/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2012 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 .
*/
#if !defined(MATERIAL_H_INCLUDED)
#define MATERIAL_H_INCLUDED
#include "endgame.h"
#include "misc.h"
#include "position.h"
#include "types.h"
const int MaterialTableSize = 8192;
/// MaterialEntry is a class which contains various information about a
/// material configuration. It contains a material balance evaluation,
/// a function pointer to a special endgame evaluation function (which in
/// most cases is NULL, meaning that the standard evaluation function will
/// be used), and "scale factors" for black and white.
///
/// The scale factors are used to scale the evaluation score up or down.
/// For instance, in KRB vs KR endgames, the score is scaled down by a factor
/// of 4, which will result in scores of absolute value less than one pawn.
class MaterialEntry {
friend struct MaterialTable;
public:
Score material_value() const;
ScaleFactor scale_factor(const Position& pos, Color c) const;
int space_weight() const;
Phase game_phase() const;
bool specialized_eval_exists() const;
Value evaluate(const Position& pos) const;
private:
Key key;
int16_t value;
uint8_t factor[2];
EndgameBase* evaluationFunction;
EndgameBase* scalingFunction[2];
int spaceWeight;
Phase gamePhase;
};
/// The MaterialTable class represents a material hash table. The most important
/// method is probe(), which returns a pointer to a MaterialEntry object.
struct MaterialTable {
MaterialEntry* probe(const Position& pos);
static Phase game_phase(const Position& pos);
template static int imbalance(const int pieceCount[][8]);
HashTable entries;
Endgames endgames;
};
/// MaterialEntry::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 need not
/// to be a constant: It can also be a function which should be applied to
/// the position. For instance, in KBP vs K endgames, a scaling function
/// which checks for draws with rook pawns and wrong-colored bishops.
inline ScaleFactor MaterialEntry::scale_factor(const Position& pos, Color c) const {
if (!scalingFunction[c])
return ScaleFactor(factor[c]);
ScaleFactor sf = (*scalingFunction[c])(pos);
return sf == SCALE_FACTOR_NONE ? ScaleFactor(factor[c]) : sf;
}
inline Value MaterialEntry::evaluate(const Position& pos) const {
return (*evaluationFunction)(pos);
}
inline Score MaterialEntry::material_value() const {
return make_score(value, value);
}
inline int MaterialEntry::space_weight() const {
return spaceWeight;
}
inline Phase MaterialEntry::game_phase() const {
return gamePhase;
}
inline bool MaterialEntry::specialized_eval_exists() const {
return evaluationFunction != NULL;
}
#endif // !defined(MATERIAL_H_INCLUDED)