Enable NEON for armv8

apple silicon platform with NEON
USE_NEON instead of IS_ARM New platform apple-silicon with default USE_NEON nnue_common.h includes arm_neon.h for USE_NEON
2026-05-20 05:07:46 +00:00 · 2020-08-05 10:45:17 -07:00 · 2020-08-05 16:45:07 +02:00 · 2020-08-05 07:46:45 +02:00 · 2020-08-05 07:29:12 +02:00 · 2020-08-05 07:20:23 +02:00
59 changed files with 4447 additions and 1479 deletions
@@ -1,5 +1,5 @@
 language: cpp
-dist: xenial
+dist: bionic

 matrix:
  include:
@@ -7,7 +7,6 @@ matrix:
      compiler: gcc
      addons:
        apt:
-          sources: ['ubuntu-toolchain-r-test']
          packages: ['g++-8', 'g++-8-multilib', 'g++-multilib', 'valgrind', 'expect', 'curl']
      env:
        - COMPILER=g++-8
@@ -17,23 +16,23 @@ matrix:
      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']
+          packages: ['clang-10', 'llvm-10-dev', 'g++-multilib', 'valgrind', 'expect', 'curl']
      env:
-        - COMPILER=clang++-6.0
+        - COMPILER=clang++-10
        - COMP=clang
-        - LDFLAGS=-fuse-ld=lld

    - os: osx
+      osx_image: xcode12
      compiler: gcc
      env:
        - COMPILER=g++
        - COMP=gcc

    - os: osx
+      osx_image: xcode12
      compiler: clang
      env:
-        - COMPILER=clang++ V='Apple LLVM 9.4.1' # Apple LLVM version 9.1.0 (clang-902.0.39.2)
+        - COMPILER=clang++
        - COMP=clang

 branches:
@@ -48,26 +47,34 @@ script:
  - 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
+
+  #
+  # Compiler version string
+  - $COMPILER -v
+
  #
  # Verify bench number against various builds
-  - export CXXFLAGS=-Werror
+  - export CXXFLAGS="-Werror -D_GLIBCXX_DEBUG"
  - 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 $benchref
+  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then make clean && make -j2 ARCH=x86-32 optimize=no debug=yes build && ../tests/signature.sh $benchref; fi
+  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then make clean && make -j2 ARCH=x86-32 build && ../tests/signature.sh $benchref; fi

  #
  # Check perft and reproducible search
+  - export CXXFLAGS="-Werror"
+  - make clean && make -j2 ARCH=x86-64 build
  - ../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
+  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then make clean && make -j2 ARCH=x86-64 sanitize=undefined optimize=no debug=yes build > /dev/null && ../tests/instrumented.sh --sanitizer-undefined; fi
+  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then make clean && make -j2 ARCH=x86-64 sanitize=thread    optimize=no debug=yes build > /dev/null && ../tests/instrumented.sh --sanitizer-thread; fi
@@ -1,10 +1,17 @@
-# List of authors for Stockfish, as of January 7, 2020
+# List of authors for Stockfish, as of August 4, 2020

+# 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)
@@ -36,18 +43,21 @@ Dariusz Orzechowski
 David Zar
 Daylen Yang (daylen)
 DiscanX
+Dominik Schlösser (domschl)
 double-beep
 Eduardo Cáceres (eduherminio)
 Eelco de Groot (KingDefender)
 Elvin Liu (solarlight2)
 erbsenzaehler
 Ernesto Gatti
+Linmiao Xu (linrock)
 Fabian Beuke (madnight)
 Fabian Fichter (ianfab)
 fanon
 Fauzi Akram Dabat (FauziAkram)
 Felix Wittmann
 gamander
+Gary Heckman (gheckman)
 gguliash
 Gian-Carlo Pascutto (gcp)
 Gontran Lemaire (gonlem)
@@ -113,6 +123,8 @@ Nick Pelling (nickpelling)
 Nicklas Persson (NicklasPersson)
 Niklas Fiekas (niklasf)
 Nikolay Kostov (NikolayIT)
+Nguyen Pham (nguyenpham)
+Norman Schmidt (FireFather)
 Ondrej Mosnáček (WOnder93)
 Oskar Werkelin Ahlin
 Pablo Vazquez
@@ -122,6 +134,8 @@ Pasquale Pigazzini (ppigazzini)
 Patrick Jansen (mibere)
 pellanda
 Peter Zsifkovits (CoffeeOne)
+Praveen Kumar Tummala (praveentml)
+Rahul Dsilva (silversolver1)
 Ralph Stößer (Ralph Stoesser)
 Raminder Singh
 renouve
@@ -130,6 +144,7 @@ Richard Lloyd
 Rodrigo Exterckötter Tjäder
 Ron Britvich (Britvich)
 Ronald de Man (syzygy1, syzygy)
+rqs
 Ryan Schmitt
 Ryan Takker
 Sami Kiminki (skiminki)
@@ -138,6 +153,7 @@ Sergei Antonov (saproj)
 Sergei Ivanov (svivanov72)
 sf-x
 Shane Booth (shane31)
+Shawn Varghese (xXH4CKST3RXx)
 Stefan Geschwentner (locutus2)
 Stefano Cardanobile (Stefano80)
 Steinar Gunderson (sesse)
@@ -147,17 +163,17 @@ 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
-
-
-
-
@@ -4,7 +4,13 @@
 [![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
+derived from Glaurung 2.1. It features two evaluation functions, the classical
+evaluation based on handcrafted terms, and the NNUE evaluation based on
+efficiently updateable neural networks. The classical evaluation runs efficiently
+on most 64bit CPU architectures, while the NNUE evaluation benefits strongly from the
+vector intrinsics available on modern CPUs (avx2 or similar).
+
+Stockfish 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
@@ -22,30 +28,26 @@ This distribution of Stockfish consists of the following files:
  * src, a subdirectory containing the full source code, including a Makefile
    that can be used to compile Stockfish on Unix-like systems.

+To use the NNUE evaluation an additional data file with neural network parameters
+needs to be downloaded. The filename for the default set can be found as the default
+value of the `EvalFile` UCI option, with the format
+`nn-[SHA256 first 12 digits].nnue` (e.g. nn-c157e0a5755b.nnue). This file can be downloaded from
+```
+https://tests.stockfishchess.org/api/nn/[filename]
+```
+replacing `[filename]` as needed.

-## UCI parameters
+
+## UCI options

 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.
+    The size of the hash table in MB. It is recommended to set Hash after setting Threads.

  * #### Ponder
    Let Stockfish ponder its next move while the opponent is thinking.
@@ -54,10 +56,32 @@ Currently, Stockfish has the following UCI options:
    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.
+  * #### Use NNUE
+    Toggle between the NNUE and classical evaluation functions. If set to "true",
+    the network parameters must be availabe to load from file (see also EvalFile).
+
+  * #### EvalFile
+    The name of the file of the NNUE evaluation parameters. Depending on the GUI the
+    filename should include the full path to the folder/directory that contains the file.
+
+  * #### Contempt
+    A positive value for contempt favors middle game positions and avoids draws,
+    effective for the classical evaluation only.
+
+  * #### 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.
+
+  * #### 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.
@@ -66,26 +90,10 @@ Currently, Stockfish has the following UCI options:
    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.
+  * #### 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
@@ -112,6 +120,47 @@ Currently, Stockfish has the following UCI options:
    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.
+
+  * #### Clear Hash
+    Clear the hash table.
+
+  * #### Debug Log File
+    Write all communication to and from the engine into a text file.
+
+## classical and 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 evalutions 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 stronger playing strength, even if the nodes per second computed by the engine
+is somewhat lower (roughly 60% of nps is typical).
+
+Note that the NNUE evaluation depends on the Stockfish binary and the network parameter
+file (see EvalFile). Not every parameter file is compatible with a given Stockfish binary.
+The default value of the EvalFile UCI option is the name of a network that is guaranteed
+to be compatible with that binary.

 ## What to expect from Syzygybases?

@@ -138,20 +187,50 @@ 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 nps, 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. Logout/login may be needed
+afterwards. Due to memory fragmentation, it may not always be
+possible to allocate large pages even when enabled. A reboot
+might alleviate this problem. To determine whether large pages
+are in use, see the engine log.

 ## 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, certain hardware
+instructions, big-endian machines such as Power PC, and other platforms.

-Stockfish has support for 32 or 64-bit CPUs, the hardware POPCNT
-instruction, 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.

-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.
+```
+    cd src
+    make help
+    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 version and
 compiler you used to create your executable. These informations can
@@ -4,10 +4,10 @@ clone_depth: 50
 branches:
  only:
    - master
-    - appveyor
+    - nnue-player-wip

 # 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 +36,11 @@ 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})'
@@ -51,10 +54,11 @@ 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
-      $g = "Visual Studio 15 2017"
-      If (${env:PLATFORM} -eq 'x64') { $g = $g + ' Win64' }
-      cmake -G "${g}" .
-      Write-Host "Generated files for: " $g
+      $g = "Visual Studio 16 2019"
+      If (${env:PLATFORM} -eq 'x64') { $a = "x64" }
+      If (${env:PLATFORM} -eq 'x86') { $a = "Win32" }
+      cmake -G "${g}" -A ${a} .
+      Write-Host "Generated files for: " $g $a

 build_script:
  - cmake --build . --config %CONFIGURATION% -- /verbosity:minimal
@@ -35,10 +35,15 @@ BINDIR = $(PREFIX)/bin
 ### Built-in benchmark for pgo-builds
 PGOBENCH = ./$(EXE) bench

-### Object files
-OBJS = benchmark.o bitbase.o bitboard.o endgame.o evaluate.o main.o \
-	material.o misc.o movegen.o movepick.o pawns.o position.o psqt.o \
-	search.o thread.o timeman.o tt.o uci.o ucioption.o syzygy/tbprobe.o
+### Source and object files
+SRCS = benchmark.cpp bitbase.cpp bitboard.cpp endgame.cpp evaluate.cpp main.cpp \
+	material.cpp misc.cpp movegen.cpp movepick.cpp pawns.cpp position.cpp psqt.cpp \
+	search.cpp thread.cpp timeman.cpp tt.cpp uci.cpp ucioption.cpp tune.cpp syzygy/tbprobe.cpp \
+	nnue/evaluate_nnue.cpp nnue/features/half_kp.cpp
+
+OBJS = $(notdir $(SRCS:.cpp=.o))
+
+VPATH = syzygy:nnue:nnue/features

 ### Establish the operating system name
 KERNEL = $(shell uname -s)
@@ -50,7 +55,7 @@ endif
 ### Section 2. High-level Configuration
 ### ==========================================================================
 #
-# flag                --- Comp switch --- Description
+# flag                --- Comp switch      --- Description
 # ----------------------------------------------------------------------------
 #
 # debug = yes/no      --- -DNDEBUG         --- Enable/Disable debug mode
@@ -63,7 +68,14 @@ endif
 # 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
+# sse3 = yes/no       --- -msse3           --- Use Intel Streaming SIMD Extensions 3
+# ssse3 = yes/no      --- -mssse3          --- Use Intel Supplemental Streaming SIMD Extensions 3
+# sse41 = yes/no      --- -msse4.1         --- Use Intel Streaming SIMD Extensions 4.1
+# sse42 = yes/no      --- -msse4.2         --- Use Intel Streaming SIMD Extensions 4.2
+# avx2 = yes/no       --- -mavx2           --- Use Intel Advanced Vector Extensions 2
 # pext = yes/no       --- -DUSE_PEXT       --- Use pext x86_64 asm-instruction
+# avx512 = yes/no     --- -mavx512bw       --- Use Intel Advanced Vector Extensions 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
@@ -73,82 +85,178 @@ endif
 optimize = yes
 debug = no
 sanitize = no
-bits = 32
+bits = 64
 prefetch = no
 popcnt = no
 sse = no
+sse3 = no
+ssse3 = no
+sse41 = no
+sse42 = no
+avx2 = no
 pext = no
+avx512 = no
+neon = no

 ### 2.2 Architecture specific
-
 ifeq ($(ARCH),general-32)
 	arch = any
+	bits = 32
 endif

 ifeq ($(ARCH),x86-32-old)
 	arch = i386
+	bits = 32
 endif

 ifeq ($(ARCH),x86-32)
 	arch = i386
+	bits = 32
 	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 ($(ARCH),x86-64-sse3)
+	arch = x86_64
+	prefetch = yes
+	sse = yes
+	sse3 = yes
+endif
+
+ifeq ($(ARCH),x86-64-sse3-popcnt)
+	arch = x86_64
+	prefetch = yes
+	sse = yes
+	sse3 = yes
+	popcnt = yes
+endif
+
+ifeq ($(ARCH),x86-64-ssse3)
+	arch = x86_64
+	prefetch = yes
+	sse = yes
+	sse3 = yes
+	ssse3 = yes
+endif
+
+ifeq ($(ARCH),x86-64-sse41)
+	arch = x86_64
+	prefetch = yes
+	popcnt = yes
+	sse = yes
+	sse3 = yes
+	ssse3 = yes
+	sse41 = yes
+endif
+
 ifeq ($(ARCH),x86-64-modern)
 	arch = x86_64
-	bits = 64
 	prefetch = yes
 	popcnt = yes
 	sse = yes
+	sse3 = yes
+	ssse3 = yes
+	sse41 = yes
+endif
+
+ifeq ($(ARCH),x86-64-sse42)
+	arch = x86_64
+	prefetch = yes
+	popcnt = yes
+	sse = yes
+	sse3 = yes
+	ssse3 = yes
+	sse41 = yes
+	sse42 = yes
+endif
+
+ifeq ($(ARCH),x86-64-avx2)
+	arch = x86_64
+	prefetch = yes
+	popcnt = yes
+	sse = yes
+	sse3 = yes
+	ssse3 = yes
+	sse41 = yes
+	sse42 = yes
+	avx2 = yes
 endif

 ifeq ($(ARCH),x86-64-bmi2)
 	arch = x86_64
-	bits = 64
 	prefetch = yes
 	popcnt = yes
 	sse = yes
+	sse3 = yes
+	ssse3 = yes
+	sse41 = yes
+	sse42 = yes
+	avx2 = yes
 	pext = yes
 endif

+ifeq ($(ARCH),x86-64-avx512)
+	arch = x86_64
+	prefetch = yes
+	popcnt = yes
+	sse = yes
+	sse3 = yes
+	ssse3 = yes
+	sse41 = yes
+	sse42 = yes
+	avx2 = yes
+	pext = yes
+	avx512 = yes
+endif
+
 ifeq ($(ARCH),armv7)
 	arch = armv7
 	prefetch = yes
+	bits = 32
+endif
+
+ifeq ($(ARCH),armv8)
+	arch = armv8-a
+	prefetch = yes
+	popcnt = yes
+	neon = yes
+endif
+
+ifeq ($(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

-
 ### ==========================================================================
-### Section 3. Low-level configuration
+### Section 3. Low-level Configuration
 ### ==========================================================================

 ### 3.1 Selecting compiler (default = gcc)
-
-CXXFLAGS += -Wall -Wcast-qual -fno-exceptions -std=c++11 $(EXTRACXXFLAGS)
-DEPENDFLAGS += -std=c++11
+CXXFLAGS += -Wall -Wcast-qual -fno-exceptions -std=c++17 $(EXTRACXXFLAGS)
+DEPENDFLAGS += -std=c++17
 LDFLAGS += $(EXTRALDFLAGS)

 ifeq ($(COMP),)
@@ -160,7 +268,7 @@ ifeq ($(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)
@@ -217,7 +325,7 @@ ifeq ($(COMP),clang)
 	endif
 	endif

-	ifeq ($(ARCH),armv7)
+	ifeq ($(ARCH),$(filter $(ARCH),armv7 armv8))
 		ifeq ($(OS),Android)
 			CXXFLAGS += -m$(bits)
 			LDFLAGS += -m$(bits)
@@ -242,8 +350,8 @@ endif
 endif

 ifeq ($(KERNEL),Darwin)
-	CXXFLAGS += -arch $(arch) -mmacosx-version-min=10.9
-	LDFLAGS += -arch $(arch) -mmacosx-version-min=10.9
+	CXXFLAGS += -arch $(arch) -mmacosx-version-min=10.15
+	LDFLAGS += -arch $(arch) -mmacosx-version-min=10.15
 endif

 ### Travis CI script uses COMPILER to overwrite CXX
@@ -276,8 +384,8 @@ endif

 ### 3.2.2 Debugging with undefined behavior sanitizers
 ifneq ($(sanitize),no)
-        CXXFLAGS += -g3 -fsanitize=$(sanitize) -fuse-ld=gold
-        LDFLAGS += -fsanitize=$(sanitize) -fuse-ld=gold
+        CXXFLAGS += -g3 -fsanitize=$(sanitize)
+        LDFLAGS += -fsanitize=$(sanitize)
 endif

 ### 3.3 Optimization
@@ -315,7 +423,7 @@ endif

 ### 3.6 popcnt
 ifeq ($(popcnt),yes)
-	ifeq ($(arch),ppc64)
+	ifeq ($(arch),$(filter $(arch),ppc64 armv8-a arm64))
 		CXXFLAGS += -DUSE_POPCNT
 	else ifeq ($(comp),icc)
 		CXXFLAGS += -msse3 -DUSE_POPCNT
@@ -324,15 +432,65 @@ 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 $(comp),gcc clang mingw))
+		CXXFLAGS += -mavx512bw
+	endif
+endif
+
+ifeq ($(sse42),yes)
+	CXXFLAGS += -DUSE_SSE42
+	ifeq ($(comp),$(filter $(comp),gcc clang mingw))
+		CXXFLAGS += -msse4.2
+	endif
+endif
+
+ifeq ($(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 $(comp),gcc clang mingw))
+		CXXFLAGS += -mssse3
+	endif
+endif
+
+ifeq ($(sse3),yes)
+	CXXFLAGS += -DUSE_SSE3
+	ifeq ($(comp),$(filter $(comp),gcc clang mingw))
+		CXXFLAGS += -msse3
+	endif
+endif
+
+ifeq ($(neon),yes)
+	CXXFLAGS += -DUSE_NEON
+endif
+
+ifeq ($(arch),x86_64)
+	CXXFLAGS += -DUSE_SSE2
+endif
+
 ### 3.7 pext
 ifeq ($(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 ($(optimize),yes)
@@ -342,6 +500,9 @@ ifeq ($(debug), no)
 		LDFLAGS += $(CXXFLAGS)
 	endif

+# 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 know to work, older might not.
+# So, only enable it for a cross from Linux by default.
 	ifeq ($(comp),mingw)
 	ifeq ($(KERNEL),Linux)
 		CXXFLAGS += -flto
@@ -358,9 +519,8 @@ ifeq ($(OS), Android)
 	LDFLAGS += -fPIE -pie
 endif

-
 ### ==========================================================================
-### Section 4. Public targets
+### Section 4. Public Targets
 ### ==========================================================================

 help:
@@ -372,21 +532,31 @@ help:
 	@echo "Supported targets:"
 	@echo ""
 	@echo "build                   > Standard build"
-	@echo "profile-build           > PGO build"
+	@echo "profile-build           > Standard build with PGO"
 	@echo "strip                   > Strip executable"
 	@echo "install                 > Install executable"
 	@echo "clean                   > Clean up"
+	@echo "net                     > Download the default nnue net"
 	@echo ""
 	@echo "Supported archs:"
 	@echo ""
-	@echo "x86-64-bmi2             > x86 64-bit with pext support (also enables SSE4)"
-	@echo "x86-64-modern           > x86 64-bit with popcnt support (also enables SSE3)"
+	@echo "x86-64-avx512           > x86 64-bit with avx512 support"
+	@echo "x86-64-bmi2             > x86 64-bit with bmi2 support"
+	@echo "x86-64-avx2             > x86 64-bit with avx2 support"
+	@echo "x86-64-sse42            > x86 64-bit with sse42 support"
+	@echo "x86-64-modern           > x86 64-bit with sse41 support (x86-64-sse41)"
+	@echo "x86-64-sse41            > x86 64-bit with sse41 support"
+	@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-sse3             > x86 64-bit with sse3 support"
 	@echo "x86-64                  > x86 64-bit generic"
 	@echo "x86-32                  > x86 32-bit (also enables SSE)"
 	@echo "x86-32-old              > x86 32-bit fall back for old hardware"
 	@echo "ppc-64                  > PPC 64-bit"
 	@echo "ppc-32                  > PPC 32-bit"
 	@echo "armv7                   > ARMv7 32-bit"
+	@echo "armv8                   > ARMv8 64-bit"
+	@echo "apple-silicon           > Apple silicon ARM64"
 	@echo "general-64              > unspecified 64-bit"
 	@echo "general-32              > unspecified 32-bit"
 	@echo ""
@@ -409,7 +579,7 @@ help:
 	@echo ""


-.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

@@ -443,21 +613,28 @@ install:
 clean: objclean profileclean
 	@rm -f .depend *~ core

+net:
+	$(eval nnuenet := $(shell grep EvalFile ucioption.cpp | grep Option | 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 := $(shell if hash curl 2>/dev/null; then echo "curl -sL"; elif hash wget 2>/dev/null; then echo "wget -qO-"; fi))
+	@if test -f "$(nnuenet)"; then echo "Already available."; else echo "Downloading $(nnuedownloadurl)"; $(curl_or_wget) $(nnuedownloadurl) > $(nnuenet); 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
 	@rm -f stockfish.profdata *.profraw

 default:
 	help

 ### ==========================================================================
-### Section 5. Private targets
+### Section 5. Private Targets
 ### ==========================================================================

 all: $(EXE) .depend
@@ -475,7 +652,14 @@ config-sanity:
 	@echo "prefetch: '$(prefetch)'"
 	@echo "popcnt: '$(popcnt)'"
 	@echo "sse: '$(sse)'"
+	@echo "sse3: '$(sse3)'"
+	@echo "ssse3: '$(ssse3)'"
+	@echo "sse41: '$(sse41)'"
+	@echo "sse42: '$(sse42)'"
+	@echo "avx2: '$(avx2)'"
 	@echo "pext: '$(pext)'"
+	@echo "avx512: '$(avx512)'"
+	@echo "neon: '$(neon)'"
 	@echo ""
 	@echo "Flags:"
 	@echo "CXX: $(CXX)"
@@ -488,12 +672,20 @@ config-sanity:
 	@test "$(sanitize)" = "undefined" || test "$(sanitize)" = "thread" || test "$(sanitize)" = "address" || test "$(sanitize)" = "no"
 	@test "$(optimize)" = "yes" || test "$(optimize)" = "no"
 	@test "$(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)" = "armv7" || test "$(arch)" = "armv8-a" || test "$(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 "$(sse3)" = "yes" || test "$(sse3)" = "no"
+	@test "$(ssse3)" = "yes" || test "$(ssse3)" = "no"
+	@test "$(sse41)" = "yes" || test "$(sse41)" = "no"
+	@test "$(sse42)" = "yes" || test "$(sse42)" = "no"
+	@test "$(avx2)" = "yes" || test "$(avx2)" = "no"
 	@test "$(pext)" = "yes" || test "$(pext)" = "no"
+	@test "$(avx512)" = "yes" || test "$(avx512)" = "no"
+	@test "$(neon)" = "yes" || test "$(neon)" = "no"
 	@test "$(comp)" = "gcc" || test "$(comp)" = "icc" || test "$(comp)" = "mingw" || test "$(comp)" = "clang"

 $(EXE): $(OBJS)
@@ -536,7 +728,6 @@ icc-profile-use:
 	all

 .depend:
-	-@$(CXX) $(DEPENDFLAGS) -MM $(OBJS:.o=.cpp) > $@ 2> /dev/null
+	-@$(CXX) $(DEPENDFLAGS) -MM $(SRCS) > $@ 2> /dev/null

 -include .depend
-
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -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
@@ -87,7 +86,7 @@ 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"
 };

@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -19,8 +17,8 @@
 */

 #include <cassert>
-#include <numeric>
 #include <vector>
+#include <bitset>

 #include "bitboard.h"
 #include "types.h"
@@ -31,8 +29,7 @@ namespace {
  // 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
-  uint32_t KPKBitbase[MAX_INDEX / 32];
+  std::bitset<MAX_INDEX> KPKBitbase;

  // A KPK bitbase index is an integer in [0, IndexMax] range
  //
@@ -43,8 +40,8 @@ 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) {
-    return int(wksq) | (bksq << 6) | (us << 12) | (file_of(psq) << 13) | ((RANK_7 - rank_of(psq)) << 15);
+  unsigned index(Color stm, Square bksq, Square wksq, Square psq) {
+    return int(wksq) | (bksq << 6) | (stm << 12) | (file_of(psq) << 13) | ((RANK_7 - rank_of(psq)) << 15);
  }

  enum Result {
@@ -60,12 +57,9 @@ namespace {
    KPKPosition() = default;
    explicit KPKPosition(unsigned idx);
    operator Result() const { return result; }
-    Result classify(const std::vector<KPKPosition>& db)
-    { return us == WHITE ? classify<WHITE>(db) : classify<BLACK>(db); }
+    Result classify(const std::vector<KPKPosition>& db);

-    template<Color Us> Result classify(const std::vector<KPKPosition>& db);
-
-    Color us;
+    Color stm;
    Square ksq[COLOR_NB], psq;
    Result result;
  };
@@ -73,12 +67,11 @@ namespace {
 } // namespace


-bool Bitbases::probe(Square wksq, Square wpsq, Square bksq, Color us) {
+bool Bitbases::probe(Square wksq, Square wpsq, Square bksq, Color stm) {

  assert(file_of(wpsq) <= FILE_D);

-  unsigned idx = index(us, bksq, wksq, wpsq);
-  return KPKBitbase[idx / 32] & (1 << (idx & 0x1F));
+  return KPKBitbase[index(stm, bksq, wksq, wpsq)];
 }


@@ -97,10 +90,10 @@ 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);
 }


@@ -110,28 +103,28 @@ namespace {

    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
-    else if (   us == WHITE
+    // Win if the pawn can be promoted without getting captured
+    else if (   stm == WHITE
             && rank_of(psq) == RANK_7
-             && ksq[us] != psq + NORTH
-             && (    distance(ksq[~us], psq + NORTH) > 1
-                 || (PseudoAttacks[KING][ksq[us]] & (psq + NORTH))))
+             && ksq[WHITE] != psq + NORTH
+             && (    distance(ksq[BLACK], psq + NORTH) > 1
+                 || (distance(ksq[WHITE], psq + NORTH) == 1)))
        result = WIN;

-    // Immediate draw if it is a stalemate or a king captures undefended pawn
-    else if (   us == BLACK
-             && (  !(PseudoAttacks[KING][ksq[us]] & ~(PseudoAttacks[KING][ksq[~us]] | PawnAttacks[~us][psq]))
-                 || (PseudoAttacks[KING][ksq[us]] & psq & ~PseudoAttacks[KING][ksq[~us]])))
+    // Draw if it is stalemate or the black king can capture the pawn
+    else if (   stm == BLACK
+             && (  !(attacks_bb<KING>(ksq[BLACK]) & ~(attacks_bb<KING>(ksq[WHITE]) | pawn_attacks_bb(WHITE, psq)))
+                 || (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
@@ -151,27 +143,25 @@ 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.
-
-    constexpr Color  Them = (Us == WHITE ? BLACK : WHITE);
-    constexpr Result Good = (Us == WHITE ? WIN   : DRAW);
-    constexpr Result Bad  = (Us == WHITE ? DRAW  : WIN);
+    const Result Good = (stm == WHITE ? WIN   : DRAW);
+    const Result Bad  = (stm == 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)]
-                         : db[index(Them, pop_lsb(&b), ksq[Them]  , psq)];
+        r |= stm == WHITE ? db[index(BLACK, ksq[BLACK] , pop_lsb(&b), 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[Them])
-            r |= db[index(Them, ksq[Them], ksq[Us], psq + NORTH + NORTH)];
+            && psq + NORTH != ksq[WHITE]
+            && psq + NORTH != ksq[BLACK])
+            r |= db[index(BLACK, ksq[BLACK], ksq[WHITE], psq + NORTH + NORTH)];
    }

    return result = r & Good  ? Good  : r & UNKNOWN ? UNKNOWN : Bad;
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -40,7 +38,7 @@ 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[]);
 }


@@ -56,8 +54,9 @@ 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 +68,7 @@ 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);
@@ -78,36 +77,20 @@ 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)
-  {
-      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);
+  init_magics(ROOK, RookTable, RookMagics);
+  init_magics(BISHOP, BishopTable, BishopMagics);

  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);

@@ -121,22 +104,20 @@ void Bitboards::init() {

 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 (Square s = sq + directions[i];
-             is_ok(s) && distance(s, s - directions[i]) == 1;
-             s += directions[i])
-        {
-            attack |= s;
+    for(Direction d : (pt == ROOK ? RookDirections : BishopDirections))
+    {
+        Square s = sq;
+        while(safe_destination(s, d) && !(occupied & s))
+            attacks |= (s += d);
+    }

-            if (occupied & s)
-                break;
-        }
-
-    return attack;
+    return attacks;
  }


@@ -145,7 +126,7 @@ 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 +146,7 @@ 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 +158,7 @@ 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];
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -106,10 +104,11 @@ 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 +122,39 @@ 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 +176,12 @@ 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.
@@ -188,19 +194,33 @@ 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
-/// If the given squares are not on a same file/rank/diagonal, return 0.
+/// line_bb() returns a bitboard representing an entire line (from board edge
+/// 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 line_bb(Square s1, Square s2) {
+
+  assert(is_ok(s1) && is_ok(s2));
+  return LineBB[s1][s2];
+}
+
+
+/// between_bb() returns a bitboard representing squares that are linearly
+/// between the two given squares (excluding the given squares). If the given
+/// squares are not on a same file/rank/diagonal, we return 0. For instance,
+/// between_bb(SQ_C4, SQ_F7) will return a bitboard with squares D5 and E6.

 inline Bitboard between_bb(Square s1, Square s2) {
-  return LineBB[s1][s2] & ( (AllSquares << (s1 +  (s1 < s2)))
-                           ^(AllSquares << (s2 + !(s1 < s2))));
+  Bitboard b = line_bb(s1, s2) & ((AllSquares << s1) ^ (AllSquares << s2));
+  return b & (b - 1); //exclude lsb
 }


@@ -208,25 +228,25 @@ inline Bitboard between_bb(Square s1, Square s2) {
 /// 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) {
-  return c == WHITE ? ~Rank1BB << 8 * (rank_of(s) - RANK_1)
-                    : ~Rank8BB >> 8 * (RANK_8 - rank_of(s));
+constexpr Bitboard forward_ranks_bb(Color c, Square s) {
+  return c == WHITE ? ~Rank1BB << 8 * relative_rank(WHITE, 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,
-/// starting from the given square.
+/// be attacked by a pawn of the given color when it moves along its file, starting
+/// 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 +254,8 @@ 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) {
-  return forward_ranks_bb(c, s) & (adjacent_files_bb(s) | file_bb(s));
+constexpr Bitboard passed_pawn_span(Color c, Square s) {
+  return pawn_attack_span(c, s) | forward_file_bb(c, s);
 }


@@ -243,7 +263,7 @@ 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 +275,53 @@ 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) {
-  return v < lo ? lo : v > hi ? hi : v;
+inline int edge_distance(File f) { return std::min(f, File(FILE_H - f)); }
+inline int edge_distance(Rank r) { return std::min(r, Rank(RANK_8 - r)); }
+
+
+/// 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);
 }

-/// 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) 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(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];
-  return m.attacks[m.index(occupied)];
+  assert((Pt != PAWN) && (is_ok(s)));
+
+  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)
  {
@@ -376,14 +426,17 @@ inline Square msb(Bitboard b) {
 /// pop_lsb() finds and clears the least significant bit in a non-zero bitboard

 inline Square pop_lsb(Bitboard* b) {
+  assert(*b);
  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);
 }

@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -24,42 +22,25 @@
 #include "endgame.h"
 #include "movegen.h"

-using std::string;
-
 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] = {
-    100, 90, 80, 70, 70, 80, 90, 100,
-     90, 70, 60, 50, 50, 60, 70,  90,
-     80, 60, 40, 30, 30, 40, 60,  80,
-     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
-  };
+  // Values range from 27 (center squares) to 90 (in the corners)
+  inline int push_to_edge(Square s) {
+      int rd = edge_distance(rank_of(s)), fd = edge_distance(file_of(s));
+      return 90 - (7 * fd * fd / 2 + 7 * rd * rd / 2);
+  }

-  // Table used to drive the king towards a corner square of the
-  // right color in KBN vs K endgames.
-  constexpr int PushToCorners[SQUARE_NB] = {
-     6400, 6080, 5760, 5440, 5120, 4800, 4480, 4160,
-     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
-  };
+  // Used to drive the king towards A1H8 corners in KBN vs K endgames.
+  // Values range from 0 on A8H1 diagonal to 7 in A1H8 corners
+  inline int push_to_corner(Square s) {
+      return abs(7 - rank_of(s) - file_of(s));
+  }

-  // Tables used to drive a piece towards or away from another piece
-  constexpr int PushClose[8] = { 0, 0, 100, 80, 60, 40, 20, 10 };
-  constexpr int PushAway [8] = { 0, 5, 20, 40, 60, 80, 90, 100 };
-
-  // Pawn Rank based scaling factors used in KRPPKRP endgame
-  constexpr int KRPPKRPScaleFactors[RANK_NB] = { 0, 9, 10, 14, 21, 44, 0, 0 };
+  // Drive a piece close to or away from another piece
+  inline int push_close(Square s1, Square s2) { return 140 - 20 * distance(s1, s2); }
+  inline int push_away(Square s1, Square s2) { return 120 - push_close(s1, s2); }

 #ifndef NDEBUG
  bool verify_material(const Position& pos, Color c, Value npm, int pawnsCnt) {
@@ -74,9 +55,9 @@ 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 +79,6 @@ 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 +103,20 @@ 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 loserKSq = pos.square<KING>(weakSide);
+  Square strongKing = pos.square<KING>(strongSide);
+  Square weakKing   = pos.square<KING>(weakSide);

  Value result =  pos.non_pawn_material(strongSide)
                + pos.count<PAWN>(strongSide) * PawnValueEg
-                + PushToEdges[loserKSq]
-                + PushClose[distance(winnerKSq, loserKSq)];
+                + push_to_edge(weakKing)
+                + 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 +130,18 @@ 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 loserKSq = pos.square<KING>(weakSide);
-  Square bishopSq = pos.square<BISHOP>(strongSide);
+  Square strongKing   = pos.square<KING>(strongSide);
+  Square strongBishop = 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
-                + PushClose[distance(winnerKSq, loserKSq)]
-                + PushToCorners[opposite_colors(bishopSq, SQ_A1) ? ~loserKSq : loserKSq];
+  Value result =  (VALUE_KNOWN_WIN + 3520)
+                + push_close(strongKing, weakKing)
+                + 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 +154,16 @@ 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 bksq = normalize(pos, strongSide, pos.square<KING>(weakSide));
-  Square psq  = normalize(pos, strongSide, pos.square<PAWN>(strongSide));
+  Square strongKing = normalize(pos, strongSide, pos.square<KING>(strongSide));
+  Square strongPawn = 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 +179,35 @@ 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 bksq = relative_square(strongSide, pos.square<KING>(weakSide));
-  Square rsq  = relative_square(strongSide, pos.square<ROOK>(strongSide));
-  Square psq  = relative_square(strongSide, pos.square<PAWN>(weakSide));
-
-  Square queeningSq = make_square(file_of(psq), RANK_1);
+  Square strongKing = pos.square<KING>(strongSide);
+  Square weakKing   = pos.square<KING>(weakSide);
+  Square strongRook = pos.square<ROOK>(strongSide);
+  Square weakPawn   = pos.square<PAWN>(weakSide);
+  Square queeningSquare = make_square(file_of(weakPawn), relative_rank(weakSide, RANK_8));
  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)
-      result = RookValueEg - distance(wksq, psq);
+  if (forward_file_bb(strongSide, strongKing) & weakPawn)
+      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)
-           && distance(bksq, rsq) >= 3)
-      result = RookValueEg - distance(wksq, psq);
+  else if (   distance(weakKing, weakPawn) >= 3 + (pos.side_to_move() == weakSide)
+           && distance(weakKing, strongRook) >= 3)
+      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
-           && distance(bksq, psq) == 1
-           && rank_of(wksq) >= RANK_4
-           && distance(wksq, psq) > 2 + (pos.side_to_move() == strongSide))
-      result = Value(80) - 8 * distance(wksq, psq);
+  else if (   relative_rank(strongSide, weakKing) <= RANK_3
+           && distance(weakKing, weakPawn) == 1
+           && relative_rank(strongSide, strongKing) >= RANK_4
+           && distance(strongKing, weakPawn) > 2 + (pos.side_to_move() == strongSide))
+      result = Value(80) - 8 * distance(strongKing, weakPawn);

  else
-      result =  Value(200) - 8 * (  distance(wksq, psq + SOUTH)
-                                  - distance(bksq, psq + SOUTH)
-                                  - distance(psq, queeningSq));
+      result =  Value(200) - 8 * (  distance(strongKing, weakPawn + pawn_push(weakSide))
+                                  - distance(weakKing, weakPawn + pawn_push(weakSide))
+                                  - distance(weakPawn, queeningSquare));

  return strongSide == pos.side_to_move() ? result : -result;
 }
@@ -243,7 +221,7 @@ 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 +234,9 @@ 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 bnsq = pos.square<KNIGHT>(weakSide);
-  Value result = Value(PushToEdges[bksq] + PushAway[distance(bksq, bnsq)]);
+  Square weakKing   = pos.square<KING>(weakSide);
+  Square weakKnight = pos.square<KNIGHT>(weakSide);
+  Value result = Value(push_to_edge(weakKing) + push_away(weakKing, weakKnight));
  return strongSide == pos.side_to_move() ? result : -result;
 }

@@ -273,22 +251,22 @@ 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 loserKSq = pos.square<KING>(weakSide);
-  Square pawnSq = pos.square<PAWN>(weakSide);
+  Square strongKing = pos.square<KING>(strongSide);
+  Square weakKing   = pos.square<KING>(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
-      || distance(loserKSq, pawnSq) != 1
-      || !((FileABB | FileCBB | FileFBB | FileHBB) & pawnSq))
+  if (   relative_rank(weakSide, weakPawn) != RANK_7
+      || distance(weakKing, weakPawn) != 1
+      || ((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 +276,32 @@ 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 loserKSq = pos.square<KING>(weakSide);
+  Square strongKing = pos.square<KING>(strongSide);
+  Square weakKing   = pos.square<KING>(weakSide);

  Value result =  QueenValueEg
                - RookValueEg
-                + PushToEdges[loserKSq]
-                + PushClose[distance(winnerKSq, loserKSq)];
+                + push_to_edge(weakKing)
+                + 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
-                - PawnValueEg
-                + PushToEdges[pos.square<KING>(weakSide)];
+  Square weakKing = pos.square<KING>(weakSide);
+  Square weakPawn = pos.square<PAWN>(weakSide);
+
+  Value result =      PawnValueEg
+               +  2 * push_to_edge(weakKing)
+               - 10 * relative_rank(weakSide, weakPawn);

  return strongSide == pos.side_to_move() ? result : -result;
 }
@@ -342,51 +324,47 @@ 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);
-  File pawnsFile = file_of(lsb(pawns));
+  Bitboard strongPawns = pos.pieces(strongSide, PAWN);
+  Bitboard allPawns = pos.pieces(PAWN);

-  // All pawns are on a single rook file?
-  if (    (pawnsFile == FILE_A || pawnsFile == FILE_H)
-      && !(pawns & ~file_bb(pawnsFile)))
+  Square strongBishop = pos.square<BISHOP>(strongSide);
+  Square weakKing = pos.square<KING>(weakSide);
+  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 queeningSq = relative_square(strongSide, make_square(pawnsFile, RANK_8));
-      Square kingSq = pos.square<KING>(weakSide);
+      Square queeningSquare = relative_square(strongSide, make_square(file_of(lsb(strongPawns)), RANK_8));

-      if (   opposite_colors(queeningSq, bishopSq)
-          && distance(queeningSq, kingSq) <= 1)
+      if (   opposite_colors(queeningSquare, strongBishop)
+          && 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)
-      && !(pos.pieces(PAWN) & ~file_bb(pawnsFile))
+  if ((!(allPawns & ~FileBBB) || !(allPawns & ~FileGBB))
      && pos.non_pawn_material(weakSide) == 0
      && pos.count<PAWN>(weakSide) >= 1)
  {
-      // Get weakSide pawn that is closest to the home rank
-      Square weakPawnSq = 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);
+      // Get the least advanced weakSide pawn
+      Square weakPawn = frontmost_sq(strongSide, pos.pieces(weakSide, PAWN));

      // 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
-      if (   relative_rank(strongSide, weakPawnSq) == RANK_7
-          && (pos.pieces(strongSide, PAWN) & (weakPawnSq + pawn_push(weakSide)))
-          && (opposite_colors(bishopSq, weakPawnSq) || pos.count<PAWN>(strongSide) == 1))
+      // the bishop cannot attack it or they only have one pawn left.
+      if (   relative_rank(strongSide, weakPawn) == RANK_7
+          && (strongPawns & (weakPawn + pawn_push(weakSide)))
+          && (opposite_colors(strongBishop, weakPawn) || !more_than_one(strongPawns)))
      {
-          int strongKingDist = distance(weakPawnSq, strongKingSq);
-          int weakKingDist = distance(weakPawnSq, weakKingSq);
+          int strongKingDist = distance(weakPawn, strongKing);
+          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)
-          if (   relative_rank(strongSide, weakKingSq) >= RANK_7
+          // problem such as 8/4k1p1/6P1/1K6/3B4/8/8/8 w).
+          if (   relative_rank(strongSide, weakKing) >= RANK_7
              && weakKingDist <= 2
              && weakKingDist <= strongKingDist)
              return SCALE_FACTOR_DRAW;
@@ -406,15 +384,16 @@ 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 rsq = pos.square<ROOK>(weakSide);
+  Square strongKing = pos.square<KING>(strongSide);
+  Square weakKing   = pos.square<KING>(weakSide);
+  Square weakRook   = pos.square<ROOK>(weakSide);

-  if (    relative_rank(weakSide, kingSq) <= RANK_2
-      &&  relative_rank(weakSide, pos.square<KING>(strongSide)) >= RANK_4
-      &&  relative_rank(weakSide, rsq) == RANK_3
+  if (    relative_rank(weakSide,   weakKing) <= RANK_2
+      &&  relative_rank(weakSide, strongKing) >= RANK_4
+      &&  relative_rank(weakSide,   weakRook) == RANK_3
      && (  pos.pieces(weakSide, PAWN)
-          & pos.attacks_from<KING>(kingSq)
-          & pos.attacks_from<PAWN>(rsq, strongSide)))
+          & attacks_bb<KING>(weakKing)
+          & pawn_attacks_bb(strongSide, weakRook)))
          return SCALE_FACTOR_DRAW;

  return SCALE_FACTOR_NONE;
@@ -434,89 +413,89 @@ 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 bksq = normalize(pos, strongSide, pos.square<KING>(weakSide));
-  Square wrsq = normalize(pos, strongSide, pos.square<ROOK>(strongSide));
-  Square wpsq = normalize(pos, strongSide, pos.square<PAWN>(strongSide));
-  Square brsq = normalize(pos, strongSide, pos.square<ROOK>(weakSide));
+  Square strongKing = normalize(pos, strongSide, pos.square<KING>(strongSide));
+  Square strongRook = normalize(pos, strongSide, pos.square<ROOK>(strongSide));
+  Square strongPawn = normalize(pos, strongSide, pos.square<PAWN>(strongSide));
+  Square weakKing = normalize(pos, strongSide, pos.square<KING>(weakSide));
+  Square weakRook = normalize(pos, strongSide, pos.square<ROOK>(weakSide));

-  File f = file_of(wpsq);
-  Rank r = rank_of(wpsq);
-  Square queeningSq = make_square(f, RANK_8);
+  File pawnFile = file_of(strongPawn);
+  Rank pawnRank = rank_of(strongPawn);
+  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
-      && distance(bksq, queeningSq) <= 1
-      && wksq <= SQ_H5
-      && (rank_of(brsq) == RANK_6 || (r <= RANK_3 && rank_of(wrsq) != RANK_6)))
+  if (   pawnRank <= RANK_5
+      && distance(weakKing, queeningSquare) <= 1
+      && strongKing <= SQ_H5
+      && (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
-      && distance(bksq, queeningSq) <= 1
-      && rank_of(wksq) + tempo <= RANK_6
-      && (rank_of(brsq) == RANK_1 || (!tempo && distance<File>(brsq, wpsq) >= 3)))
+  if (   pawnRank == RANK_6
+      && distance(weakKing, queeningSquare) <= 1
+      && rank_of(strongKing) + tempo <= RANK_6
+      && (rank_of(weakRook) == RANK_1 || (!tempo && distance<File>(weakRook, strongPawn) >= 3)))
      return SCALE_FACTOR_DRAW;

-  if (   r >= RANK_6
-      && bksq == queeningSq
-      && rank_of(brsq) == RANK_1
-      && (!tempo || distance(wksq, wpsq) >= 2))
+  if (   pawnRank >= RANK_6
+      && weakKing == queeningSquare
+      && rank_of(weakRook) == RANK_1
+      && (!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
-      && wrsq == SQ_A8
-      && (bksq == SQ_H7 || bksq == SQ_G7)
-      && file_of(brsq) == FILE_A
-      && (rank_of(brsq) <= RANK_3 || file_of(wksq) >= FILE_D || rank_of(wksq) <= RANK_5))
+  if (   strongPawn == SQ_A7
+      && strongRook == SQ_A8
+      && (weakKing == SQ_H7 || weakKing == SQ_G7)
+      && file_of(weakRook) == FILE_A
+      && (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
-      && bksq == wpsq + NORTH
-      && distance(wksq, wpsq) - tempo >= 2
-      && distance(wksq, brsq) - tempo >= 2)
+  if (   pawnRank <= RANK_5
+      && weakKing == strongPawn + NORTH
+      && distance(strongKing, strongPawn) - 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
-      && f != FILE_A
-      && file_of(wrsq) == f
-      && wrsq != queeningSq
-      && (distance(wksq, queeningSq) < distance(bksq, queeningSq) - 2 + tempo)
-      && (distance(wksq, queeningSq) < distance(bksq, wrsq) + tempo))
-      return ScaleFactor(SCALE_FACTOR_MAX - 2 * distance(wksq, queeningSq));
+  if (   pawnRank == RANK_7
+      && pawnFile != FILE_A
+      && file_of(strongRook) == pawnFile
+      && strongRook != queeningSquare
+      && (distance(strongKing, queeningSquare) < distance(weakKing, queeningSquare) - 2 + tempo)
+      && (distance(strongKing, queeningSquare) < distance(weakKing, strongRook) + tempo))
+      return ScaleFactor(SCALE_FACTOR_MAX - 2 * distance(strongKing, queeningSquare));

  // Similar to the above, but with the pawn further back
-  if (   f != FILE_A
-      && file_of(wrsq) == f
-      && wrsq < wpsq
-      && (distance(wksq, queeningSq) < distance(bksq, queeningSq) - 2 + tempo)
-      && (distance(wksq, wpsq + NORTH) < distance(bksq, wpsq + NORTH) - 2 + tempo)
-      && (  distance(bksq, wrsq) + tempo >= 3
-          || (    distance(wksq, queeningSq) < distance(bksq, wrsq) + tempo
-              && (distance(wksq, wpsq + NORTH) < distance(bksq, wrsq) + tempo))))
+  if (   pawnFile != FILE_A
+      && file_of(strongRook) == pawnFile
+      && strongRook < strongPawn
+      && (distance(strongKing, queeningSquare) < distance(weakKing, queeningSquare) - 2 + tempo)
+      && (distance(strongKing, strongPawn + NORTH) < distance(weakKing, strongPawn + NORTH) - 2 + tempo)
+      && (  distance(weakKing, strongRook) + tempo >= 3
+          || (    distance(strongKing, queeningSquare) < distance(weakKing, strongRook) + tempo
+              && (distance(strongKing, strongPawn + NORTH) < distance(weakKing, strongPawn) + tempo))))
      return ScaleFactor(  SCALE_FACTOR_MAX
-                         - 8 * distance(wpsq, queeningSq)
-                         - 2 * distance(wksq, queeningSq));
+                         - 8 * distance(strongPawn, queeningSquare)
+                         - 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
-          && distance(wksq, bksq) > 2)
-          return ScaleFactor(24 - 2 * distance(wksq, bksq));
+      if (   distance<File>(weakKing, strongPawn) == 1
+          && distance(strongKing, weakKing) > 2)
+          return ScaleFactor(24 - 2 * distance(strongKing, weakKing));
  }
  return SCALE_FACTOR_NONE;
 }
@@ -530,10 +509,11 @@ 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 bsq = pos.square<BISHOP>(weakSide);
-      Square psq = pos.square<PAWN>(strongSide);
-      Rank rk = relative_rank(strongSide, psq);
+      Square weakKing = pos.square<KING>(weakSide);
+      Square weakBishop = pos.square<BISHOP>(weakSide);
+      Square strongKing = pos.square<KING>(strongSide);
+      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 +521,11 @@ 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 +535,10 @@ 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
-          && distance(psq + 2 * push, ksq) <= 1
-          && (PseudoAttacks[BISHOP][bsq] & (psq + push))
-          && distance<File>(bsq, psq) >= 2)
+      if (   pawnRank == RANK_6
+          && distance(strongPawn + 2 * push, weakKing) <= 1
+          && (attacks_bb<BISHOP>(weakBishop) & (strongPawn + push))
+          && distance<File>(weakBishop, strongPawn) >= 2)
          return ScaleFactor(8);
  }

@@ -573,28 +553,28 @@ 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 wpsq2 = pos.squares<PAWN>(strongSide)[1];
-  Square bksq = pos.square<KING>(weakSide);
+  Square strongPawn1 = pos.squares<PAWN>(strongSide)[0];
+  Square strongPawn2 = pos.squares<PAWN>(strongSide)[1];
+  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
-      && distance<File>(bksq, wpsq2) <= 1
-      && relative_rank(strongSide, bksq) > r)
+  if (   distance<File>(weakKing, strongPawn1) <= 1
+      && distance<File>(weakKing, strongPawn2) <= 1
+      && relative_rank(strongSide, weakKing) > pawnRank)
  {
-      assert(r > RANK_1 && r < RANK_7);
-      return ScaleFactor(KRPPKRPScaleFactors[r]);
+      assert(pawnRank > RANK_1 && pawnRank < RANK_7);
+      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 +583,12 @@ 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);
-  Bitboard pawns = pos.pieces(strongSide, PAWN);
+  Square weakKing = pos.square<KING>(weakSide);
+  Bitboard strongPawns = pos.pieces(strongSide, PAWN);

-  // If all pawns are ahead of the king, on a single rook file and
-  // the king is within one file of the pawns, it's a draw.
-  if (   !(pawns & ~forward_ranks_bb(weakSide, ksq))
-      && !((pawns & ~FileABB) && (pawns & ~FileHBB))
-      &&  distance<File>(ksq, lsb(pawns)) <= 1)
+  // If all pawns are ahead of the king on a single rook file, it's a draw.
+  if (   !(strongPawns & ~(FileABB | FileHBB))
+      && !(strongPawns & ~passed_pawn_span(weakSide, weakKing)))
      return SCALE_FACTOR_DRAW;

  return SCALE_FACTOR_NONE;
@@ -627,20 +605,19 @@ 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 strongBishopSq = pos.square<BISHOP>(strongSide);
-  Square weakBishopSq = pos.square<BISHOP>(weakSide);
-  Square weakKingSq = pos.square<KING>(weakSide);
+  Square strongPawn = pos.square<PAWN>(strongSide);
+  Square strongBishop = pos.square<BISHOP>(strongSide);
+  Square weakBishop = pos.square<BISHOP>(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)
-      && relative_rank(strongSide, pawnSq) < relative_rank(strongSide, weakKingSq)
-      && (   opposite_colors(weakKingSq, strongBishopSq)
-          || relative_rank(strongSide, weakKingSq) <= RANK_6))
+  if (   (forward_file_bb(strongSide, strongPawn) & weakKing)
+      && (   opposite_colors(weakKing, strongBishop)
+          || relative_rank(strongSide, weakKing) <= 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 +631,36 @@ 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 bbsq = pos.square<BISHOP>(weakSide);
+  Square strongBishop = pos.square<BISHOP>(strongSide);
+  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 psq1 = pos.squares<PAWN>(strongSide)[0];
-  Square psq2 = pos.squares<PAWN>(strongSide)[1];
+  Square weakKing = pos.square<KING>(weakSide);
+  Square strongPawn1 = pos.squares<PAWN>(strongSide)[0];
+  Square strongPawn2 = pos.squares<PAWN>(strongSide)[1];
  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);
-      blockSq2 = make_square(file_of(psq2), rank_of(psq1));
+      blockSq1 = strongPawn1 + pawn_push(strongSide);
+      blockSq2 = make_square(file_of(strongPawn2), rank_of(strongPawn1));
  }
  else
  {
-      blockSq1 = psq2 + pawn_push(strongSide);
-      blockSq2 = make_square(file_of(psq1), rank_of(psq2));
+      blockSq1 = strongPawn2 + pawn_push(strongSide);
+      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)
-        && relative_rank(strongSide, ksq) >= relative_rank(strongSide, blockSq1)
-        && opposite_colors(ksq, wbsq))
+    if (   file_of(weakKing) == file_of(blockSq1)
+        && relative_rank(strongSide, weakKing) >= relative_rank(strongSide, blockSq1)
+        && opposite_colors(weakKing, strongBishop))
        return SCALE_FACTOR_DRAW;
    else
        return SCALE_FACTOR_NONE;
@@ -692,17 +669,17 @@ 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
-        && opposite_colors(ksq, wbsq)
-        && (   bbsq == blockSq2
-            || (pos.attacks_from<BISHOP>(blockSq2) & pos.pieces(weakSide, BISHOP))
-            || distance<Rank>(psq1, psq2) >= 2))
+    if (   weakKing == blockSq1
+        && opposite_colors(weakKing, strongBishop)
+        && (   weakBishop == blockSq2
+            || (attacks_bb<BISHOP>(blockSq2, pos.pieces()) & pos.pieces(weakSide, BISHOP))
+            || distance<Rank>(strongPawn1, strongPawn2) >= 2))
        return SCALE_FACTOR_DRAW;

-    else if (   ksq == blockSq2
-             && opposite_colors(ksq, wbsq)
-             && (   bbsq == blockSq1
-                 || (pos.attacks_from<BISHOP>(blockSq1) & pos.pieces(weakSide, BISHOP))))
+    else if (   weakKing == blockSq2
+             && opposite_colors(weakKing, strongBishop)
+             && (   weakBishop == blockSq1
+                 || (attacks_bb<BISHOP>(blockSq1, pos.pieces()) & pos.pieces(weakSide, BISHOP))))
        return SCALE_FACTOR_DRAW;
    else
        return SCALE_FACTOR_NONE;
@@ -714,7 +691,7 @@ 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 +700,22 @@ 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 strongBishopSq = pos.square<BISHOP>(strongSide);
-  Square weakKingSq = pos.square<KING>(weakSide);
+  Square strongPawn = pos.square<PAWN>(strongSide);
+  Square strongBishop = pos.square<BISHOP>(strongSide);
+  Square weakKing = pos.square<KING>(weakSide);

-  if (   file_of(weakKingSq) == file_of(pawnSq)
-      && relative_rank(strongSide, pawnSq) < relative_rank(strongSide, weakKingSq)
-      && (   opposite_colors(weakKingSq, strongBishopSq)
-          || relative_rank(strongSide, weakKingSq) <= RANK_6))
+  if (   file_of(weakKing) == file_of(strongPawn)
+      && relative_rank(strongSide, strongPawn) < relative_rank(strongSide, weakKing)
+      && (   opposite_colors(weakKing, strongBishop)
+          || 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 +726,18 @@ 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 bksq = normalize(pos, strongSide, pos.square<KING>(weakSide));
-  Square psq  = normalize(pos, strongSide, pos.square<PAWN>(strongSide));
+  Square strongKing = normalize(pos, strongSide, pos.square<KING>(strongSide));
+  Square weakKing   = normalize(pos, strongSide, pos.square<KING>(weakSide));
+  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;
 }
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -21,10 +19,10 @@
 #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"
@@ -57,8 +55,6 @@ 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
 };

@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -20,22 +18,57 @@

 #include <algorithm>
 #include <cassert>
+#include <cstdlib>
 #include <cstring>   // For std::memset
 #include <iomanip>
 #include <sstream>
+#include <iostream>

 #include "bitboard.h"
 #include "evaluate.h"
 #include "material.h"
 #include "pawns.h"
 #include "thread.h"
+#include "uci.h"
+
+namespace Eval {
+
+  bool useNNUE;
+  std::string eval_file_loaded="None";
+
+  void init_NNUE() {
+
+    useNNUE = Options["Use NNUE"];
+    std::string eval_file = std::string(Options["EvalFile"]);
+    if (useNNUE && eval_file_loaded != eval_file)
+        if (Eval::NNUE::load_eval_file(eval_file))
+            eval_file_loaded = eval_file;
+  }
+
+  void verify_NNUE() {
+
+    std::string eval_file = std::string(Options["EvalFile"]);
+    if (useNNUE && eval_file_loaded != eval_file)
+    {
+        std::cerr << "Use of NNUE evaluation, but the file " << eval_file << " was not loaded successfully. "
+                  << "These network evaluation parameters must be available, compatible with this version of the code. "
+                  << "The UCI option EvalFile might need to specify the full path, including the directory/folder name, to the file." << std::endl;
+        std::exit(EXIT_FAILURE);
+    }
+
+    if (useNNUE)
+        sync_cout << "info string NNUE evaluation using " << eval_file << " enabled." << sync_endl;
+    else
+        sync_cout << "info string classical evaluation enabled." << sync_endl;
+  }
+}

 namespace Trace {

  enum Tracing { NO_TRACE, TRACE };

  enum Term { // The first 8 entries are reserved for PieceType
-    MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, INITIATIVE, TOTAL, TERM_NB
+    MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, WINNABLE, TOTAL, TERM_NB
  };

  Score scores[TERM_NB][COLOR_NB];
@@ -59,7 +92,7 @@ namespace Trace {

  std::ostream& operator<<(std::ostream& os, Term t) {

-    if (t == MATERIAL || t == IMBALANCE || t == INITIATIVE || t == TOTAL)
+    if (t == MATERIAL || t == IMBALANCE || t == WINNABLE || t == TOTAL)
        os << " ----  ----"    << " | " << " ----  ----";
    else
        os << scores[t][WHITE] << " | " << scores[t][BLACK];
@@ -74,79 +107,92 @@ using namespace Trace;
 namespace {

  // Threshold for lazy and space evaluation
-  constexpr Value LazyThreshold  = Value(1400);
+  constexpr Value LazyThreshold1  = Value(1400);
+  constexpr Value LazyThreshold2  = Value(1300);
  constexpr Value SpaceThreshold = Value(12222);

  // KingAttackWeights[PieceType] contains king attack weights by piece type
  constexpr int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 81, 52, 44, 10 };

-  // Penalties for enemy's safe checks
-  constexpr int QueenSafeCheck  = 780;
-  constexpr int RookSafeCheck   = 1080;
-  constexpr int BishopSafeCheck = 635;
-  constexpr int KnightSafeCheck = 790;
+  // SafeCheck[PieceType][single/multiple] contains safe check bonus by piece type,
+  // higher if multiple safe checks are possible for that piece type.
+  constexpr int SafeCheck[][2] = {
+      {}, {}, {792, 1283}, {645, 967}, {1084, 1897}, {772, 1119}
+  };

 #define S(mg, eg) make_score(mg, eg)

  // MobilityBonus[PieceType-2][attacked] contains bonuses for middle and end game,
  // indexed by piece type and number of attacked squares in the mobility area.
  constexpr Score MobilityBonus[][32] = {
-    { S(-62,-81), S(-53,-56), S(-12,-30), S( -4,-14), S(  3,  8), S( 13, 15), // Knights
-      S( 22, 23), S( 28, 27), S( 33, 33) },
-    { S(-48,-59), S(-20,-23), S( 16, -3), S( 26, 13), S( 38, 24), S( 51, 42), // Bishops
+    { S(-62,-81), S(-53,-56), S(-12,-31), S( -4,-16), S(  3,  5), S( 13, 11), // Knight
+      S( 22, 17), S( 28, 20), S( 33, 25) },
+    { S(-48,-59), S(-20,-23), S( 16, -3), S( 26, 13), S( 38, 24), S( 51, 42), // Bishop
      S( 55, 54), S( 63, 57), S( 63, 65), S( 68, 73), S( 81, 78), S( 81, 86),
      S( 91, 88), S( 98, 97) },
-    { S(-58,-76), S(-27,-18), S(-15, 28), S(-10, 55), S( -5, 69), S( -2, 82), // Rooks
-      S(  9,112), S( 16,118), S( 30,132), S( 29,142), S( 32,155), S( 38,165),
-      S( 46,166), S( 48,169), S( 58,171) },
-    { S(-39,-36), S(-21,-15), S(  3,  8), S(  3, 18), S( 14, 34), S( 22, 54), // Queens
-      S( 28, 61), S( 41, 73), S( 43, 79), S( 48, 92), S( 56, 94), S( 60,104),
-      S( 60,113), S( 66,120), S( 67,123), S( 70,126), S( 71,133), S( 73,136),
-      S( 79,140), S( 88,143), S( 88,148), S( 99,166), S(102,170), S(102,175),
-      S(106,184), S(109,191), S(113,206), S(116,212) }
+    { S(-60,-78), S(-20,-17), S(  2, 23), S(  3, 39), S(  3, 70), S( 11, 99), // Rook
+      S( 22,103), S( 31,121), S( 40,134), S( 40,139), S( 41,158), S( 48,164),
+      S( 57,168), S( 57,169), S( 62,172) },
+    { S(-30,-48), S(-12,-30), S( -8, -7), S( -9, 19), S( 20, 40), S( 23, 55), // Queen
+      S( 23, 59), S( 35, 75), S( 38, 78), S( 53, 96), S( 64, 96), S( 65,100),
+      S( 65,121), S( 66,127), S( 67,131), S( 67,133), S( 72,136), S( 72,141),
+      S( 77,147), S( 79,150), S( 93,151), S(108,168), S(108,168), S(108,171),
+      S(110,182), S(114,182), S(114,192), S(116,219) }
  };

-  // RookOnFile[semiopen/open] contains bonuses for each rook when there is
-  // no (friendly) pawn on the rook file.
-  constexpr Score RookOnFile[] = { S(21, 4), S(47, 25) };
+  // KingProtector[knight/bishop] contains penalty for each distance unit to own king
+  constexpr Score KingProtector[] = { S(8, 9), S(6, 9) };

-  // ThreatByMinor/ByRook[attacked PieceType] contains bonuses according to
-  // which piece type attacks which one. Attacks on lesser pieces which are
-  // pawn-defended are not considered.
-  constexpr Score ThreatByMinor[PIECE_TYPE_NB] = {
-    S(0, 0), S(6, 32), S(59, 41), S(79, 56), S(90, 119), S(79, 161)
-  };
-
-  constexpr Score ThreatByRook[PIECE_TYPE_NB] = {
-    S(0, 0), S(3, 44), S(38, 71), S(38, 61), S(0, 38), S(51, 38)
-  };
+  // Outpost[knight/bishop] contains bonuses for each knight or bishop occupying a
+  // pawn protected square on rank 4 to 6 which is also safe from a pawn attack.
+  constexpr Score Outpost[] = { S(56, 36), S(30, 23) };

  // PassedRank[Rank] contains a bonus according to the rank of a passed pawn
  constexpr Score PassedRank[RANK_NB] = {
    S(0, 0), S(10, 28), S(17, 33), S(15, 41), S(62, 72), S(168, 177), S(276, 260)
  };

+  // RookOnFile[semiopen/open] contains bonuses for each rook when there is
+  // no (friendly) pawn on the rook file.
+  constexpr Score RookOnFile[] = { S(19, 7), S(48, 29) };
+
+  // ThreatByMinor/ByRook[attacked PieceType] contains bonuses according to
+  // which piece type attacks which one. Attacks on lesser pieces which are
+  // pawn-defended are not considered.
+  constexpr Score ThreatByMinor[PIECE_TYPE_NB] = {
+    S(0, 0), S(5, 32), S(57, 41), S(77, 56), S(88, 119), S(79, 161)
+  };
+
+  constexpr Score ThreatByRook[PIECE_TYPE_NB] = {
+    S(0, 0), S(3, 46), S(37, 68), S(42, 60), S(0, 38), S(58, 41)
+  };
+
  // Assorted bonuses and penalties
-  constexpr Score BishopPawns        = S(  3,  7);
-  constexpr Score CorneredBishop     = S( 50, 50);
-  constexpr Score FlankAttacks       = S(  8,  0);
-  constexpr Score Hanging            = S( 69, 36);
-  constexpr Score KingProtector      = S(  7,  8);
-  constexpr Score KnightOnQueen      = S( 16, 12);
-  constexpr Score LongDiagonalBishop = S( 45,  0);
-  constexpr Score MinorBehindPawn    = S( 18,  3);
-  constexpr Score Outpost            = S( 30, 21);
-  constexpr Score PassedFile         = S( 11,  8);
-  constexpr Score PawnlessFlank      = S( 17, 95);
-  constexpr Score RestrictedPiece    = S(  7,  7);
-  constexpr Score ReachableOutpost   = S( 32, 10);
-  constexpr Score RookOnQueenFile    = S(  7,  6);
-  constexpr Score SliderOnQueen      = S( 59, 18);
-  constexpr Score ThreatByKing       = S( 24, 89);
-  constexpr Score ThreatByPawnPush   = S( 48, 39);
-  constexpr Score ThreatBySafePawn   = S(173, 94);
-  constexpr Score TrappedRook        = S( 52, 10);
-  constexpr Score WeakQueen          = S( 49, 15);
+  constexpr Score BadOutpost          = S( -7, 36);
+  constexpr Score BishopOnKingRing    = S( 24,  0);
+  constexpr Score BishopPawns         = S(  3,  7);
+  constexpr Score BishopXRayPawns     = S(  4,  5);
+  constexpr Score CorneredBishop      = S( 50, 50);
+  constexpr Score FlankAttacks        = S(  8,  0);
+  constexpr Score Hanging             = S( 69, 36);
+  constexpr Score KnightOnQueen       = S( 16, 11);
+  constexpr Score LongDiagonalBishop  = S( 45,  0);
+  constexpr Score MinorBehindPawn     = S( 18,  3);
+  constexpr Score PassedFile          = S( 11,  8);
+  constexpr Score PawnlessFlank       = S( 17, 95);
+  constexpr Score QueenInfiltration   = S( -2, 14);
+  constexpr Score ReachableOutpost    = S( 31, 22);
+  constexpr Score RestrictedPiece     = S(  7,  7);
+  constexpr Score RookOnKingRing      = S( 16,  0);
+  constexpr Score RookOnQueenFile     = S(  6, 11);
+  constexpr Score SliderOnQueen       = S( 60, 18);
+  constexpr Score ThreatByKing        = S( 24, 89);
+  constexpr Score ThreatByPawnPush    = S( 48, 39);
+  constexpr Score ThreatBySafePawn    = S(173, 94);
+  constexpr Score TrappedRook         = S( 55, 13);
+  constexpr Score WeakQueenProtection = S( 14,  0);
+  constexpr Score WeakQueen           = S( 56, 15);
+

 #undef S

@@ -167,8 +213,7 @@ namespace {
    template<Color Us> Score threats() const;
    template<Color Us> Score passed() const;
    template<Color Us> Score space() const;
-    ScaleFactor scale_factor(Value eg) const;
-    Score initiative(Score score) const;
+    Value winnable(Score score) const;

    const Position& pos;
    Material::Entry* me;
@@ -210,10 +255,11 @@ namespace {

  // Evaluation::initialize() computes king and pawn attacks, and the king ring
  // bitboard for a given color. This is done at the beginning of the evaluation.
+
  template<Tracing T> template<Color Us>
  void Evaluation<T>::initialize() {

-    constexpr Color     Them = (Us == WHITE ? BLACK : WHITE);
+    constexpr Color     Them = ~Us;
    constexpr Direction Up   = pawn_push(Us);
    constexpr Direction Down = -Up;
    constexpr Bitboard LowRanks = (Us == WHITE ? Rank2BB | Rank3BB : Rank7BB | Rank6BB);
@@ -230,15 +276,15 @@ namespace {
    mobilityArea[Us] = ~(b | pos.pieces(Us, KING, QUEEN) | pos.blockers_for_king(Us) | pe->pawn_attacks(Them));

    // Initialize attackedBy[] for king and pawns
-    attackedBy[Us][KING] = pos.attacks_from<KING>(ksq);
+    attackedBy[Us][KING] = attacks_bb<KING>(ksq);
    attackedBy[Us][PAWN] = pe->pawn_attacks(Us);
    attackedBy[Us][ALL_PIECES] = attackedBy[Us][KING] | attackedBy[Us][PAWN];
    attackedBy2[Us] = dblAttackByPawn | (attackedBy[Us][KING] & attackedBy[Us][PAWN]);

    // Init our king safety tables
-    Square s = make_square(clamp(file_of(ksq), FILE_B, FILE_G),
-                           clamp(rank_of(ksq), RANK_2, RANK_7));
-    kingRing[Us] = PseudoAttacks[KING][s] | s;
+    Square s = make_square(Utility::clamp(file_of(ksq), FILE_B, FILE_G),
+                           Utility::clamp(rank_of(ksq), RANK_2, RANK_7));
+    kingRing[Us] = attacks_bb<KING>(s) | s;

    kingAttackersCount[Them] = popcount(kingRing[Us] & pe->pawn_attacks(Them));
    kingAttacksCount[Them] = kingAttackersWeight[Them] = 0;
@@ -249,10 +295,11 @@ namespace {


  // Evaluation::pieces() scores pieces of a given color and type
+
  template<Tracing T> template<Color Us, PieceType Pt>
  Score Evaluation<T>::pieces() {

-    constexpr Color     Them = (Us == WHITE ? BLACK : WHITE);
+    constexpr Color     Them = ~Us;
    constexpr Direction Down = -pawn_push(Us);
    constexpr Bitboard OutpostRanks = (Us == WHITE ? Rank4BB | Rank5BB | Rank6BB
                                                   : Rank5BB | Rank4BB | Rank3BB);
@@ -268,10 +315,10 @@ namespace {
        // Find attacked squares, including x-ray attacks for bishops and rooks
        b = Pt == BISHOP ? attacks_bb<BISHOP>(s, pos.pieces() ^ pos.pieces(QUEEN))
          : Pt ==   ROOK ? attacks_bb<  ROOK>(s, pos.pieces() ^ pos.pieces(QUEEN) ^ pos.pieces(Us, ROOK))
-                         : pos.attacks_from<Pt>(s);
+                         : attacks_bb<Pt>(s, pos.pieces());

        if (pos.blockers_for_king(Us) & s)
-            b &= LineBB[pos.square<KING>(Us)][s];
+            b &= line_bb(pos.square<KING>(Us), s);

        attackedBy2[Us] |= attackedBy[Us][ALL_PIECES] & b;
        attackedBy[Us][Pt] |= b;
@@ -284,35 +331,52 @@ namespace {
            kingAttacksCount[Us] += popcount(b & attackedBy[Them][KING]);
        }

+        else if (Pt == ROOK && (file_bb(s) & kingRing[Them]))
+            score += RookOnKingRing;
+
+        else if (Pt == BISHOP && (attacks_bb<BISHOP>(s, pos.pieces(PAWN)) & kingRing[Them]))
+            score += BishopOnKingRing;
+
        int mob = popcount(b & mobilityArea[Us]);

        mobility[Us] += MobilityBonus[Pt - 2][mob];

        if (Pt == BISHOP || Pt == KNIGHT)
        {
-            // Bonus if piece is on an outpost square or can reach one
+            // Bonus if the piece is on an outpost square or can reach one
+            // Reduced bonus for knights (BadOutpost) if few relevant targets
            bb = OutpostRanks & attackedBy[Us][PAWN] & ~pe->pawn_attacks_span(Them);
-            if (bb & s)
-                score += Outpost * (Pt == KNIGHT ? 2 : 1);
+            Bitboard targets = pos.pieces(Them) & ~pos.pieces(PAWN);

+            if (   Pt == KNIGHT
+                && bb & s & ~CenterFiles // on a side outpost
+                && !(b & targets)        // no relevant attacks
+                && (!more_than_one(targets & (s & QueenSide ? QueenSide : KingSide))))
+                score += BadOutpost;
+            else if (bb & s)
+                score += Outpost[Pt == BISHOP];
            else if (Pt == KNIGHT && bb & b & ~pos.pieces(Us))
                score += ReachableOutpost;

-            // Knight and Bishop bonus for being right behind a pawn
+            // Bonus for a knight or bishop shielded by pawn
            if (shift<Down>(pos.pieces(PAWN)) & s)
                score += MinorBehindPawn;

            // Penalty if the piece is far from the king
-            score -= KingProtector * distance(s, pos.square<KING>(Us));
+            score -= KingProtector[Pt == BISHOP] * distance(pos.square<KING>(Us), s);

            if (Pt == BISHOP)
            {
-                // Penalty according to number of pawns on the same color square as the
-                // bishop, bigger when the center files are blocked with pawns.
+                // Penalty according to the number of our pawns on the same color square as the
+                // bishop, bigger when the center files are blocked with pawns and smaller
+                // when the bishop is outside the pawn chain.
                Bitboard blocked = pos.pieces(Us, PAWN) & shift<Down>(pos.pieces());

                score -= BishopPawns * pos.pawns_on_same_color_squares(Us, s)
-                                     * (1 + popcount(blocked & CenterFiles));
+                                     * (!(attackedBy[Us][PAWN] & s) + popcount(blocked & CenterFiles));
+
+                // Penalty for all enemy pawns x-rayed
+                score -= BishopXRayPawns * popcount(attacks_bb<BISHOP>(s) & pos.pieces(Them, PAWN));

                // Bonus for bishop on a long diagonal which can "see" both center squares
                if (more_than_one(attacks_bb<BISHOP>(s, pos.pieces(PAWN)) & Center))
@@ -358,6 +422,10 @@ namespace {
            Bitboard queenPinners;
            if (pos.slider_blockers(pos.pieces(Them, ROOK, BISHOP), s, queenPinners))
                score -= WeakQueen;
+
+            // Bonus for queen on weak square in enemy camp
+            if (relative_rank(Us, s) > RANK_4 && (~pe->pawn_attacks_span(Them) & s))
+                score += QueenInfiltration;
        }
    }
    if (T)
@@ -368,10 +436,11 @@ namespace {


  // Evaluation::king() assigns bonuses and penalties to a king of a given color
+
  template<Tracing T> template<Color Us>
  Score Evaluation<T>::king() const {

-    constexpr Color    Them = (Us == WHITE ? BLACK : WHITE);
+    constexpr Color    Them = ~Us;
    constexpr Bitboard Camp = (Us == WHITE ? AllSquares ^ Rank6BB ^ Rank7BB ^ Rank8BB
                                           : AllSquares ^ Rank1BB ^ Rank2BB ^ Rank3BB);

@@ -396,41 +465,33 @@ namespace {
    b2 = attacks_bb<BISHOP>(ksq, pos.pieces() ^ pos.pieces(Us, QUEEN));

    // Enemy rooks checks
-    rookChecks = b1 & safe & attackedBy[Them][ROOK];
-
+    rookChecks = b1 & attackedBy[Them][ROOK] & safe;
    if (rookChecks)
-        kingDanger += RookSafeCheck;
+        kingDanger += SafeCheck[ROOK][more_than_one(rookChecks)];
    else
        unsafeChecks |= b1 & attackedBy[Them][ROOK];

-    // Enemy queen safe checks: we count them only if they are from squares from
-    // which we can't give a rook check, because rook checks are more valuable.
-    queenChecks =  (b1 | b2)
-                 & attackedBy[Them][QUEEN]
-                 & safe
-                 & ~attackedBy[Us][QUEEN]
-                 & ~rookChecks;
-
+    // Enemy queen safe checks: count them only if the checks are from squares from
+    // which opponent cannot give a rook check, because rook checks are more valuable.
+    queenChecks =  (b1 | b2) & attackedBy[Them][QUEEN] & safe
+                 & ~(attackedBy[Us][QUEEN] | rookChecks);
    if (queenChecks)
-        kingDanger += QueenSafeCheck;
+        kingDanger += SafeCheck[QUEEN][more_than_one(queenChecks)];

-    // Enemy bishops checks: we count them only if they are from squares from
-    // which we can't give a queen check, because queen checks are more valuable.
-    bishopChecks =  b2
-                  & attackedBy[Them][BISHOP]
-                  & safe
+    // Enemy bishops checks: count them only if they are from squares from which
+    // opponent cannot give a queen check, because queen checks are more valuable.
+    bishopChecks =  b2 & attackedBy[Them][BISHOP] & safe
                  & ~queenChecks;
-
    if (bishopChecks)
-        kingDanger += BishopSafeCheck;
+        kingDanger += SafeCheck[BISHOP][more_than_one(bishopChecks)];
+
    else
        unsafeChecks |= b2 & attackedBy[Them][BISHOP];

    // Enemy knights checks
-    knightChecks = pos.attacks_from<KNIGHT>(ksq) & attackedBy[Them][KNIGHT];
-
+    knightChecks = attacks_bb<KNIGHT>(ksq) & attackedBy[Them][KNIGHT];
    if (knightChecks & safe)
-        kingDanger += KnightSafeCheck;
+        kingDanger += SafeCheck[KNIGHT][more_than_one(knightChecks & safe)];
    else
        unsafeChecks |= knightChecks;

@@ -440,7 +501,7 @@ namespace {
    b2 = b1 & attackedBy2[Them];
    b3 = attackedBy[Us][ALL_PIECES] & KingFlank[file_of(ksq)] & Camp;

-    int kingFlankAttack = popcount(b1) + popcount(b2);
+    int kingFlankAttack  = popcount(b1) + popcount(b2);
    int kingFlankDefense = popcount(b3);

    kingDanger +=        kingAttackersCount[Them] * kingAttackersWeight[Them]
@@ -476,10 +537,11 @@ namespace {

  // Evaluation::threats() assigns bonuses according to the types of the
  // attacking and the attacked pieces.
+
  template<Tracing T> template<Color Us>
  Score Evaluation<T>::threats() const {

-    constexpr Color     Them     = (Us == WHITE ? BLACK   : WHITE);
+    constexpr Color     Them     = ~Us;
    constexpr Direction Up       = pawn_push(Us);
    constexpr Bitboard  TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);

@@ -517,13 +579,15 @@ namespace {
        b =  ~attackedBy[Them][ALL_PIECES]
           | (nonPawnEnemies & attackedBy2[Us]);
        score += Hanging * popcount(weak & b);
+
+        // Additional bonus if weak piece is only protected by a queen
+        score += WeakQueenProtection * popcount(weak & attackedBy[Them][QUEEN]);
    }

    // Bonus for restricting their piece moves
    b =   attackedBy[Them][ALL_PIECES]
       & ~stronglyProtected
       &  attackedBy[Us][ALL_PIECES];
-
    score += RestrictedPiece * popcount(b);

    // Protected or unattacked squares
@@ -548,17 +612,21 @@ namespace {
    // Bonus for threats on the next moves against enemy queen
    if (pos.count<QUEEN>(Them) == 1)
    {
+        bool queenImbalance = pos.count<QUEEN>() == 1;
+
        Square s = pos.square<QUEEN>(Them);
-        safe = mobilityArea[Us] & ~stronglyProtected;
+        safe =   mobilityArea[Us]
+              & ~pos.pieces(Us, PAWN)
+              & ~stronglyProtected;

-        b = attackedBy[Us][KNIGHT] & pos.attacks_from<KNIGHT>(s);
+        b = attackedBy[Us][KNIGHT] & attacks_bb<KNIGHT>(s);

-        score += KnightOnQueen * popcount(b & safe);
+        score += KnightOnQueen * popcount(b & safe) * (1 + queenImbalance);

-        b =  (attackedBy[Us][BISHOP] & pos.attacks_from<BISHOP>(s))
-           | (attackedBy[Us][ROOK  ] & pos.attacks_from<ROOK  >(s));
+        b =  (attackedBy[Us][BISHOP] & attacks_bb<BISHOP>(s, pos.pieces()))
+           | (attackedBy[Us][ROOK  ] & attacks_bb<ROOK  >(s, pos.pieces()));

-        score += SliderOnQueen * popcount(b & safe & attackedBy2[Us]);
+        score += SliderOnQueen * popcount(b & safe & attackedBy2[Us]) * (1 + queenImbalance);
    }

    if (T)
@@ -573,18 +641,32 @@ namespace {
  template<Tracing T> template<Color Us>
  Score Evaluation<T>::passed() const {

-    constexpr Color     Them = (Us == WHITE ? BLACK : WHITE);
+    constexpr Color     Them = ~Us;
    constexpr Direction Up   = pawn_push(Us);
+    constexpr Direction Down = -Up;

    auto king_proximity = [&](Color c, Square s) {
      return std::min(distance(pos.square<KING>(c), s), 5);
    };

-    Bitboard b, bb, squaresToQueen, unsafeSquares;
+    Bitboard b, bb, squaresToQueen, unsafeSquares, blockedPassers, helpers;
    Score score = SCORE_ZERO;

    b = pe->passed_pawns(Us);

+    blockedPassers = b & shift<Down>(pos.pieces(Them, PAWN));
+    if (blockedPassers)
+    {
+        helpers =  shift<Up>(pos.pieces(Us, PAWN))
+                 & ~pos.pieces(Them)
+                 & (~attackedBy2[Them] | attackedBy[Us][ALL_PIECES]);
+
+        // Remove blocked candidate passers that don't have help to pass
+        b &=  ~blockedPassers
+            | shift<WEST>(helpers)
+            | shift<EAST>(helpers);
+    }
+
    while (b)
    {
        Square s = pop_lsb(&b);
@@ -635,13 +717,7 @@ namespace {
            }
        } // r > RANK_3

-        // Scale down bonus for candidate passers which need more than one
-        // pawn push to become passed, or have a pawn in front of them.
-        if (   !pos.pawn_passed(Us, s + Up)
-            || (pos.pieces(PAWN) & (s + Up)))
-            bonus = bonus / 2;
-
-        score += bonus - PassedFile * map_to_queenside(file_of(s));
+        score += bonus - PassedFile * edge_distance(file_of(s));
    }

    if (T)
@@ -651,20 +727,19 @@ namespace {
  }


-  // Evaluation::space() computes the space evaluation for a given side. The
-  // space evaluation is a simple bonus based on the number of safe squares
-  // available for minor pieces on the central four files on ranks 2--4. Safe
-  // squares one, two or three squares behind a friendly pawn are counted
-  // twice. Finally, the space bonus is multiplied by a weight. The aim is to
-  // improve play on game opening.
+  // Evaluation::space() computes a space evaluation for a given side, aiming to improve game
+  // play in the opening. It is based on the number of safe squares on the 4 central files
+  // on ranks 2 to 4. Completely safe squares behind a friendly pawn are counted twice.
+  // Finally, the space bonus is multiplied by a weight which decreases according to occupancy.

  template<Tracing T> template<Color Us>
  Score Evaluation<T>::space() const {

+    // Early exit if, for example, both queens or 6 minor pieces have been exchanged
    if (pos.non_pawn_material() < SpaceThreshold)
        return SCORE_ZERO;

-    constexpr Color Them     = (Us == WHITE ? BLACK : WHITE);
+    constexpr Color Them     = ~Us;
    constexpr Direction Down = -pawn_push(Us);
    constexpr Bitboard SpaceMask =
      Us == WHITE ? CenterFiles & (Rank2BB | Rank3BB | Rank4BB)
@@ -681,7 +756,7 @@ namespace {
    behind |= shift<Down+Down>(behind);

    int bonus = popcount(safe) + popcount(behind & safe & ~attackedBy[Them][ALL_PIECES]);
-    int weight = pos.count<ALL_PIECES>(Us) - 1;
+    int weight = pos.count<ALL_PIECES>(Us) - 3 + std::min(pe->blocked_count(), 9);
    Score score = make_score(bonus * weight * weight / 16, 0);

    if (T)
@@ -691,73 +766,87 @@ namespace {
  }


-  // Evaluation::initiative() computes the initiative correction value
-  // for the position. It is a second order bonus/malus based on the
-  // known attacking/defending status of the players.
+  // Evaluation::winnable() adjusts the midgame and endgame score components, based on
+  // the known attacking/defending status of the players. The final value is derived
+  // by interpolation from the midgame and endgame values.

  template<Tracing T>
-  Score Evaluation<T>::initiative(Score score) const {
-
-    Value mg = mg_value(score);
-    Value eg = eg_value(score);
+  Value Evaluation<T>::winnable(Score score) const {

    int outflanking =  distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK))
                     - distance<Rank>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));

-    bool infiltration =   rank_of(pos.square<KING>(WHITE)) > RANK_4
-                       || rank_of(pos.square<KING>(BLACK)) < RANK_5;
-
    bool pawnsOnBothFlanks =   (pos.pieces(PAWN) & QueenSide)
                            && (pos.pieces(PAWN) & KingSide);

-    bool almostUnwinnable =   !pe->passed_count()
-                           &&  outflanking < 0
+    bool almostUnwinnable =   outflanking < 0
                           && !pawnsOnBothFlanks;

+    bool infiltration =   rank_of(pos.square<KING>(WHITE)) > RANK_4
+                       || rank_of(pos.square<KING>(BLACK)) < RANK_5;
+
    // Compute the initiative bonus for the attacking side
    int complexity =   9 * pe->passed_count()
-                    + 11 * pos.count<PAWN>()
+                    + 12 * pos.count<PAWN>()
                    +  9 * outflanking
-                    + 12 * infiltration
                    + 21 * pawnsOnBothFlanks
+                    + 24 * infiltration
                    + 51 * !pos.non_pawn_material()
                    - 43 * almostUnwinnable
-                    - 100 ;
+                    -110 ;
+
+    Value mg = mg_value(score);
+    Value eg = eg_value(score);

    // Now apply the bonus: note that we find the attacking side by extracting the
    // sign of the midgame or endgame values, and that we carefully cap the bonus
    // so that the midgame and endgame scores do not change sign after the bonus.
-    int u = ((mg > 0) - (mg < 0)) * std::max(std::min(complexity + 50, 0), -abs(mg));
+    int u = ((mg > 0) - (mg < 0)) * Utility::clamp(complexity + 50, -abs(mg), 0);
    int v = ((eg > 0) - (eg < 0)) * std::max(complexity, -abs(eg));

-    if (T)
-        Trace::add(INITIATIVE, make_score(u, v));
-
-    return make_score(u, v);
-  }
-
-
-  // Evaluation::scale_factor() computes the scale factor for the winning side
-
-  template<Tracing T>
-  ScaleFactor Evaluation<T>::scale_factor(Value eg) const {
+    mg += u;
+    eg += v;

+    // Compute the scale factor for the winning side
    Color strongSide = eg > VALUE_DRAW ? WHITE : BLACK;
    int sf = me->scale_factor(pos, strongSide);

-    // If scale is not already specific, scale down the endgame via general heuristics
+    // If scale factor is not already specific, scale down via general heuristics
    if (sf == SCALE_FACTOR_NORMAL)
    {
-        if (   pos.opposite_bishops()
-            && pos.non_pawn_material() == 2 * BishopValueMg)
-            sf = 22 ;
+        if (pos.opposite_bishops())
+        {
+            if (   pos.non_pawn_material(WHITE) == BishopValueMg
+                && pos.non_pawn_material(BLACK) == BishopValueMg)
+                sf = 18 + 4 * popcount(pe->passed_pawns(strongSide));
+            else
+                sf = 22 + 3 * pos.count<ALL_PIECES>(strongSide);
+        }
+        else if (  pos.non_pawn_material(WHITE) == RookValueMg
+                && pos.non_pawn_material(BLACK) == RookValueMg
+                && pos.count<PAWN>(strongSide) - pos.count<PAWN>(~strongSide) <= 1
+                && bool(KingSide & pos.pieces(strongSide, PAWN)) != bool(QueenSide & pos.pieces(strongSide, PAWN))
+                && (attacks_bb<KING>(pos.square<KING>(~strongSide)) & pos.pieces(~strongSide, PAWN)))
+            sf = 36;
+        else if (pos.count<QUEEN>() == 1)
+            sf = 37 + 3 * (pos.count<QUEEN>(WHITE) == 1 ? pos.count<BISHOP>(BLACK) + pos.count<KNIGHT>(BLACK)
+                                                        : pos.count<BISHOP>(WHITE) + pos.count<KNIGHT>(WHITE));
        else
-            sf = std::min(sf, 36 + (pos.opposite_bishops() ? 2 : 7) * pos.count<PAWN>(strongSide));
-
-        sf = std::max(0, sf - (pos.rule50_count() - 12) / 4);
+            sf = std::min(sf, 36 + 7 * pos.count<PAWN>(strongSide));
    }

-    return ScaleFactor(sf);
+    // Interpolate between the middlegame and (scaled by 'sf') endgame score
+    v =  mg * int(me->game_phase())
+       + eg * int(PHASE_MIDGAME - me->game_phase()) * ScaleFactor(sf) / SCALE_FACTOR_NORMAL;
+    v /= PHASE_MIDGAME;
+
+    if (T)
+    {
+        Trace::add(WINNABLE, make_score(u, eg * ScaleFactor(sf) / SCALE_FACTOR_NORMAL - eg_value(score)));
+        Trace::add(TOTAL, make_score(mg, eg * ScaleFactor(sf) / SCALE_FACTOR_NORMAL));
+    }
+
+    return Value(v);
  }


@@ -788,16 +877,19 @@ namespace {
    score += pe->pawn_score(WHITE) - pe->pawn_score(BLACK);

    // Early exit if score is high
-    Value v = (mg_value(score) + eg_value(score)) / 2;
-    if (abs(v) > LazyThreshold + pos.non_pawn_material() / 64)
-       return pos.side_to_move() == WHITE ? v : -v;
+    auto lazy_skip = [&](Value lazyThreshold) {
+        return abs(mg_value(score) + eg_value(score)) / 2 > lazyThreshold + pos.non_pawn_material() / 64;
+    };
+
+    if (lazy_skip(LazyThreshold1))
+        goto make_v;

    // Main evaluation begins here
-
    initialize<WHITE>();
    initialize<BLACK>();

-    // Pieces should be evaluated first (populate attack tables)
+    // Pieces evaluated first (also populates attackedBy, attackedBy2).
+    // Note that the order of evaluation of the terms is left unspecified.
    score +=  pieces<WHITE, KNIGHT>() - pieces<BLACK, KNIGHT>()
            + pieces<WHITE, BISHOP>() - pieces<BLACK, BISHOP>()
            + pieces<WHITE, ROOK  >() - pieces<BLACK, ROOK  >()
@@ -805,19 +897,19 @@ namespace {

    score += mobility[WHITE] - mobility[BLACK];

+    // More complex interactions that require fully populated attack bitboards
    score +=  king<   WHITE>() - king<   BLACK>()
-            + threats<WHITE>() - threats<BLACK>()
-            + passed< WHITE>() - passed< BLACK>()
+            + passed< WHITE>() - passed< BLACK>();
+
+    if (lazy_skip(LazyThreshold2))
+        goto make_v;
+
+    score +=  threats<WHITE>() - threats<BLACK>()
            + space<  WHITE>() - space<  BLACK>();

-    score += initiative(score);
-
-    // Interpolate between a middlegame and a (scaled by 'sf') endgame score
-    ScaleFactor sf = scale_factor(eg_value(score));
-    v =  mg_value(score) * int(me->game_phase())
-       + eg_value(score) * int(PHASE_MIDGAME - me->game_phase()) * sf / SCALE_FACTOR_NORMAL;
-
-    v /= PHASE_MIDGAME;
+make_v:
+    // Derive single value from mg and eg parts of score
+    Value v = winnable(score);

    // In case of tracing add all remaining individual evaluation terms
    if (T)
@@ -826,11 +918,18 @@ namespace {
        Trace::add(IMBALANCE, me->imbalance());
        Trace::add(PAWN, pe->pawn_score(WHITE), pe->pawn_score(BLACK));
        Trace::add(MOBILITY, mobility[WHITE], mobility[BLACK]);
-        Trace::add(TOTAL, score);
    }

-    return  (pos.side_to_move() == WHITE ? v : -v) // Side to move point of view
-           + Eval::Tempo;
+    // Evaluation grain
+    v = (v / 16) * 16;
+
+    // Side to move point of view
+    v = (pos.side_to_move() == WHITE ? v : -v) + Tempo;
+
+    // Damp down the evaluation linearly when shuffling
+    v = v * (100 - pos.rule50_count()) / 100;
+
+    return v;
  }

 } // namespace
@@ -840,49 +939,64 @@ namespace {
 /// evaluation of the position from the point of view of the side to move.

 Value Eval::evaluate(const Position& pos) {
-  return Evaluation<NO_TRACE>(pos).value();
-}

+  if (Eval::useNNUE)
+      return NNUE::evaluate(pos);
+  else
+      return Evaluation<NO_TRACE>(pos).value();
+}

 /// trace() is like evaluate(), but instead of returning a value, it returns
 /// a string (suitable for outputting to stdout) that contains the detailed
 /// descriptions and values of each evaluation term. Useful for debugging.
+/// Trace scores are from white's point of view

 std::string Eval::trace(const Position& pos) {

  if (pos.checkers())
-      return "Total evaluation: none (in check)";
-
-  std::memset(scores, 0, sizeof(scores));
-
-  pos.this_thread()->contempt = SCORE_ZERO; // Reset any dynamic contempt
-
-  Value v = Evaluation<TRACE>(pos).value();
-
-  v = pos.side_to_move() == WHITE ? v : -v; // Trace scores are from white's point of view
+      return "Final evaluation: none (in check)";

  std::stringstream ss;
-  ss << std::showpoint << std::noshowpos << std::fixed << std::setprecision(2)
-     << "     Term    |    White    |    Black    |    Total   \n"
-     << "             |   MG    EG  |   MG    EG  |   MG    EG \n"
-     << " ------------+-------------+-------------+------------\n"
-     << "    Material | " << Term(MATERIAL)
-     << "   Imbalance | " << Term(IMBALANCE)
-     << "       Pawns | " << Term(PAWN)
-     << "     Knights | " << Term(KNIGHT)
-     << "     Bishops | " << Term(BISHOP)
-     << "       Rooks | " << Term(ROOK)
-     << "      Queens | " << Term(QUEEN)
-     << "    Mobility | " << Term(MOBILITY)
-     << " King safety | " << Term(KING)
-     << "     Threats | " << Term(THREAT)
-     << "      Passed | " << Term(PASSED)
-     << "       Space | " << Term(SPACE)
-     << "  Initiative | " << Term(INITIATIVE)
-     << " ------------+-------------+-------------+------------\n"
-     << "       Total | " << Term(TOTAL);
+  ss << std::showpoint << std::noshowpos << std::fixed << std::setprecision(2);

-  ss << "\nTotal evaluation: " << to_cp(v) << " (white side)\n";
+  Value v;
+
+  if (Eval::useNNUE)
+  {
+      v = NNUE::evaluate(pos);
+  }
+  else
+  {
+      std::memset(scores, 0, sizeof(scores));
+
+      pos.this_thread()->contempt = SCORE_ZERO; // Reset any dynamic contempt
+
+      v = Evaluation<TRACE>(pos).value();
+
+      ss << std::showpoint << std::noshowpos << std::fixed << std::setprecision(2)
+         << "     Term    |    White    |    Black    |    Total   \n"
+         << "             |   MG    EG  |   MG    EG  |   MG    EG \n"
+         << " ------------+-------------+-------------+------------\n"
+         << "    Material | " << Term(MATERIAL)
+         << "   Imbalance | " << Term(IMBALANCE)
+         << "       Pawns | " << Term(PAWN)
+         << "     Knights | " << Term(KNIGHT)
+         << "     Bishops | " << Term(BISHOP)
+         << "       Rooks | " << Term(ROOK)
+         << "      Queens | " << Term(QUEEN)
+         << "    Mobility | " << Term(MOBILITY)
+         << " King safety | " << Term(KING)
+         << "     Threats | " << Term(THREAT)
+         << "      Passed | " << Term(PASSED)
+         << "       Space | " << Term(SPACE)
+         << "    Winnable | " << Term(WINNABLE)
+         << " ------------+-------------+-------------+------------\n"
+         << "       Total | " << Term(TOTAL);
+  }
+
+  v = pos.side_to_move() == WHITE ? v : -v;
+
+  ss << "\nFinal evaluation: " << to_cp(v) << " (white side)\n";

  return ss.str();
 }
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -29,11 +27,23 @@ class Position;

 namespace Eval {

-constexpr Value Tempo = Value(28); // Must be visible to search
+  std::string trace(const Position& pos);
+  Value evaluate(const Position& pos);

-std::string trace(const Position& pos);
+  extern bool useNNUE;
+  extern std::string eval_file_loaded;
+  void init_NNUE();
+  void verify_NNUE();

-Value evaluate(const Position& pos);
-}
+  namespace NNUE {
+
+    Value evaluate(const Position& pos);
+    Value compute_eval(const Position& pos);
+    void  update_eval(const Position& pos);
+    bool  load_eval_file(const std::string& evalFile);
+
+  } // namespace NNUE
+
+} // namespace Eval

 #endif // #ifndef EVALUATE_H_INCLUDED
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -21,12 +19,12 @@
 #include <iostream>

 #include "bitboard.h"
+#include "endgame.h"
 #include "position.h"
 #include "search.h"
 #include "thread.h"
 #include "tt.h"
 #include "uci.h"
-#include "endgame.h"
 #include "syzygy/tbprobe.h"

 namespace PSQT {
@@ -38,13 +36,15 @@ int main(int argc, char* argv[]) {
  std::cout << engine_info() << std::endl;

  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::init_NNUE();

  UCI::loop(argc, argv);

@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -44,12 +42,12 @@ namespace {
  constexpr int QuadraticTheirs[][PIECE_TYPE_NB] = {
    //           THEIR PIECES
    // pair pawn knight bishop rook queen
-    {   0                               }, // Bishop pair
-    {  36,    0                         }, // Pawn
-    {   9,   63,   0                    }, // Knight      OUR PIECES
-    {  59,   65,  42,     0             }, // Bishop
-    {  46,   39,  24,   -24,    0       }, // Rook
-    {  97,  100, -42,   137,  268,    0 }  // Queen
+    {                                   }, // Bishop pair
+    {  36,                              }, // Pawn
+    {   9,   63,                        }, // Knight      OUR PIECES
+    {  59,   65,  42,                   }, // Bishop
+    {  46,   39,  24,   -24,            }, // Rook
+    {  97,  100, -42,   137,  268,      }  // Queen
  };

  // Endgame evaluation and scaling functions are accessed directly and not through
@@ -79,12 +77,14 @@ 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]) {

-    constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
+    constexpr Color Them = ~Us;

    int bonus = 0;

@@ -94,9 +94,9 @@ 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 +110,7 @@ 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 +130,7 @@ 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   = Utility::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));
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -44,7 +42,7 @@ struct Entry {
  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
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -46,6 +44,12 @@ 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

 #include "misc.h"
 #include "thread.h"
@@ -56,7 +60,7 @@ 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 = "";

 /// 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
@@ -142,10 +146,8 @@ const string engine_info(bool to_uci) {
      ss << setw(2) << day << setw(2) << (1 + months.find(month) / 4) << year.substr(2);
  }

-  ss << (Is64Bit ? " 64" : "")
-     << (HasPext ? " BMI2" : (HasPopCnt ? " POPCNT" : ""))
-     << (to_uci  ? "\nid author ": " by ")
-     << "T. Romstad, M. Costalba, J. Kiiski, G. Linscott";
+  ss << (to_uci  ? "\nid author ": " by ")
+     << "the Stockfish developers (see AUTHORS file)";

  return ss.str();
 }
@@ -155,9 +157,9 @@ const string engine_info(bool to_uci) {

 const std::string compiler_info() {

-  #define STRINGIFY2(x) #x
-  #define STRINGIFY(x) STRINGIFY2(x)
-  #define VER_STRING(major, minor, patch) STRINGIFY(major) "." STRINGIFY(minor) "." STRINGIFY(patch)
+  #define stringify2(x) #x
+  #define stringify(x) stringify2(x)
+  #define make_version_string(major, minor, patch) stringify(major) "." stringify(minor) "." stringify(patch)

 /// Predefined macros hell:
 ///
@@ -171,26 +173,26 @@ 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 __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 +212,33 @@ 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_AVX512)
+    compiler += " AVX512";
+  #endif
+  #if defined(USE_AVX2)
+    compiler += " AVX2";
+  #endif
+  #if defined(USE_SSE42)
+    compiler += " SSE42";
+  #endif
+  #if defined(USE_SSE41)
+    compiler += " SSE41";
+  #endif
+  #if defined(USE_SSSE3)
+    compiler += " SSSE3";
+  #endif
+  #if defined(USE_SSE3)
+    compiler += " SSE3";
+  #endif
+    compiler += (HasPext ? " BMI2" : "");
+    compiler += (HasPopCnt ? " POPCNT" : "");
+  #if !defined(NDEBUG)
+    compiler += " DEBUG";
+  #endif
+
+  compiler += "\n__VERSION__ macro expands to: ";
  #ifdef __VERSION__
     compiler += __VERSION__;
  #else
@@ -288,6 +316,156 @@ void prefetch(void* addr) {

 #endif

+/// Wrappers for systems where the c++17 implementation doesn't 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(__APPLE__)
+  return aligned_alloc(alignment, size);
+#elif defined(_WIN32)
+  return _mm_malloc(size, alignment);
+#else
+  return std::aligned_alloc(alignment, size);
+#endif
+}
+
+void std_aligned_free(void* ptr) {
+#if defined(__APPLE__)
+  free(ptr);
+#elif defined(_WIN32)
+  _mm_free(ptr);
+#else
+  free(ptr);
+#endif
+}
+
+/// aligned_ttmem_alloc() will return suitably aligned memory, and if possible use large pages.
+/// The returned pointer is the aligned one, while the mem argument is the one that needs
+/// to be passed to free. With c++17 some of this functionality could be simplified.
+
+#if defined(__linux__) && !defined(__ANDROID__)
+
+void* aligned_ttmem_alloc(size_t allocSize, void*& mem) {
+
+  constexpr size_t alignment = 2 * 1024 * 1024; // assumed 2MB page sizes
+  size_t size = ((allocSize + alignment - 1) / alignment) * alignment; // multiple of alignment
+  if (posix_memalign(&mem, alignment, size))
+     mem = nullptr;
+  madvise(mem, allocSize, MADV_HUGEPAGE);
+  return mem;
+}
+
+#elif defined(_WIN64)
+
+static void* aligned_ttmem_alloc_large_pages(size_t allocSize) {
+
+  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;
+}
+
+void* aligned_ttmem_alloc(size_t allocSize, void*& mem) {
+
+  static bool firstCall = true;
+
+  // Try to allocate large pages
+  mem = aligned_ttmem_alloc_large_pages(allocSize);
+
+  // Suppress info strings on the first call. The first call occurs before 'uci'
+  // is received and in that case this output confuses some GUIs.
+  if (!firstCall)
+  {
+      if (mem)
+          sync_cout << "info string Hash table allocation: Windows large pages used." << sync_endl;
+      else
+          sync_cout << "info string Hash table allocation: Windows large pages not used." << sync_endl;
+  }
+  firstCall = false;
+
+  // 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_ttmem_alloc(size_t allocSize, void*& mem) {
+
+  constexpr size_t alignment = 64; // assumed cache line size
+  size_t size = allocSize + alignment - 1; // allocate some extra space
+  mem = malloc(size);
+  void* ret = reinterpret_cast<void*>((uintptr_t(mem) + alignment - 1) & ~uintptr_t(alignment - 1));
+  return ret;
+}
+
+#endif
+
+
+/// aligned_ttmem_free() will free the previously allocated ttmem
+
+#if defined(_WIN64)
+
+void aligned_ttmem_free(void* mem) {
+
+  if (mem && !VirtualFree(mem, 0, MEM_RELEASE))
+  {
+      DWORD err = GetLastError();
+      std::cerr << "Failed to free transposition table. Error code: 0x" <<
+          std::hex << err << std::dec << std::endl;
+      exit(EXIT_FAILURE);
+  }
+}
+
+#else
+
+void aligned_ttmem_free(void *mem) {
+  free(mem);
+}
+
+#endif
+
+
 namespace WinProcGroup {

 #ifndef _WIN32
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -33,6 +31,10 @@ const std::string engine_info(bool to_uci = false);
 const 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_ttmem_alloc(size_t size, void*& mem);
+void aligned_ttmem_free(void* mem); // nop if mem == nullptr

 void dbg_hit_on(bool b);
 void dbg_hit_on(bool c, bool b);
@@ -63,6 +65,14 @@ std::ostream& operator<<(std::ostream&, SyncCout);
 #define sync_cout std::cout << IO_LOCK
 #define sync_endl std::endl << IO_UNLOCK

+namespace Utility {
+
+/// Clamp a value between lo and hi. Available in c++17.
+template<class T> constexpr const T& clamp(const T& v, const T& lo, const T& hi) {
+  return v < lo ? lo : v > hi ? hi : v;
+}
+
+}

 /// xorshift64star Pseudo-Random Number Generator
 /// This class is based on original code written and dedicated
@@ -100,6 +110,19 @@ 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
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -29,22 +27,20 @@ namespace {
  ExtMove* make_promotions(ExtMove* moveList, Square to, Square ksq) {

    if (Type == CAPTURES || Type == EVASIONS || Type == NON_EVASIONS)
+    {
        *moveList++ = make<PROMOTION>(to - D, to, QUEEN);
+        if (attacks_bb<KNIGHT>(to) & ksq)
+            *moveList++ = make<PROMOTION>(to - D, to, KNIGHT);
+    }

    if (Type == QUIETS || Type == EVASIONS || Type == NON_EVASIONS)
    {
        *moveList++ = make<PROMOTION>(to - D, to, ROOK);
        *moveList++ = make<PROMOTION>(to - D, to, BISHOP);
-        *moveList++ = make<PROMOTION>(to - D, to, KNIGHT);
+        if (!(attacks_bb<KNIGHT>(to) & ksq))
+            *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;
  }

@@ -52,8 +48,7 @@ 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 == WHITE ? BLACK      : WHITE);
+    constexpr Color     Them     = ~Us;
    constexpr Bitboard  TRank7BB = (Us == WHITE ? Rank7BB    : Rank2BB);
    constexpr Bitboard  TRank3BB = (Us == WHITE ? Rank3BB    : Rank6BB);
    constexpr Direction Up       = pawn_push(Us);
@@ -85,8 +80,8 @@ namespace {

        if (Type == QUIET_CHECKS)
        {
-            b1 &= pos.attacks_from<PAWN>(ksq, Them);
-            b2 &= pos.attacks_from<PAWN>(ksq, Them);
+            b1 &= pawn_attacks_bb(Them, ksq);
+            b2 &= pawn_attacks_bb(Them, ksq);

            // Add pawn pushes which give discovered check. This is possible only
            // if the pawn is not on the same file as the enemy king, because we
@@ -167,7 +162,7 @@ namespace {
            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);

@@ -180,27 +175,26 @@ namespace {
  }


-  template<PieceType Pt, bool Checks>
-  ExtMove* generate_moves(const Position& pos, ExtMove* moveList, Color us,
-                          Bitboard target) {
+  template<Color Us, PieceType Pt, bool Checks>
+  ExtMove* generate_moves(const Position& pos, ExtMove* moveList, Bitboard target) {

    static_assert(Pt != KING && Pt != PAWN, "Unsupported piece type in generate_moves()");

-    const Square* pl = pos.squares<Pt>(us);
+    const Square* pl = pos.squares<Pt>(Us);

    for (Square from = *pl; from != SQ_NONE; from = *++pl)
    {
        if (Checks)
        {
            if (    (Pt == BISHOP || Pt == ROOK || Pt == QUEEN)
-                && !(PseudoAttacks[Pt][from] & target & pos.check_squares(Pt)))
+                && !(attacks_bb<Pt>(from) & target & pos.check_squares(Pt)))
                continue;

-            if (pos.blockers_for_king(~us) & from)
+            if (pos.blockers_for_king(~Us) & from)
                continue;
        }

-        Bitboard b = pos.attacks_from<Pt>(from) & target;
+        Bitboard b = attacks_bb<Pt>(from, pos.pieces()) & target;

        if (Checks)
            b &= pos.check_squares(Pt);
@@ -214,33 +208,49 @@ namespace {


  template<Color Us, GenType Type>
-  ExtMove* generate_all(const Position& pos, ExtMove* moveList, Bitboard target) {
-
-    constexpr CastlingRights OO  = Us & KING_SIDE;
-    constexpr CastlingRights OOO = Us & QUEEN_SIDE;
+  ExtMove* generate_all(const Position& pos, ExtMove* moveList) {
    constexpr bool Checks = Type == QUIET_CHECKS; // Reduce template instantations
+    Bitboard target;
+
+    switch (Type)
+    {
+        case CAPTURES:
+            target =  pos.pieces(~Us);
+            break;
+        case QUIETS:
+        case QUIET_CHECKS:
+            target = ~pos.pieces();
+            break;
+        case EVASIONS:
+        {
+            Square checksq = lsb(pos.checkers());
+            target = between_bb(pos.square<KING>(Us), checksq) | checksq;
+            break;
+        }
+        case NON_EVASIONS:
+            target = ~pos.pieces(Us);
+            break;
+        default:
+            static_assert(true, "Unsupported type in generate_all()");
+    }

    moveList = generate_pawn_moves<Us, Type>(pos, moveList, target);
-    moveList = generate_moves<KNIGHT, Checks>(pos, moveList, Us, target);
-    moveList = generate_moves<BISHOP, Checks>(pos, moveList, Us, target);
-    moveList = generate_moves<  ROOK, Checks>(pos, moveList, Us, target);
-    moveList = generate_moves< QUEEN, Checks>(pos, moveList, Us, 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 (Type != QUIET_CHECKS && Type != EVASIONS)
    {
        Square ksq = pos.square<KING>(Us);
-        Bitboard b = pos.attacks_from<KING>(ksq) & target;
+        Bitboard b = attacks_bb<KING>(ksq) & target;
        while (b)
            *moveList++ = make_move(ksq, pop_lsb(&b));

-        if (Type != CAPTURES && pos.can_castle(CastlingRights(OO | OOO)))
-        {
-            if (!pos.castling_impeded(OO) && pos.can_castle(OO))
-                *moveList++ = make<CASTLING>(ksq, pos.castling_rook_square(OO));
-
-            if (!pos.castling_impeded(OOO) && pos.can_castle(OOO))
-                *moveList++ = make<CASTLING>(ksq, pos.castling_rook_square(OOO));
-        }
+        if ((Type != CAPTURES) && pos.can_castle(Us & ANY_CASTLING))
+            for(CastlingRights cr : { Us & KING_SIDE, Us & QUEEN_SIDE } )
+                if (!pos.castling_impeded(cr) && pos.can_castle(cr))
+                    *moveList++ = make<CASTLING>(ksq, pos.castling_rook_square(cr));
    }

    return moveList;
@@ -249,8 +259,8 @@ namespace {
 } // namespace


-/// <CAPTURES>     Generates all pseudo-legal captures and queen promotions
-/// <QUIETS>       Generates all pseudo-legal non-captures and underpromotions
+/// <CAPTURES>     Generates all pseudo-legal captures plus queen and checking knight promotions
+/// <QUIETS>       Generates all pseudo-legal non-captures and underpromotions(except checking knight)
 /// <NON_EVASIONS> Generates all pseudo-legal captures and non-captures
 ///
 /// Returns a pointer to the end of the move list.
@@ -263,12 +273,8 @@ ExtMove* generate(const Position& pos, ExtMove* moveList) {

  Color us = pos.side_to_move();

-  Bitboard target =  Type == CAPTURES     ?  pos.pieces(~us)
-                   : Type == QUIETS       ? ~pos.pieces()
-                   : Type == NON_EVASIONS ? ~pos.pieces(us) : 0;
-
-  return us == WHITE ? generate_all<WHITE, Type>(pos, moveList, target)
-                     : generate_all<BLACK, Type>(pos, moveList, target);
+  return us == WHITE ? generate_all<WHITE, Type>(pos, moveList)
+                     : generate_all<BLACK, Type>(pos, moveList);
 }

 // Explicit template instantiations
@@ -277,35 +283,32 @@ template ExtMove* generate<QUIETS>(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.
+/// generate<QUIET_CHECKS> generates all pseudo-legal non-captures.
+/// 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);
+  Bitboard dc = pos.blockers_for_king(~us) & pos.pieces(us) & ~pos.pieces(PAWN);

  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();
+     Bitboard b = attacks_bb(pt, from, pos.pieces()) & ~pos.pieces();

     if (pt == KING)
-         b &= ~PseudoAttacks[QUEEN][pos.square<KING>(~us)];
+         b &= ~attacks_bb<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());
+  return us == WHITE ? generate_all<WHITE, QUIET_CHECKS>(pos, moveList)
+                     : generate_all<BLACK, QUIET_CHECKS>(pos, moveList);
 }


@@ -325,13 +328,10 @@ ExtMove* generate<EVASIONS>(const Position& pos, ExtMove* moveList) {
  // 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;
-  }
+      sliderAttacks |= line_bb(ksq, pop_lsb(&sliders)) & ~pos.checkers();

  // Generate evasions for king, capture and non capture moves
-  Bitboard b = pos.attacks_from<KING>(ksq) & ~pos.pieces(us) & ~sliderAttacks;
+  Bitboard b = attacks_bb<KING>(ksq) & ~pos.pieces(us) & ~sliderAttacks;
  while (b)
      *moveList++ = make_move(ksq, pop_lsb(&b));

@@ -339,11 +339,8 @@ ExtMove* generate<EVASIONS>(const Position& pos, ExtMove* moveList) {
      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);
+  return us == WHITE ? generate_all<WHITE, EVASIONS>(pos, moveList)
+                     : generate_all<BLACK, EVASIONS>(pos, moveList);
 }


@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -56,45 +54,39 @@ 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,
-                       const CapturePieceToHistory* cph, const PieceToHistory** ch, Move cm, Move* killers)
-           : pos(p), mainHistory(mh), captureHistory(cph), continuationHistory(ch),
-             refutations{{killers[0], 0}, {killers[1], 0}, {cm, 0}}, depth(d) {
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh, const LowPlyHistory* lp,
+                       const CapturePieceToHistory* cph, const PieceToHistory** ch, Move cm, const Move* killers, int pl)
+           : pos(p), mainHistory(mh), lowPlyHistory(lp), captureHistory(cph), continuationHistory(ch),
+             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;
-  ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE;
-  stage += (ttMove == MOVE_NONE);
+  stage = (pos.checkers() ? EVASION_TT : MAIN_TT) +
+          !(ttm && pos.pseudo_legal(ttm));
 }

 /// 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;
-  ttMove =   ttm
-          && (depth > DEPTH_QS_RECAPTURES || to_sq(ttm) == recaptureSquare)
-          && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE;
-  stage += (ttMove == MOVE_NONE);
+  stage = (pos.checkers() ? EVASION_TT : QSEARCH_TT) +
+           !(ttm && (depth > DEPTH_QS_RECAPTURES || to_sq(ttm) == recaptureSquare)
+                 && pos.pseudo_legal(ttm));
 }

 /// 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;
-  ttMove =   ttm
-          && pos.capture(ttm)
-          && pos.pseudo_legal(ttm)
-          && pos.see_ge(ttm, threshold) ? ttm : MOVE_NONE;
-  stage += (ttMove == MOVE_NONE);
+  stage = PROBCUT_TT + !(ttm && pos.capture(ttm)
+                             && pos.pseudo_legal(ttm)
+                             && pos.see_ge(ttm, threshold));
 }

 /// MovePicker::score() assigns a numerical value to each move in a list, used
@@ -115,7 +107,8 @@ void MovePicker::score() {
                   + 2 * (*continuationHistory[0])[pos.moved_piece(m)][to_sq(m)]
                   + 2 * (*continuationHistory[1])[pos.moved_piece(m)][to_sq(m)]
                   + 2 * (*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
      {
@@ -174,7 +167,7 @@ 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);
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -88,6 +86,12 @@ enum StatsType { NoCaptures, Captures };
 /// 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;

+/// 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
 typedef Stats<Move, NOT_USED, PIECE_NB, SQUARE_NB> CounterMoveHistory;
@@ -123,10 +127,12 @@ 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 +143,7 @@ private:

  const Position& pos;
  const ButterflyHistory* mainHistory;
+  const LowPlyHistory* lowPlyHistory;
  const CapturePieceToHistory* captureHistory;
  const PieceToHistory** continuationHistory;
  Move ttMove;
@@ -145,6 +152,7 @@ private:
  Square recaptureSquare;
  Value threshold;
  Depth depth;
+  int ply;
  ExtMove moves[MAX_MOVES];
 };

@@ -0,0 +1,54 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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 and network structure used in NNUE evaluation function
+
+#ifndef NNUE_HALFKP_256X2_32_32_H_INCLUDED
+#define NNUE_HALFKP_256X2_32_32_H_INCLUDED
+
+#include "../features/feature_set.h"
+#include "../features/half_kp.h"
+
+#include "../layers/input_slice.h"
+#include "../layers/affine_transform.h"
+#include "../layers/clipped_relu.h"
+
+namespace Eval::NNUE {
+
+// Input features used in evaluation function
+using RawFeatures = Features::FeatureSet<
+    Features::HalfKP<Features::Side::kFriend>>;
+
+// Number of input feature dimensions after conversion
+constexpr IndexType kTransformedFeatureDimensions = 256;
+
+namespace Layers {
+
+// Define network structure
+using InputLayer = InputSlice<kTransformedFeatureDimensions * 2>;
+using HiddenLayer1 = ClippedReLU<AffineTransform<InputLayer, 32>>;
+using HiddenLayer2 = ClippedReLU<AffineTransform<HiddenLayer1, 32>>;
+using OutputLayer = AffineTransform<HiddenLayer2, 1>;
+
+}  // namespace Layers
+
+using Network = Layers::OutputLayer;
+
+}  // namespace Eval::NNUE
+
+#endif // #ifndef NNUE_HALFKP_256X2_32_32_H_INCLUDED
@@ -0,0 +1,178 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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 <fstream>
+#include <iostream>
+#include <set>
+
+#include "../evaluate.h"
+#include "../position.h"
+#include "../misc.h"
+#include "../uci.h"
+
+#include "evaluate_nnue.h"
+
+ExtPieceSquare kpp_board_index[PIECE_NB] = {
+ // convention: W - us, B - them
+ // viewed from other side, W and B are reversed
+    { PS_NONE,     PS_NONE     },
+    { PS_W_PAWN,   PS_B_PAWN   },
+    { PS_W_KNIGHT, PS_B_KNIGHT },
+    { PS_W_BISHOP, PS_B_BISHOP },
+    { PS_W_ROOK,   PS_B_ROOK   },
+    { PS_W_QUEEN,  PS_B_QUEEN  },
+    { PS_W_KING,   PS_B_KING   },
+    { PS_NONE,     PS_NONE     },
+    { PS_NONE,     PS_NONE     },
+    { PS_B_PAWN,   PS_W_PAWN   },
+    { PS_B_KNIGHT, PS_W_KNIGHT },
+    { PS_B_BISHOP, PS_W_BISHOP },
+    { PS_B_ROOK,   PS_W_ROOK   },
+    { PS_B_QUEEN,  PS_W_QUEEN  },
+    { PS_B_KING,   PS_W_KING   },
+    { PS_NONE,     PS_NONE     }
+};
+
+
+namespace Eval::NNUE {
+
+  // Input feature converter
+  AlignedPtr<FeatureTransformer> feature_transformer;
+
+  // Evaluation function
+  AlignedPtr<Network> network;
+
+  // Evaluation function file name
+  std::string fileName;
+
+  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));
+  }
+
+  // Read evaluation function parameters
+  template <typename T>
+  bool ReadParameters(std::istream& stream, const AlignedPtr<T>& pointer) {
+
+    std::uint32_t header;
+    stream.read(reinterpret_cast<char*>(&header), sizeof(header));
+    if (!stream || header != T::GetHashValue()) return false;
+    return pointer->ReadParameters(stream);
+  }
+
+  }  // namespace Detail
+
+  // Initialize the evaluation function parameters
+  void Initialize() {
+
+    Detail::Initialize(feature_transformer);
+    Detail::Initialize(network);
+  }
+
+  // Read network header
+  bool ReadHeader(std::istream& stream,
+    std::uint32_t* hash_value, std::string* architecture) {
+
+    std::uint32_t version, size;
+    stream.read(reinterpret_cast<char*>(&version), sizeof(version));
+    stream.read(reinterpret_cast<char*>(hash_value), sizeof(*hash_value));
+    stream.read(reinterpret_cast<char*>(&size), sizeof(size));
+    if (!stream || version != kVersion) return false;
+    architecture->resize(size);
+    stream.read(&(*architecture)[0], size);
+    return !stream.fail();
+  }
+
+  // Read network parameters
+  bool ReadParameters(std::istream& stream) {
+
+    std::uint32_t hash_value;
+    std::string architecture;
+    if (!ReadHeader(stream, &hash_value, &architecture)) return false;
+    if (hash_value != kHashValue) return false;
+    if (!Detail::ReadParameters(stream, feature_transformer)) return false;
+    if (!Detail::ReadParameters(stream, network)) return false;
+    return stream && stream.peek() == std::ios::traits_type::eof();
+  }
+
+  // Proceed with the difference calculation if possible
+  static void UpdateAccumulatorIfPossible(const Position& pos) {
+
+    feature_transformer->UpdateAccumulatorIfPossible(pos);
+  }
+
+  // Calculate the evaluation value
+  static Value ComputeScore(const Position& pos, bool refresh) {
+
+    auto& accumulator = pos.state()->accumulator;
+    if (!refresh && accumulator.computed_score) {
+      return accumulator.score;
+    }
+
+    alignas(kCacheLineSize) TransformedFeatureType
+        transformed_features[FeatureTransformer::kBufferSize];
+    feature_transformer->Transform(pos, transformed_features, refresh);
+    alignas(kCacheLineSize) char buffer[Network::kBufferSize];
+    const auto output = network->Propagate(transformed_features, buffer);
+
+    auto score = static_cast<Value>(output[0] / FV_SCALE);
+
+    accumulator.score = score;
+    accumulator.computed_score = true;
+    return accumulator.score;
+  }
+
+  // Load the evaluation function file
+  bool load_eval_file(const std::string& evalFile) {
+
+    Initialize();
+    fileName = evalFile;
+
+    std::ifstream stream(evalFile, std::ios::binary);
+
+    const bool result = ReadParameters(stream);
+
+    return result;
+  }
+
+  // Evaluation function. Perform differential calculation.
+  Value evaluate(const Position& pos) {
+    Value v = ComputeScore(pos, false);
+    v = Utility::clamp(v, VALUE_TB_LOSS_IN_MAX_PLY + 1, VALUE_TB_WIN_IN_MAX_PLY - 1);
+
+    return v;
+  }
+
+  // Evaluation function. Perform full calculation.
+  Value compute_eval(const Position& pos) {
+    return ComputeScore(pos, true);
+  }
+
+  // Proceed with the difference calculation if possible
+  void update_eval(const Position& pos) {
+    UpdateAccumulatorIfPossible(pos);
+  }
+
+} // namespace Eval::NNUE
@@ -0,0 +1,48 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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 Eval::NNUE {
+
+  // Hash value of evaluation function structure
+  constexpr std::uint32_t kHashValue =
+      FeatureTransformer::GetHashValue() ^ Network::GetHashValue();
+
+  // 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>
+  using AlignedPtr = std::unique_ptr<T, AlignedDeleter<T>>;
+
+}  // namespace Eval::NNUE
+
+#endif // #ifndef NNUE_EVALUATE_NNUE_H_INCLUDED
@@ -0,0 +1,135 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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 template that represents the input feature set of the NNUE evaluation function
+
+#ifndef NNUE_FEATURE_SET_H_INCLUDED
+#define NNUE_FEATURE_SET_H_INCLUDED
+
+#include "features_common.h"
+#include <array>
+
+namespace Eval::NNUE::Features {
+
+  // Class template that represents a list of values
+  template <typename T, T... Values>
+  struct CompileTimeList;
+
+  template <typename T, T First, T... Remaining>
+  struct CompileTimeList<T, First, Remaining...> {
+    static constexpr bool Contains(T value) {
+      return value == First || CompileTimeList<T, Remaining...>::Contains(value);
+    }
+    static constexpr std::array<T, sizeof...(Remaining) + 1>
+        kValues = {{First, Remaining...}};
+  };
+
+  // Base class of feature set
+  template <typename Derived>
+  class FeatureSetBase {
+
+   public:
+    // Get a list of indices for active features
+    template <typename IndexListType>
+    static void AppendActiveIndices(
+        const Position& pos, TriggerEvent trigger, IndexListType active[2]) {
+
+      for (Color perspective : { WHITE, BLACK }) {
+        Derived::CollectActiveIndices(
+            pos, trigger, perspective, &active[perspective]);
+      }
+    }
+
+    // Get a list of indices for recently changed features
+    template <typename PositionType, typename IndexListType>
+    static void AppendChangedIndices(
+        const PositionType& pos, TriggerEvent trigger,
+        IndexListType removed[2], IndexListType added[2], bool reset[2]) {
+
+      const auto& dp = pos.state()->dirtyPiece;
+      if (dp.dirty_num == 0) return;
+
+      for (Color perspective : { WHITE, BLACK }) {
+        reset[perspective] = false;
+        switch (trigger) {
+          case TriggerEvent::kFriendKingMoved:
+            reset[perspective] =
+                dp.pieceId[0] == PIECE_ID_KING + perspective;
+            break;
+          default:
+            assert(false);
+            break;
+        }
+        if (reset[perspective]) {
+          Derived::CollectActiveIndices(
+              pos, trigger, perspective, &added[perspective]);
+        } else {
+          Derived::CollectChangedIndices(
+              pos, trigger, perspective,
+              &removed[perspective], &added[perspective]);
+        }
+      }
+    }
+  };
+
+  // Class template that represents the feature set
+  template <typename FeatureType>
+  class FeatureSet<FeatureType> : public FeatureSetBase<FeatureSet<FeatureType>> {
+
+   public:
+    // Hash value embedded in the evaluation file
+    static constexpr std::uint32_t kHashValue = FeatureType::kHashValue;
+    // Number of feature dimensions
+    static constexpr IndexType kDimensions = FeatureType::kDimensions;
+    // Maximum number of simultaneously active features
+    static constexpr IndexType kMaxActiveDimensions =
+        FeatureType::kMaxActiveDimensions;
+    // Trigger for full calculation instead of difference calculation
+    using SortedTriggerSet =
+        CompileTimeList<TriggerEvent, FeatureType::kRefreshTrigger>;
+    static constexpr auto kRefreshTriggers = SortedTriggerSet::kValues;
+
+   private:
+    // Get a list of indices for active features
+    static void CollectActiveIndices(
+        const Position& pos, const TriggerEvent trigger, const Color perspective,
+        IndexList* const active) {
+      if (FeatureType::kRefreshTrigger == trigger) {
+        FeatureType::AppendActiveIndices(pos, perspective, active);
+      }
+    }
+
+    // Get a list of indices for recently changed features
+    static void CollectChangedIndices(
+        const Position& pos, const TriggerEvent trigger, const Color perspective,
+        IndexList* const removed, IndexList* const added) {
+
+      if (FeatureType::kRefreshTrigger == trigger) {
+        FeatureType::AppendChangedIndices(pos, perspective, removed, added);
+      }
+    }
+
+    // Make the base class and the class template that recursively uses itself a friend
+    friend class FeatureSetBase<FeatureSet>;
+    template <typename... FeatureTypes>
+    friend class FeatureSet;
+  };
+
+}  // namespace Eval::NNUE::Features
+
+#endif // #ifndef NNUE_FEATURE_SET_H_INCLUDED
@@ -0,0 +1,45 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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/>.
+*/
+
+//Common header of input features of NNUE evaluation function
+
+#ifndef NNUE_FEATURES_COMMON_H_INCLUDED
+#define NNUE_FEATURES_COMMON_H_INCLUDED
+
+#include "../../evaluate.h"
+#include "../nnue_common.h"
+
+namespace Eval::NNUE::Features {
+
+  class IndexList;
+
+  template <typename... FeatureTypes>
+  class FeatureSet;
+
+  // Trigger to perform full calculations instead of difference only
+  enum class TriggerEvent {
+    kFriendKingMoved // calculate full evaluation when own king moves
+  };
+
+  enum class Side {
+    kFriend // side to move
+  };
+
+}  // namespace Eval::NNUE::Features
+
+#endif // #ifndef NNUE_FEATURES_COMMON_H_INCLUDED
@@ -0,0 +1,92 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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
+
+#include "half_kp.h"
+#include "index_list.h"
+
+namespace Eval::NNUE::Features {
+
+  // Find the index of the feature quantity from the king position and PieceSquare
+  template <Side AssociatedKing>
+  inline IndexType HalfKP<AssociatedKing>::MakeIndex(Square sq_k, PieceSquare p) {
+    return static_cast<IndexType>(PS_END) * static_cast<IndexType>(sq_k) + p;
+  }
+
+  // Get pieces information
+  template <Side AssociatedKing>
+  inline void HalfKP<AssociatedKing>::GetPieces(
+      const Position& pos, Color perspective,
+      PieceSquare** pieces, Square* sq_target_k) {
+
+    *pieces = (perspective == BLACK) ?
+        pos.eval_list()->piece_list_fb() :
+        pos.eval_list()->piece_list_fw();
+    const PieceId target = (AssociatedKing == Side::kFriend) ?
+        static_cast<PieceId>(PIECE_ID_KING + perspective) :
+        static_cast<PieceId>(PIECE_ID_KING + ~perspective);
+    *sq_target_k = static_cast<Square>(((*pieces)[target] - PS_W_KING) % SQUARE_NB);
+  }
+
+  // Get a list of indices for active features
+  template <Side AssociatedKing>
+  void HalfKP<AssociatedKing>::AppendActiveIndices(
+      const Position& pos, Color perspective, IndexList* active) {
+
+    // Do nothing if array size is small to avoid compiler warning
+    if (RawFeatures::kMaxActiveDimensions < kMaxActiveDimensions) return;
+
+    PieceSquare* pieces;
+    Square sq_target_k;
+    GetPieces(pos, perspective, &pieces, &sq_target_k);
+    for (PieceId i = PIECE_ID_ZERO; i < PIECE_ID_KING; ++i) {
+      if (pieces[i] != PS_NONE) {
+        active->push_back(MakeIndex(sq_target_k, pieces[i]));
+      }
+    }
+  }
+
+  // Get a list of indices for recently changed features
+  template <Side AssociatedKing>
+  void HalfKP<AssociatedKing>::AppendChangedIndices(
+      const Position& pos, Color perspective,
+      IndexList* removed, IndexList* added) {
+
+    PieceSquare* pieces;
+    Square sq_target_k;
+    GetPieces(pos, perspective, &pieces, &sq_target_k);
+    const auto& dp = pos.state()->dirtyPiece;
+    for (int i = 0; i < dp.dirty_num; ++i) {
+      if (dp.pieceId[i] >= PIECE_ID_KING) continue;
+      const auto old_p = static_cast<PieceSquare>(
+          dp.old_piece[i].from[perspective]);
+      if (old_p != PS_NONE) {
+        removed->push_back(MakeIndex(sq_target_k, old_p));
+      }
+      const auto new_p = static_cast<PieceSquare>(
+          dp.new_piece[i].from[perspective]);
+      if (new_p != PS_NONE) {
+        added->push_back(MakeIndex(sq_target_k, new_p));
+      }
+    }
+  }
+
+  template class HalfKP<Side::kFriend>;
+
+}  // namespace Eval::NNUE::Features
@@ -0,0 +1,67 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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_KP_H_INCLUDED
+#define NNUE_FEATURES_HALF_KP_H_INCLUDED
+
+#include "../../evaluate.h"
+#include "features_common.h"
+
+namespace Eval::NNUE::Features {
+
+  // Feature HalfKP: Combination of the position of own king
+  // and the position of pieces other than kings
+  template <Side AssociatedKing>
+  class HalfKP {
+
+   public:
+    // Feature name
+    static constexpr const char* kName = "HalfKP(Friend)";
+    // Hash value embedded in the evaluation file
+    static constexpr std::uint32_t kHashValue =
+        0x5D69D5B9u ^ (AssociatedKing == Side::kFriend);
+    // Number of feature dimensions
+    static constexpr IndexType kDimensions =
+        static_cast<IndexType>(SQUARE_NB) * static_cast<IndexType>(PS_END);
+    // Maximum number of simultaneously active features
+    static constexpr IndexType kMaxActiveDimensions = PIECE_ID_KING;
+    // Trigger for full calculation instead of difference calculation
+    static constexpr TriggerEvent kRefreshTrigger = TriggerEvent::kFriendKingMoved;
+
+    // Get a list of indices for active features
+    static void AppendActiveIndices(const Position& pos, Color perspective,
+                                    IndexList* active);
+
+    // Get a list of indices for recently changed features
+    static void AppendChangedIndices(const Position& pos, Color perspective,
+                                     IndexList* removed, IndexList* added);
+
+    // Index of a feature for a given king position and another piece on some square
+    static IndexType MakeIndex(Square sq_k, PieceSquare p);
+
+   private:
+    // Get pieces information
+    static void GetPieces(const Position& pos, Color perspective,
+                          PieceSquare** pieces, Square* sq_target_k);
+  };
+
+}  // namespace Eval::NNUE::Features
+
+#endif // #ifndef NNUE_FEATURES_HALF_KP_H_INCLUDED
@@ -0,0 +1,64 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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 index list of input features
+
+#ifndef NNUE_FEATURES_INDEX_LIST_H_INCLUDED
+#define NNUE_FEATURES_INDEX_LIST_H_INCLUDED
+
+#include "../../position.h"
+#include "../nnue_architecture.h"
+
+namespace Eval::NNUE::Features {
+
+  // Class template used for feature index list
+  template <typename T, std::size_t MaxSize>
+  class ValueList {
+
+   public:
+    std::size_t size() const { return size_; }
+    void resize(std::size_t size) { size_ = size; }
+    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_; }
+
+    void swap(ValueList& other) {
+      const std::size_t max_size = std::max(size_, other.size_);
+      for (std::size_t i = 0; i < max_size; ++i) {
+        std::swap(values_[i], other.values_[i]);
+      }
+      std::swap(size_, other.size_);
+    }
+
+   private:
+    T values_[MaxSize];
+    std::size_t size_ = 0;
+  };
+
+  //Type of feature index list
+  class IndexList
+      : public ValueList<IndexType, RawFeatures::kMaxActiveDimensions> {
+  };
+
+}  // namespace Eval::NNUE::Features
+
+#endif // NNUE_FEATURES_INDEX_LIST_H_INCLUDED
@@ -0,0 +1,215 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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 Eval::NNUE::Layers {
+
+  // Affine transformation layer
+  template <typename PreviousLayer, IndexType OutputDimensions>
+  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 kInputDimensions =
+        PreviousLayer::kOutputDimensions;
+    static constexpr IndexType kOutputDimensions = OutputDimensions;
+    static constexpr IndexType kPaddedInputDimensions =
+        CeilToMultiple<IndexType>(kInputDimensions, kMaxSimdWidth);
+
+    // Size of forward propagation buffer used in this layer
+    static constexpr std::size_t kSelfBufferSize =
+        CeilToMultiple(kOutputDimensions * sizeof(OutputType), kCacheLineSize);
+
+    // Size of the forward propagation buffer used from the input layer to this layer
+    static constexpr std::size_t kBufferSize =
+        PreviousLayer::kBufferSize + kSelfBufferSize;
+
+    // Hash value embedded in the evaluation file
+    static constexpr std::uint32_t GetHashValue() {
+      std::uint32_t hash_value = 0xCC03DAE4u;
+      hash_value += kOutputDimensions;
+      hash_value ^= PreviousLayer::GetHashValue() >> 1;
+      hash_value ^= PreviousLayer::GetHashValue() << 31;
+      return hash_value;
+    }
+
+   // Read network parameters
+    bool ReadParameters(std::istream& stream) {
+      if (!previous_layer_.ReadParameters(stream)) return false;
+      stream.read(reinterpret_cast<char*>(biases_),
+                  kOutputDimensions * sizeof(BiasType));
+      stream.read(reinterpret_cast<char*>(weights_),
+                  kOutputDimensions * kPaddedInputDimensions *
+                  sizeof(WeightType));
+      return !stream.fail();
+    }
+
+    // Forward propagation
+    const OutputType* Propagate(
+        const TransformedFeatureType* transformed_features, char* buffer) const {
+      const auto input = previous_layer_.Propagate(
+          transformed_features, buffer + kSelfBufferSize);
+      const auto output = reinterpret_cast<OutputType*>(buffer);
+
+  #if defined(USE_AVX512)
+      constexpr IndexType kNumChunks = kPaddedInputDimensions / (kSimdWidth * 2);
+      const __m512i kOnes = _mm512_set1_epi16(1);
+      const auto input_vector = reinterpret_cast<const __m512i*>(input);
+
+  #elif defined(USE_AVX2)
+      constexpr IndexType kNumChunks = kPaddedInputDimensions / kSimdWidth;
+      const __m256i kOnes = _mm256_set1_epi16(1);
+      const auto input_vector = reinterpret_cast<const __m256i*>(input);
+
+  #elif defined(USE_SSSE3)
+      constexpr IndexType kNumChunks = kPaddedInputDimensions / kSimdWidth;
+      const __m128i kOnes = _mm_set1_epi16(1);
+      const auto input_vector = reinterpret_cast<const __m128i*>(input);
+
+  #elif defined(USE_NEON)
+      constexpr IndexType kNumChunks = kPaddedInputDimensions / kSimdWidth;
+      const auto input_vector = reinterpret_cast<const int8x8_t*>(input);
+  #endif
+
+      for (IndexType i = 0; i < kOutputDimensions; ++i) {
+        const IndexType offset = i * kPaddedInputDimensions;
+
+  #if defined(USE_AVX512)
+        __m512i sum = _mm512_setzero_si512();
+        const auto row = reinterpret_cast<const __m512i*>(&weights_[offset]);
+        for (IndexType j = 0; j < kNumChunks; ++j) {
+
+  #if defined(__MINGW32__) || defined(__MINGW64__)
+            __m512i product = _mm512_maddubs_epi16(_mm512_loadu_si512(&input_vector[j]), _mm512_load_si512(&row[j]));
+  #else
+            __m512i product = _mm512_maddubs_epi16(_mm512_load_si512(&input_vector[j]), _mm512_load_si512(&row[j]));
+  #endif
+
+            product = _mm512_madd_epi16(product, kOnes);
+            sum = _mm512_add_epi32(sum, product);
+        }
+        output[i] = _mm512_reduce_add_epi32(sum) + biases_[i];
+
+        // Note: Changing kMaxSimdWidth from 32 to 64 breaks loading existing networks.
+        // As a result kPaddedInputDimensions may not be an even multiple of 64(512bit)
+        // and we have to do one more 256bit chunk.
+        if (kPaddedInputDimensions != kNumChunks * kSimdWidth * 2)
+        {
+            const auto iv_256  = reinterpret_cast<const __m256i*>(input);
+            const auto row_256 = reinterpret_cast<const __m256i*>(&weights_[offset]);
+            int j = kNumChunks * 2;
+
+  #if defined(__MINGW32__) || defined(__MINGW64__)  // See HACK comment below in AVX2.
+            __m256i sum256 = _mm256_maddubs_epi16(_mm256_loadu_si256(&iv_256[j]), _mm256_load_si256(&row_256[j]));
+  #else
+            __m256i sum256 = _mm256_maddubs_epi16(_mm256_load_si256(&iv_256[j]), _mm256_load_si256(&row_256[j]));
+  #endif
+
+            sum256 = _mm256_madd_epi16(sum256, _mm256_set1_epi16(1));
+            sum256 = _mm256_hadd_epi32(sum256, sum256);
+            sum256 = _mm256_hadd_epi32(sum256, sum256);
+            const __m128i lo = _mm256_extracti128_si256(sum256, 0);
+            const __m128i hi = _mm256_extracti128_si256(sum256, 1);
+            output[i] += _mm_cvtsi128_si32(lo) + _mm_cvtsi128_si32(hi);
+        }
+
+  #elif defined(USE_AVX2)
+        __m256i sum = _mm256_setzero_si256();
+        const auto row = reinterpret_cast<const __m256i*>(&weights_[offset]);
+        for (IndexType j = 0; j < kNumChunks; ++j) {
+          __m256i product = _mm256_maddubs_epi16(
+
+  #if defined(__MINGW32__) || defined(__MINGW64__)
+            // HACK: Use _mm256_loadu_si256() instead of _mm256_load_si256. Because the binary
+            //       compiled with g++ in MSYS2 crashes here because the output memory is not aligned
+            //       even though alignas is specified.
+            _mm256_loadu_si256
+  #else
+            _mm256_load_si256
+  #endif
+
+            (&input_vector[j]), _mm256_load_si256(&row[j]));
+          product = _mm256_madd_epi16(product, kOnes);
+          sum = _mm256_add_epi32(sum, product);
+        }
+        sum = _mm256_hadd_epi32(sum, sum);
+        sum = _mm256_hadd_epi32(sum, sum);
+        const __m128i lo = _mm256_extracti128_si256(sum, 0);
+        const __m128i hi = _mm256_extracti128_si256(sum, 1);
+        output[i] = _mm_cvtsi128_si32(lo) + _mm_cvtsi128_si32(hi) + biases_[i];
+
+  #elif defined(USE_SSSE3)
+        __m128i sum = _mm_cvtsi32_si128(biases_[i]);
+        const auto row = reinterpret_cast<const __m128i*>(&weights_[offset]);
+        for (IndexType j = 0; j < kNumChunks; ++j) {
+          __m128i product = _mm_maddubs_epi16(
+              _mm_load_si128(&input_vector[j]), _mm_load_si128(&row[j]));
+          product = _mm_madd_epi16(product, kOnes);
+          sum = _mm_add_epi32(sum, product);
+        }
+        sum = _mm_hadd_epi32(sum, sum);
+        sum = _mm_hadd_epi32(sum, sum);
+        output[i] = _mm_cvtsi128_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 < kNumChunks; ++j) {
+          int16x8_t product = vmull_s8(input_vector[j * 2], row[j * 2]);
+          product = vmlal_s8(product, input_vector[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 < kInputDimensions; ++j) {
+          sum += weights_[offset + j] * input[j];
+        }
+        output[i] = sum;
+  #endif
+
+      }
+      return output;
+    }
+
+   private:
+    using BiasType = OutputType;
+    using WeightType = std::int8_t;
+
+    PreviousLayer previous_layer_;
+
+    alignas(kCacheLineSize) BiasType biases_[kOutputDimensions];
+    alignas(kCacheLineSize)
+        WeightType weights_[kOutputDimensions * kPaddedInputDimensions];
+  };
+
+}  // namespace Eval::NNUE::Layers
+
+#endif // #ifndef NNUE_LAYERS_AFFINE_TRANSFORM_H_INCLUDED
@@ -0,0 +1,186 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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 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 kInputDimensions =
+        PreviousLayer::kOutputDimensions;
+    static constexpr IndexType kOutputDimensions = kInputDimensions;
+
+    // Size of forward propagation buffer used in this layer
+    static constexpr std::size_t kSelfBufferSize =
+        CeilToMultiple(kOutputDimensions * sizeof(OutputType), kCacheLineSize);
+
+    // Size of the forward propagation buffer used from the input layer to this layer
+    static constexpr std::size_t kBufferSize =
+        PreviousLayer::kBufferSize + kSelfBufferSize;
+
+    // Hash value embedded in the evaluation file
+    static constexpr std::uint32_t GetHashValue() {
+      std::uint32_t hash_value = 0x538D24C7u;
+      hash_value += PreviousLayer::GetHashValue();
+      return hash_value;
+    }
+
+    // Read network parameters
+    bool ReadParameters(std::istream& stream) {
+      return previous_layer_.ReadParameters(stream);
+    }
+
+    // Forward propagation
+    const OutputType* Propagate(
+        const TransformedFeatureType* transformed_features, char* buffer) const {
+      const auto input = previous_layer_.Propagate(
+          transformed_features, buffer + kSelfBufferSize);
+      const auto output = reinterpret_cast<OutputType*>(buffer);
+
+  #if defined(USE_AVX2)
+      constexpr IndexType kNumChunks = kInputDimensions / kSimdWidth;
+      const __m256i kZero = _mm256_setzero_si256();
+      const __m256i kOffsets = _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 < kNumChunks; ++i) {
+        const __m256i words0 = _mm256_srai_epi16(_mm256_packs_epi32(
+
+  #if defined(__MINGW32__) || defined(__MINGW64__)
+          // HACK: Use _mm256_loadu_si256() instead of _mm256_load_si256. Because the binary
+          //       compiled with g++ in MSYS2 crashes here because the output memory is not aligned
+          //       even though alignas is specified.
+          _mm256_loadu_si256
+  #else
+          _mm256_load_si256
+  #endif
+
+          (&in[i * 4 + 0]),
+
+  #if defined(__MINGW32__) || defined(__MINGW64__)
+          _mm256_loadu_si256
+  #else
+          _mm256_load_si256
+  #endif
+
+          (&in[i * 4 + 1])), kWeightScaleBits);
+        const __m256i words1 = _mm256_srai_epi16(_mm256_packs_epi32(
+
+  #if defined(__MINGW32__) || defined(__MINGW64__)
+          _mm256_loadu_si256
+  #else
+          _mm256_load_si256
+  #endif
+
+          (&in[i * 4 + 2]),
+
+  #if defined(__MINGW32__) || defined(__MINGW64__)
+          _mm256_loadu_si256
+  #else
+          _mm256_load_si256
+  #endif
+
+          (&in[i * 4 + 3])), kWeightScaleBits);
+
+  #if defined(__MINGW32__) || defined(__MINGW64__)
+        _mm256_storeu_si256
+  #else
+        _mm256_store_si256
+  #endif
+
+          (&out[i], _mm256_permutevar8x32_epi32(_mm256_max_epi8(
+            _mm256_packs_epi16(words0, words1), kZero), kOffsets));
+      }
+      constexpr IndexType kStart = kNumChunks * kSimdWidth;
+
+  #elif defined(USE_SSSE3)
+      constexpr IndexType kNumChunks = kInputDimensions / kSimdWidth;
+
+  #ifdef USE_SSE41
+      const __m128i kZero = _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 < kNumChunks; ++i) {
+        const __m128i words0 = _mm_srai_epi16(_mm_packs_epi32(
+            _mm_load_si128(&in[i * 4 + 0]),
+            _mm_load_si128(&in[i * 4 + 1])), kWeightScaleBits);
+        const __m128i words1 = _mm_srai_epi16(_mm_packs_epi32(
+            _mm_load_si128(&in[i * 4 + 2]),
+            _mm_load_si128(&in[i * 4 + 3])), kWeightScaleBits);
+        const __m128i packedbytes = _mm_packs_epi16(words0, words1);
+        _mm_store_si128(&out[i],
+
+  #ifdef USE_SSE41
+          _mm_max_epi8(packedbytes, kZero)
+  #else
+          _mm_subs_epi8(_mm_adds_epi8(packedbytes, k0x80s), k0x80s)
+  #endif
+
+        );
+      }
+      constexpr IndexType kStart = kNumChunks * kSimdWidth;
+
+  #elif defined(USE_NEON)
+      constexpr IndexType kNumChunks = kInputDimensions / (kSimdWidth / 2);
+      const int8x8_t kZero = {0};
+      const auto in = reinterpret_cast<const int32x4_t*>(input);
+      const auto out = reinterpret_cast<int8x8_t*>(output);
+      for (IndexType i = 0; i < kNumChunks; ++i) {
+        int16x8_t shifted;
+        const auto pack = reinterpret_cast<int16x4_t*>(&shifted);
+        pack[0] = vqshrn_n_s32(in[i * 2 + 0], kWeightScaleBits);
+        pack[1] = vqshrn_n_s32(in[i * 2 + 1], kWeightScaleBits);
+        out[i] = vmax_s8(vqmovn_s16(shifted), kZero);
+      }
+      constexpr IndexType kStart = kNumChunks * (kSimdWidth / 2);
+  #else
+      constexpr IndexType kStart = 0;
+  #endif
+
+      for (IndexType i = kStart; i < kInputDimensions; ++i) {
+        output[i] = static_cast<OutputType>(
+            std::max(0, std::min(127, input[i] >> kWeightScaleBits)));
+      }
+      return output;
+    }
+
+   private:
+    PreviousLayer previous_layer_;
+  };
+
+}  // namespace Eval::NNUE::Layers
+
+#endif // NNUE_LAYERS_CLIPPED_RELU_H_INCLUDED
@@ -0,0 +1,68 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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 Eval::NNUE::Layers {
+
+// Input layer
+template <IndexType OutputDimensions, IndexType Offset = 0>
+class InputSlice {
+ public:
+  // Need to maintain alignment
+  static_assert(Offset % kMaxSimdWidth == 0, "");
+
+  // Output type
+  using OutputType = TransformedFeatureType;
+
+  // Output dimensionality
+  static constexpr IndexType kOutputDimensions = OutputDimensions;
+
+  // Size of forward propagation buffer used from the input layer to this layer
+  static constexpr std::size_t kBufferSize = 0;
+
+  // Hash value embedded in the evaluation file
+  static constexpr std::uint32_t GetHashValue() {
+    std::uint32_t hash_value = 0xEC42E90Du;
+    hash_value ^= kOutputDimensions ^ (Offset << 10);
+    return hash_value;
+  }
+
+  // Read network parameters
+  bool ReadParameters(std::istream& /*stream*/) {
+    return true;
+  }
+
+  // Forward propagation
+  const OutputType* Propagate(
+      const TransformedFeatureType* transformed_features,
+      char* /*buffer*/) const {
+    return transformed_features + Offset;
+  }
+
+ private:
+};
+
+}  // namespace Layers
+
+#endif // #ifndef NNUE_LAYERS_INPUT_SLICE_H_INCLUDED
@@ -0,0 +1,39 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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 Eval::NNUE {
+
+  // Class that holds the result of affine transformation of input features
+  struct alignas(32) Accumulator {
+    std::int16_t
+        accumulation[2][kRefreshTriggers.size()][kTransformedFeatureDimensions];
+    Value score;
+    bool computed_accumulation;
+    bool computed_score;
+  };
+
+}  // namespace Eval::NNUE
+
+#endif // NNUE_ACCUMULATOR_H_INCLUDED
@@ -0,0 +1,38 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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
+
+// Defines the network structure
+#include "architectures/halfkp_256x2-32-32.h"
+
+namespace Eval::NNUE {
+
+  static_assert(kTransformedFeatureDimensions % kMaxSimdWidth == 0, "");
+  static_assert(Network::kOutputDimensions == 1, "");
+  static_assert(std::is_same<Network::OutputType, std::int32_t>::value, "");
+
+  // Trigger for full calculation instead of difference calculation
+  constexpr auto kRefreshTriggers = RawFeatures::kRefreshTriggers;
+
+}  // namespace Eval::NNUE
+
+#endif // #ifndef NNUE_ARCHITECTURE_H_INCLUDED
@@ -0,0 +1,77 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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
+
+#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_NEON)
+#include <arm_neon.h>
+#endif
+
+namespace Eval::NNUE {
+
+  // Version of the evaluation file
+  constexpr std::uint32_t kVersion = 0x7AF32F16u;
+
+  // Constant used in evaluation value calculation
+  constexpr int FV_SCALE = 16;
+  constexpr int kWeightScaleBits = 6;
+
+  // Size of cache line (in bytes)
+  constexpr std::size_t kCacheLineSize = 64;
+
+  // SIMD width (in bytes)
+  #if defined(USE_AVX2)
+  constexpr std::size_t kSimdWidth = 32;
+
+  #elif defined(USE_SSE2)
+  constexpr std::size_t kSimdWidth = 16;
+
+  #elif defined(USE_NEON)
+  constexpr std::size_t kSimdWidth = 16;
+  #endif
+
+  constexpr std::size_t kMaxSimdWidth = 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 CeilToMultiple(IntType n, IntType base) {
+    return (n + base - 1) / base * base;
+  }
+
+}  // namespace Eval::NNUE
+
+#endif // #ifndef NNUE_COMMON_H_INCLUDED
@@ -0,0 +1,355 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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 "features/index_list.h"
+
+#include <cstring> // std::memset()
+
+namespace Eval::NNUE {
+
+  // Input feature converter
+  class FeatureTransformer {
+
+   private:
+    // Number of output dimensions for one side
+    static constexpr IndexType kHalfDimensions = kTransformedFeatureDimensions;
+
+   public:
+    // Output type
+    using OutputType = TransformedFeatureType;
+
+    // Number of input/output dimensions
+    static constexpr IndexType kInputDimensions = RawFeatures::kDimensions;
+    static constexpr IndexType kOutputDimensions = kHalfDimensions * 2;
+
+    // Size of forward propagation buffer
+    static constexpr std::size_t kBufferSize =
+        kOutputDimensions * sizeof(OutputType);
+
+    // Hash value embedded in the evaluation file
+    static constexpr std::uint32_t GetHashValue() {
+      return RawFeatures::kHashValue ^ kOutputDimensions;
+    }
+
+    // Read network parameters
+    bool ReadParameters(std::istream& stream) {
+      stream.read(reinterpret_cast<char*>(biases_),
+                  kHalfDimensions * sizeof(BiasType));
+      stream.read(reinterpret_cast<char*>(weights_),
+                  kHalfDimensions * kInputDimensions * sizeof(WeightType));
+      return !stream.fail();
+    }
+
+    // Proceed with the difference calculation if possible
+    bool UpdateAccumulatorIfPossible(const Position& pos) const {
+      const auto now = pos.state();
+      if (now->accumulator.computed_accumulation) {
+        return true;
+      }
+      const auto prev = now->previous;
+      if (prev && prev->accumulator.computed_accumulation) {
+        UpdateAccumulator(pos);
+        return true;
+      }
+      return false;
+    }
+
+    // Convert input features
+    void Transform(const Position& pos, OutputType* output, bool refresh) const {
+      if (refresh || !UpdateAccumulatorIfPossible(pos)) {
+        RefreshAccumulator(pos);
+      }
+      const auto& accumulation = pos.state()->accumulator.accumulation;
+
+  #if defined(USE_AVX2)
+      constexpr IndexType kNumChunks = kHalfDimensions / kSimdWidth;
+      constexpr int kControl = 0b11011000;
+      const __m256i kZero = _mm256_setzero_si256();
+
+  #elif defined(USE_SSSE3)
+      constexpr IndexType kNumChunks = kHalfDimensions / kSimdWidth;
+
+  #ifdef USE_SSE41
+      const __m128i kZero = _mm_setzero_si128();
+  #else
+      const __m128i k0x80s = _mm_set1_epi8(-128);
+  #endif
+
+  #elif defined(USE_NEON)
+      constexpr IndexType kNumChunks = kHalfDimensions / (kSimdWidth / 2);
+      const int8x8_t kZero = {0};
+  #endif
+
+      const Color perspectives[2] = {pos.side_to_move(), ~pos.side_to_move()};
+      for (IndexType p = 0; p < 2; ++p) {
+        const IndexType offset = kHalfDimensions * p;
+
+  #if defined(USE_AVX2)
+        auto out = reinterpret_cast<__m256i*>(&output[offset]);
+        for (IndexType j = 0; j < kNumChunks; ++j) {
+          __m256i sum0 =
+
+  #if defined(__MINGW32__) || defined(__MINGW64__)
+            // HACK: Use _mm256_loadu_si256() instead of _mm256_load_si256. Because the binary
+            //       compiled with g++ in MSYS2 crashes here because the output memory is not aligned
+            //       even though alignas is specified.
+            _mm256_loadu_si256
+  #else
+            _mm256_load_si256
+  #endif
+
+            (&reinterpret_cast<const __m256i*>(
+              accumulation[perspectives[p]][0])[j * 2 + 0]);
+          __m256i sum1 =
+
+  #if defined(__MINGW32__) || defined(__MINGW64__)
+            _mm256_loadu_si256
+  #else
+            _mm256_load_si256
+  #endif
+
+            (&reinterpret_cast<const __m256i*>(
+              accumulation[perspectives[p]][0])[j * 2 + 1]);
+
+  #if defined(__MINGW32__) || defined(__MINGW64__)
+          _mm256_storeu_si256
+  #else
+          _mm256_store_si256
+  #endif
+
+          (&out[j], _mm256_permute4x64_epi64(_mm256_max_epi8(
+              _mm256_packs_epi16(sum0, sum1), kZero), kControl));
+        }
+
+  #elif defined(USE_SSSE3)
+        auto out = reinterpret_cast<__m128i*>(&output[offset]);
+        for (IndexType j = 0; j < kNumChunks; ++j) {
+          __m128i sum0 = _mm_load_si128(&reinterpret_cast<const __m128i*>(
+              accumulation[perspectives[p]][0])[j * 2 + 0]);
+          __m128i sum1 = _mm_load_si128(&reinterpret_cast<const __m128i*>(
+              accumulation[perspectives[p]][0])[j * 2 + 1]);
+      const __m128i packedbytes = _mm_packs_epi16(sum0, sum1);
+
+          _mm_store_si128(&out[j],
+
+  #ifdef USE_SSE41
+            _mm_max_epi8(packedbytes, kZero)
+  #else
+            _mm_subs_epi8(_mm_adds_epi8(packedbytes, k0x80s), k0x80s)
+  #endif
+
+          );
+        }
+
+  #elif defined(USE_NEON)
+        const auto out = reinterpret_cast<int8x8_t*>(&output[offset]);
+        for (IndexType j = 0; j < kNumChunks; ++j) {
+          int16x8_t sum = reinterpret_cast<const int16x8_t*>(
+              accumulation[perspectives[p]][0])[j];
+          out[j] = vmax_s8(vqmovn_s16(sum), kZero);
+        }
+
+  #else
+        for (IndexType j = 0; j < kHalfDimensions; ++j) {
+          BiasType sum = accumulation[static_cast<int>(perspectives[p])][0][j];
+          output[offset + j] = static_cast<OutputType>(
+              std::max<int>(0, std::min<int>(127, sum)));
+        }
+  #endif
+
+      }
+    }
+
+   private:
+    // Calculate cumulative value without using difference calculation
+    void RefreshAccumulator(const Position& pos) const {
+      auto& accumulator = pos.state()->accumulator;
+      IndexType i = 0;
+      Features::IndexList active_indices[2];
+      RawFeatures::AppendActiveIndices(pos, kRefreshTriggers[i],
+                                       active_indices);
+      for (Color perspective : { WHITE, BLACK }) {
+        std::memcpy(accumulator.accumulation[perspective][i], biases_,
+                   kHalfDimensions * sizeof(BiasType));
+        for (const auto index : active_indices[perspective]) {
+          const IndexType offset = kHalfDimensions * index;
+
+  #if defined(USE_AVX2)
+          auto accumulation = reinterpret_cast<__m256i*>(
+              &accumulator.accumulation[perspective][i][0]);
+          auto column = reinterpret_cast<const __m256i*>(&weights_[offset]);
+          constexpr IndexType kNumChunks = kHalfDimensions / (kSimdWidth / 2);
+          for (IndexType j = 0; j < kNumChunks; ++j) {
+  #if defined(__MINGW32__) || defined(__MINGW64__)
+            _mm256_storeu_si256(&accumulation[j], _mm256_add_epi16(_mm256_loadu_si256(&accumulation[j]), column[j]));
+  #else
+            accumulation[j] = _mm256_add_epi16(accumulation[j], column[j]);
+  #endif
+          }
+
+  #elif defined(USE_SSE2)
+          auto accumulation = reinterpret_cast<__m128i*>(
+              &accumulator.accumulation[perspective][i][0]);
+          auto column = reinterpret_cast<const __m128i*>(&weights_[offset]);
+          constexpr IndexType kNumChunks = kHalfDimensions / (kSimdWidth / 2);
+          for (IndexType j = 0; j < kNumChunks; ++j) {
+            accumulation[j] = _mm_add_epi16(accumulation[j], column[j]);
+          }
+
+  #elif defined(USE_NEON)
+          auto accumulation = reinterpret_cast<int16x8_t*>(
+              &accumulator.accumulation[perspective][i][0]);
+          auto column = reinterpret_cast<const int16x8_t*>(&weights_[offset]);
+          constexpr IndexType kNumChunks = kHalfDimensions / (kSimdWidth / 2);
+          for (IndexType j = 0; j < kNumChunks; ++j) {
+            accumulation[j] = vaddq_s16(accumulation[j], column[j]);
+          }
+
+  #else
+          for (IndexType j = 0; j < kHalfDimensions; ++j) {
+            accumulator.accumulation[perspective][i][j] += weights_[offset + j];
+          }
+  #endif
+
+        }
+      }
+
+      accumulator.computed_accumulation = true;
+      accumulator.computed_score = false;
+    }
+
+    // Calculate cumulative value using difference calculation
+    void UpdateAccumulator(const Position& pos) const {
+      const auto prev_accumulator = pos.state()->previous->accumulator;
+      auto& accumulator = pos.state()->accumulator;
+      IndexType i = 0;
+      Features::IndexList removed_indices[2], added_indices[2];
+      bool reset[2];
+      RawFeatures::AppendChangedIndices(pos, kRefreshTriggers[i],
+                                        removed_indices, added_indices, reset);
+      for (Color perspective : { WHITE, BLACK }) {
+
+  #if defined(USE_AVX2)
+        constexpr IndexType kNumChunks = kHalfDimensions / (kSimdWidth / 2);
+        auto accumulation = reinterpret_cast<__m256i*>(
+            &accumulator.accumulation[perspective][i][0]);
+
+  #elif defined(USE_SSE2)
+        constexpr IndexType kNumChunks = kHalfDimensions / (kSimdWidth / 2);
+        auto accumulation = reinterpret_cast<__m128i*>(
+            &accumulator.accumulation[perspective][i][0]);
+
+  #elif defined(USE_NEON)
+        constexpr IndexType kNumChunks = kHalfDimensions / (kSimdWidth / 2);
+        auto accumulation = reinterpret_cast<int16x8_t*>(
+            &accumulator.accumulation[perspective][i][0]);
+  #endif
+
+        if (reset[perspective]) {
+          std::memcpy(accumulator.accumulation[perspective][i], biases_,
+                      kHalfDimensions * sizeof(BiasType));
+        } else {
+          std::memcpy(accumulator.accumulation[perspective][i],
+                      prev_accumulator.accumulation[perspective][i],
+                      kHalfDimensions * sizeof(BiasType));
+          // Difference calculation for the deactivated features
+          for (const auto index : removed_indices[perspective]) {
+            const IndexType offset = kHalfDimensions * index;
+
+  #if defined(USE_AVX2)
+            auto column = reinterpret_cast<const __m256i*>(&weights_[offset]);
+            for (IndexType j = 0; j < kNumChunks; ++j) {
+              accumulation[j] = _mm256_sub_epi16(accumulation[j], column[j]);
+            }
+
+  #elif defined(USE_SSE2)
+            auto column = reinterpret_cast<const __m128i*>(&weights_[offset]);
+            for (IndexType j = 0; j < kNumChunks; ++j) {
+              accumulation[j] = _mm_sub_epi16(accumulation[j], column[j]);
+            }
+
+  #elif defined(USE_NEON)
+            auto column = reinterpret_cast<const int16x8_t*>(&weights_[offset]);
+            for (IndexType j = 0; j < kNumChunks; ++j) {
+              accumulation[j] = vsubq_s16(accumulation[j], column[j]);
+            }
+
+  #else
+            for (IndexType j = 0; j < kHalfDimensions; ++j) {
+              accumulator.accumulation[perspective][i][j] -=
+                  weights_[offset + j];
+            }
+  #endif
+
+          }
+        }
+        { // Difference calculation for the activated features
+          for (const auto index : added_indices[perspective]) {
+            const IndexType offset = kHalfDimensions * index;
+
+  #if defined(USE_AVX2)
+            auto column = reinterpret_cast<const __m256i*>(&weights_[offset]);
+            for (IndexType j = 0; j < kNumChunks; ++j) {
+              accumulation[j] = _mm256_add_epi16(accumulation[j], column[j]);
+            }
+
+  #elif defined(USE_SSE2)
+            auto column = reinterpret_cast<const __m128i*>(&weights_[offset]);
+            for (IndexType j = 0; j < kNumChunks; ++j) {
+              accumulation[j] = _mm_add_epi16(accumulation[j], column[j]);
+            }
+
+  #elif defined(USE_NEON)
+            auto column = reinterpret_cast<const int16x8_t*>(&weights_[offset]);
+            for (IndexType j = 0; j < kNumChunks; ++j) {
+              accumulation[j] = vaddq_s16(accumulation[j], column[j]);
+            }
+
+  #else
+            for (IndexType j = 0; j < kHalfDimensions; ++j) {
+              accumulator.accumulation[perspective][i][j] +=
+                  weights_[offset + j];
+            }
+  #endif
+
+          }
+        }
+      }
+
+      accumulator.computed_accumulation = true;
+      accumulator.computed_score = false;
+    }
+
+    using BiasType = std::int16_t;
+    using WeightType = std::int16_t;
+
+    alignas(kCacheLineSize) BiasType biases_[kHalfDimensions];
+    alignas(kCacheLineSize)
+        WeightType weights_[kHalfDimensions * kInputDimensions];
+  };
+
+}  // namespace Eval::NNUE
+
+#endif // #ifndef NNUE_FEATURE_TRANSFORMER_H_INCLUDED
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -33,12 +31,18 @@ namespace {

  // Pawn penalties
  constexpr Score Backward      = S( 9, 24);
-  constexpr Score BlockedStorm  = S(82, 82);
  constexpr Score Doubled       = S(11, 56);
  constexpr Score Isolated      = S( 5, 15);
  constexpr Score WeakLever     = S( 0, 56);
  constexpr Score WeakUnopposed = S(13, 27);

+  // Bonus for blocked pawns at 5th or 6th rank
+  constexpr Score BlockedPawn[2] = { S(-11, -4), S(-3, 4) };
+
+  constexpr Score BlockedStorm[RANK_NB] = {
+    S(0, 0), S(0, 0), S(76, 78), S(-10, 15), S(-7, 10), S(-4, 6), S(-1, 2)
+  };
+
  // Connected pawn bonus
  constexpr int Connected[RANK_NB] = { 0, 7, 8, 12, 29, 48, 86 };

@@ -65,10 +69,16 @@ namespace {
  #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);

    Bitboard neighbours, stoppers, support, phalanx, opposed;
@@ -86,6 +96,7 @@ 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)
@@ -98,8 +109,8 @@ namespace {
        opposed    = theirPawns & forward_file_bb(Us, s);
        blocked    = theirPawns & (s + Up);
        stoppers   = theirPawns & passed_pawn_span(Us, s);
-        lever      = theirPawns & PawnAttacks[Us][s];
-        leverPush  = theirPawns & PawnAttacks[Us][s + Up];
+        lever      = theirPawns & pawn_attacks_bb(Us, s);
+        leverPush  = theirPawns & pawn_attacks_bb(Us, s + Up);
        doubled    = ourPawns   & (s - Up);
        neighbours = ourPawns   & adjacent_files_bb(s);
        phalanx    = neighbours & rank_bb(s);
@@ -118,12 +129,15 @@ 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)
@@ -139,16 +153,26 @@ namespace {
        }

        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
-                     + WeakUnopposed * !opposed;
+            score -=  Backward
+                    + WeakUnopposed * !opposed;

        if (!support)
-            score -=   Doubled * doubled
-                     + WeakLever * more_than_one(lever);
+            score -=  Doubled * doubled
+                    + WeakLever * more_than_one(lever);
+
+        if (blocked && r > RANK_4)
+            score += BlockedPawn[r-4];
    }

    return score;
@@ -158,6 +182,7 @@ 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 +197,7 @@ 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 +209,17 @@ 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 = Utility::clamp(file_of(ksq), FILE_B, FILE_G);
  for (File f = File(center - 1); f <= File(center + 1); ++f)
  {
      b = ourPawns & file_bb(f);
@@ -202,11 +228,11 @@ 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);
  }
@@ -238,9 +264,9 @@ 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)));
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -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];
@@ -59,6 +58,7 @@ struct Entry {
  Square kingSquares[COLOR_NB];
  Score kingSafety[COLOR_NB];
  int castlingRights[COLOR_NB];
+  int blockedCount;
 };

 typedef HashTable<Entry, 131072> Table;
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -64,10 +62,11 @@ 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: ";

@@ -104,8 +103,7 @@ Key cuckoo[8192];
 Move cuckooMove[8192];


-/// Position::init() initializes at startup the various arrays used to compute
-/// hash keys.
+/// Position::init() initializes at startup the various arrays used to compute hash keys

 void Position::init() {

@@ -119,15 +117,7 @@ void Position::init() {
      Zobrist::enpassant[f] = rng.rand<Key>();

  for (int cr = NO_CASTLING; cr <= ANY_CASTLING; ++cr)
-  {
-      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::castling[cr] = rng.rand<Key>();

  Zobrist::side = rng.rand<Key>();
  Zobrist::noPawns = rng.rand<Key>();
@@ -139,7 +129,7 @@ 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 +176,9 @@ 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
-      in position to make an en passant capture, and if there really is a pawn
-      that might have advanced two squares.
+      is the position "behind" the pawn. Following X-FEN standard, this is recorded only
+      if there is a pawn in position to make an en passant capture, and if there really
+      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
@@ -208,6 +198,9 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th
  std::fill_n(&pieceList[0][0], sizeof(pieceList) / sizeof(Square), SQ_NONE);
  st = si;

+  // Each piece on board gets a unique ID used to track the piece later
+  PieceId piece_id, next_piece_id = PIECE_ID_ZERO;
+
  ss >> std::noskipws;

  // 1. Piece placement
@@ -221,7 +214,19 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th

      else if ((idx = PieceToChar.find(token)) != string::npos)
      {
-          put_piece(Piece(idx), sq);
+          auto pc = Piece(idx);
+          put_piece(pc, sq);
+
+          if (Eval::useNNUE)
+          {
+              // Kings get a fixed ID, other pieces get ID in order of placement
+              piece_id =
+                (idx == W_KING) ? PIECE_ID_WKING :
+                (idx == B_KING) ? PIECE_ID_BKING :
+                next_piece_id++;
+              evalList.put_piece(piece_id, sq, pc);
+          }
+
          ++sq;
      }
  }
@@ -259,17 +264,25 @@ 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))
-          || !(pieces(~sideToMove, PAWN) & (st->epSquare + pawn_push(~sideToMove))))
-          st->epSquare = SQ_NONE;
+      // En passant square will be considered only if
+      // a) side to move have a pawn threatening epSquare
+      // 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
@@ -306,7 +319,7 @@ void Position::set_castling_right(Color c, Square rfrom) {
  Square rto = relative_square(c, cr & KING_SIDE ? SQ_F1 : SQ_D1);

  castlingPath[cr] =   (between_bb(rfrom, rto) | between_bb(kfrom, kto) | rto | kto)
-                    & ~(square_bb(kfrom) | rfrom);
+                    & ~(kfrom | rfrom);
 }


@@ -319,10 +332,10 @@ void Position::set_check_info(StateInfo* si) const {

  Square ksq = square<KING>(~sideToMove);

-  si->checkSquares[PAWN]   = attacks_from<PAWN>(ksq, ~sideToMove);
-  si->checkSquares[KNIGHT] = attacks_from<KNIGHT>(ksq);
-  si->checkSquares[BISHOP] = attacks_from<BISHOP>(ksq);
-  si->checkSquares[ROOK]   = attacks_from<ROOK>(ksq);
+  si->checkSquares[PAWN]   = pawn_attacks_bb(~sideToMove, ksq);
+  si->checkSquares[KNIGHT] = attacks_bb<KNIGHT>(ksq);
+  si->checkSquares[BISHOP] = attacks_bb<BISHOP>(ksq, pieces());
+  si->checkSquares[ROOK]   = attacks_bb<ROOK>(ksq, pieces());
  si->checkSquares[QUEEN]  = si->checkSquares[BISHOP] | si->checkSquares[ROOK];
  si->checkSquares[KING]   = 0;
 }
@@ -375,11 +388,13 @@ 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);

@@ -453,8 +468,8 @@ 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))
-                      | (PseudoAttacks[BISHOP][s] & pieces(QUEEN, BISHOP))) & sliders;
+  Bitboard snipers = (  (attacks_bb<  ROOK>(s) & pieces(QUEEN, ROOK))
+                      | (attacks_bb<BISHOP>(s) & pieces(QUEEN, BISHOP))) & sliders;
  Bitboard occupancy = pieces() ^ snipers;

  while (snipers)
@@ -478,12 +493,12 @@ 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))
-        | (attacks_from<PAWN>(s, WHITE)    & pieces(BLACK, PAWN))
-        | (attacks_from<KNIGHT>(s)         & pieces(KNIGHT))
+  return  (pawn_attacks_bb(BLACK, s)       & pieces(WHITE, PAWN))
+        | (pawn_attacks_bb(WHITE, s)       & pieces(BLACK, PAWN))
+        | (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));
 }


@@ -586,15 +601,15 @@ 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
@@ -633,11 +648,11 @@ 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;

@@ -664,11 +679,11 @@ bool Position::gives_check(Move m) const {
  case CASTLING:
  {
      Square kfrom = from;
-      Square rfrom = to; // Castling is encoded as 'King captures the rook'
+      Square rfrom = to; // Castling is encoded as 'king captures the rook'
      Square kto = relative_square(sideToMove, rfrom > kfrom ? SQ_G1 : SQ_C1);
      Square rto = relative_square(sideToMove, rfrom > kfrom ? SQ_F1 : SQ_D1);

-      return   (PseudoAttacks[ROOK][rto] & square<KING>(~sideToMove))
+      return   (attacks_bb<ROOK>(rto) & square<KING>(~sideToMove))
            && (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & square<KING>(~sideToMove));
  }
  default:
@@ -703,6 +718,14 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
  ++st->rule50;
  ++st->pliesFromNull;

+  // Used by NNUE
+  st->accumulator.computed_accumulation = false;
+  st->accumulator.computed_score = false;
+  PieceId dp0 = PIECE_ID_NONE;
+  PieceId dp1 = PIECE_ID_NONE;
+  auto& dp = st->dirtyPiece;
+  dp.dirty_num = 1;
+
  Color us = sideToMove;
  Color them = ~us;
  Square from = from_sq(m);
@@ -743,8 +766,6 @@ 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 +773,21 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
      else
          st->nonPawnMaterial[them] -= PieceValue[MG][captured];

+      if (Eval::useNNUE)
+      {
+          dp.dirty_num = 2; // 2 pieces moved
+          dp1 = piece_id_on(capsq);
+          dp.pieceId[1] = dp1;
+          dp.old_piece[1] = evalList.piece_with_id(dp1);
+          evalList.put_piece(dp1, capsq, NO_PIECE);
+          dp.new_piece[1] = evalList.piece_with_id(dp1);
+      }
+
      // Update board and piece lists
-      remove_piece(captured, capsq);
+      remove_piece(capsq);
+
+      if (type_of(m) == ENPASSANT)
+          board[capsq] = NO_PIECE;

      // Update material hash key and prefetch access to materialTable
      k ^= Zobrist::psq[captured][capsq];
@@ -777,21 +811,32 @@ 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 & cr];
-      st->castlingRights &= ~cr;
+      k ^= Zobrist::castling[st->castlingRights];
+      st->castlingRights &= ~(castlingRightsMask[from] | castlingRightsMask[to]);
+      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)
+      {
+          dp0 = piece_id_on(from);
+          dp.pieceId[0] = dp0;
+          dp.old_piece[0] = evalList.piece_with_id(dp0);
+          evalList.put_piece(dp0, to, pc);
+          dp.new_piece[0] = evalList.piece_with_id(dp0);
+      }
+
+      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
      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 +849,16 @@ 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)
+          {
+              dp0 = piece_id_on(to);
+              evalList.put_piece(dp0, to, promotion);
+              dp.new_piece[0] = evalList.piece_with_id(dp0);
+          }
+
          // Update hash keys
          k ^= Zobrist::psq[pc][to] ^ Zobrist::psq[promotion][to];
          st->pawnKey ^= Zobrist::psq[pc][to];
@@ -884,7 +936,7 @@ 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);
  }
@@ -896,7 +948,13 @@ 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 (Eval::useNNUE)
+      {
+          PieceId dp0 = st->dirtyPiece.pieceId[0];
+          evalList.put_piece(dp0, from, pc);
+      }

      if (st->capturedPiece)
      {
@@ -914,6 +972,14 @@ void Position::undo_move(Move m) {
          }

          put_piece(st->capturedPiece, capsq); // Restore the captured piece
+
+          if (Eval::useNNUE)
+          {
+              PieceId dp1 = st->dirtyPiece.pieceId[1];
+              assert(evalList.piece_with_id(dp1).from[WHITE] == PS_NONE);
+              assert(evalList.piece_with_id(dp1).from[BLACK] == PS_NONE);
+              evalList.put_piece(dp1, capsq, st->capturedPiece);
+          }
      }
  }

@@ -935,10 +1001,38 @@ 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 (Eval::useNNUE)
+  {
+      PieceId dp0, dp1;
+      auto& dp = st->dirtyPiece;
+      dp.dirty_num = 2; // 2 pieces moved
+
+      if (Do)
+      {
+          dp0 = piece_id_on(from);
+          dp1 = piece_id_on(rfrom);
+          dp.pieceId[0] = dp0;
+          dp.old_piece[0] = evalList.piece_with_id(dp0);
+          evalList.put_piece(dp0, to, make_piece(us, KING));
+          dp.new_piece[0] = evalList.piece_with_id(dp0);
+          dp.pieceId[1] = dp1;
+          dp.old_piece[1] = evalList.piece_with_id(dp1);
+          evalList.put_piece(dp1, rto, make_piece(us, ROOK));
+          dp.new_piece[1] = evalList.piece_with_id(dp1);
+      }
+      else
+      {
+          dp0 = piece_id_on(to);
+          dp1 = piece_id_on(rto);
+          evalList.put_piece(dp0, from, make_piece(us, KING));
+          evalList.put_piece(dp1, rfrom, make_piece(us, ROOK));
+      }
+  }
+
  // Remove both pieces first since squares could overlap in Chess960
-  remove_piece(make_piece(us, KING), Do ? from : to);
-  remove_piece(make_piece(us, ROOK), Do ? rfrom : rto);
-  board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do it for us
+  remove_piece(Do ? from : to);
+  remove_piece(Do ? rfrom : rto);
+  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);
 }
@@ -952,7 +1046,14 @@ void Position::do_null_move(StateInfo& newSt) {
  assert(!checkers());
  assert(&newSt != st);

-  std::memcpy(&newSt, st, sizeof(StateInfo));
+  if (Eval::useNNUE)
+  {
+      std::memcpy(&newSt, st, sizeof(StateInfo));
+      st->accumulator.computed_score = false;
+  }
+  else
+      std::memcpy(&newSt, st, offsetof(StateInfo, accumulator));
+
  newSt.previous = st;
  st = &newSt;

@@ -1108,6 +1209,7 @@ 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 +1220,7 @@ 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 true;
-
-  return false;
+  return st->repetition && st->repetition < ply;
 }


@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -27,8 +25,11 @@
 #include <string>

 #include "bitboard.h"
+#include "evaluate.h"
 #include "types.h"

+#include "nnue/nnue_accumulator.h"
+

 /// 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
@@ -54,8 +55,13 @@ struct StateInfo {
  Bitboard   pinners[COLOR_NB];
  Bitboard   checkSquares[PIECE_TYPE_NB];
  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
@@ -83,7 +89,6 @@ public:
  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;
@@ -99,7 +104,7 @@ public:
  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;
@@ -113,9 +118,6 @@ public:
  // 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
@@ -166,6 +168,10 @@ public:
  bool pos_is_ok() const;
  void flip();

+  // Used by NNUE
+  StateInfo* state() const;
+  const EvalList* eval_list() const;
+
 private:
  // Initialization helpers (used while setting up a position)
  void set_castling_right(Color c, Square rfrom);
@@ -174,11 +180,14 @@ private:

  // Other helpers
  void put_piece(Piece pc, Square s);
-  void remove_piece(Piece pc, Square s);
-  void move_piece(Piece pc, Square from, Square to);
+  void remove_piece(Square s);
+  void move_piece(Square from, Square to);
  template<bool Do>
  void do_castling(Color us, Square from, Square& to, Square& rfrom, Square& rto);

+  // ID of a piece on a given square
+  PieceId piece_id_on(Square sq) const;
+
  // Data members
  Piece board[SQUARE_NB];
  Bitboard byTypeBB[PIECE_TYPE_NB];
@@ -195,6 +204,9 @@ private:
  Thread* thisThread;
  StateInfo* st;
  bool chess960;
+
+  // List of pieces used in NNUE evaluation function
+  EvalList evalList;
 };

 namespace PSQT {
@@ -207,28 +219,25 @@ 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 {
-  return byTypeBB[ALL_PIECES];
-}
-
-inline Bitboard Position::pieces(PieceType pt) const {
+inline Bitboard Position::pieces(PieceType pt = ALL_PIECES) 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 +245,11 @@ 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 {
@@ -248,7 +257,7 @@ 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 {
@@ -257,7 +266,7 @@ template<PieceType Pt> inline const Square* Position::squares(Color c) const {

 template<PieceType Pt> inline Square Position::square(Color c) const {
  assert(pieceCount[make_piece(c, Pt)] == 1);
-  return pieceList[make_piece(c, Pt)][0];
+  return squares<Pt>(c)[0];
 }

 inline Square Position::ep_square() const {
@@ -272,14 +281,14 @@ inline bool Position::can_castle(CastlingRights cr) const {
  return st->castlingRights & cr;
 }

-inline int Position::castling_rights(Color c) const {
-  return st->castlingRights & (c == WHITE ? WHITE_CASTLING : BLACK_CASTLING);
+inline CastlingRights Position::castling_rights(Color c) const {
+  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 +297,8 @@ 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 {
@@ -360,7 +351,7 @@ 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 +363,8 @@ inline int Position::rule50_count() const {
 }

 inline bool Position::opposite_bishops() const {
-  return   pieceCount[W_BISHOP] == 1
-        && pieceCount[B_BISHOP] == 1
+  return   count<BISHOP>(WHITE) == 1
+        && count<BISHOP>(BLACK) == 1
        && opposite_colors(square<BISHOP>(WHITE), square<BISHOP>(BLACK));
 }

@@ -403,8 +394,7 @@ inline Thread* Position::this_thread() const {
 inline void Position::put_piece(Piece pc, Square s) {

  board[s] = pc;
-  byTypeBB[ALL_PIECES] |= s;
-  byTypeBB[type_of(pc)] |= s;
+  byTypeBB[ALL_PIECES] |= byTypeBB[type_of(pc)] |= s;
  byColorBB[color_of(pc)] |= s;
  index[s] = pieceCount[pc]++;
  pieceList[pc][index[s]] = s;
@@ -412,12 +402,13 @@ inline void Position::put_piece(Piece pc, Square s) {
  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
  // 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.
+  Piece pc = board[s];
  byTypeBB[ALL_PIECES] ^= s;
  byTypeBB[type_of(pc)] ^= s;
  byColorBB[color_of(pc)] ^= s;
@@ -430,10 +421,11 @@ inline void Position::remove_piece(Piece pc, Square s) {
  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[]
  // is accessed just by known occupied squares.
+  Piece pc = board[from];
  Bitboard fromTo = from | to;
  byTypeBB[ALL_PIECES] ^= fromTo;
  byTypeBB[type_of(pc)] ^= fromTo;
@@ -449,4 +441,25 @@ inline void Position::do_move(Move m, StateInfo& newSt) {
  do_move(m, newSt, gives_check(m));
 }

+inline StateInfo* Position::state() const {
+
+  return st;
+}
+
+inline const EvalList* Position::eval_list() const {
+
+  return &evalList;
+}
+
+inline PieceId Position::piece_id_on(Square sq) const
+{
+
+  assert(piece_on(sq) != NO_PIECE);
+
+  PieceId pid = evalList.piece_id_list[sq];
+  assert(is_ok(pid));
+
+  return pid;
+}
+
 #endif // #ifndef POSITION_H_INCLUDED
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -21,11 +19,7 @@
 #include <algorithm>

 #include "types.h"
-
-Value PieceValue[PHASE_NB][PIECE_NB] = {
-  { VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg },
-  { VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg }
-};
+#include "bitboard.h"

 namespace PSQT {

@@ -95,9 +89,9 @@ constexpr Score PBonus[RANK_NB][FILE_NB] =
   { },
   { 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( -9,-10), S(-15,-10), S( 11,-10), S( 15,  4), S( 32,  4), S( 22,  3), S(  5, -6), S(-22, -4) },
-   { 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( 13,  9), S(  0,  4), S(-13,  3), S(  1,-12), S( 11,-12), S( -2, -6), S(-13, 13), S(  5,  8) },
-   { 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( -4,  6), S(-23, -2), S(  6, -8), S( 20, -4), S( 40,-13), S( 17,-12), S(  4,-10), S( -8, -9) },
+   { S( 13, 10), S(  0,  5), S(-13,  4), S(  1, -5), S( 11, -5), S( -2, -5), S(-13, 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( -8, 13) },
   { S( -7,  0), S(  7,-11), S( -3, 12), S(-13, 21), S(  5, 25), S(-16, 19), S( 10,  4), S( -8,  7) }
  };

@@ -105,24 +99,22 @@ constexpr Score PBonus[RANK_NB][FILE_NB] =

 Score psq[PIECE_NB][SQUARE_NB];

-// 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
-// tables are initialized by flipping and changing the sign of the white scores.
+
+// PSQT::init() initializes piece-square tables: the white halves of the tables are
+// copied from Bonus[] and PBonus[], adding the piece value, then the black halves of
+// 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];
-      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)
      {
-          File f = map_to_queenside(file_of(s));
-          psq[ pc][ s] = score + (type_of(pc) == PAWN ? PBonus[rank_of(s)][file_of(s)]
-                                                      : Bonus[pc][rank_of(s)][f]);
-          psq[~pc][~s] = -psq[pc][s];
+          File f = File(edge_distance(file_of(s)));
+          psq[ pc][s] = score + (type_of(pc) == PAWN ? PBonus[rank_of(s)][file_of(s)]
+                                                     : Bonus[pc][rank_of(s)][f]);
+          psq[~pc][flip_rank(s)] = -psq[pc][s];
      }
  }
 }
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -61,13 +59,13 @@ namespace {
  // Different node types, used as a template parameter
  enum NodeType { NonPV, PV };

-  constexpr uint64_t ttHitAverageWindow     = 4096;
-  constexpr uint64_t ttHitAverageResolution = 1024;
+  constexpr uint64_t TtHitAverageWindow     = 4096;
+  constexpr uint64_t TtHitAverageResolution = 1024;

  // Razor and futility margins
-  constexpr int RazorMargin = 531;
+  constexpr int RazorMargin = 527;
  Value futility_margin(Depth d, bool improving) {
-    return Value(217 * (d - improving));
+    return Value(227 * (d - improving));
  }

  // Reductions lookup table, initialized at startup
@@ -75,16 +73,16 @@ namespace {

  Depth reduction(bool i, Depth d, int mn) {
    int r = Reductions[d] * Reductions[mn];
-    return (r + 511) / 1024 + (!i && r > 1007);
+    return (r + 570) / 1024 + (!i && r > 1018);
  }

  constexpr int futility_move_count(bool improving, Depth depth) {
-    return (5 + depth * depth) * (1 + improving) / 2 - 1;
+    return (3 + depth * depth) / (2 - improving);
  }

  // History and stats update bonus, based on depth
  int stat_bonus(Depth d) {
-    return d > 15 ? -8 : 19 * d * d + 155 * d - 132;
+    return d > 15 ? 27 : 17 * d * d + 133 * d - 134;
  }

  // Add a small random component to draw evaluations to avoid 3fold-blindness
@@ -156,7 +154,7 @@ namespace {
  Value value_from_tt(Value v, int ply, int r50c);
  void update_pv(Move* pv, Move move, Move* childPv);
  void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus);
-  void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus);
+  void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus, int depth);
  void update_all_stats(const Position& pos, Stack* ss, Move bestMove, Value bestValue, Value beta, Square prevSq,
                        Move* quietsSearched, int quietCount, Move* capturesSearched, int captureCount, Depth depth);

@@ -194,7 +192,7 @@ namespace {
 void Search::init() {

  for (int i = 1; i < MAX_MOVES; ++i)
-      Reductions[i] = int((24.8 + std::log(Threads.size()) / 2) * std::log(i));
+      Reductions[i] = int((24.8 + std::log(Threads.size())) * std::log(i));
 }


@@ -227,6 +225,8 @@ void MainThread::search() {
  Time.init(Limits, us, rootPos.game_ply());
  TT.new_search();

+  Eval::verify_NNUE();
+
  if (rootMoves.empty())
  {
      rootMoves.emplace_back(MOVE_NONE);
@@ -236,14 +236,8 @@ void MainThread::search() {
  }
  else
  {
-      for (Thread* th : Threads)
-      {
-          th->bestMoveChanges = 0;
-          if (th != this)
-              th->start_searching();
-      }
-
-      Thread::search(); // Let's start searching!
+      Threads.start_searching(); // start non-main threads
+      Thread::search();          // main thread start searching
  }

  // When we reach the maximum depth, we can arrive here without a raise of
@@ -260,9 +254,7 @@ void MainThread::search() {
  Threads.stop = true;

  // Wait until all threads have finished
-  for (Thread* th : Threads)
-      if (th != this)
-          th->wait_for_search_finished();
+  Threads.wait_for_search_finished();

  // When playing in 'nodes as time' mode, subtract the searched nodes from
  // the available ones before exiting.
@@ -271,38 +263,13 @@ void MainThread::search() {

  Thread* bestThread = this;

-  // Check if there are threads with a better score than main thread
-  if (    Options["MultiPV"] == 1
+  if (   int(Options["MultiPV"]) == 1
      && !Limits.depth
-      && !(Skill(Options["Skill Level"]).enabled() || Options["UCI_LimitStrength"])
-      &&  rootMoves[0].pv[0] != MOVE_NONE)
-  {
-      std::map<Move, int64_t> votes;
-      Value minScore = this->rootMoves[0].score;
+      && !(Skill(Options["Skill Level"]).enabled() || int(Options["UCI_LimitStrength"]))
+      && rootMoves[0].pv[0] != MOVE_NONE)
+      bestThread = Threads.get_best_thread();

-      // Find out minimum score
-      for (Thread* th: Threads)
-          minScore = std::min(minScore, th->rootMoves[0].score);
-
-      // Vote according to score and depth, and select the best thread
-      for (Thread* th : Threads)
-      {
-          votes[th->rootMoves[0].pv[0]] +=
-              (th->rootMoves[0].score - minScore + 14) * int(th->completedDepth);
-
-          if (bestThread->rootMoves[0].score >= VALUE_MATE_IN_MAX_PLY)
-          {
-              // Make sure we pick the shortest mate
-              if (th->rootMoves[0].score > bestThread->rootMoves[0].score)
-                  bestThread = th;
-          }
-          else if (   th->rootMoves[0].score >= VALUE_MATE_IN_MAX_PLY
-                   || votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]])
-              bestThread = th;
-      }
-  }
-
-  previousScore = bestThread->rootMoves[0].score;
+  bestPreviousScore = bestThread->rootMoves[0].score;

  // Send again PV info if we have a new best thread
  if (bestThread != this)
@@ -348,15 +315,18 @@ void Thread::search() {

  if (mainThread)
  {
-      if (mainThread->previousScore == VALUE_INFINITE)
-          for (int i=0; i<4; ++i)
+      if (mainThread->bestPreviousScore == VALUE_INFINITE)
+          for (int i = 0; i < 4; ++i)
              mainThread->iterValue[i] = VALUE_ZERO;
      else
-          for (int i=0; i<4; ++i)
-              mainThread->iterValue[i] = mainThread->previousScore;
+          for (int i = 0; i < 4; ++i)
+              mainThread->iterValue[i] = mainThread->bestPreviousScore;
  }

-  size_t multiPV = Options["MultiPV"];
+  std::copy(&lowPlyHistory[2][0], &lowPlyHistory.back().back() + 1, &lowPlyHistory[0][0]);
+  std::fill(&lowPlyHistory[MAX_LPH - 2][0], &lowPlyHistory.back().back() + 1, 0);
+
+  size_t multiPV = size_t(Options["MultiPV"]);

  // Pick integer skill levels, but non-deterministically round up or down
  // such that the average integer skill corresponds to the input floating point one.
@@ -365,7 +335,7 @@ void Thread::search() {
  // for match (TC 60+0.6) results spanning a wide range of k values.
  PRNG rng(now());
  double floatLevel = Options["UCI_LimitStrength"] ?
-                        clamp(std::pow((Options["UCI_Elo"] - 1346.6) / 143.4, 1 / 0.806), 0.0, 20.0) :
+                      Utility::clamp(std::pow((Options["UCI_Elo"] - 1346.6) / 143.4, 1 / 0.806), 0.0, 20.0) :
                        double(Options["Skill Level"]);
  int intLevel = int(floatLevel) +
                 ((floatLevel - int(floatLevel)) * 1024 > rng.rand<unsigned>() % 1024  ? 1 : 0);
@@ -377,7 +347,7 @@ void Thread::search() {
      multiPV = std::max(multiPV, (size_t)4);

  multiPV = std::min(multiPV, rootMoves.size());
-  ttHitAverage = ttHitAverageWindow * ttHitAverageResolution / 2;
+  ttHitAverage = TtHitAverageWindow * TtHitAverageResolution / 2;

  int ct = int(Options["Contempt"]) * PawnValueEg / 100; // From centipawns

@@ -432,13 +402,13 @@ void Thread::search() {
          // Reset aspiration window starting size
          if (rootDepth >= 4)
          {
-              Value previousScore = rootMoves[pvIdx].previousScore;
-              delta = Value(21 + abs(previousScore) / 256);
-              alpha = std::max(previousScore - delta,-VALUE_INFINITE);
-              beta  = std::min(previousScore + delta, VALUE_INFINITE);
+              Value prev = rootMoves[pvIdx].previousScore;
+              delta = Value(19);
+              alpha = std::max(prev - delta,-VALUE_INFINITE);
+              beta  = std::min(prev + delta, VALUE_INFINITE);

              // Adjust contempt based on root move's previousScore (dynamic contempt)
-              int dct = ct + (102 - ct / 2) * previousScore / (abs(previousScore) + 157);
+              int dct = ct + (110 - ct / 2) * prev / (abs(prev) + 140);

              contempt = (us == WHITE ?  make_score(dct, dct / 2)
                                      : -make_score(dct, dct / 2));
@@ -536,13 +506,13 @@ void Thread::search() {
          && !Threads.stop
          && !mainThread->stopOnPonderhit)
      {
-          double fallingEval = (332 +  6 * (mainThread->previousScore - bestValue)
-                                    +  6 * (mainThread->iterValue[iterIdx]  - bestValue)) / 704.0;
-          fallingEval = clamp(fallingEval, 0.5, 1.5);
+          double fallingEval = (296 + 6 * (mainThread->bestPreviousScore - bestValue)
+                                    + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 725.0;
+          fallingEval = Utility::clamp(fallingEval, 0.5, 1.5);

          // If the bestMove is stable over several iterations, reduce time accordingly
-          timeReduction = lastBestMoveDepth + 9 < completedDepth ? 1.94 : 0.91;
-          double reduction = (1.41 + mainThread->previousTimeReduction) / (2.27 * timeReduction);
+          timeReduction = lastBestMoveDepth + 10 < completedDepth ? 1.92 : 0.95;
+          double reduction = (1.47 + mainThread->previousTimeReduction) / (2.22 * timeReduction);

          // Use part of the gained time from a previous stable move for the current move
          for (Thread* th : Threads)
@@ -552,9 +522,11 @@ void Thread::search() {
          }
          double bestMoveInstability = 1 + totBestMoveChanges / Threads.size();

-          // Stop the search if we have only one legal move, or if available time elapsed
-          if (   rootMoves.size() == 1
-              || Time.elapsed() > Time.optimum() * fallingEval * reduction * bestMoveInstability)
+          double totalTime = rootMoves.size() == 1 ? 0 :
+                             Time.optimum() * fallingEval * reduction * bestMoveInstability;
+
+          // Stop the search if we have exceeded the totalTime, at least 1ms search
+          if (Time.elapsed() > totalTime)
          {
              // If we are allowed to ponder do not stop the search now but
              // keep pondering until the GUI sends "ponderhit" or "stop".
@@ -565,7 +537,7 @@ void Thread::search() {
          }
          else if (   Threads.increaseDepth
                   && !mainThread->ponder
-                   && Time.elapsed() > Time.optimum() * fallingEval * reduction * bestMoveInstability * 0.6)
+                   && Time.elapsed() > totalTime * 0.56)
                   Threads.increaseDepth = false;
          else
                   Threads.increaseDepth = true;
@@ -624,15 +596,16 @@ namespace {
    Key posKey;
    Move ttMove, move, excludedMove, bestMove;
    Depth extension, newDepth;
-    Value bestValue, value, ttValue, eval, maxValue;
-    bool ttHit, ttPv, inCheck, givesCheck, improving, didLMR, priorCapture;
-    bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture, singularLMR;
+    Value bestValue, value, ttValue, eval, maxValue, probcutBeta;
+    bool ttHit, ttPv, formerPv, givesCheck, improving, didLMR, priorCapture;
+    bool captureOrPromotion, doFullDepthSearch, moveCountPruning,
+         ttCapture, singularQuietLMR;
    Piece movedPiece;
    int moveCount, captureCount, quietCount;

    // Step 1. Initialize node
    Thread* thisThread = pos.this_thread();
-    inCheck = pos.checkers();
+    ss->inCheck = pos.checkers();
    priorCapture = pos.captured_piece();
    Color us = pos.side_to_move();
    moveCount = captureCount = quietCount = ss->moveCount = 0;
@@ -653,8 +626,8 @@ namespace {
        if (   Threads.stop.load(std::memory_order_relaxed)
            || pos.is_draw(ss->ply)
            || ss->ply >= MAX_PLY)
-            return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos)
-                                                    : value_draw(pos.this_thread());
+            return (ss->ply >= MAX_PLY && !ss->inCheck) ? evaluate(pos)
+                                                        : value_draw(pos.this_thread());

        // Step 3. Mate distance pruning. Even if we mate at the next move our score
        // would be at best mate_in(ss->ply+1), but if alpha is already bigger because
@@ -689,15 +662,24 @@ namespace {
    // search to overwrite a previous full search TT value, so we use a different
    // position key in case of an excluded move.
    excludedMove = ss->excludedMove;
-    posKey = pos.key() ^ Key(excludedMove << 16); // Isn't a very good hash
+    posKey = excludedMove == MOVE_NONE ? pos.key() : pos.key() ^ make_key(excludedMove);
    tte = TT.probe(posKey, ttHit);
    ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE;
    ttMove =  rootNode ? thisThread->rootMoves[thisThread->pvIdx].pv[0]
            : ttHit    ? tte->move() : MOVE_NONE;
    ttPv = PvNode || (ttHit && tte->is_pv());
+    formerPv = ttPv && !PvNode;
+
+    if (   ttPv
+        && depth > 12
+        && ss->ply - 1 < MAX_LPH
+        && !priorCapture
+        && is_ok((ss-1)->currentMove))
+        thisThread->lowPlyHistory[ss->ply - 1][from_to((ss-1)->currentMove)] << stat_bonus(depth - 5);
+
    // thisThread->ttHitAverage can be used to approximate the running average of ttHit
-    thisThread->ttHitAverage =   (ttHitAverageWindow - 1) * thisThread->ttHitAverage / ttHitAverageWindow
-                                + ttHitAverageResolution * ttHit;
+    thisThread->ttHitAverage =   (TtHitAverageWindow - 1) * thisThread->ttHitAverage / TtHitAverageWindow
+                                + TtHitAverageResolution * ttHit;

    // At non-PV nodes we check for an early TT cutoff
    if (  !PvNode
@@ -713,7 +695,7 @@ namespace {
            if (ttValue >= beta)
            {
                if (!pos.capture_or_promotion(ttMove))
-                    update_quiet_stats(pos, ss, ttMove, stat_bonus(depth));
+                    update_quiet_stats(pos, ss, ttMove, stat_bonus(depth), depth);

                // Extra penalty for early quiet moves of the previous ply
                if ((ss-1)->moveCount <= 2 && !priorCapture)
@@ -755,9 +737,10 @@ namespace {

                int drawScore = TB::UseRule50 ? 1 : 0;

-                value =  wdl < -drawScore ? -VALUE_MATE + MAX_PLY + ss->ply + 1
-                       : wdl >  drawScore ?  VALUE_MATE - MAX_PLY - ss->ply - 1
-                                          :  VALUE_DRAW + 2 * wdl * drawScore;
+                // use the range VALUE_MATE_IN_MAX_PLY to VALUE_TB_WIN_IN_MAX_PLY to score
+                value =  wdl < -drawScore ? VALUE_MATED_IN_MAX_PLY + ss->ply + 1
+                       : wdl >  drawScore ? VALUE_MATE_IN_MAX_PLY - ss->ply - 1
+                                          : VALUE_DRAW + 2 * wdl * drawScore;

                Bound b =  wdl < -drawScore ? BOUND_UPPER
                         : wdl >  drawScore ? BOUND_LOWER : BOUND_EXACT;
@@ -783,12 +766,15 @@ namespace {
        }
    }

+    CapturePieceToHistory& captureHistory = thisThread->captureHistory;
+
    // Step 6. Static evaluation of the position
-    if (inCheck)
+    if (ss->inCheck)
    {
+        // Skip early pruning when in check
        ss->staticEval = eval = VALUE_NONE;
        improving = false;
-        goto moves_loop;  // Skip early pruning when in check
+        goto moves_loop;
    }
    else if (ttHit)
    {
@@ -814,19 +800,19 @@ namespace {
            ss->staticEval = eval = evaluate(pos) + bonus;
        }
        else
-            ss->staticEval = eval = -(ss-1)->staticEval + 2 * Eval::Tempo;
+            ss->staticEval = eval = -(ss-1)->staticEval + 2 * Tempo;

        tte->save(posKey, VALUE_NONE, ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval);
    }

    // Step 7. Razoring (~1 Elo)
    if (   !rootNode // The required rootNode PV handling is not available in qsearch
-        &&  depth < 2
+        &&  depth == 1
        &&  eval <= alpha - RazorMargin)
        return qsearch<NT>(pos, ss, alpha, beta);

-    improving =  (ss-2)->staticEval == VALUE_NONE ? (ss->staticEval >= (ss-4)->staticEval
-              || (ss-4)->staticEval == VALUE_NONE) : ss->staticEval >= (ss-2)->staticEval;
+    improving =  (ss-2)->staticEval == VALUE_NONE ? (ss->staticEval > (ss-4)->staticEval
+              || (ss-4)->staticEval == VALUE_NONE) : ss->staticEval > (ss-2)->staticEval;

    // Step 8. Futility pruning: child node (~50 Elo)
    if (   !PvNode
@@ -838,10 +824,10 @@ namespace {
    // Step 9. Null move search with verification search (~40 Elo)
    if (   !PvNode
        && (ss-1)->currentMove != MOVE_NULL
-        && (ss-1)->statScore < 23397
+        && (ss-1)->statScore < 23824
        &&  eval >= beta
        &&  eval >= ss->staticEval
-        &&  ss->staticEval >= beta - 32 * depth + 292 - improving * 30
+        &&  ss->staticEval >= beta - 33 * depth - 33 * improving + 112 * ttPv + 311
        && !excludedMove
        &&  pos.non_pawn_material(us)
        && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@@ -849,7 +835,7 @@ namespace {
        assert(eval - beta >= 0);

        // Null move dynamic reduction based on depth and value
-        Depth R = (854 + 68 * depth) / 258 + std::min(int(eval - beta) / 192, 3);
+        Depth R = (737 + 77 * depth) / 246 + std::min(int(eval - beta) / 192, 3);

        ss->currentMove = MOVE_NULL;
        ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
@@ -862,8 +848,8 @@ namespace {

        if (nullValue >= beta)
        {
-            // Do not return unproven mate scores
-            if (nullValue >= VALUE_MATE_IN_MAX_PLY)
+            // Do not return unproven mate or TB scores
+            if (nullValue >= VALUE_TB_WIN_IN_MAX_PLY)
                nullValue = beta;

            if (thisThread->nmpMinPly || (abs(beta) < VALUE_KNOWN_WIN && depth < 13))
@@ -885,18 +871,32 @@ namespace {
        }
    }

+    probcutBeta = beta + 176 - 49 * improving;
+
    // Step 10. ProbCut (~10 Elo)
    // If we have a good enough capture and a reduced search returns a value
    // much above beta, we can (almost) safely prune the previous move.
    if (   !PvNode
-        &&  depth >= 5
-        &&  abs(beta) < VALUE_MATE_IN_MAX_PLY)
+        &&  depth > 4
+        &&  abs(beta) < VALUE_TB_WIN_IN_MAX_PLY
+        && !(   ttHit
+             && tte->depth() >= depth - 3
+             && ttValue != VALUE_NONE
+             && ttValue < probcutBeta))
    {
-        Value raisedBeta = std::min(beta + 189 - 45 * improving, VALUE_INFINITE);
-        MovePicker mp(pos, ttMove, raisedBeta - ss->staticEval, &thisThread->captureHistory);
+        if (   ttHit
+            && tte->depth() >= depth - 3
+            && ttValue != VALUE_NONE
+            && ttValue >= probcutBeta
+            && ttMove
+            && pos.capture_or_promotion(ttMove))
+            return probcutBeta;
+
+        assert(probcutBeta < VALUE_INFINITE);
+        MovePicker mp(pos, ttMove, probcutBeta - ss->staticEval, &captureHistory);
        int probCutCount = 0;

-        while (  (move = mp.next_move()) != MOVE_NONE
+        while (   (move = mp.next_move()) != MOVE_NONE
               && probCutCount < 2 + 2 * cutNode)
            if (move != excludedMove && pos.legal(move))
            {
@@ -907,7 +907,7 @@ namespace {
                probCutCount++;

                ss->currentMove = move;
-                ss->continuationHistory = &thisThread->continuationHistory[inCheck]
+                ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
                                                                          [captureOrPromotion]
                                                                          [pos.moved_piece(move)]
                                                                          [to_sq(move)];
@@ -915,16 +915,24 @@ namespace {
                pos.do_move(move, st);

                // Perform a preliminary qsearch to verify that the move holds
-                value = -qsearch<NonPV>(pos, ss+1, -raisedBeta, -raisedBeta+1);
+                value = -qsearch<NonPV>(pos, ss+1, -probcutBeta, -probcutBeta+1);

                // If the qsearch held, perform the regular search
-                if (value >= raisedBeta)
-                    value = -search<NonPV>(pos, ss+1, -raisedBeta, -raisedBeta+1, depth - 4, !cutNode);
+                if (value >= probcutBeta)
+                    value = -search<NonPV>(pos, ss+1, -probcutBeta, -probcutBeta+1, depth - 4, !cutNode);

                pos.undo_move(move);

-                if (value >= raisedBeta)
+                if (value >= probcutBeta)
+                {
+                    if ( !(ttHit
+                       && tte->depth() >= depth - 3
+                       && ttValue != VALUE_NONE))
+                        tte->save(posKey, value_to_tt(value, ss->ply), ttPv,
+                            BOUND_LOWER,
+                            depth - 3, move, ss->staticEval);
                    return value;
+                }
            }
    }

@@ -947,13 +955,15 @@ moves_loop: // When in check, search starts from here
    Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq];

    MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory,
-                                      &thisThread->captureHistory,
+                                      &thisThread->lowPlyHistory,
+                                      &captureHistory,
                                      contHist,
                                      countermove,
-                                      ss->killers);
+                                      ss->killers,
+                                      ss->ply);

    value = bestValue;
-    singularLMR = moveCountPruning = false;
+    singularQuietLMR = moveCountPruning = false;
    ttCapture = ttMove && pos.capture_or_promotion(ttMove);

    // Mark this node as being searched
@@ -996,17 +1006,17 @@ moves_loop: // When in check, search starts from here
      // Step 13. Pruning at shallow depth (~200 Elo)
      if (  !rootNode
          && pos.non_pawn_material(us)
-          && bestValue > VALUE_MATED_IN_MAX_PLY)
+          && bestValue > VALUE_TB_LOSS_IN_MAX_PLY)
      {
          // Skip quiet moves if movecount exceeds our FutilityMoveCount threshold
          moveCountPruning = moveCount >= futility_move_count(improving, depth);

+          // Reduced depth of the next LMR search
+          int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0);
+
          if (   !captureOrPromotion
              && !givesCheck)
          {
-              // Reduced depth of the next LMR search
-              int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0);
-
              // Countermoves based pruning (~20 Elo)
              if (   lmrDepth < 4 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1)
                  && (*contHist[0])[movedPiece][to_sq(move)] < CounterMovePruneThreshold
@@ -1015,20 +1025,40 @@ moves_loop: // When in check, search starts from here

              // Futility pruning: parent node (~5 Elo)
              if (   lmrDepth < 6
-                  && !inCheck
-                  && ss->staticEval + 235 + 172 * lmrDepth <= alpha
-                  &&  thisThread->mainHistory[us][from_to(move)]
-                    + (*contHist[0])[movedPiece][to_sq(move)]
+                  && !ss->inCheck
+                  && ss->staticEval + 284 + 188 * lmrDepth <= alpha
+                  &&  (*contHist[0])[movedPiece][to_sq(move)]
                    + (*contHist[1])[movedPiece][to_sq(move)]
-                    + (*contHist[3])[movedPiece][to_sq(move)] < 25000)
+                    + (*contHist[3])[movedPiece][to_sq(move)]
+                    + (*contHist[5])[movedPiece][to_sq(move)] / 2 < 28388)
                  continue;

              // Prune moves with negative SEE (~20 Elo)
-              if (!pos.see_ge(move, Value(-(32 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth)))
+              if (!pos.see_ge(move, Value(-(29 - std::min(lmrDepth, 17)) * lmrDepth * lmrDepth)))
                  continue;
          }
-          else if (!pos.see_ge(move, Value(-194) * depth)) // (~25 Elo)
+          else
+          {
+              // Capture history based pruning when the move doesn't give check
+              if (   !givesCheck
+                  && lmrDepth < 1
+                  && captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] < 0)
                  continue;
+
+              // Futility pruning for captures
+              if (   !givesCheck
+                  && lmrDepth < 6
+                  && !(PvNode && abs(bestValue) < 2)
+                  && PieceValue[MG][type_of(movedPiece)] >= PieceValue[MG][type_of(pos.piece_on(to_sq(move)))]
+                  && !ss->inCheck
+                  && ss->staticEval + 267 + 391 * lmrDepth
+                     + PieceValue[MG][type_of(pos.piece_on(to_sq(move)))] <= alpha)
+                  continue;
+
+              // See based pruning
+              if (!pos.see_ge(move, Value(-202) * depth)) // (~25 Elo)
+                  continue;
+          }
      }

      // Step 14. Extensions (~75 Elo)
@@ -1037,7 +1067,7 @@ moves_loop: // When in check, search starts from here
      // search of (alpha-s, beta-s), and just one fails high on (alpha, beta),
      // then that move is singular and should be extended. To verify this we do
      // a reduced search on all the other moves but the ttMove and if the
-      // result is lower than ttValue minus a margin then we will extend the ttMove.
+      // result is lower than ttValue minus a margin, then we will extend the ttMove.
      if (    depth >= 6
          &&  move == ttMove
          && !rootNode
@@ -1048,16 +1078,16 @@ moves_loop: // When in check, search starts from here
          &&  tte->depth() >= depth - 3
          &&  pos.legal(move))
      {
-          Value singularBeta = ttValue - 2 * depth;
-          Depth halfDepth = depth / 2;
+          Value singularBeta = ttValue - ((formerPv + 4) * depth) / 2;
+          Depth singularDepth = (depth - 1 + 3 * formerPv) / 2;
          ss->excludedMove = move;
-          value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, halfDepth, cutNode);
+          value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, singularDepth, cutNode);
          ss->excludedMove = MOVE_NONE;

          if (value < singularBeta)
          {
              extension = 1;
-              singularLMR = true;
+              singularQuietLMR = !ttCapture;
          }

          // Multi-cut pruning
@@ -1067,6 +1097,18 @@ moves_loop: // When in check, search starts from here
          // a soft bound.
          else if (singularBeta >= beta)
              return singularBeta;
+
+          // If the eval of ttMove is greater than beta we try also if there is another
+          // move that pushes it over beta, if so also produce a cutoff.
+          else if (ttValue >= beta)
+          {
+              ss->excludedMove = move;
+              value = search<NonPV>(pos, ss, beta - 1, beta, (depth + 3) / 2, cutNode);
+              ss->excludedMove = MOVE_NONE;
+
+              if (value >= beta)
+                  return beta;
+          }
      }

      // Check extension (~2 Elo)
@@ -1104,7 +1146,7 @@ moves_loop: // When in check, search starts from here

      // Update the current move (this must be done after singular extension search)
      ss->currentMove = move;
-      ss->continuationHistory = &thisThread->continuationHistory[inCheck]
+      ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
                                                                [captureOrPromotion]
                                                                [movedPiece]
                                                                [to_sq(move)];
@@ -1115,21 +1157,28 @@ moves_loop: // When in check, search starts from here
      // Step 16. Reduced depth search (LMR, ~200 Elo). If the move fails high it will be
      // re-searched at full depth.
      if (    depth >= 3
-          &&  moveCount > 1 + rootNode + (rootNode && bestValue < alpha)
+          &&  moveCount > 1 + 2 * rootNode
          && (!rootNode || thisThread->best_move_count(move) == 0)
          && (  !captureOrPromotion
              || moveCountPruning
              || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha
              || cutNode
-              || thisThread->ttHitAverage < 375 * ttHitAverageResolution * ttHitAverageWindow / 1024))
+              || thisThread->ttHitAverage < 415 * TtHitAverageResolution * TtHitAverageWindow / 1024))
      {
          Depth r = reduction(improving, depth, moveCount);

-          // Decrease reduction if the ttHit running average is large
-          if (thisThread->ttHitAverage > 500 * ttHitAverageResolution * ttHitAverageWindow / 1024)
+          // Decrease reduction at non-check cut nodes for second move at low depths
+          if (   cutNode
+              && depth <= 10
+              && moveCount <= 2
+              && !ss->inCheck)
              r--;

-          // Reduction if other threads are searching this position.
+          // Decrease reduction if the ttHit running average is large
+          if (thisThread->ttHitAverage > 473 * TtHitAverageResolution * TtHitAverageWindow / 1024)
+              r--;
+
+          // Reduction if other threads are searching this position
          if (th.marked())
              r++;

@@ -1137,13 +1186,16 @@ moves_loop: // When in check, search starts from here
          if (ttPv)
              r -= 2;

+          if (moveCountPruning && !formerPv)
+              r++;
+
          // Decrease reduction if opponent's move count is high (~5 Elo)
-          if ((ss-1)->moveCount > 14)
+          if ((ss-1)->moveCount > 13)
              r--;

          // Decrease reduction if ttMove has been singularly extended (~3 Elo)
-          if (singularLMR)
-              r -= 2;
+          if (singularQuietLMR)
+              r -= 1 + formerPv;

          if (!captureOrPromotion)
          {
@@ -1160,44 +1212,50 @@ moves_loop: // When in check, search starts from here
              // hence break make_move(). (~2 Elo)
              else if (    type_of(move) == NORMAL
                       && !pos.see_ge(reverse_move(move)))
-                  r -= 2;
+                  r -= 2 + ttPv - (type_of(movedPiece) == PAWN);

              ss->statScore =  thisThread->mainHistory[us][from_to(move)]
                             + (*contHist[0])[movedPiece][to_sq(move)]
                             + (*contHist[1])[movedPiece][to_sq(move)]
                             + (*contHist[3])[movedPiece][to_sq(move)]
-                             - 4926;
-
-              // Reset statScore to zero if negative and most stats shows >= 0
-              if (    ss->statScore < 0
-                  && (*contHist[0])[movedPiece][to_sq(move)] >= 0
-                  && (*contHist[1])[movedPiece][to_sq(move)] >= 0
-                  && thisThread->mainHistory[us][from_to(move)] >= 0)
-                  ss->statScore = 0;
+                             - 4826;

              // Decrease/increase reduction by comparing opponent's stat score (~10 Elo)
-              if (ss->statScore >= -102 && (ss-1)->statScore < -114)
+              if (ss->statScore >= -100 && (ss-1)->statScore < -112)
                  r--;

-              else if ((ss-1)->statScore >= -116 && ss->statScore < -154)
+              else if ((ss-1)->statScore >= -125 && ss->statScore < -138)
                  r++;

              // Decrease/increase reduction for moves with a good/bad history (~30 Elo)
-              r -= ss->statScore / 16384;
+              r -= ss->statScore / 14615;
+          }
+          else
+          {
+            // Increase reduction for captures/promotions if late move and at low depth
+            if (depth < 8 && moveCount > 2)
+                r++;
+
+            // Unless giving check, this capture is likely bad
+            if (   !givesCheck
+                && ss->staticEval + PieceValue[EG][pos.captured_piece()] + 211 * depth <= alpha)
+                r++;
          }

-          // Increase reduction for captures/promotions if late move and at low depth
-          else if (depth < 8 && moveCount > 2)
-              r++;
-
-          Depth d = clamp(newDepth - r, 1, newDepth);
+          Depth d = Utility::clamp(newDepth - r, 1, newDepth);

          value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);

-          doFullDepthSearch = (value > alpha && d != newDepth), didLMR = true;
+          doFullDepthSearch = value > alpha && d != newDepth;
+
+          didLMR = true;
      }
      else
-          doFullDepthSearch = !PvNode || moveCount > 1, didLMR = false;
+      {
+          doFullDepthSearch = !PvNode || moveCount > 1;
+
+          didLMR = false;
+      }

      // Step 17. Full depth search when LMR is skipped or fails high
      if (doFullDepthSearch)
@@ -1257,7 +1315,7 @@ moves_loop: // When in check, search starts from here
                  rm.pv.push_back(*m);

              // We record how often the best move has been changed in each
-              // iteration. This information is used for time management: When
+              // iteration. This information is used for time management: when
              // the best move changes frequently, we allocate some more time.
              if (moveCount > 1)
                  ++thisThread->bestMoveChanges;
@@ -1314,11 +1372,11 @@ moves_loop: // When in check, search starts from here
    // must be a mate or a stalemate. If we are in a singular extension search then
    // return a fail low score.

-    assert(moveCount || !inCheck || excludedMove || !MoveList<LEGAL>(pos).size());
+    assert(moveCount || !ss->inCheck || excludedMove || !MoveList<LEGAL>(pos).size());

    if (!moveCount)
        bestValue = excludedMove ? alpha
-                   :     inCheck ? mated_in(ss->ply) : VALUE_DRAW;
+                   :     ss->inCheck ? mated_in(ss->ply) : VALUE_DRAW;

    else if (bestMove)
        update_all_stats(pos, ss, bestMove, bestValue, beta, prevSq,
@@ -1332,7 +1390,7 @@ moves_loop: // When in check, search starts from here
    if (PvNode)
        bestValue = std::min(bestValue, maxValue);

-    if (!excludedMove)
+    if (!excludedMove && !(rootNode && thisThread->pvIdx))
        tte->save(posKey, value_to_tt(bestValue, ss->ply), ttPv,
                  bestValue >= beta ? BOUND_LOWER :
                  PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
@@ -1362,7 +1420,7 @@ moves_loop: // When in check, search starts from here
    Move ttMove, move, bestMove;
    Depth ttDepth;
    Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha;
-    bool ttHit, pvHit, inCheck, givesCheck, captureOrPromotion, evasionPrunable;
+    bool ttHit, pvHit, givesCheck, captureOrPromotion;
    int moveCount;

    if (PvNode)
@@ -1375,20 +1433,20 @@ moves_loop: // When in check, search starts from here
    Thread* thisThread = pos.this_thread();
    (ss+1)->ply = ss->ply + 1;
    bestMove = MOVE_NONE;
-    inCheck = pos.checkers();
+    ss->inCheck = pos.checkers();
    moveCount = 0;

    // Check for an immediate draw or maximum ply reached
    if (   pos.is_draw(ss->ply)
        || ss->ply >= MAX_PLY)
-        return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos) : VALUE_DRAW;
+        return (ss->ply >= MAX_PLY && !ss->inCheck) ? evaluate(pos) : VALUE_DRAW;

    assert(0 <= ss->ply && ss->ply < MAX_PLY);

    // Decide whether or not to include checks: this fixes also the type of
    // TT entry depth that we are going to use. Note that in qsearch we use
    // only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS.
-    ttDepth = inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS
+    ttDepth = ss->inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS
                                                  : DEPTH_QS_NO_CHECKS;
    // Transposition table lookup
    posKey = pos.key();
@@ -1406,7 +1464,7 @@ moves_loop: // When in check, search starts from here
        return ttValue;

    // Evaluate the position statically
-    if (inCheck)
+    if (ss->inCheck)
    {
        ss->staticEval = VALUE_NONE;
        bestValue = futilityBase = -VALUE_INFINITE;
@@ -1427,13 +1485,13 @@ moves_loop: // When in check, search starts from here
        else
            ss->staticEval = bestValue =
            (ss-1)->currentMove != MOVE_NULL ? evaluate(pos)
-                                             : -(ss-1)->staticEval + 2 * Eval::Tempo;
+                                             : -(ss-1)->staticEval + 2 * Tempo;

        // Stand pat. Return immediately if static value is at least beta
        if (bestValue >= beta)
        {
            if (!ttHit)
-                tte->save(posKey, value_to_tt(bestValue, ss->ply), pvHit, BOUND_LOWER,
+                tte->save(posKey, value_to_tt(bestValue, ss->ply), false, BOUND_LOWER,
                          DEPTH_NONE, MOVE_NONE, ss->staticEval);

            return bestValue;
@@ -1442,7 +1500,7 @@ moves_loop: // When in check, search starts from here
        if (PvNode && bestValue > alpha)
            alpha = bestValue;

-        futilityBase = bestValue + 154;
+        futilityBase = bestValue + 141;
    }

    const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,
@@ -1451,8 +1509,8 @@ moves_loop: // When in check, search starts from here

    // Initialize a MovePicker object for the current position, and prepare
    // to search the moves. Because the depth is <= 0 here, only captures,
-    // queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will
-    // be generated.
+    // queen and checking knight promotions, and other checks(only if depth >= DEPTH_QS_CHECKS)
+    // will be generated.
    MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory,
                                      &thisThread->captureHistory,
                                      contHist,
@@ -1469,7 +1527,7 @@ moves_loop: // When in check, search starts from here
      moveCount++;

      // Futility pruning
-      if (   !inCheck
+      if (   !ss->inCheck
          && !givesCheck
          &&  futilityBase > -VALUE_KNOWN_WIN
          && !pos.advanced_pawn_push(move))
@@ -1491,14 +1549,8 @@ moves_loop: // When in check, search starts from here
          }
      }

-      // Detect non-capture evasions that are candidates to be pruned
-      evasionPrunable =    inCheck
-                       &&  (depth != 0 || moveCount > 2)
-                       &&  bestValue > VALUE_MATED_IN_MAX_PLY
-                       && !pos.capture(move);
-
-      // Don't search moves with negative SEE values
-      if (  (!inCheck || evasionPrunable) && !pos.see_ge(move))
+      // Do not search moves with negative SEE values
+      if (  !ss->inCheck && !pos.see_ge(move))
          continue;

      // Speculative prefetch as early as possible
@@ -1512,7 +1564,7 @@ moves_loop: // When in check, search starts from here
      }

      ss->currentMove = move;
-      ss->continuationHistory = &thisThread->continuationHistory[inCheck]
+      ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
                                                                [captureOrPromotion]
                                                                [pos.moved_piece(move)]
                                                                [to_sq(move)];
@@ -1544,9 +1596,9 @@ moves_loop: // When in check, search starts from here
       }
    }

-    // All legal moves have been searched. A special case: If we're in check
+    // All legal moves have been searched. A special case: if we're in check
    // and no legal moves were found, it is checkmate.
-    if (inCheck && bestValue == -VALUE_INFINITE)
+    if (ss->inCheck && bestValue == -VALUE_INFINITE)
        return mated_in(ss->ply); // Plies to mate from the root

    tte->save(posKey, value_to_tt(bestValue, ss->ply), pvHit,
@@ -1560,28 +1612,47 @@ moves_loop: // When in check, search starts from here
  }


-  // value_to_tt() adjusts a mate score from "plies to mate from the root" to
-  // "plies to mate from the current position". Non-mate scores are unchanged.
+  // value_to_tt() adjusts a mate or TB score from "plies to mate from the root" to
+  // "plies to mate from the current position". Standard scores are unchanged.
  // The function is called before storing a value in the transposition table.

  Value value_to_tt(Value v, int ply) {

    assert(v != VALUE_NONE);

-    return  v >= VALUE_MATE_IN_MAX_PLY  ? v + ply
-          : v <= VALUE_MATED_IN_MAX_PLY ? v - ply : v;
+    return  v >= VALUE_TB_WIN_IN_MAX_PLY  ? v + ply
+          : v <= VALUE_TB_LOSS_IN_MAX_PLY ? v - ply : v;
  }


-  // value_from_tt() is the inverse of value_to_tt(): It adjusts a mate score
-  // from the transposition table (which refers to the plies to mate/be mated
-  // from current position) to "plies to mate/be mated from the root".
+  // value_from_tt() is the inverse of value_to_tt(): it adjusts a mate or TB score
+  // from the transposition table (which refers to the plies to mate/be mated from
+  // current position) to "plies to mate/be mated (TB win/loss) from the root". However,
+  // for mate scores, to avoid potentially false mate scores related to the 50 moves rule
+  // and the graph history interaction, we return an optimal TB score instead.

  Value value_from_tt(Value v, int ply, int r50c) {

-    return  v == VALUE_NONE             ? VALUE_NONE
-          : v >= VALUE_MATE_IN_MAX_PLY  ? VALUE_MATE - v > 99 - r50c ? VALUE_MATE_IN_MAX_PLY  : v - ply
-          : v <= VALUE_MATED_IN_MAX_PLY ? VALUE_MATE + v > 99 - r50c ? VALUE_MATED_IN_MAX_PLY : v + ply : v;
+    if (v == VALUE_NONE)
+        return VALUE_NONE;
+
+    if (v >= VALUE_TB_WIN_IN_MAX_PLY)  // TB win or better
+    {
+        if (v >= VALUE_MATE_IN_MAX_PLY && VALUE_MATE - v > 99 - r50c)
+            return VALUE_MATE_IN_MAX_PLY - 1; // do not return a potentially false mate score
+
+        return v - ply;
+    }
+
+    if (v <= VALUE_TB_LOSS_IN_MAX_PLY) // TB loss or worse
+    {
+        if (v <= VALUE_MATED_IN_MAX_PLY && VALUE_MATE + v > 99 - r50c)
+            return VALUE_MATED_IN_MAX_PLY + 1; // do not return a potentially false mate score
+
+        return v + ply;
+    }
+
+    return v;
  }


@@ -1613,7 +1684,7 @@ moves_loop: // When in check, search starts from here

    if (!pos.capture_or_promotion(bestMove))
    {
-        update_quiet_stats(pos, ss, bestMove, bonus2);
+        update_quiet_stats(pos, ss, bestMove, bonus2, depth);

        // Decrease all the non-best quiet moves
        for (int i = 0; i < quietCount; ++i)
@@ -1641,19 +1712,23 @@ moves_loop: // When in check, search starts from here


  // update_continuation_histories() updates histories of the move pairs formed
-  // by moves at ply -1, -2, and -4 with current move.
+  // by moves at ply -1, -2, -4, and -6 with current move.

  void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) {

    for (int i : {1, 2, 4, 6})
+    {
+        if (ss->inCheck && i > 2)
+            break;
        if (is_ok((ss-i)->currentMove))
            (*(ss-i)->continuationHistory)[pc][to] << bonus;
+    }
  }


  // update_quiet_stats() updates move sorting heuristics

-  void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus) {
+  void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus, int depth) {

    if (ss->killers[0] != move)
    {
@@ -1674,6 +1749,9 @@ moves_loop: // When in check, search starts from here
        Square prevSq = to_sq((ss-1)->currentMove);
        thisThread->counterMoves[pos.piece_on(prevSq)][prevSq] = move;
    }
+
+    if (depth > 11 && ss->ply < MAX_LPH)
+        thisThread->lowPlyHistory[ss->ply][from_to(move)] << stat_bonus(depth - 6);
  }

  // When playing with strength handicap, choose best move among a set of RootMoves
@@ -1711,6 +1789,7 @@ moves_loop: // When in check, search starts from here

 } // namespace

+
 /// MainThread::check_time() is used to print debug info and, more importantly,
 /// to detect when we are out of available time and thus stop the search.

@@ -1767,7 +1846,7 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) {
      Depth d = updated ? depth : depth - 1;
      Value v = updated ? rootMoves[i].score : rootMoves[i].previousScore;

-      bool tb = TB::RootInTB && abs(v) < VALUE_MATE - MAX_PLY;
+      bool tb = TB::RootInTB && abs(v) < VALUE_MATE_IN_MAX_PLY;
      v = tb ? rootMoves[i].tbScore : v;

      if (ss.rdbuf()->in_avail()) // Not at first line
@@ -1779,6 +1858,9 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) {
         << " multipv "  << i + 1
         << " score "    << UCI::value(v);

+      if (Options["UCI_ShowWDL"])
+          ss << UCI::wdl(v, pos.game_ply());
+
      if (!tb && i == pvIdx)
          ss << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : "");

@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -49,6 +47,7 @@ struct Stack {
  Value staticEval;
  int statScore;
  int moveCount;
+  bool inCheck;
 };


@@ -90,7 +89,7 @@ struct LimitsType {
  }

  bool use_time_management() const {
-    return !(mate | movetime | depth | nodes | perft | infinite);
+    return time[WHITE] || time[BLACK];
  }

  std::vector<Move> searchmoves;
@@ -1,7 +1,6 @@
 /*
  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (c) 2013 Ronald de Man
-  Copyright (C) 2016-2020 Marco Costalba, Lucas Braesch
+  Copyright (C) 2004-2020 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
@@ -60,13 +59,12 @@ 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";
@@ -404,7 +402,17 @@ 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 +424,12 @@ 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]);
-            if (otherKey == key || !std::get<WDL>(hashTable[bucket])) {
+            Key otherKey = hashTable[bucket].key;
+            if (otherKey == key || !hashTable[bucket].get<WDL>()) {
                hashTable[bucket] = entry;
                return;
            }
@@ -430,7 +438,7 @@ 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 +451,8 @@ 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))
-                return std::get<Type>(*entry);
+            if (entry->key == key || !entry->get<Type>())
+                return entry->get<Type>();
        }
    }

@@ -521,7 +529,7 @@ 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);
@@ -567,7 +575,7 @@ 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]);
@@ -706,7 +714,7 @@ Ret do_probe_table(const Position& pos, T* entry, WDLScore wdl, ProbeState* resu

        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
@@ -743,7 +751,7 @@ 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.
@@ -762,7 +770,7 @@ 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 +778,7 @@ 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;
@@ -975,7 +983,7 @@ 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[]
@@ -1191,7 +1199,7 @@ 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 +1352,7 @@ 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 +1361,7 @@ 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});

@@ -1460,7 +1468,7 @@ 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;

@@ -1,7 +1,6 @@
 /*
  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (c) 2013 Ronald de Man
-  Copyright (C) 2016-2020 Marco Costalba, Lucas Braesch
+  Copyright (C) 2004-2020 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
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -52,9 +50,10 @@ Thread::~Thread() {
  stdThread.join();
 }

+
 /// Thread::bestMoveCount(Move move) return best move counter for the given root move

-int Thread::best_move_count(Move move) {
+int Thread::best_move_count(Move move) const {

  auto rm = std::find(rootMoves.begin() + pvIdx,
                      rootMoves.begin() + pvLast, move);
@@ -62,25 +61,27 @@ int Thread::best_move_count(Move move) {
  return rm != rootMoves.begin() + pvLast ? rm->bestMoveCount : 0;
 }

+
 /// Thread::clear() reset histories, usually before a new game

 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 (auto& to : continuationHistory[inCheck][c])
-        for (auto& h : to)
-          h->fill(0);
-
-  for (bool inCheck : { false, true })
-    for (StatsType c : { NoCaptures, Captures })
-      continuationHistory[inCheck][c][NO_PIECE][0]->fill(Search::CounterMovePruneThreshold - 1);
+      for (StatsType c : { NoCaptures, Captures })
+      {
+          for (auto& to : continuationHistory[inCheck][c])
+                for (auto& h : to)
+                      h->fill(0);
+          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() {
@@ -151,14 +152,15 @@ 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 +168,11 @@ 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.

@@ -208,7 +211,7 @@ void ThreadPool::start_thinking(Position& pos, StateListPtr& states,

  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);
@@ -218,3 +221,54 @@ void ThreadPool::start_thinking(Position& pos, StateListPtr& states,

  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();
+}
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -56,7 +54,7 @@ public:
  void idle_loop();
  void start_searching();
  void wait_for_search_finished();
-  int best_move_count(Move move);
+  int best_move_count(Move move) const;

  Pawns::Table pawnsTable;
  Material::Table materialTable;
@@ -71,6 +69,7 @@ public:
  Depth rootDepth, completedDepth;
  CounterMoveHistory counterMoves;
  ButterflyHistory mainHistory;
+  LowPlyHistory lowPlyHistory;
  CapturePieceToHistory captureHistory;
  ContinuationHistory continuationHistory[2][2];
  Score contempt;
@@ -87,7 +86,7 @@ struct MainThread : public Thread {
  void check_time();

  double previousTimeReduction;
-  Value previousScore;
+  Value bestPreviousScore;
  Value iterValue[4];
  int callsCnt;
  bool stopOnPonderhit;
@@ -108,6 +107,9 @@ 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;

@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -28,66 +26,21 @@

 TimeManagement Time; // Our global time management object

-namespace {

-  enum TimeType { OptimumTime, MaxTime };
-
-  constexpr int MoveHorizon   = 50;   // Plan time management at most this many moves ahead
-  constexpr double MaxRatio   = 7.3;  // When in trouble, we can step over reserved time with this ratio
-  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
+/// 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:
+//      1) x basetime (+ z increment)
+//      2) x moves in y seconds (+ z increment)

 void TimeManagement::init(Search::LimitsType& limits, Color us, int ply) {

-  TimePoint minThinkingTime = Options["Minimum Thinking Time"];
-  TimePoint moveOverhead    = Options["Move Overhead"];
-  TimePoint slowMover       = Options["Slow Mover"];
-  TimePoint npmsec          = Options["nodestime"];
-  TimePoint hypMyTime;
+  TimePoint moveOverhead    = TimePoint(Options["Move Overhead"]);
+  TimePoint slowMover       = TimePoint(Options["Slow Mover"]);
+  TimePoint npmsec          = TimePoint(Options["nodestime"]);
+
+  // opt_scale is a percentage of available time to use for the current move.
+  // max_scale is a multiplier applied to optimumTime.
+  double opt_scale, max_scale;

  // 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 +58,40 @@ 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
-  // and choose the minimum of calculated search time values. Usually the greatest
-  // hypMTG gives the minimum values.
-  for (int hypMTG = 1; hypMTG <= maxMTG; ++hypMTG)
+  // Make sure timeLeft is > 0 since we may use it as a divisor
+  TimePoint timeLeft =  std::max(TimePoint(1),
+      limits.time[us] + limits.inc[us] * (mtg - 1) - moveOverhead * (2 + mtg));
+
+  // 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
-      hypMyTime =  limits.time[us]
-                 + limits.inc[us] * (hypMTG - 1)
-                 - 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);
+      opt_scale = std::min(0.008 + std::pow(ply + 3.0, 0.5) / 250.0,
+                           0.2 * limits.time[us] / double(timeLeft));
+      max_scale = std::min(7.0, 4.0 + ply / 12.0);
  }

+  // x moves in y seconds (+ z increment)
+  else
+  {
+      opt_scale = std::min((0.8 + ply / 128.0) / mtg,
+                            0.8 * limits.time[us] / double(timeLeft));
+      max_scale = std::min(6.3, 1.5 + 0.11 * mtg);
+  }
+
+  // Never use more than 80% of the available time for this move
+  optimumTime = TimePoint(opt_scale * timeLeft);
+  maximumTime = TimePoint(std::min(0.8 * limits.time[us] - moveOverhead, max_scale * optimumTime));
+
  if (Options["Ponder"])
      optimumTime += optimumTime / 4;
 }
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -30,23 +28,23 @@

 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
-  if (  (k >> 48) != key16
+  if ((uint16_t)k != key16
      || d - DEPTH_OFFSET > depth8 - 4
      || b == BOUND_EXACT)
  {
      assert(d >= DEPTH_OFFSET);

-      key16     = (uint16_t)(k >> 48);
+      key16     = (uint16_t)k;
      value16   = (int16_t)v;
      eval16    = (int16_t)ev;
      genBound8 = (uint8_t)(TT.generation8 | uint8_t(pv) << 2 | b);
@@ -63,11 +61,10 @@ void TranspositionTable::resize(size_t mbSize) {

  Threads.main()->wait_for_search_finished();

+  aligned_ttmem_free(mem);
+
  clusterCount = mbSize * 1024 * 1024 / sizeof(Cluster);
-
-  free(mem);
-  mem = malloc(clusterCount * sizeof(Cluster) + CacheLineSize - 1);
-
+  table = static_cast<Cluster*>(aligned_ttmem_alloc(clusterCount * sizeof(Cluster), mem));
  if (!mem)
  {
      std::cerr << "Failed to allocate " << mbSize
@@ -75,7 +72,6 @@ void TranspositionTable::resize(size_t mbSize) {
      exit(EXIT_FAILURE);
  }

-  table = (Cluster*)((uintptr_t(mem) + CacheLineSize - 1) & ~(CacheLineSize - 1));
  clear();
 }

@@ -96,8 +92,8 @@ void TranspositionTable::clear() {
              WinProcGroup::bindThisThread(idx);

          // Each thread will zero its part of the hash table
-          const size_t stride = clusterCount / Options["Threads"],
-                       start  = stride * idx,
+          const size_t stride = size_t(clusterCount / Options["Threads"]),
+                       start  = size_t(stride * idx),
                       len    = idx != Options["Threads"] - 1 ?
                                stride : clusterCount - start;

@@ -105,10 +101,11 @@ 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
@@ -119,7 +116,7 @@ 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)
@@ -150,9 +147,9 @@ 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;

-  return cnt * 1000 / (ClusterSize * (1000 / ClusterSize));
+  return cnt / ClusterSize;
 }
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -41,7 +39,7 @@ 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);

@@ -57,36 +55,33 @@ private:
 };


-/// A TranspositionTable consists of a power of 2 number of clusters and each
-/// cluster consists of ClusterSize number of TTEntry. Each non-empty entry
-/// contains information of exactly one position. The size of a cluster should
-/// divide the size of a cache line size, to ensure that clusters never cross
-/// cache lines. This ensures best cache performance, as the cacheline is
-/// prefetched, as soon as possible.
+/// A TranspositionTable is an array of Cluster, of size clusterCount. Each
+/// cluster consists of ClusterSize number of TTEntry. Each non-empty TTEntry
+/// contains information on exactly one position. The size of a Cluster should
+/// divide the size of a cache line for best performance, as the cacheline is
+/// prefetched when 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");

 public:
- ~TranspositionTable() { free(mem); }
+ ~TranspositionTable() { aligned_ttmem_free(mem); }
  void new_search() { generation8 += 8; } // Lower 3 bits are used by PV flag and Bound
  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:
@@ -0,0 +1,144 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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;
+
+bool Tune::update_on_last;
+const UCI::Option* LastOption = nullptr;
+BoolConditions Conditions;
+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(); }
+
+
+// Set binary conditions according to a probability that depends
+// on the corresponding parameter value.
+
+void BoolConditions::set() {
+
+  static PRNG rng(now());
+  static bool startup = true; // To workaround fishtest bench
+
+  for (size_t i = 0; i < binary.size(); i++)
+      binary[i] = !startup && (values[i] + int(rng.rand<unsigned>() % variance) > threshold);
+
+  startup = false;
+
+  for (size_t i = 0; i < binary.size(); i++)
+      sync_cout << binary[i] << sync_endl;
+}
+
+
+// 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>
+
+void Tune::read_results() {
+
+  /* ...insert your values here... */
+}
@@ -0,0 +1,193 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 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>
+
+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)
+
+
+/// BoolConditions struct is used to tune boolean conditions in the
+/// code by toggling them on/off according to a probability that
+/// depends on the value of a tuned integer parameter: for high
+/// values of the parameter condition is always disabled, for low
+/// values is always enabled, otherwise it is enabled with a given
+/// probability that depnends on the parameter under tuning.
+
+struct BoolConditions {
+  void init(size_t size) { values.resize(size, defaultValue), binary.resize(size, 0); }
+  void set();
+
+  std::vector<int> binary, values;
+  int defaultValue = 465, variance = 40, threshold = 500;
+  SetRange range = SetRange(0, 1000);
+};
+
+extern BoolConditions Conditions;
+
+inline void set_conditions() { Conditions.set(); }
+
+
+/// 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 facilty 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...);
+  }
+
+  // Template specialization for BoolConditions
+  template<typename... Args>
+  int add(const SetRange& range, std::string&& names, BoolConditions& cond, Args&&... args) {
+    for (size_t size = cond.values.size(), i = 0; i < size; i++)
+        add(cond.range, next(names, i == size - 1) + "_" + std::to_string(i), cond.values[i]);
+    return add(range, 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
+
+// Some macro to tune toggling of boolean conditions
+#define CONDITION(x) (Conditions.binary[__COUNTER__] || (x))
+#define TUNE_CONDITIONS() int UNIQUE(c, __LINE__) = (Conditions.init(__COUNTER__), 0); \
+                          TUNE(Conditions, set_conditions)
+
+#endif // #ifndef TUNE_H_INCLUDED
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -40,7 +38,6 @@

 #include <cassert>
 #include <cctype>
-#include <climits>
 #include <cstdint>
 #include <cstdlib>
 #include <algorithm>
@@ -176,14 +173,17 @@ enum Value : int {
  VALUE_INFINITE  = 32001,
  VALUE_NONE      = 32002,

-  VALUE_MATE_IN_MAX_PLY  =  VALUE_MATE - 2 * MAX_PLY,
-  VALUE_MATED_IN_MAX_PLY = -VALUE_MATE + 2 * MAX_PLY,
+  VALUE_TB_WIN_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   = 124,   PawnValueEg   = 206,
  KnightValueMg = 781,   KnightValueEg = 854,
  BishopValueMg = 825,   BishopValueEg = 915,
  RookValueMg   = 1276,  RookValueEg   = 1380,
  QueenValueMg  = 2538,  QueenValueEg  = 2682,
+  Tempo = 28,

  MidgameLimit  = 15258, EndgameLimit  = 3915
 };
@@ -201,18 +201,38 @@ enum Piece {
  PIECE_NB = 16
 };

-extern Value PieceValue[PHASE_NB][PIECE_NB];
+// An ID used to track the pieces. Max. 32 pieces on board.
+enum PieceId {
+  PIECE_ID_ZERO   = 0,
+  PIECE_ID_KING   = 30,
+  PIECE_ID_WKING  = 30,
+  PIECE_ID_BKING  = 31,
+  PIECE_ID_NONE   = 32
+};
+
+inline PieceId operator++(PieceId& d, int) {
+
+  PieceId x = d;
+  d = PieceId(int(d) + 1);
+  return x;
+}
+
+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 = DEPTH_NONE
 };

 enum Square : int {
@@ -226,7 +246,8 @@ 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 +270,94 @@ enum Rank : int {
  RANK_1, RANK_2, RANK_3, RANK_4, RANK_5, RANK_6, RANK_7, RANK_8, RANK_NB
 };

+// unique number for each piece type on each square
+enum PieceSquare : uint32_t {
+  PS_NONE     =  0,
+  PS_W_PAWN   =  1,
+  PS_B_PAWN   =  1 * SQUARE_NB + 1,
+  PS_W_KNIGHT =  2 * SQUARE_NB + 1,
+  PS_B_KNIGHT =  3 * SQUARE_NB + 1,
+  PS_W_BISHOP =  4 * SQUARE_NB + 1,
+  PS_B_BISHOP =  5 * SQUARE_NB + 1,
+  PS_W_ROOK   =  6 * SQUARE_NB + 1,
+  PS_B_ROOK   =  7 * SQUARE_NB + 1,
+  PS_W_QUEEN  =  8 * SQUARE_NB + 1,
+  PS_B_QUEEN  =  9 * SQUARE_NB + 1,
+  PS_W_KING   = 10 * SQUARE_NB + 1,
+  PS_END      = PS_W_KING, // pieces without kings (pawns included)
+  PS_B_KING   = 11 * SQUARE_NB + 1,
+  PS_END2     = 12 * SQUARE_NB + 1
+};
+
+struct ExtPieceSquare {
+  PieceSquare from[COLOR_NB];
+};
+
+// Array for finding the PieceSquare corresponding to the piece on the board
+extern ExtPieceSquare kpp_board_index[PIECE_NB];
+
+constexpr bool is_ok(PieceId pid);
+constexpr Square rotate180(Square sq);
+
+// Structure holding which tracked piece (PieceId) is where (PieceSquare)
+class EvalList {
+
+public:
+  // Max. number of pieces without kings is 30 but must be a multiple of 4 in AVX2
+  static const int MAX_LENGTH = 32;
+
+  // Array that holds the piece id for the pieces on the board
+  PieceId piece_id_list[SQUARE_NB];
+
+  // List of pieces, separate from White and Black POV
+  PieceSquare* piece_list_fw() const { return const_cast<PieceSquare*>(pieceListFw); }
+  PieceSquare* piece_list_fb() const { return const_cast<PieceSquare*>(pieceListFb); }
+
+  // Place the piece pc with piece_id on the square sq on the board
+  void put_piece(PieceId piece_id, Square sq, Piece pc)
+  {
+      assert(is_ok(piece_id));
+      if (pc != NO_PIECE)
+      {
+          pieceListFw[piece_id] = PieceSquare(kpp_board_index[pc].from[WHITE] + sq);
+          pieceListFb[piece_id] = PieceSquare(kpp_board_index[pc].from[BLACK] + rotate180(sq));
+          piece_id_list[sq] = piece_id;
+      }
+      else
+      {
+          pieceListFw[piece_id] = PS_NONE;
+          pieceListFb[piece_id] = PS_NONE;
+          piece_id_list[sq] = piece_id;
+      }
+  }
+
+  // Convert the specified piece_id piece to ExtPieceSquare type and return it
+  ExtPieceSquare piece_with_id(PieceId piece_id) const
+  {
+      ExtPieceSquare eps;
+      eps.from[WHITE] = pieceListFw[piece_id];
+      eps.from[BLACK] = pieceListFb[piece_id];
+      return eps;
+  }
+
+private:
+  PieceSquare pieceListFw[MAX_LENGTH];
+  PieceSquare pieceListFb[MAX_LENGTH];
+};
+
+// For differential evaluation of pieces that changed since last turn
+struct DirtyPiece {
+
+  // Number of changed pieces
+  int dirty_num;
+
+  // The ids of changed pieces, max. 2 pieces can change in one move
+  PieceId pieceId[2];
+
+  // What changed from the piece with that piece number
+  ExtPieceSquare old_piece[2];
+  ExtPieceSquare new_piece[2];
+};

 /// 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 +383,11 @@ 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, 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, 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, T d2) { return d1 = d1 - d2; }
+inline T& operator+=(T& d1, int 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 +405,10 @@ 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(PieceSquare)
+ENABLE_INCR_OPERATORS_ON(PieceId)
+ENABLE_INCR_OPERATORS_ON(PieceType)
 ENABLE_INCR_OPERATORS_ON(Square)
 ENABLE_INCR_OPERATORS_ON(File)
 ENABLE_INCR_OPERATORS_ON(Rank)
@@ -308,12 +419,6 @@ 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 +448,23 @@ 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) {
-  return Square(s ^ SQ_A8); // Vertical flip SQ_A1 -> SQ_A8
+constexpr Square flip_rank(Square s) { // Swap A1 <-> 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
-}
-
-inline File map_to_queenside(File f) {
-  return std::min(f, File(FILE_H - f)); // Map files ABCDEFGH to files ABCDDCBA
+  return Piece(pc ^ 8); // Swap color of piece B_KNIGHT <-> W_KNIGHT
 }

 constexpr CastlingRights operator&(Color c, CastlingRights cr) {
@@ -391,6 +496,10 @@ inline Color color_of(Piece pc) {
  return Color(pc >> 3);
 }

+constexpr bool is_ok(PieceId pid) {
+  return pid < PIECE_ID_NONE;
+}
+
 constexpr bool is_ok(Square s) {
  return s >= SQ_A1 && s <= SQ_H8;
 }
@@ -427,6 +536,11 @@ constexpr Square to_sq(Move m) {
  return Square(m & 0x3F);
 }

+// Return relative square when turning the board 180 degrees
+constexpr Square rotate180(Square sq) {
+  return (Square)(sq ^ 0x3F);
+}
+
 constexpr int from_to(Move m) {
 return m & 0xFFF;
 }
@@ -456,4 +570,11 @@ 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;
+}
+
 #endif // #ifndef TYPES_H_INCLUDED
+
+#include "tune.h" // Global visibility to tuning setup
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -19,6 +17,7 @@
 */

 #include <cassert>
+#include <cmath>
 #include <iostream>
 #include <sstream>
 #include <string>
@@ -77,6 +76,20 @@ 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::verify_NNUE();
+
+    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 +128,7 @@ 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));

@@ -165,7 +178,7 @@ 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 +195,28 @@ 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[] = {-8.24404295, 64.23892342, -95.73056462, 153.86478679};
+     double bs[] = {-3.37154371, 28.44489198, -56.67657741,  72.05858751};
+     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 = Utility::clamp(double(100 * v) / PawnValueEg, -1000.0, 1000.0);
+
+     // Return win rate in per mille (rounded to nearest)
+     return int(0.5 + 1000 / (1 + std::exp((a - x) / b)));
+  }
+
 } // namespace


@@ -238,7 +273,7 @@ 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
          sync_cout << "Unknown command: " << cmd << sync_endl;
@@ -260,7 +295,7 @@ 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 +304,22 @@ 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) {
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -73,6 +71,7 @@ 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
@@ -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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 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
@@ -38,11 +36,12 @@ 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::init_NNUE(); }
+void on_eval_file(const Option& ) { Eval::init_NNUE(); }

 /// Our case insensitive less() function as required by UCI protocol
 bool CaseInsensitiveLess::operator() (const string& s1, const string& s2) const {
@@ -52,12 +51,11 @@ 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 ? 131072 : 2048;
+  constexpr int MaxHashMB = Is64Bit ? 33554432 : 2048;

  o["Debug Log File"]        << Option("", on_logger);
  o["Contempt"]              << Option(24, -100, 100);
@@ -68,18 +66,20 @@ void init(OptionsMap& o) {
  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["Minimum Thinking Time"] << Option(20, 0, 5000);
-  o["Slow Mover"]            << Option(84, 10, 1000);
+  o["Move Overhead"]         << Option(10, 0, 5000);
+  o["Slow Mover"]            << Option(100, 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(false, on_use_NNUE);
+  o["EvalFile"]              << Option("nn-97f742aaefcd.nnue", on_eval_file);
 }