if (rank_of(squares[0]) > RANK_4)
         for (int i = 0; i < size; ++i)
-            squares[i] ^= SQ_A8; // Vertical flip: SQ_A8 -> SQ_A1
+            squares[i] = flip_rank(squares[i]);
 
     // Look for the first piece of the leading group not on the A1-D4 diagonal
     // and ensure it is mapped below the diagonal.
@@ -770,7 +781,7 @@ Ret do_probe_table(const Position& pos, T* entry, WDLScore wdl, ProbeState* resu
         if (!off_A1H8(squares[i]))
             continue;
 
-        if (off_A1H8(squares[i]) > 0) // A1-H8 diagonal flip: SQ_A3 -> SQ_C3
+        if (off_A1H8(squares[i]) > 0) // A1-H8 diagonal flip: SQ_A3 -> SQ_C1
             for (int j = i; j < size; ++j)
                 squares[j] = Square(((squares[j] >> 3) | (squares[j] << 3)) & 63);
         break;
@@ -851,7 +862,7 @@ encode_remaining:
 
     while (d->groupLen[++next])
     {
-        std::sort(groupSq, groupSq + d->groupLen[next]);
+        std::stable_sort(groupSq, groupSq + d->groupLen[next]);
         uint64_t n = 0;
 
         // Map down a square if "comes later" than a square in the previous
@@ -975,7 +986,7 @@ uint8_t* set_sizes(PairsData* d, uint8_t* data) {
 
     d->sizeofBlock = 1ULL << *data++;
     d->span = 1ULL << *data++;
-    d->sparseIndexSize = (tbSize + d->span - 1) / d->span; // Round up
+    d->sparseIndexSize = size_t((tbSize + d->span - 1) / d->span); // Round up
     auto padding = number<uint8_t, LittleEndian>(data++);
     d->blocksNum = number<uint32_t, LittleEndian>(data); data += sizeof(uint32_t);
     d->blockLengthSize = d->blocksNum + padding; // Padded to ensure SparseIndex[]
@@ -990,7 +1001,7 @@ uint8_t* set_sizes(PairsData* d, uint8_t* data) {
     // so that d->lowestSym[i] >= d->lowestSym[i+1] (when read as LittleEndian).
     // Starting from this we compute a base64[] table indexed by symbol length
     // and containing 64 bit values so that d->base64[i] >= d->base64[i+1].
-    // See http://www.eecs.harvard.edu/~michaelm/E210/huffman.pdf
+    // See https://en.wikipedia.org/wiki/Huffman_coding
     for (int i = d->base64.size() - 2; i >= 0; --i) {
         d->base64[i] = (d->base64[i + 1] + number<Sym, LittleEndian>(&d->lowestSym[i])
                                          - number<Sym, LittleEndian>(&d->lowestSym[i + 1])) / 2;
@@ -1131,7 +1142,7 @@ void* mapped(TBTable<Type>& e, const Position& pos) {
     if (e.ready.load(std::memory_order_acquire))
         return e.baseAddress; // Could be nullptr if file does not exist
 
-    std::unique_lock<std::mutex> lk(mutex);
+    std::scoped_lock<std::mutex> lk(mutex);
 
     if (e.ready.load(std::memory_order_relaxed)) // Recheck under lock
         return e.baseAddress;
@@ -1191,7 +1202,7 @@ WDLScore search(Position& pos, ProbeState* result) {
     auto moveList = MoveList<LEGAL>(pos);
     size_t totalCount = moveList.size(), moveCount = 0;
 
-    for (const Move& move : moveList)
+    for (const Move move : moveList)
     {
         if (   !pos.capture(move)
             && (!CheckZeroingMoves || type_of(pos.moved_piece(move)) != PAWN))
@@ -1344,7 +1355,7 @@ void Tablebases::init(const std::string& paths) {
                 if (leadPawnsCnt == 1)
                 {
                     MapPawns[sq] = availableSquares--;
-                    MapPawns[sq ^ 7] = availableSquares--; // Horizontal flip
+                    MapPawns[flip_file(sq)] = availableSquares--;
                 }
                 LeadPawnIdx[leadPawnsCnt][sq] = idx;
                 idx += Binomial[leadPawnsCnt - 1][MapPawns[sq]];
@@ -1353,7 +1364,7 @@ void Tablebases::init(const std::string& paths) {
             LeadPawnsSize[leadPawnsCnt][f] = idx;
         }
 
-    // Add entries in TB tables if the corresponding ".rtbw" file exsists
+    // Add entries in TB tables if the corresponding ".rtbw" file exists
     for (PieceType p1 = PAWN; p1 < KING; ++p1) {
         TBTables.add({KING, p1, KING});
 
@@ -1430,7 +1441,7 @@ WDLScore Tablebases::probe_wdl(Position& pos, ProbeState* result) {
 // If n = 100 immediately after a capture or pawn move, then the position
 // is also certainly a win, and during the whole phase until the next
 // capture or pawn move, the inequality to be preserved is
-// dtz + 50-movecounter <= 100.
+// dtz + 50-move-counter <= 100.
 //
 // In short, if a move is available resulting in dtz + 50-move-counter <= 99,
 // then do not accept moves leading to dtz + 50-move-counter == 100.
@@ -1460,7 +1471,7 @@ int Tablebases::probe_dtz(Position& pos, ProbeState* result) {
     StateInfo st;
     int minDTZ = 0xFFFF;
 
-    for (const Move& move : MoveList<LEGAL>(pos))
+    for (const Move move : MoveList<LEGAL>(pos))
     {
         bool zeroing = pos.capture(move) || type_of(pos.moved_piece(move)) == PAWN;
 
@@ -1525,6 +1536,14 @@ bool Tablebases::root_probe(Position& pos, Search::RootMoves& rootMoves) {
             WDLScore wdl = -probe_wdl(pos, &result);
             dtz = dtz_before_zeroing(wdl);
         }
+        else if (pos.is_draw(1))
+        {
+            // In case a root move leads to a draw by repetition or
+            // 50-move rule, we set dtz to zero. Note: since we are
+            // only 1 ply from the root, this must be a true 3-fold
+            // repetition inside the game history.
+            dtz = 0;
+        }
         else
         {
             // Otherwise, take dtz for the new position and correct by 1 ply
@@ -1575,6 +1594,7 @@ bool Tablebases::root_probe_wdl(Position& pos, Search::RootMoves& rootMoves) {
 
     ProbeState result;
     StateInfo st;
+    WDLScore wdl;
 
     bool rule50 = Options["Syzygy50MoveRule"];
 
@@ -1583,7 +1603,10 @@ bool Tablebases::root_probe_wdl(Position& pos, Search::RootMoves& rootMoves) {
     {
         pos.do_move(m.pv[0], st);
 
-        WDLScore wdl = -probe_wdl(pos, &result);
+        if (pos.is_draw(1))
+            wdl = WDLDraw;
+        else
+            wdl = -probe_wdl(pos, &result);
 
         pos.undo_move(m.pv[0]);
 
@@ -1600,3 +1623,5 @@ bool Tablebases::root_probe_wdl(Position& pos, Search::RootMoves& rootMoves) {
 
     return true;
 }
+
+} // namespace Stockfish

src/syzygy/tbprobe.h

@@ -1,7 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (c) 2013 Ronald de Man
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2016-2020 Marco Costalba, Lucas Braesch
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -24,7 +23,7 @@
 
 #include "../search.h"
 
-namespace Tablebases {
+namespace Stockfish::Tablebases {
 
 enum WDLScore {
     WDLLoss        = -2, // Loss
@@ -74,6 +73,6 @@ inline std::ostream& operator<<(std::ostream& os, const ProbeState v) {
     return os;
 }
 
-}
+} // namespace Stockfish::Tablebases
 
 #endif

src/thread.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -28,6 +26,8 @@
 #include "syzygy/tbprobe.h"
 #include "tt.h"
 
+namespace Stockfish {
+
 ThreadPool Threads; // Global object
 
 
@@ -52,15 +52,6 @@ Thread::~Thread() {
   stdThread.join();
 }
 
-/// Thread::bestMoveCount(Move move) return best move counter for the given root move
-
-int Thread::best_move_count(Move move) {
-
-  auto rm = std::find(rootMoves.begin() + pvIdx,
-                      rootMoves.begin() + pvLast, move);
-
-  return rm != rootMoves.begin() + pvLast ? rm->bestMoveCount : 0;
-}
 
 /// Thread::clear() reset histories, usually before a new game
 
@@ -68,19 +59,20 @@ void Thread::clear() {
 
   counterMoves.fill(MOVE_NONE);
   mainHistory.fill(0);
+  lowPlyHistory.fill(0);
   captureHistory.fill(0);
 
   for (bool inCheck : { false, true })
-    for (StatsType c : { NoCaptures, Captures })
+      for (StatsType c : { NoCaptures, Captures })
-      for (auto& to : continuationHistory[inCheck][c])
+      {
-        for (auto& h : to)
+          for (auto& to : continuationHistory[inCheck][c])
-          h->fill(0);
+                for (auto& h : to)
-
+                      h->fill(0);
-  for (bool inCheck : { false, true })
+          continuationHistory[inCheck][c][NO_PIECE][0]->fill(Search::CounterMovePruneThreshold - 1);
-    for (StatsType c : { NoCaptures, Captures })
+      }
-      continuationHistory[inCheck][c][NO_PIECE][0]->fill(Search::CounterMovePruneThreshold - 1);
 }
 
+
 /// Thread::start_searching() wakes up the thread that will start the search
 
 void Thread::start_searching() {
@@ -136,14 +128,16 @@ void Thread::idle_loop() {
 
 void ThreadPool::set(size_t requested) {
 
-  if (size() > 0) { // destroy any existing thread(s)
+  if (size() > 0)   // destroy any existing thread(s)
+  {
       main()->wait_for_search_finished();
 
       while (size() > 0)
           delete back(), pop_back();
   }
 
-  if (requested > 0) { // create new thread(s)
+  if (requested > 0)   // create new thread(s)
+  {
       push_back(new MainThread(0));
 
       while (size() < requested)
@@ -151,14 +145,15 @@ void ThreadPool::set(size_t requested) {
       clear();
 
       // Reallocate the hash with the new threadpool size
-      TT.resize(Options["Hash"]);
+      TT.resize(size_t(Options["Hash"]));
 
       // Init thread number dependent search params.
       Search::init();
   }
 }
 
-/// ThreadPool::clear() sets threadPool data to initial values.
+
+/// ThreadPool::clear() sets threadPool data to initial values
 
 void ThreadPool::clear() {
 
@@ -166,10 +161,11 @@ void ThreadPool::clear() {
       th->clear();
 
   main()->callsCnt = 0;
-  main()->previousScore = VALUE_INFINITE;
+  main()->bestPreviousScore = VALUE_INFINITE;
   main()->previousTimeReduction = 1.0;
 }
 
+
 /// ThreadPool::start_thinking() wakes up main thread waiting in idle_loop() and
 /// returns immediately. Main thread will wake up other threads and start the search.
 
@@ -201,20 +197,70 @@ void ThreadPool::start_thinking(Position& pos, StateListPtr& states,
 
   // We use Position::set() to set root position across threads. But there are
   // some StateInfo fields (previous, pliesFromNull, capturedPiece) that cannot
-  // be deduced from a fen string, so set() clears them and to not lose the info
+  // be deduced from a fen string, so set() clears them and they are set from
-  // we need to backup and later restore setupStates->back(). Note that setupStates
+  // setupStates->back() later. The rootState is per thread, earlier states are shared
-  // is shared by threads but is accessed in read-only mode.
+  // since they are read-only.
-  StateInfo tmp = setupStates->back();
-
   for (Thread* th : *this)
   {
-      th->nodes = th->tbHits = th->nmpMinPly = 0;
+      th->nodes = th->tbHits = th->nmpMinPly = th->bestMoveChanges = 0;
       th->rootDepth = th->completedDepth = 0;
       th->rootMoves = rootMoves;
-      th->rootPos.set(pos.fen(), pos.is_chess960(), &setupStates->back(), th);
+      th->rootPos.set(pos.fen(), pos.is_chess960(), &th->rootState, th);
+      th->rootState = setupStates->back();
   }
 
-  setupStates->back() = tmp;
-
   main()->start_searching();
 }
+
+Thread* ThreadPool::get_best_thread() const {
+
+    Thread* bestThread = front();
+    std::map<Move, int64_t> votes;
+    Value minScore = VALUE_NONE;
+
+    // Find minimum score of all threads
+    for (Thread* th: *this)
+        minScore = std::min(minScore, th->rootMoves[0].score);
+
+    // Vote according to score and depth, and select the best thread
+    for (Thread* th : *this)
+    {
+        votes[th->rootMoves[0].pv[0]] +=
+            (th->rootMoves[0].score - minScore + 14) * int(th->completedDepth);
+
+        if (abs(bestThread->rootMoves[0].score) >= VALUE_TB_WIN_IN_MAX_PLY)
+        {
+            // Make sure we pick the shortest mate / TB conversion or stave off mate the longest
+            if (th->rootMoves[0].score > bestThread->rootMoves[0].score)
+                bestThread = th;
+        }
+        else if (   th->rootMoves[0].score >= VALUE_TB_WIN_IN_MAX_PLY
+                 || (   th->rootMoves[0].score > VALUE_TB_LOSS_IN_MAX_PLY
+                     && votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]]))
+            bestThread = th;
+    }
+
+    return bestThread;
+}
+
+
+/// Start non-main threads
+
+void ThreadPool::start_searching() {
+
+    for (Thread* th : *this)
+        if (th != front())
+            th->start_searching();
+}
+
+
+/// Wait for non-main threads
+
+void ThreadPool::wait_for_search_finished() const {
+
+    for (Thread* th : *this)
+        if (th != front())
+            th->wait_for_search_finished();
+}
+
+} // namespace Stockfish

src/thread.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -34,6 +32,7 @@
 #include "search.h"
 #include "thread_win32_osx.h"
 
+namespace Stockfish {
 
 /// Thread class keeps together all the thread-related stuff. We use
 /// per-thread pawn and material hash tables so that once we get a
@@ -56,7 +55,7 @@ public:
   void idle_loop();
   void start_searching();
   void wait_for_search_finished();
-  int best_move_count(Move move);
+  size_t id() const { return idx; }
 
   Pawns::Table pawnsTable;
   Material::Table materialTable;
@@ -67,13 +66,15 @@ public:
   std::atomic<uint64_t> nodes, tbHits, bestMoveChanges;
 
   Position rootPos;
+  StateInfo rootState;
   Search::RootMoves rootMoves;
   Depth rootDepth, completedDepth;
   CounterMoveHistory counterMoves;
   ButterflyHistory mainHistory;
+  LowPlyHistory lowPlyHistory;
   CapturePieceToHistory captureHistory;
   ContinuationHistory continuationHistory[2][2];
-  Score contempt;
+  Score trend;
 };
 
 
@@ -87,7 +88,7 @@ struct MainThread : public Thread {
   void check_time();
 
   double previousTimeReduction;
-  Value previousScore;
+  Value bestPreviousScore;
   Value iterValue[4];
   int callsCnt;
   bool stopOnPonderhit;
@@ -108,6 +109,9 @@ struct ThreadPool : public std::vector<Thread*> {
   MainThread* main()        const { return static_cast<MainThread*>(front()); }
   uint64_t nodes_searched() const { return accumulate(&Thread::nodes); }
   uint64_t tb_hits()        const { return accumulate(&Thread::tbHits); }
+  Thread* get_best_thread() const;
+  void start_searching();
+  void wait_for_search_finished() const;
 
   std::atomic_bool stop, increaseDepth;
 
@@ -125,4 +129,6 @@ private:
 
 extern ThreadPool Threads;
 
+} // namespace Stockfish
+
 #endif // #ifndef THREAD_H_INCLUDED

src/thread_win32_osx.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -29,10 +27,12 @@
 /// The implementation calls pthread_create() with the stack size parameter
 /// equal to the linux 8MB default, on platforms that support it.
 
-#if defined(__APPLE__) || defined(__MINGW32__) || defined(__MINGW64__)
+#if defined(__APPLE__) || defined(__MINGW32__) || defined(__MINGW64__) || defined(USE_PTHREADS)
 
 #include <pthread.h>
 
+namespace Stockfish {
+
 static const size_t TH_STACK_SIZE = 8 * 1024 * 1024;
 
 template <class T, class P = std::pair<T*, void(T::*)()>>
@@ -59,10 +59,16 @@ public:
   void join() { pthread_join(thread, NULL); }
 };
 
+} // namespace Stockfish
+
 #else // Default case: use STL classes
 
+namespace Stockfish {
+
 typedef std::thread NativeThread;
 
+} // namespace Stockfish
+
 #endif
 
 #endif // #ifndef THREAD_WIN32_OSX_H_INCLUDED

src/timeman.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -26,68 +24,25 @@
 #include "timeman.h"
 #include "uci.h"
 
+namespace Stockfish {
+
 TimeManagement Time; // Our global time management object
 
-namespace {
 
-  enum TimeType { OptimumTime, MaxTime };
+/// TimeManagement::init() is called at the beginning of the search and calculates
-
+/// the bounds of time allowed for the current game ply. We currently support:
-  constexpr int MoveHorizon   = 50;   // Plan time management at most this many moves ahead
+//      1) x basetime (+ z increment)
-  constexpr double MaxRatio   = 7.3;  // When in trouble, we can step over reserved time with this ratio
+//      2) x moves in y seconds (+ z increment)
-  constexpr double StealRatio = 0.34; // However we must not steal time from remaining moves over this ratio
-
-
-  // move_importance() is a skew-logistic function based on naive statistical
-  // analysis of "how many games are still undecided after n half-moves". Game
-  // is considered "undecided" as long as neither side has >275cp advantage.
-  // Data was extracted from the CCRL game database with some simple filtering criteria.
-
-  double move_importance(int ply) {
-
-    constexpr double XScale = 6.85;
-    constexpr double XShift = 64.5;
-    constexpr double Skew   = 0.171;
-
-    return pow((1 + exp((ply - XShift) / XScale)), -Skew) + DBL_MIN; // Ensure non-zero
-  }
-
-  template<TimeType T>
-  TimePoint remaining(TimePoint myTime, int movesToGo, int ply, TimePoint slowMover) {
-
-    constexpr double TMaxRatio   = (T == OptimumTime ? 1.0 : MaxRatio);
-    constexpr double TStealRatio = (T == OptimumTime ? 0.0 : StealRatio);
-
-    double moveImportance = (move_importance(ply) * slowMover) / 100.0;
-    double otherMovesImportance = 0.0;
-
-    for (int i = 1; i < movesToGo; ++i)
-        otherMovesImportance += move_importance(ply + 2 * i);
-
-    double ratio1 = (TMaxRatio * moveImportance) / (TMaxRatio * moveImportance + otherMovesImportance);
-    double ratio2 = (moveImportance + TStealRatio * otherMovesImportance) / (moveImportance + otherMovesImportance);
-
-    return TimePoint(myTime * std::min(ratio1, ratio2)); // Intel C++ asks for an explicit cast
-  }
-
-} // namespace
-
-
-/// init() is called at the beginning of the search and calculates the allowed
-/// thinking time out of the time control and current game ply. We support four
-/// different kinds of time controls, passed in 'limits':
-///
-///  inc == 0 && movestogo == 0 means: x basetime  [sudden death!]
-///  inc == 0 && movestogo != 0 means: x moves in y minutes
-///  inc >  0 && movestogo == 0 means: x basetime + z increment
-///  inc >  0 && movestogo != 0 means: x moves in y minutes + z increment
 
 void TimeManagement::init(Search::LimitsType& limits, Color us, int ply) {
 
-  TimePoint minThinkingTime = Options["Minimum Thinking Time"];
+  TimePoint moveOverhead    = TimePoint(Options["Move Overhead"]);
-  TimePoint moveOverhead    = Options["Move Overhead"];
+  TimePoint slowMover       = TimePoint(Options["Slow Mover"]);
-  TimePoint slowMover       = Options["Slow Mover"];
+  TimePoint npmsec          = TimePoint(Options["nodestime"]);
-  TimePoint npmsec          = Options["nodestime"];
+
-  TimePoint hypMyTime;
+  // optScale is a percentage of available time to use for the current move.
+  // maxScale is a multiplier applied to optimumTime.
+  double optScale, maxScale;
 
   // If we have to play in 'nodes as time' mode, then convert from time
   // to nodes, and use resulting values in time management formulas.
@@ -105,29 +60,42 @@ void TimeManagement::init(Search::LimitsType& limits, Color us, int ply) {
   }
 
   startTime = limits.startTime;
-  optimumTime = maximumTime = std::max(limits.time[us], minThinkingTime);
 
-  const int maxMTG = limits.movestogo ? std::min(limits.movestogo, MoveHorizon) : MoveHorizon;
+  // Maximum move horizon of 50 moves
+  int mtg = limits.movestogo ? std::min(limits.movestogo, 50) : 50;
 
-  // We calculate optimum time usage for different hypothetical "moves to go" values
+  // Make sure timeLeft is > 0 since we may use it as a divisor
-  // and choose the minimum of calculated search time values. Usually the greatest
+  TimePoint timeLeft =  std::max(TimePoint(1),
-  // hypMTG gives the minimum values.
+      limits.time[us] + limits.inc[us] * (mtg - 1) - moveOverhead * (2 + mtg));
-  for (int hypMTG = 1; hypMTG <= maxMTG; ++hypMTG)
+
+  // A user may scale time usage by setting UCI option "Slow Mover"
+  // Default is 100 and changing this value will probably lose elo.
+  timeLeft = slowMover * timeLeft / 100;
+
+  // x basetime (+ z increment)
+  // If there is a healthy increment, timeLeft can exceed actual available
+  // game time for the current move, so also cap to 20% of available game time.
+  if (limits.movestogo == 0)
   {
-      // Calculate thinking time for hypothetical "moves to go"-value
+      optScale = std::min(0.0084 + std::pow(ply + 3.0, 0.5) * 0.0042,
-      hypMyTime =  limits.time[us]
+                           0.2 * limits.time[us] / double(timeLeft));
-                 + limits.inc[us] * (hypMTG - 1)
+      maxScale = std::min(7.0, 4.0 + ply / 12.0);
-                 - moveOverhead * (2 + std::min(hypMTG, 40));
-
-      hypMyTime = std::max(hypMyTime, TimePoint(0));
-
-      TimePoint t1 = minThinkingTime + remaining<OptimumTime>(hypMyTime, hypMTG, ply, slowMover);
-      TimePoint t2 = minThinkingTime + remaining<MaxTime    >(hypMyTime, hypMTG, ply, slowMover);
-
-      optimumTime = std::min(t1, optimumTime);
-      maximumTime = std::min(t2, maximumTime);
   }
 
+  // x moves in y seconds (+ z increment)
+  else
+  {
+      optScale = std::min((0.8 + ply / 128.0) / mtg,
+                            0.8 * limits.time[us] / double(timeLeft));
+      maxScale = std::min(6.3, 1.5 + 0.11 * mtg);
+  }
+
+  // Never use more than 80% of the available time for this move
+  optimumTime = TimePoint(optScale * timeLeft);
+  maximumTime = TimePoint(std::min(0.8 * limits.time[us] - moveOverhead, maxScale * optimumTime));
+
   if (Options["Ponder"])
       optimumTime += optimumTime / 4;
 }
+
+} // namespace Stockfish

src/timeman.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -25,6 +23,8 @@
 #include "search.h"
 #include "thread.h"
 
+namespace Stockfish {
+
 /// The TimeManagement class computes the optimal time to think depending on
 /// the maximum available time, the game move number and other parameters.
 
@@ -46,4 +46,6 @@ private:
 
 extern TimeManagement Time;
 
+} // namespace Stockfish
+
 #endif // #ifndef TIMEMAN_H_INCLUDED

src/tt.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -28,29 +26,32 @@
 #include "tt.h"
 #include "uci.h"
 
+namespace Stockfish {
+
 TranspositionTable TT; // Our global transposition table
 
-/// TTEntry::save populates the TTEntry with a new node's data, possibly
+/// TTEntry::save() populates the TTEntry with a new node's data, possibly
 /// overwriting an old position. Update is not atomic and can be racy.
 
 void TTEntry::save(Key k, Value v, bool pv, Bound b, Depth d, Move m, Value ev) {
 
   // Preserve any existing move for the same position
-  if (m || (k >> 48) != key16)
+  if (m || (uint16_t)k != key16)
       move16 = (uint16_t)m;
 
-  // Overwrite less valuable entries
+  // Overwrite less valuable entries (cheapest checks first)
-  if (  (k >> 48) != key16
+  if (b == BOUND_EXACT
-      || d - DEPTH_OFFSET > depth8 - 4
+      || (uint16_t)k != key16
-      || b == BOUND_EXACT)
+      || d - DEPTH_OFFSET > depth8 - 4)
   {
-      assert(d >= DEPTH_OFFSET);
+      assert(d > DEPTH_OFFSET);
+      assert(d < 256 + DEPTH_OFFSET);
 
-      key16     = (uint16_t)(k >> 48);
+      key16     = (uint16_t)k;
+      depth8    = (uint8_t)(d - DEPTH_OFFSET);
+      genBound8 = (uint8_t)(TT.generation8 | uint8_t(pv) << 2 | b);
       value16   = (int16_t)v;
       eval16    = (int16_t)ev;
-      genBound8 = (uint8_t)(TT.generation8 | uint8_t(pv) << 2 | b);
-      depth8    = (uint8_t)(d - DEPTH_OFFSET);
   }
 }
 
@@ -63,19 +64,18 @@ void TranspositionTable::resize(size_t mbSize) {
 
   Threads.main()->wait_for_search_finished();
 
+  aligned_large_pages_free(table);
+
   clusterCount = mbSize * 1024 * 1024 / sizeof(Cluster);
 
-  free(mem);
+  table = static_cast<Cluster*>(aligned_large_pages_alloc(clusterCount * sizeof(Cluster)));
-  mem = malloc(clusterCount * sizeof(Cluster) + CacheLineSize - 1);
+  if (!table)
-
-  if (!mem)
   {
       std::cerr << "Failed to allocate " << mbSize
                 << "MB for transposition table." << std::endl;
       exit(EXIT_FAILURE);
   }
 
-  table = (Cluster*)((uintptr_t(mem) + CacheLineSize - 1) & ~(CacheLineSize - 1));
   clear();
 }
 
@@ -96,8 +96,8 @@ void TranspositionTable::clear() {
               WinProcGroup::bindThisThread(idx);
 
           // Each thread will zero its part of the hash table
-          const size_t stride = clusterCount / Options["Threads"],
+          const size_t stride = size_t(clusterCount / Options["Threads"]),
-                       start  = stride * idx,
+                       start  = size_t(stride * idx),
                        len    = idx != Options["Threads"] - 1 ?
                                 stride : clusterCount - start;
 
@@ -105,10 +105,11 @@ void TranspositionTable::clear() {
       });
   }
 
-  for (std::thread& th: threads)
+  for (std::thread& th : threads)
       th.join();
 }
 
+
 /// TranspositionTable::probe() looks up the current position in the transposition
 /// table. It returns true and a pointer to the TTEntry if the position is found.
 /// Otherwise, it returns false and a pointer to an empty or least valuable TTEntry
@@ -119,25 +120,26 @@ void TranspositionTable::clear() {
 TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
 
   TTEntry* const tte = first_entry(key);
-  const uint16_t key16 = key >> 48;  // Use the high 16 bits as key inside the cluster
+  const uint16_t key16 = (uint16_t)key;  // Use the low 16 bits as key inside the cluster
 
   for (int i = 0; i < ClusterSize; ++i)
-      if (!tte[i].key16 || tte[i].key16 == key16)
+      if (tte[i].key16 == key16 || !tte[i].depth8)
       {
-          tte[i].genBound8 = uint8_t(generation8 | (tte[i].genBound8 & 0x7)); // Refresh
+          tte[i].genBound8 = uint8_t(generation8 | (tte[i].genBound8 & (GENERATION_DELTA - 1))); // Refresh
 
-          return found = (bool)tte[i].key16, &tte[i];
+          return found = (bool)tte[i].depth8, &tte[i];
       }
 
   // Find an entry to be replaced according to the replacement strategy
   TTEntry* replace = tte;
   for (int i = 1; i < ClusterSize; ++i)
       // Due to our packed storage format for generation and its cyclic
-      // nature we add 263 (256 is the modulus plus 7 to keep the unrelated
+      // nature we add GENERATION_CYCLE (256 is the modulus, plus what
-      // lowest three bits from affecting the result) to calculate the entry
+      // is needed to keep the unrelated lowest n bits from affecting
-      // age correctly even after generation8 overflows into the next cycle.
+      // the result) to calculate the entry age correctly even after
-      if (  replace->depth8 - ((263 + generation8 - replace->genBound8) & 0xF8)
+      // generation8 overflows into the next cycle.
-          >   tte[i].depth8 - ((263 + generation8 -   tte[i].genBound8) & 0xF8))
+      if (  replace->depth8 - ((GENERATION_CYCLE + generation8 - replace->genBound8) & GENERATION_MASK)
+          >   tte[i].depth8 - ((GENERATION_CYCLE + generation8 -   tte[i].genBound8) & GENERATION_MASK))
           replace = &tte[i];
 
   return found = false, replace;
@@ -150,9 +152,11 @@ TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
 int TranspositionTable::hashfull() const {
 
   int cnt = 0;
-  for (int i = 0; i < 1000 / ClusterSize; ++i)
+  for (int i = 0; i < 1000; ++i)
       for (int j = 0; j < ClusterSize; ++j)
-          cnt += (table[i].entry[j].genBound8 & 0xF8) == generation8;
+          cnt += table[i].entry[j].depth8 && (table[i].entry[j].genBound8 & GENERATION_MASK) == generation8;
 
-  return cnt * 1000 / (ClusterSize * (1000 / ClusterSize));
+  return cnt / ClusterSize;
 }
+
+} // namespace Stockfish

src/tt.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -24,16 +22,18 @@
 #include "misc.h"
 #include "types.h"
 
+namespace Stockfish {
+
 /// TTEntry struct is the 10 bytes transposition table entry, defined as below:
 ///
 /// key        16 bit
-/// move       16 bit
+/// depth       8 bit
-/// value      16 bit
-/// eval value 16 bit
 /// generation  5 bit
 /// pv node     1 bit
 /// bound type  2 bit
-/// depth       8 bit
+/// move       16 bit
+/// value      16 bit
+/// eval value 16 bit
 
 struct TTEntry {
 
@@ -41,7 +41,7 @@ struct TTEntry {
   Value value() const { return (Value)value16; }
   Value eval()  const { return (Value)eval16; }
   Depth depth() const { return (Depth)depth8 + DEPTH_OFFSET; }
-  bool is_pv() const { return (bool)(genBound8 & 0x4); }
+  bool is_pv()  const { return (bool)(genBound8 & 0x4); }
   Bound bound() const { return (Bound)(genBound8 & 0x3); }
   void save(Key k, Value v, bool pv, Bound b, Depth d, Move m, Value ev);
 
@@ -49,44 +49,47 @@ private:
   friend class TranspositionTable;
 
   uint16_t key16;
+  uint8_t  depth8;
+  uint8_t  genBound8;
   uint16_t move16;
   int16_t  value16;
   int16_t  eval16;
-  uint8_t  genBound8;
-  uint8_t  depth8;
 };
 
 
-/// A TranspositionTable consists of a power of 2 number of clusters and each
+/// A TranspositionTable is an array of Cluster, of size clusterCount. Each
-/// cluster consists of ClusterSize number of TTEntry. Each non-empty entry
+/// cluster consists of ClusterSize number of TTEntry. Each non-empty TTEntry
-/// contains information of exactly one position. The size of a cluster should
+/// contains information on exactly one position. The size of a Cluster should
-/// divide the size of a cache line size, to ensure that clusters never cross
+/// divide the size of a cache line for best performance, as the cacheline is
-/// cache lines. This ensures best cache performance, as the cacheline is
+/// prefetched when possible.
-/// prefetched, as soon as possible.
 
 class TranspositionTable {
 
-  static constexpr int CacheLineSize = 64;
   static constexpr int ClusterSize = 3;
 
   struct Cluster {
     TTEntry entry[ClusterSize];
-    char padding[2]; // Align to a divisor of the cache line size
+    char padding[2]; // Pad to 32 bytes
   };
 
-  static_assert(CacheLineSize % sizeof(Cluster) == 0, "Cluster size incorrect");
+  static_assert(sizeof(Cluster) == 32, "Unexpected Cluster size");
+
+  // Constants used to refresh the hash table periodically
+  static constexpr unsigned GENERATION_BITS  = 3;                                // nb of bits reserved for other things
+  static constexpr int      GENERATION_DELTA = (1 << GENERATION_BITS);           // increment for generation field
+  static constexpr int      GENERATION_CYCLE = 255 + (1 << GENERATION_BITS);     // cycle length
+  static constexpr int      GENERATION_MASK  = (0xFF << GENERATION_BITS) & 0xFF; // mask to pull out generation number
 
 public:
- ~TranspositionTable() { free(mem); }
+ ~TranspositionTable() { aligned_large_pages_free(table); }
-  void new_search() { generation8 += 8; } // Lower 3 bits are used by PV flag and Bound
+  void new_search() { generation8 += GENERATION_DELTA; } // Lower bits are used for other things
   TTEntry* probe(const Key key, bool& found) const;
   int hashfull() const;
   void resize(size_t mbSize);
   void clear();
 
-  // The 32 lowest order bits of the key are used to get the index of the cluster
   TTEntry* first_entry(const Key key) const {
-    return &table[(uint32_t(key) * uint64_t(clusterCount)) >> 32].entry[0];
+    return &table[mul_hi64(key, clusterCount)].entry[0];
   }
 
 private:
@@ -94,10 +97,11 @@ private:
 
   size_t clusterCount;
   Cluster* table;
-  void* mem;
   uint8_t generation8; // Size must be not bigger than TTEntry::genBound8
 };
 
 extern TranspositionTable TT;
 
+} // namespace Stockfish
+
 #endif // #ifndef TT_H_INCLUDED

src/tune.cpp

@@ -0,0 +1,133 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <algorithm>
+#include <iostream>
+#include <sstream>
+
+#include "types.h"
+#include "misc.h"
+#include "uci.h"
+
+using std::string;
+
+namespace Stockfish {
+
+bool Tune::update_on_last;
+const UCI::Option* LastOption = nullptr;
+static std::map<std::string, int> TuneResults;
+
+string Tune::next(string& names, bool pop) {
+
+  string name;
+
+  do {
+      string token = names.substr(0, names.find(','));
+
+      if (pop)
+          names.erase(0, token.size() + 1);
+
+      std::stringstream ws(token);
+      name += (ws >> token, token); // Remove trailing whitespace
+
+  } while (  std::count(name.begin(), name.end(), '(')
+           - std::count(name.begin(), name.end(), ')'));
+
+  return name;
+}
+
+static void on_tune(const UCI::Option& o) {
+
+  if (!Tune::update_on_last || LastOption == &o)
+      Tune::read_options();
+}
+
+static void make_option(const string& n, int v, const SetRange& r) {
+
+  // Do not generate option when there is nothing to tune (ie. min = max)
+  if (r(v).first == r(v).second)
+      return;
+
+  if (TuneResults.count(n))
+      v = TuneResults[n];
+
+  Options[n] << UCI::Option(v, r(v).first, r(v).second, on_tune);
+  LastOption = &Options[n];
+
+  // Print formatted parameters, ready to be copy-pasted in Fishtest
+  std::cout << n << ","
+            << v << ","
+            << r(v).first << "," << r(v).second << ","
+            << (r(v).second - r(v).first) / 20.0 << ","
+            << "0.0020"
+            << std::endl;
+}
+
+template<> void Tune::Entry<int>::init_option() { make_option(name, value, range); }
+
+template<> void Tune::Entry<int>::read_option() {
+  if (Options.count(name))
+      value = int(Options[name]);
+}
+
+template<> void Tune::Entry<Value>::init_option() { make_option(name, value, range); }
+
+template<> void Tune::Entry<Value>::read_option() {
+  if (Options.count(name))
+      value = Value(int(Options[name]));
+}
+
+template<> void Tune::Entry<Score>::init_option() {
+  make_option("m" + name, mg_value(value), range);
+  make_option("e" + name, eg_value(value), range);
+}
+
+template<> void Tune::Entry<Score>::read_option() {
+  if (Options.count("m" + name))
+      value = make_score(int(Options["m" + name]), eg_value(value));
+
+  if (Options.count("e" + name))
+      value = make_score(mg_value(value), int(Options["e" + name]));
+}
+
+// Instead of a variable here we have a PostUpdate function: just call it
+template<> void Tune::Entry<Tune::PostUpdate>::init_option() {}
+template<> void Tune::Entry<Tune::PostUpdate>::read_option() { value(); }
+
+} // namespace Stockfish
+
+
+// Init options with tuning session results instead of default values. Useful to
+// get correct bench signature after a tuning session or to test tuned values.
+// Just copy fishtest tuning results in a result.txt file and extract the
+// values with:
+//
+// cat results.txt | sed 's/^param: \([^,]*\), best: \([^,]*\).*/  TuneResults["\1"] = int(round(\2));/'
+//
+// Then paste the output below, as the function body
+
+#include <cmath>
+
+namespace Stockfish {
+
+void Tune::read_results() {
+
+  /* ...insert your values here... */
+}
+
+} // namespace Stockfish

src/tune.h

@@ -0,0 +1,163 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef TUNE_H_INCLUDED
+#define TUNE_H_INCLUDED
+
+#include <memory>
+#include <string>
+#include <type_traits>
+#include <vector>
+
+namespace Stockfish {
+
+typedef std::pair<int, int> Range; // Option's min-max values
+typedef Range (RangeFun) (int);
+
+// Default Range function, to calculate Option's min-max values
+inline Range default_range(int v) {
+  return v > 0 ? Range(0, 2 * v) : Range(2 * v, 0);
+}
+
+struct SetRange {
+  explicit SetRange(RangeFun f) : fun(f) {}
+  SetRange(int min, int max) : fun(nullptr), range(min, max) {}
+  Range operator()(int v) const { return fun ? fun(v) : range; }
+
+  RangeFun* fun;
+  Range range;
+};
+
+#define SetDefaultRange SetRange(default_range)
+
+
+/// Tune class implements the 'magic' code that makes the setup of a fishtest
+/// tuning session as easy as it can be. Mainly you have just to remove const
+/// qualifiers from the variables you want to tune and flag them for tuning, so
+/// if you have:
+///
+///   const Score myScore = S(10, 15);
+///   const Value myValue[][2] = { { V(100), V(20) }, { V(7), V(78) } };
+///
+/// If you have a my_post_update() function to run after values have been updated,
+/// and a my_range() function to set custom Option's min-max values, then you just
+/// remove the 'const' qualifiers and write somewhere below in the file:
+///
+///   TUNE(SetRange(my_range), myScore, myValue, my_post_update);
+///
+/// You can also set the range directly, and restore the default at the end
+///
+///   TUNE(SetRange(-100, 100), myScore, SetDefaultRange);
+///
+/// In case update function is slow and you have many parameters, you can add:
+///
+///   UPDATE_ON_LAST();
+///
+/// And the values update, including post update function call, will be done only
+/// once, after the engine receives the last UCI option, that is the one defined
+/// and created as the last one, so the GUI should send the options in the same
+/// order in which have been defined.
+
+class Tune {
+
+  typedef void (PostUpdate) (); // Post-update function
+
+  Tune() { read_results(); }
+  Tune(const Tune&) = delete;
+  void operator=(const Tune&) = delete;
+  void read_results();
+
+  static Tune& instance() { static Tune t; return t; } // Singleton
+
+  // Use polymorphism to accomodate Entry of different types in the same vector
+  struct EntryBase {
+    virtual ~EntryBase() = default;
+    virtual void init_option() = 0;
+    virtual void read_option() = 0;
+  };
+
+  template<typename T>
+  struct Entry : public EntryBase {
+
+    static_assert(!std::is_const<T>::value, "Parameter cannot be const!");
+
+    static_assert(   std::is_same<T,   int>::value
+                  || std::is_same<T, Value>::value
+                  || std::is_same<T, Score>::value
+                  || std::is_same<T, PostUpdate>::value, "Parameter type not supported!");
+
+    Entry(const std::string& n, T& v, const SetRange& r) : name(n), value(v), range(r) {}
+    void operator=(const Entry&) = delete; // Because 'value' is a reference
+    void init_option() override;
+    void read_option() override;
+
+    std::string name;
+    T& value;
+    SetRange range;
+  };
+
+  // Our facility to fill the container, each Entry corresponds to a parameter
+  // to tune. We use variadic templates to deal with an unspecified number of
+  // entries, each one of a possible different type.
+  static std::string next(std::string& names, bool pop = true);
+
+  int add(const SetRange&, std::string&&) { return 0; }
+
+  template<typename T, typename... Args>
+  int add(const SetRange& range, std::string&& names, T& value, Args&&... args) {
+    list.push_back(std::unique_ptr<EntryBase>(new Entry<T>(next(names), value, range)));
+    return add(range, std::move(names), args...);
+  }
+
+  // Template specialization for arrays: recursively handle multi-dimensional arrays
+  template<typename T, size_t N, typename... Args>
+  int add(const SetRange& range, std::string&& names, T (&value)[N], Args&&... args) {
+    for (size_t i = 0; i < N; i++)
+        add(range, next(names, i == N - 1) + "[" + std::to_string(i) + "]", value[i]);
+    return add(range, std::move(names), args...);
+  }
+
+  // Template specialization for SetRange
+  template<typename... Args>
+  int add(const SetRange&, std::string&& names, SetRange& value, Args&&... args) {
+    return add(value, (next(names), std::move(names)), args...);
+  }
+
+  std::vector<std::unique_ptr<EntryBase>> list;
+
+public:
+  template<typename... Args>
+  static int add(const std::string& names, Args&&... args) {
+    return instance().add(SetDefaultRange, names.substr(1, names.size() - 2), args...); // Remove trailing parenthesis
+  }
+  static void init() { for (auto& e : instance().list) e->init_option(); read_options(); } // Deferred, due to UCI::Options access
+  static void read_options() { for (auto& e : instance().list) e->read_option(); }
+  static bool update_on_last;
+};
+
+// Some macro magic :-) we define a dummy int variable that compiler initializes calling Tune::add()
+#define STRINGIFY(x) #x
+#define UNIQUE2(x, y) x ## y
+#define UNIQUE(x, y) UNIQUE2(x, y) // Two indirection levels to expand __LINE__
+#define TUNE(...) int UNIQUE(p, __LINE__) = Tune::add(STRINGIFY((__VA_ARGS__)), __VA_ARGS__)
+
+#define UPDATE_ON_LAST() bool UNIQUE(p, __LINE__) = Tune::update_on_last = true
+
+} // namespace Stockfish
+
+#endif // #ifndef TUNE_H_INCLUDED

src/types.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -40,7 +38,6 @@
 
 #include <cassert>
 #include <cctype>
-#include <climits>
 #include <cstdint>
 #include <cstdlib>
 #include <algorithm>
@@ -60,6 +57,12 @@
 /// _WIN32             Building on Windows (any)
 /// _WIN64             Building on Windows 64 bit
 
+#if defined(__GNUC__ ) && (__GNUC__ < 9 || (__GNUC__ == 9 && __GNUC_MINOR__ <= 2)) && defined(_WIN32) && !defined(__clang__)
+#define ALIGNAS_ON_STACK_VARIABLES_BROKEN
+#endif
+
+#define ASSERT_ALIGNED(ptr, alignment) assert(reinterpret_cast<uintptr_t>(ptr) % alignment == 0)
+
 #if defined(_WIN64) && defined(_MSC_VER) // No Makefile used
 #  include <intrin.h> // Microsoft header for _BitScanForward64()
 #  define IS_64BIT
@@ -80,6 +83,8 @@
 #  define pext(b, m) 0
 #endif
 
+namespace Stockfish {
+
 #ifdef USE_POPCNT
 constexpr bool HasPopCnt = true;
 #else
@@ -110,7 +115,7 @@ constexpr int MAX_PLY   = 246;
 /// bit  6-11: origin square (from 0 to 63)
 /// bit 12-13: promotion piece type - 2 (from KNIGHT-2 to QUEEN-2)
 /// bit 14-15: special move flag: promotion (1), en passant (2), castling (3)
-/// NOTE: EN-PASSANT bit is set only when a pawn can be captured
+/// NOTE: en passant bit is set only when a pawn can be captured
 ///
 /// Special cases are MOVE_NONE and MOVE_NULL. We can sneak these in because in
 /// any normal move destination square is always different from origin square
@@ -124,7 +129,7 @@ enum Move : int {
 enum MoveType {
   NORMAL,
   PROMOTION = 1 << 14,
-  ENPASSANT = 2 << 14,
+  EN_PASSANT = 2 << 14,
   CASTLING  = 3 << 14
 };
 
@@ -176,10 +181,12 @@ enum Value : int {
   VALUE_INFINITE  = 32001,
   VALUE_NONE      = 32002,
 
-  VALUE_MATE_IN_MAX_PLY  =  VALUE_MATE - 2 * MAX_PLY,
+  VALUE_TB_WIN_IN_MAX_PLY  =  VALUE_MATE - 2 * MAX_PLY,
-  VALUE_MATED_IN_MAX_PLY = -VALUE_MATE + 2 * MAX_PLY,
+  VALUE_TB_LOSS_IN_MAX_PLY = -VALUE_TB_WIN_IN_MAX_PLY,
+  VALUE_MATE_IN_MAX_PLY  =  VALUE_MATE - MAX_PLY,
+  VALUE_MATED_IN_MAX_PLY = -VALUE_MATE_IN_MAX_PLY,
 
-  PawnValueMg   = 128,   PawnValueEg   = 213,
+  PawnValueMg   = 126,   PawnValueEg   = 208,
   KnightValueMg = 781,   KnightValueEg = 854,
   BishopValueMg = 825,   BishopValueEg = 915,
   RookValueMg   = 1276,  RookValueEg   = 1380,
@@ -196,23 +203,28 @@ enum PieceType {
 
 enum Piece {
   NO_PIECE,
-  W_PAWN = 1, W_KNIGHT, W_BISHOP, W_ROOK, W_QUEEN, W_KING,
+  W_PAWN = PAWN,     W_KNIGHT, W_BISHOP, W_ROOK, W_QUEEN, W_KING,
-  B_PAWN = 9, B_KNIGHT, B_BISHOP, B_ROOK, B_QUEEN, B_KING,
+  B_PAWN = PAWN + 8, B_KNIGHT, B_BISHOP, B_ROOK, B_QUEEN, B_KING,
   PIECE_NB = 16
 };
 
-extern Value PieceValue[PHASE_NB][PIECE_NB];
+constexpr Value PieceValue[PHASE_NB][PIECE_NB] = {
+  { VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg, VALUE_ZERO, VALUE_ZERO,
+    VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg, VALUE_ZERO, VALUE_ZERO },
+  { VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg, VALUE_ZERO, VALUE_ZERO,
+    VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg, VALUE_ZERO, VALUE_ZERO }
+};
 
 typedef int Depth;
 
 enum : int {
-
   DEPTH_QS_CHECKS     =  0,
   DEPTH_QS_NO_CHECKS  = -1,
   DEPTH_QS_RECAPTURES = -5,
 
   DEPTH_NONE   = -6,
-  DEPTH_OFFSET = DEPTH_NONE,
+
+  DEPTH_OFFSET = -7 // value used only for TT entry occupancy check
 };
 
 enum Square : int {
@@ -226,7 +238,8 @@ enum Square : int {
   SQ_A8, SQ_B8, SQ_C8, SQ_D8, SQ_E8, SQ_F8, SQ_G8, SQ_H8,
   SQ_NONE,
 
-  SQUARE_NB = 64
+  SQUARE_ZERO = 0,
+  SQUARE_NB   = 64
 };
 
 enum Direction : int {
@@ -249,6 +262,21 @@ enum Rank : int {
   RANK_1, RANK_2, RANK_3, RANK_4, RANK_5, RANK_6, RANK_7, RANK_8, RANK_NB
 };
 
+// Keep track of what a move changes on the board (used by NNUE)
+struct DirtyPiece {
+
+  // Number of changed pieces
+  int dirty_num;
+
+  // Max 3 pieces can change in one move. A promotion with capture moves
+  // both the pawn and the captured piece to SQ_NONE and the piece promoted
+  // to from SQ_NONE to the capture square.
+  Piece piece[3];
+
+  // From and to squares, which may be SQ_NONE
+  Square from[3];
+  Square to[3];
+};
 
 /// Score enum stores a middlegame and an endgame value in a single integer (enum).
 /// The least significant 16 bits are used to store the middlegame value and the
@@ -274,11 +302,11 @@ inline Value mg_value(Score s) {
 }
 
 #define ENABLE_BASE_OPERATORS_ON(T)                                \
-constexpr T operator+(T d1, T d2) { return T(int(d1) + int(d2)); } \
+constexpr T operator+(T d1, int d2) { return T(int(d1) + d2); }    \
-constexpr T operator-(T d1, T d2) { return T(int(d1) - int(d2)); } \
+constexpr T operator-(T d1, int d2) { return T(int(d1) - d2); }    \
 constexpr T operator-(T d) { return T(-int(d)); }                  \
-inline T& operator+=(T& d1, T d2) { return d1 = d1 + d2; }         \
+inline T& operator+=(T& d1, int d2) { return d1 = d1 + d2; }       \
-inline T& operator-=(T& d1, T d2) { return d1 = d1 - d2; }
+inline T& operator-=(T& d1, int d2) { return d1 = d1 - d2; }
 
 #define ENABLE_INCR_OPERATORS_ON(T)                                \
 inline T& operator++(T& d) { return d = T(int(d) + 1); }           \
@@ -296,8 +324,8 @@ inline T& operator/=(T& d, int i) { return d = T(int(d) / i); }
 ENABLE_FULL_OPERATORS_ON(Value)
 ENABLE_FULL_OPERATORS_ON(Direction)
 
-ENABLE_INCR_OPERATORS_ON(PieceType)
 ENABLE_INCR_OPERATORS_ON(Piece)
+ENABLE_INCR_OPERATORS_ON(PieceType)
 ENABLE_INCR_OPERATORS_ON(Square)
 ENABLE_INCR_OPERATORS_ON(File)
 ENABLE_INCR_OPERATORS_ON(Rank)
@@ -308,12 +336,6 @@ ENABLE_BASE_OPERATORS_ON(Score)
 #undef ENABLE_INCR_OPERATORS_ON
 #undef ENABLE_BASE_OPERATORS_ON
 
-/// Additional operators to add integers to a Value
-constexpr Value operator+(Value v, int i) { return Value(int(v) + i); }
-constexpr Value operator-(Value v, int i) { return Value(int(v) - i); }
-inline Value& operator+=(Value& v, int i) { return v = v + i; }
-inline Value& operator-=(Value& v, int i) { return v = v - i; }
-
 /// Additional operators to add a Direction to a Square
 constexpr Square operator+(Square s, Direction d) { return Square(int(s) + int(d)); }
 constexpr Square operator-(Square s, Direction d) { return Square(int(s) - int(d)); }
@@ -343,23 +365,23 @@ inline Score operator*(Score s, int i) {
 
 /// Multiplication of a Score by a boolean
 inline Score operator*(Score s, bool b) {
-  return Score(int(s) * int(b));
+  return b ? s : SCORE_ZERO;
 }
 
 constexpr Color operator~(Color c) {
   return Color(c ^ BLACK); // Toggle color
 }
 
-constexpr Square operator~(Square s) {
+constexpr Square flip_rank(Square s) { // Swap A1 <-> A8
-  return Square(s ^ SQ_A8); // Vertical flip SQ_A1 -> SQ_A8
+  return Square(s ^ SQ_A8);
+}
+
+constexpr Square flip_file(Square s) { // Swap A1 <-> H1
+  return Square(s ^ SQ_H1);
 }
 
 constexpr Piece operator~(Piece pc) {
-  return Piece(pc ^ 8); // Swap color of piece B_KNIGHT -> W_KNIGHT
+  return Piece(pc ^ 8); // Swap color of piece B_KNIGHT <-> W_KNIGHT
-}
-
-inline File map_to_queenside(File f) {
-  return std::min(f, File(FILE_H - f)); // Map files ABCDEFGH to files ABCDDCBA
 }
 
 constexpr CastlingRights operator&(Color c, CastlingRights cr) {
@@ -456,4 +478,13 @@ constexpr bool is_ok(Move m) {
   return from_sq(m) != to_sq(m); // Catch MOVE_NULL and MOVE_NONE
 }
 
+/// Based on a congruential pseudo random number generator
+constexpr Key make_key(uint64_t seed) {
+  return seed * 6364136223846793005ULL + 1442695040888963407ULL;
+}
+
+} // namespace Stockfish
+
 #endif // #ifndef TYPES_H_INCLUDED
+
+#include "tune.h" // Global visibility to tuning setup

src/uci.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -19,6 +17,7 @@
 */
 
 #include <cassert>
+#include <cmath>
 #include <iostream>
 #include <sstream>
 #include <string>
@@ -35,6 +34,8 @@
 
 using namespace std;
 
+namespace Stockfish {
+
 extern vector<string> setup_bench(const Position&, istream&);
 
 namespace {
@@ -77,6 +78,20 @@ namespace {
     }
   }
 
+  // trace_eval() prints the evaluation for the current position, consistent with the UCI
+  // options set so far.
+
+  void trace_eval(Position& pos) {
+
+    StateListPtr states(new std::deque<StateInfo>(1));
+    Position p;
+    p.set(pos.fen(), Options["UCI_Chess960"], &states->back(), Threads.main());
+
+    Eval::NNUE::verify();
+
+    sync_cout << "\n" << Eval::trace(p) << sync_endl;
+  }
+
 
   // setoption() is called when engine receives the "setoption" UCI command. The
   // function updates the UCI option ("name") to the given value ("value").
@@ -115,7 +130,7 @@ namespace {
     limits.startTime = now(); // As early as possible!
 
     while (is >> token)
-        if (token == "searchmoves")
+        if (token == "searchmoves") // Needs to be the last command on the line
             while (is >> token)
                 limits.searchmoves.push_back(UCI::to_move(pos, token));
 
@@ -157,7 +172,7 @@ namespace {
 
         if (token == "go" || token == "eval")
         {
-            cerr << "\nPosition: " << cnt++ << '/' << num << endl;
+            cerr << "\nPosition: " << cnt++ << '/' << num << " (" << pos.fen() << ")" << endl;
             if (token == "go")
             {
                go(pos, is, states);
@@ -165,7 +180,7 @@ namespace {
                nodes += Threads.nodes_searched();
             }
             else
-               sync_cout << "\n" << Eval::trace(pos) << sync_endl;
+               trace_eval(pos);
         }
         else if (token == "setoption")  setoption(is);
         else if (token == "position")   position(pos, is, states);
@@ -182,6 +197,28 @@ namespace {
          << "\nNodes/second    : " << 1000 * nodes / elapsed << endl;
   }
 
+  // The win rate model returns the probability (per mille) of winning given an eval
+  // and a game-ply. The model fits rather accurately the LTC fishtest statistics.
+  int win_rate_model(Value v, int ply) {
+
+     // The model captures only up to 240 plies, so limit input (and rescale)
+     double m = std::min(240, ply) / 64.0;
+
+     // Coefficients of a 3rd order polynomial fit based on fishtest data
+     // for two parameters needed to transform eval to the argument of a
+     // logistic function.
+     double as[] = {-3.68389304,  30.07065921, -60.52878723, 149.53378557};
+     double bs[] = {-2.0181857,   15.85685038, -29.83452023,  47.59078827};
+     double a = (((as[0] * m + as[1]) * m + as[2]) * m) + as[3];
+     double b = (((bs[0] * m + bs[1]) * m + bs[2]) * m) + bs[3];
+
+     // Transform eval to centipawns with limited range
+     double x = std::clamp(double(100 * v) / PawnValueEg, -2000.0, 2000.0);
+
+     // Return win rate in per mille (rounded to nearest)
+     return int(0.5 + 1000 / (1 + std::exp((a - x) / b)));
+  }
+
 } // namespace
 
 
@@ -238,9 +275,17 @@ void UCI::loop(int argc, char* argv[]) {
       else if (token == "flip")     pos.flip();
       else if (token == "bench")    bench(pos, is, states);
       else if (token == "d")        sync_cout << pos << sync_endl;
-      else if (token == "eval")     sync_cout << Eval::trace(pos) << sync_endl;
+      else if (token == "eval")     trace_eval(pos);
       else if (token == "compiler") sync_cout << compiler_info() << sync_endl;
-      else
+      else if (token == "export_net")
+      {
+          std::optional<std::string> filename;
+          std::string f;
+          if (is >> skipws >> f)
+              filename = f;
+          Eval::NNUE::save_eval(filename);
+      }
+      else if (!token.empty() && token[0] != '#')
           sync_cout << "Unknown command: " << cmd << sync_endl;
 
   } while (token != "quit" && argc == 1); // Command line args are one-shot
@@ -260,7 +305,7 @@ string UCI::value(Value v) {
 
   stringstream ss;
 
-  if (abs(v) < VALUE_MATE - MAX_PLY)
+  if (abs(v) < VALUE_MATE_IN_MAX_PLY)
       ss << "cp " << v * 100 / PawnValueEg;
   else
       ss << "mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2;
@@ -269,6 +314,22 @@ string UCI::value(Value v) {
 }
 
 
+/// UCI::wdl() report WDL statistics given an evaluation and a game ply, based on
+/// data gathered for fishtest LTC games.
+
+string UCI::wdl(Value v, int ply) {
+
+  stringstream ss;
+
+  int wdl_w = win_rate_model( v, ply);
+  int wdl_l = win_rate_model(-v, ply);
+  int wdl_d = 1000 - wdl_w - wdl_l;
+  ss << " wdl " << wdl_w << " " << wdl_d << " " << wdl_l;
+
+  return ss.str();
+}
+
+
 /// UCI::square() converts a Square to a string in algebraic notation (g1, a7, etc.)
 
 std::string UCI::square(Square s) {
@@ -318,3 +379,5 @@ Move UCI::to_move(const Position& pos, string& str) {
 
   return MOVE_NONE;
 }
+
+} // namespace Stockfish

src/uci.h

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -26,6 +24,8 @@
 
 #include "types.h"
 
+namespace Stockfish {
+
 class Position;
 
 namespace UCI {
@@ -73,10 +73,13 @@ std::string value(Value v);
 std::string square(Square s);
 std::string move(Move m, bool chess960);
 std::string pv(const Position& pos, Depth depth, Value alpha, Value beta);
+std::string wdl(Value v, int ply);
 Move to_move(const Position& pos, std::string& str);
 
 } // namespace UCI
 
 extern UCI::OptionsMap Options;
 
+} // namespace Stockfish
+
 #endif // #ifndef UCI_H_INCLUDED

src/ucioption.cpp

@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -23,6 +21,7 @@
 #include <ostream>
 #include <sstream>
 
+#include "evaluate.h"
 #include "misc.h"
 #include "search.h"
 #include "thread.h"
@@ -32,17 +31,20 @@
 
 using std::string;
 
+namespace Stockfish {
+
 UCI::OptionsMap Options; // Global object
 
 namespace UCI {
 
 /// 'On change' actions, triggered by an option's value change
 void on_clear_hash(const Option&) { Search::clear(); }
-void on_hash_size(const Option& o) { TT.resize(o); }
+void on_hash_size(const Option& o) { TT.resize(size_t(o)); }
 void on_logger(const Option& o) { start_logger(o); }
-void on_threads(const Option& o) { Threads.set(o); }
+void on_threads(const Option& o) { Threads.set(size_t(o)); }
 void on_tb_path(const Option& o) { Tablebases::init(o); }
-
+void on_use_NNUE(const Option& ) { Eval::NNUE::init(); }
+void on_eval_file(const Option& ) { Eval::NNUE::init(); }
 
 /// Our case insensitive less() function as required by UCI protocol
 bool CaseInsensitiveLess::operator() (const string& s1, const string& s2) const {
@@ -52,34 +54,33 @@ bool CaseInsensitiveLess::operator() (const string& s1, const string& s2) const
 }
 
 
-/// init() initializes the UCI options to their hard-coded default values
+/// UCI::init() initializes the UCI options to their hard-coded default values
 
 void init(OptionsMap& o) {
 
-  // at most 2^32 clusters.
+  constexpr int MaxHashMB = Is64Bit ? 33554432 : 2048;
-  constexpr int MaxHashMB = Is64Bit ? 131072 : 2048;
 
   o["Debug Log File"]        << Option("", on_logger);
-  o["Contempt"]              << Option(24, -100, 100);
-  o["Analysis Contempt"]     << Option("Both var Off var White var Black var Both", "Both");
   o["Threads"]               << Option(1, 1, 512, on_threads);
   o["Hash"]                  << Option(16, 1, MaxHashMB, on_hash_size);
   o["Clear Hash"]            << Option(on_clear_hash);
   o["Ponder"]                << Option(false);
   o["MultiPV"]               << Option(1, 1, 500);
   o["Skill Level"]           << Option(20, 0, 20);
-  o["Move Overhead"]         << Option(30, 0, 5000);
+  o["Move Overhead"]         << Option(10, 0, 5000);
-  o["Minimum Thinking Time"] << Option(20, 0, 5000);
+  o["Slow Mover"]            << Option(100, 10, 1000);
-  o["Slow Mover"]            << Option(84, 10, 1000);
   o["nodestime"]             << Option(0, 0, 10000);
   o["UCI_Chess960"]          << Option(false);
   o["UCI_AnalyseMode"]       << Option(false);
   o["UCI_LimitStrength"]     << Option(false);
   o["UCI_Elo"]               << Option(1350, 1350, 2850);
+  o["UCI_ShowWDL"]           << Option(false);
   o["SyzygyPath"]            << Option("<empty>", on_tb_path);
   o["SyzygyProbeDepth"]      << Option(1, 1, 100);
   o["Syzygy50MoveRule"]      << Option(true);
   o["SyzygyProbeLimit"]      << Option(7, 0, 7);
+  o["Use NNUE"]              << Option(true, on_use_NNUE);
+  o["EvalFile"]              << Option(EvalFileDefaultName, on_eval_file);
 }
 
 
@@ -189,3 +190,5 @@ Option& Option::operator=(const string& v) {
 }
 
 } // namespace UCI
+
+} // namespace Stockfish

tests/instrumented.sh

@@ -13,14 +13,14 @@ case $1 in
   --valgrind)
     echo "valgrind testing started"
     prefix=''
-    exeprefix='valgrind --error-exitcode=42'
+    exeprefix='valgrind --error-exitcode=42 --errors-for-leak-kinds=all --leak-check=full'
     postfix='1>/dev/null'
     threads="1"
   ;;
   --valgrind-thread)
     echo "valgrind-thread testing started"
     prefix=''
-    exeprefix='valgrind --error-exitcode=42'
+    exeprefix='valgrind --fair-sched=try --error-exitcode=42'
     postfix='1>/dev/null'
     threads="2"
   ;;
@@ -39,16 +39,16 @@ case $1 in
     threads="2"
 
 cat << EOF > tsan.supp
-race:TTEntry::move
+race:Stockfish::TTEntry::move
-race:TTEntry::depth
+race:Stockfish::TTEntry::depth
-race:TTEntry::bound
+race:Stockfish::TTEntry::bound
-race:TTEntry::save
+race:Stockfish::TTEntry::save
-race:TTEntry::value
+race:Stockfish::TTEntry::value
-race:TTEntry::eval
+race:Stockfish::TTEntry::eval
-race:TTEntry::is_pv
+race:Stockfish::TTEntry::is_pv
 
-race:TranspositionTable::probe
+race:Stockfish::TranspositionTable::probe
-race:TranspositionTable::hashfull
+race:Stockfish::TranspositionTable::hashfull
 
 EOF
 
@@ -70,7 +70,7 @@ for args in "eval" \
             "go depth 10" \
             "go movetime 1000" \
             "go wtime 8000 btime 8000 winc 500 binc 500" \
-            "bench 128 $threads 10 default depth"
+            "bench 128 $threads 8 default depth"
 do
 
    echo "$prefix $exeprefix ./stockfish $args $postfix"
@@ -80,7 +80,7 @@ done
 
 # more general testing, following an uci protocol exchange
 cat << EOF > game.exp
- set timeout 10
+ set timeout 240
  spawn $exeprefix ./stockfish
 
  send "uci\n"
@@ -98,7 +98,7 @@ cat << EOF > game.exp
  expect "bestmove"
 
  send "position fen 5rk1/1K4p1/8/8/3B4/8/8/8 b - - 0 1\n"
- send "go depth 30\n"
+ send "go depth 10\n"
  expect "bestmove"
 
  send "quit\n"
@@ -121,7 +121,7 @@ cat << EOF > syzygy.exp
  send "uci\n"
  send "setoption name SyzygyPath value ../tests/syzygy/\n"
  expect "info string Found 35 tablebases" {} timeout {exit 1}
- send "bench 128 1 10 default depth\n"
+ send "bench 128 1 8 default depth\n"
  send "quit\n"
  expect eof
 

tests/reprosearch.sh

@@ -10,7 +10,7 @@ trap 'error ${LINENO}' ERR
 
 echo "reprosearch testing started"
 
-# repeat two short games, separated by ucinewgame. 
+# repeat two short games, separated by ucinewgame.
 # with go nodes $nodes they should result in exactly
 # the same node count for each iteration.
 cat << EOF > repeat.exp