2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
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 const int MaterialTableSize = 1024;
39 /// MaterialInfo is a class which contains various information about a
40 /// material configuration. It contains a material balance evaluation,
41 /// a function pointer to a special endgame evaluation function (which in
42 /// most cases is NULL, meaning that the standard evaluation function will
43 /// be used), and "scale factors" for black and white.
45 /// The scale factors are used to scale the evaluation score up or down.
46 /// For instance, in KRB vs KR endgames, the score is scaled down by a factor
47 /// of 4, which will result in scores of absolute value less than one pawn.
51 friend class MaterialInfoTable;
54 Score material_value() const;
55 ScaleFactor scale_factor(const Position& pos, Color c) const;
56 int space_weight() const;
57 Phase game_phase() const;
58 bool specialized_eval_exists() const;
59 Value evaluate(const Position& pos) const;
65 EndgameEvaluationFunctionBase* evaluationFunction;
66 EndgameScalingFunctionBase* scalingFunction[2];
71 /// The MaterialInfoTable class represents a pawn hash table. The most important
72 /// method is get_material_info, which returns a pointer to a MaterialInfo object.
73 class EndgameFunctions;
75 class MaterialInfoTable : public SimpleHash<MaterialInfo, MaterialTableSize> {
79 MaterialInfo* get_material_info(const Position& pos);
80 static Phase game_phase(const Position& pos);
82 EndgameFunctions* funcs;
91 /// MaterialInfo::material_value simply returns the material balance
92 /// evaluation that is independent from game phase.
94 inline Score MaterialInfo::material_value() const {
96 return make_score(value, value);
99 /// MaterialInfo::scale_factor takes a position and a color as input, and
100 /// returns a scale factor for the given color. We have to provide the
101 /// position in addition to the color, because the scale factor need not
102 /// to be a constant: It can also be a function which should be applied to
103 /// the position. For instance, in KBP vs K endgames, a scaling function
104 /// which checks for draws with rook pawns and wrong-colored bishops.
106 inline ScaleFactor MaterialInfo::scale_factor(const Position& pos, Color c) const {
108 if (scalingFunction[c] != NULL)
110 ScaleFactor sf = scalingFunction[c]->apply(pos);
111 if (sf != SCALE_FACTOR_NONE)
114 return ScaleFactor(factor[c]);
118 /// MaterialInfo::space_weight() simply returns the weight for the space
119 /// evaluation for this material configuration.
121 inline int MaterialInfo::space_weight() const {
126 /// MaterialInfo::game_phase() returns the game phase according
127 /// to this material configuration.
129 inline Phase MaterialInfo::game_phase() const {
135 /// MaterialInfo::specialized_eval_exists decides whether there is a
136 /// specialized evaluation function for the current material configuration,
137 /// or if the normal evaluation function should be used.
139 inline bool MaterialInfo::specialized_eval_exists() const {
141 return evaluationFunction != NULL;
145 /// MaterialInfo::evaluate applies a specialized evaluation function
146 /// to a given position object. It should only be called when
147 /// specialized_eval_exists() returns 'true'.
149 inline Value MaterialInfo::evaluate(const Position& pos) const {
151 return evaluationFunction->apply(pos);
154 #endif // !defined(MATERIAL_H_INCLUDED)