Stockfish/src/value.h

/*
  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
  Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad

  Stockfish is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  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/>.
*/


#if !defined(VALUE_H_INCLUDED)
#define VALUE_H_INCLUDED

////
//// Includes
////

#include "piece.h"


////
//// Types
////

enum ValueType {
  VALUE_TYPE_NONE  = 0,
  VALUE_TYPE_UPPER = 1,  // Upper bound
  VALUE_TYPE_LOWER = 2,  // Lower bound
  VALUE_TYPE_EXACT = VALUE_TYPE_UPPER | VALUE_TYPE_LOWER
};


enum Value {
  VALUE_DRAW      = 0,
  VALUE_KNOWN_WIN = 15000,
  VALUE_MATE      = 30000,
  VALUE_INFINITE  = 30001,
  VALUE_NONE      = 30002,
  VALUE_ENSURE_SIGNED = -1
};


enum ScaleFactor {
  SCALE_FACTOR_ZERO   = 0,
  SCALE_FACTOR_NORMAL = 64,
  SCALE_FACTOR_MAX    = 128,
  SCALE_FACTOR_NONE   = 255
};


/// Score enum keeps a midgame and an endgame value in a single
/// integer (enum), first LSB 16 bits are used to store endgame
/// value, while upper bits are used for midgame value.

// Compiler is free to choose the enum type as long as can keep
// its data, so ensure Score to be an integer type.
enum Score { ENSURE_32_BITS_SIZE_P = (1 << 16), ENSURE_32_BITS_SIZE_N = -(1 << 16)};

// Extracting the _signed_ lower and upper 16 bits it not so trivial
// because according to the standard a simple cast to short is
// implementation defined and so is a right shift of a signed integer.
inline Value mg_value(Score s) { return Value(((int(s) + 32768) & ~0xffff) / 0x10000); }

// Unfortunatly on Intel 64 bit we have a small speed regression, so use a faster code in
// this case, although not 100% standard compliant it seems to work for Intel and MSVC.
#if defined(IS_64BIT) && (!defined(__GNUC__) || defined(__INTEL_COMPILER))
inline Value eg_value(Score s) { return Value(int16_t(s & 0xffff)); }
#else
inline Value eg_value(Score s) { return Value((int)(unsigned(s) & 0x7fffu) - (int)(unsigned(s) & 0x8000u)); }
#endif

inline Score make_score(int mg, int eg) { return Score((mg << 16) + eg); }

// Division must be handled separately for each term
inline Score operator/(Score s, int i) { return make_score(mg_value(s) / i, eg_value(s) / i); }

// Only declared but not defined. We don't want to multiply two scores due to
// a very high risk of overflow. So user should explicitly convert to integer.
inline Score operator*(Score s1, Score s2);


////
//// Constants and variables
////

/// Piece values, middle game and endgame

/// Important: If the material values are changed, one must also
/// adjust the piece square tables, and the method game_phase() in the
/// Position class!
///
/// Values modified by Joona Kiiski

const Value PawnValueMidgame   = Value(0x0C6);
const Value PawnValueEndgame   = Value(0x102);
const Value KnightValueMidgame = Value(0x331);
const Value KnightValueEndgame = Value(0x34E);
const Value BishopValueMidgame = Value(0x344);
const Value BishopValueEndgame = Value(0x359);
const Value RookValueMidgame   = Value(0x4F6);
const Value RookValueEndgame   = Value(0x4FE);
const Value QueenValueMidgame  = Value(0x9D9);
const Value QueenValueEndgame  = Value(0x9FE);

const Value PieceValueMidgame[17] = {
  Value(0),
  PawnValueMidgame, KnightValueMidgame, BishopValueMidgame,
  RookValueMidgame, QueenValueMidgame,
  Value(0), Value(0), Value(0),
  PawnValueMidgame, KnightValueMidgame, BishopValueMidgame,
  RookValueMidgame, QueenValueMidgame,
  Value(0), Value(0), Value(0)
};

const Value PieceValueEndgame[17] = {
  Value(0),
  PawnValueEndgame, KnightValueEndgame, BishopValueEndgame,
  RookValueEndgame, QueenValueEndgame,
  Value(0), Value(0), Value(0),
  PawnValueEndgame, KnightValueEndgame, BishopValueEndgame,
  RookValueEndgame, QueenValueEndgame,
  Value(0), Value(0), Value(0)
};

/// Bonus for having the side to move (modified by Joona Kiiski)

const Score TempoValue = make_score(48, 22);


////
//// Inline functions
////

inline Value operator+ (Value v, int i) { return Value(int(v) + i); }
inline Value operator- (Value v, int i) { return Value(int(v) - i); }


inline Value value_mate_in(int ply) {
  return VALUE_MATE - ply;
}

inline Value value_mated_in(int ply) {
  return -VALUE_MATE + ply;
}

inline bool is_upper_bound(ValueType vt) {
  return (int(vt) & int(VALUE_TYPE_UPPER)) != 0;
}

inline bool is_lower_bound(ValueType vt) {
  return (int(vt) & int(VALUE_TYPE_LOWER)) != 0;
}

inline Value piece_value_midgame(PieceType pt) {
  return PieceValueMidgame[pt];
}

inline Value piece_value_endgame(PieceType pt) {
  return PieceValueEndgame[pt];
}

inline Value piece_value_midgame(Piece p) {
  return PieceValueMidgame[p];
}

inline Value piece_value_endgame(Piece p) {
  return PieceValueEndgame[p];
}

#endif // !defined(VALUE_H_INCLUDED)