mirror of
https://github.com/sockspls/badfish
synced 2025-04-29 16:23:09 +00:00
6e8bd8bf2d
No functional changes, altough a bit of code reshuffle. Signed-off-by: Marco Costalba <mcostalba@gmail.com>
351 lines
11 KiB
C++
351 lines
11 KiB
C++
/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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Copyright (C) 2008 Marco Costalba
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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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////
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//// Includes
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////
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#include <cassert>
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#include <map>
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#include "material.h"
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////
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//// Local definitions
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////
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namespace {
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const Value BishopPairMidgameBonus = Value(100);
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const Value BishopPairEndgameBonus = Value(100);
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Key KNNKMaterialKey, KKNNMaterialKey;
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}
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////
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//// Classes
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////
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/// See header for a class description. It is declared here to avoid
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/// to include <map> in the header file.
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class EndgameFunctions {
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public:
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EndgameFunctions();
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EndgameEvaluationFunction* getEEF(Key key) const;
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ScalingFunction* getESF(Key key, Color* c) const;
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private:
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void add(Key k, EndgameEvaluationFunction* f);
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void add(Key k, Color c, ScalingFunction* f);
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struct ScalingInfo
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{
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Color col;
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ScalingFunction* fun;
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};
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std::map<Key, EndgameEvaluationFunction*> EEFmap;
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std::map<Key, ScalingInfo> ESFmap;
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};
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////
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//// Functions
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////
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/// Constructor for the MaterialInfoTable class
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MaterialInfoTable::MaterialInfoTable(unsigned int numOfEntries) {
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size = numOfEntries;
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entries = new MaterialInfo[size];
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funcs = new EndgameFunctions();
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if (!entries || !funcs)
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{
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std::cerr << "Failed to allocate " << (numOfEntries * sizeof(MaterialInfo))
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<< " bytes for material hash table." << std::endl;
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exit(EXIT_FAILURE);
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}
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clear();
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}
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/// Destructor for the MaterialInfoTable class
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MaterialInfoTable::~MaterialInfoTable() {
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delete [] entries;
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delete funcs;
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}
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/// MaterialInfoTable::clear() clears a material hash table by setting
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/// all entries to 0.
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void MaterialInfoTable::clear() {
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memset(entries, 0, size * sizeof(MaterialInfo));
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}
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/// MaterialInfoTable::get_material_info() takes a position object as input,
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/// computes or looks up a MaterialInfo object, and returns a pointer to it.
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/// If the material configuration is not already present in the table, it
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/// is stored there, so we don't have to recompute everything when the
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/// same material configuration occurs again.
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MaterialInfo* MaterialInfoTable::get_material_info(const Position& pos) {
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Key key = pos.get_material_key();
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int index = key & (size - 1);
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MaterialInfo* mi = entries + index;
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// If mi->key matches the position's material hash key, it means that we
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// have analysed this material configuration before, and we can simply
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// return the information we found the last time instead of recomputing it.
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if (mi->key == key)
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return mi;
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// Clear the MaterialInfo object, and set its key
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mi->clear();
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mi->key = key;
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// A special case before looking for a specialized evaluation function
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// KNN vs K is a draw.
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if (key == KNNKMaterialKey || key == KKNNMaterialKey)
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{
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mi->factor[WHITE] = mi->factor[BLACK] = 0;
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return mi;
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}
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// Let's look if we have a specialized evaluation function for this
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// particular material configuration.
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if ((mi->evaluationFunction = funcs->getEEF(key)) != NULL)
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return mi;
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else if ( pos.non_pawn_material(BLACK) == Value(0)
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&& pos.piece_count(BLACK, PAWN) == 0
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&& pos.non_pawn_material(WHITE) >= RookValueEndgame)
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{
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mi->evaluationFunction = &EvaluateKXK;
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return mi;
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}
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else if ( pos.non_pawn_material(WHITE) == Value(0)
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&& pos.piece_count(WHITE, PAWN) == 0
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&& pos.non_pawn_material(BLACK) >= RookValueEndgame)
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{
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mi->evaluationFunction = &EvaluateKKX;
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return mi;
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}
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// OK, we didn't find any special evaluation function for the current
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// material configuration. Is there a suitable scaling function?
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//
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// The code below is rather messy, and it could easily get worse later,
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// if we decide to add more special cases. We face problems when there
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// are several conflicting applicable scaling functions and we need to
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// decide which one to use.
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Color c;
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ScalingFunction* sf;
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if ((sf = funcs->getESF(key, &c)) != NULL)
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{
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mi->scalingFunction[c] = sf;
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return mi;
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}
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if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
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&& pos.piece_count(WHITE, BISHOP) == 1
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&& pos.piece_count(WHITE, PAWN) >= 1)
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mi->scalingFunction[WHITE] = &ScaleKBPK;
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if ( pos.non_pawn_material(BLACK) == BishopValueMidgame
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&& pos.piece_count(BLACK, BISHOP) == 1
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&& pos.piece_count(BLACK, PAWN) >= 1)
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mi->scalingFunction[BLACK] = &ScaleKKBP;
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if ( pos.piece_count(WHITE, PAWN) == 0
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&& pos.non_pawn_material(WHITE) == QueenValueMidgame
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&& pos.piece_count(WHITE, QUEEN) == 1
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&& pos.piece_count(BLACK, ROOK) == 1
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&& pos.piece_count(BLACK, PAWN) >= 1)
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mi->scalingFunction[WHITE] = &ScaleKQKRP;
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else if ( pos.piece_count(BLACK, PAWN) == 0
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&& pos.non_pawn_material(BLACK) == QueenValueMidgame
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&& pos.piece_count(BLACK, QUEEN) == 1
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&& pos.piece_count(WHITE, ROOK) == 1
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&& pos.piece_count(WHITE, PAWN) >= 1)
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mi->scalingFunction[BLACK] = &ScaleKRPKQ;
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if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) == Value(0))
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{
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if (pos.piece_count(BLACK, PAWN) == 0)
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{
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assert(pos.piece_count(WHITE, PAWN) >= 2);
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mi->scalingFunction[WHITE] = &ScaleKPsK;
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}
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else if (pos.piece_count(WHITE, PAWN) == 0)
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{
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assert(pos.piece_count(BLACK, PAWN) >= 2);
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mi->scalingFunction[BLACK] = &ScaleKKPs;
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}
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else if (pos.piece_count(WHITE, PAWN) == 1 && pos.piece_count(BLACK, PAWN) == 1)
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{
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mi->scalingFunction[WHITE] = &ScaleKPKPw;
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mi->scalingFunction[BLACK] = &ScaleKPKPb;
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}
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}
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// Evaluate the material balance
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int sign;
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Value egValue = Value(0);
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Value mgValue = Value(0);
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for (c = WHITE, sign = 1; c <= BLACK; c++, sign = -sign)
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{
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// No pawns makes it difficult to win, even with a material advantage
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if ( pos.piece_count(c, PAWN) == 0
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&& pos.non_pawn_material(c) - pos.non_pawn_material(opposite_color(c)) <= BishopValueMidgame)
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{
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if ( pos.non_pawn_material(c) == pos.non_pawn_material(opposite_color(c))
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|| pos.non_pawn_material(c) < RookValueMidgame)
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mi->factor[c] = 0;
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else
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{
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switch (pos.piece_count(c, BISHOP)) {
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case 2:
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mi->factor[c] = 32;
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break;
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case 1:
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mi->factor[c] = 12;
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break;
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case 0:
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mi->factor[c] = 6;
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break;
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}
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}
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}
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// Bishop pair
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if (pos.piece_count(c, BISHOP) >= 2)
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{
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mgValue += sign * BishopPairMidgameBonus;
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egValue += sign * BishopPairEndgameBonus;
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}
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// Knights are stronger when there are many pawns on the board. The
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// formula is taken from Larry Kaufman's paper "The Evaluation of Material
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// Imbalances in Chess":
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// http://mywebpages.comcast.net/danheisman/Articles/evaluation_of_material_imbalance.htm
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mgValue += sign * Value(pos.piece_count(c, KNIGHT)*(pos.piece_count(c, PAWN)-5)*16);
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egValue += sign * Value(pos.piece_count(c, KNIGHT)*(pos.piece_count(c, PAWN)-5)*16);
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// Redundancy of major pieces, again based on Kaufman's paper:
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if (pos.piece_count(c, ROOK) >= 1)
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{
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Value v = Value((pos.piece_count(c, ROOK) - 1) * 32 + pos.piece_count(c, QUEEN) * 16);
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mgValue -= sign * v;
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egValue -= sign * v;
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}
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}
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mi->mgValue = int16_t(mgValue);
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mi->egValue = int16_t(egValue);
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return mi;
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}
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/// EndgameFunctions member definitions. This class is used to store the maps
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/// of end game and scaling functions that MaterialInfoTable will query for
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/// each key. The maps are constant and are populated only at construction,
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/// but are per-thread instead of globals to avoid expensive locks.
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EndgameFunctions::EndgameFunctions() {
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typedef Key ZM[2][8][16];
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const ZM& z = Position::zobMaterial;
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static const Color W = WHITE;
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static const Color B = BLACK;
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KNNKMaterialKey = z[W][KNIGHT][1] ^ z[W][KNIGHT][2];
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KKNNMaterialKey = z[B][KNIGHT][1] ^ z[B][KNIGHT][2];
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add(z[W][PAWN][1], &EvaluateKPK);
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add(z[B][PAWN][1], &EvaluateKKP);
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add(z[W][BISHOP][1] ^ z[W][KNIGHT][1], &EvaluateKBNK);
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add(z[B][BISHOP][1] ^ z[B][KNIGHT][1], &EvaluateKKBN);
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add(z[W][ROOK][1] ^ z[B][PAWN][1], &EvaluateKRKP);
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add(z[W][PAWN][1] ^ z[B][ROOK][1], &EvaluateKPKR);
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add(z[W][ROOK][1] ^ z[B][BISHOP][1], &EvaluateKRKB);
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add(z[W][BISHOP][1] ^ z[B][ROOK][1], &EvaluateKBKR);
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add(z[W][ROOK][1] ^ z[B][KNIGHT][1], &EvaluateKRKN);
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add(z[W][KNIGHT][1] ^ z[B][ROOK][1], &EvaluateKNKR);
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add(z[W][QUEEN][1] ^ z[B][ROOK][1], &EvaluateKQKR);
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add(z[W][ROOK][1] ^ z[B][QUEEN][1], &EvaluateKRKQ);
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add(z[W][KNIGHT][1] ^ z[W][PAWN][1], W, &ScaleKNPK);
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add(z[B][KNIGHT][1] ^ z[B][PAWN][1], B, &ScaleKKNP);
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add(z[W][ROOK][1] ^ z[W][PAWN][1] ^ z[B][ROOK][1] , W, &ScaleKRPKR);
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add(z[W][ROOK][1] ^ z[B][ROOK][1] ^ z[B][PAWN][1] , B, &ScaleKRKRP);
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add(z[W][BISHOP][1] ^ z[W][PAWN][1] ^ z[B][BISHOP][1], W, &ScaleKBPKB);
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add(z[W][BISHOP][1] ^ z[B][BISHOP][1] ^ z[B][PAWN][1] , B, &ScaleKBKBP);
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add(z[W][BISHOP][1] ^ z[W][PAWN][1] ^ z[B][KNIGHT][1], W, &ScaleKBPKN);
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add(z[W][KNIGHT][1] ^ z[B][BISHOP][1] ^ z[B][PAWN][1] , B, &ScaleKNKBP);
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add(z[W][ROOK][1] ^ z[W][PAWN][1] ^ z[W][PAWN][2] ^ z[B][ROOK][1] ^ z[B][PAWN][1], W, &ScaleKRPPKRP);
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add(z[W][ROOK][1] ^ z[W][PAWN][1] ^ z[B][ROOK][1] ^ z[B][PAWN][1] ^ z[B][PAWN][2], B, &ScaleKRPKRPP);
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}
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void EndgameFunctions::add(Key k, EndgameEvaluationFunction* f) {
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EEFmap.insert(std::pair<Key, EndgameEvaluationFunction*>(k, f));
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}
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void EndgameFunctions::add(Key k, Color c, ScalingFunction* f) {
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ScalingInfo s = {c, f};
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ESFmap.insert(std::pair<Key, ScalingInfo>(k, s));
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}
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EndgameEvaluationFunction* EndgameFunctions::getEEF(Key key) const {
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std::map<Key, EndgameEvaluationFunction*>::const_iterator it(EEFmap.find(key));
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return (it != EEFmap.end() ? it->second : NULL);
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}
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ScalingFunction* EndgameFunctions::getESF(Key key, Color* c) const {
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std::map<Key, ScalingInfo>::const_iterator it(ESFmap.find(key));
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if (it == ESFmap.end())
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return NULL;
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*c = it->second.col;
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return it->second.fun;
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}
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