153 lines
4.4 KiB
C++
153 lines
4.4 KiB
C++
/*
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Glaurung, a UCI chess playing engine.
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Copyright (C) 2004-2008 Tord Romstad
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Glaurung 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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Glaurung 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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#if !defined(MATERIAL_H_INCLUDED)
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#define MATERIAL_H_INCLUDED
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////
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//// Includes
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////
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#include "endgame.h"
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#include "position.h"
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#include "scale.h"
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////
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//// Types
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////
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/// MaterialInfo is a class which contains various information about a
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/// material configuration. It contains a material balance evaluation,
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/// a function pointer to a special endgame evaluation function (which in
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/// most cases is NULL, meaning that the standard evaluation function will
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/// be used), and "scale factors" for black and white.
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///
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/// The scale factors are used to scale the evaluation score up or down.
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/// For instance, in KRB vs KR endgames, the score is scaled down by a factor
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/// of 4, which will result in scores of absolute value less than one pawn.
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class MaterialInfo {
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friend class MaterialInfoTable;
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public:
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Value mg_value() const;
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Value eg_value() const;
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ScaleFactor scale_factor(const Position &pos, Color c) const;
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bool specialized_eval_exists() const;
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Value evaluate(const Position &pos) const;
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static void init();
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private:
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void clear();
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Key key;
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int16_t mgValue;
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int16_t egValue;
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uint8_t factor[2];
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EndgameEvaluationFunction *evaluationFunction;
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ScalingFunction *scalingFunction[2];
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};
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/// The MaterialInfoTable class represents a pawn hash table. It is basically
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/// just an array of MaterialInfo objects and a few methods for accessing these
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/// objects. The most important method is get_material_info, which looks up a
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/// position in the table and returns a pointer to a MaterialInfo object.
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class MaterialInfoTable {
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public:
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MaterialInfoTable(unsigned numOfEntries);
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~MaterialInfoTable();
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void clear();
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MaterialInfo *get_material_info(const Position &pos);
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private:
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unsigned size;
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MaterialInfo *entries;
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};
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////
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//// Inline functions
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////
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/// MaterialInfo::mg_value and MaterialInfo::eg_value simply returns the
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/// material balance evaluation for the middle game and the endgame.
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inline Value MaterialInfo::mg_value() const {
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return Value(mgValue);
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}
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inline Value MaterialInfo::eg_value() const {
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return Value(egValue);
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}
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/// MaterialInfo::clear() resets a MaterialInfo object to an empty state,
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/// with all slots at their default values.
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inline void MaterialInfo::clear() {
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mgValue = egValue = 0;
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factor[WHITE] = factor[BLACK] = uint8_t(SCALE_FACTOR_NORMAL);
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evaluationFunction = NULL;
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scalingFunction[WHITE] = scalingFunction[BLACK] = NULL;
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}
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/// MaterialInfo::scale_factor takes a position and a color as input, and
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/// returns a scale factor for the given color. We have to provide the
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/// position in addition to the color, because the scale factor need not
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/// be a constant: It can also be a function which should be applied to
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/// the position. For instance, in KBP vs K endgames, a scaling function
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/// which checks for draws with rook pawns and wrong-colored bishops.
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inline ScaleFactor MaterialInfo::scale_factor(const Position &pos, Color c)
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const {
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if(scalingFunction[c] != NULL) {
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ScaleFactor sf = scalingFunction[c]->apply(pos);
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if(sf != SCALE_FACTOR_NONE)
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return sf;
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}
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return ScaleFactor(factor[c]);
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}
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/// MaterialInfo::specialized_eval_exists decides whether there is a
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/// specialized evaluation function for the current material configuration,
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/// or if the normal evaluation function should be used.
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inline bool MaterialInfo::specialized_eval_exists() const {
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return evaluationFunction != NULL;
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}
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/// MaterialInfo::evaluate applies a specialized evaluation function to a
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/// given position object. It should only be called when
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/// this->specialized_eval_exists() returns 'true'.
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inline Value MaterialInfo::evaluate(const Position &pos) const {
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return evaluationFunction->apply(pos);
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}
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#endif // !defined(MATERIAL_H_INCLUDED)
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