2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008 Marco Costalba
6 Stockfish is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 Stockfish is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
21 #if !defined(MATERIAL_H_INCLUDED)
22 #define MATERIAL_H_INCLUDED
37 /// MaterialInfo is a class which contains various information about a
38 /// material configuration. It contains a material balance evaluation,
39 /// a function pointer to a special endgame evaluation function (which in
40 /// most cases is NULL, meaning that the standard evaluation function will
41 /// be used), and "scale factors" for black and white.
43 /// The scale factors are used to scale the evaluation score up or down.
44 /// For instance, in KRB vs KR endgames, the score is scaled down by a factor
45 /// of 4, which will result in scores of absolute value less than one pawn.
49 friend class MaterialInfoTable;
52 Value mg_value() const;
53 Value eg_value() const;
54 ScaleFactor scale_factor(const Position &pos, Color c) const;
55 bool specialized_eval_exists() const;
56 Value evaluate(const Position &pos) const;
67 EndgameEvaluationFunction *evaluationFunction;
68 ScalingFunction *scalingFunction[2];
72 /// The MaterialInfoTable class represents a pawn hash table. It is basically
73 /// just an array of MaterialInfo objects and a few methods for accessing these
74 /// objects. The most important method is get_material_info, which looks up a
75 /// position in the table and returns a pointer to a MaterialInfo object.
77 class MaterialInfoTable {
80 MaterialInfoTable(unsigned numOfEntries);
83 MaterialInfo *get_material_info(const Position &pos);
87 MaterialInfo *entries;
95 /// MaterialInfo::mg_value and MaterialInfo::eg_value simply returns the
96 /// material balance evaluation for the middle game and the endgame.
98 inline Value MaterialInfo::mg_value() const {
99 return Value(mgValue);
102 inline Value MaterialInfo::eg_value() const {
103 return Value(egValue);
107 /// MaterialInfo::clear() resets a MaterialInfo object to an empty state,
108 /// with all slots at their default values.
110 inline void MaterialInfo::clear() {
111 mgValue = egValue = 0;
112 factor[WHITE] = factor[BLACK] = uint8_t(SCALE_FACTOR_NORMAL);
113 evaluationFunction = NULL;
114 scalingFunction[WHITE] = scalingFunction[BLACK] = NULL;
118 /// MaterialInfo::scale_factor takes a position and a color as input, and
119 /// returns a scale factor for the given color. We have to provide the
120 /// position in addition to the color, because the scale factor need not
121 /// be a constant: It can also be a function which should be applied to
122 /// the position. For instance, in KBP vs K endgames, a scaling function
123 /// which checks for draws with rook pawns and wrong-colored bishops.
125 inline ScaleFactor MaterialInfo::scale_factor(const Position &pos, Color c)
127 if(scalingFunction[c] != NULL) {
128 ScaleFactor sf = scalingFunction[c]->apply(pos);
129 if(sf != SCALE_FACTOR_NONE)
132 return ScaleFactor(factor[c]);
136 /// MaterialInfo::specialized_eval_exists decides whether there is a
137 /// specialized evaluation function for the current material configuration,
138 /// or if the normal evaluation function should be used.
140 inline bool MaterialInfo::specialized_eval_exists() const {
141 return evaluationFunction != NULL;
145 /// MaterialInfo::evaluate applies a specialized evaluation function to a
146 /// given position object. It should only be called when
147 /// this->specialized_eval_exists() returns 'true'.
149 inline Value MaterialInfo::evaluate(const Position &pos) const {
150 return evaluationFunction->apply(pos);
153 #endif // !defined(MATERIAL_H_INCLUDED)