72 lines
2.8 KiB
C++
72 lines
2.8 KiB
C++
/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
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Stockfish is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Stockfish is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef MATERIAL_H_INCLUDED
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#define MATERIAL_H_INCLUDED
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#include "endgame.h"
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#include "misc.h"
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#include "position.h"
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#include "types.h"
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namespace Stockfish::Material {
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/// Material::Entry contains various information about a material configuration.
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/// It contains a material imbalance evaluation, a function pointer to a special
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/// endgame evaluation function (which in most cases is NULL, meaning that the
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/// standard evaluation function will be used), and scale factors.
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///
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/// The scale factors are used to scale the evaluation score up or down. For
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/// instance, in KRB vs KR endgames, the score is scaled down by a factor of 4,
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/// which will result in scores of absolute value less than one pawn.
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struct Entry {
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Score imbalance() const { return score; }
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Phase game_phase() const { return (Phase)gamePhase; }
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bool specialized_eval_exists() const { return evaluationFunction != nullptr; }
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Value evaluate(const Position& pos) const { return (*evaluationFunction)(pos); }
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// scale_factor() takes a position and a color as input and returns a scale factor
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// for the given color. We have to provide the position in addition to the color
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// because the scale factor may also be a function which should be applied to
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// the position. For instance, in KBP vs K endgames, the scaling function looks
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// for rook pawns and wrong-colored bishops.
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ScaleFactor scale_factor(const Position& pos, Color c) const {
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ScaleFactor sf = scalingFunction[c] ? (*scalingFunction[c])(pos)
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: SCALE_FACTOR_NONE;
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return sf != SCALE_FACTOR_NONE ? sf : ScaleFactor(factor[c]);
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}
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Key key;
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const EndgameBase<Value>* evaluationFunction;
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const EndgameBase<ScaleFactor>* scalingFunction[COLOR_NB]; // Could be one for each
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// side (e.g. KPKP, KBPsK)
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Score score;
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int16_t gamePhase;
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uint8_t factor[COLOR_NB];
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};
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typedef HashTable<Entry, 8192> Table;
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Entry* probe(const Position& pos);
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} // namespace Stockfish::Material
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#endif // #ifndef MATERIAL_H_INCLUDED
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