+++ /dev/null
-/*
- Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008 Marco Costalba
-
- Stockfish is free software: you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation, either version 3 of the License, or
- (at your option) any later version.
-
- Stockfish is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
-
- You should have received a copy of the GNU General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>.
-*/
-
-
-////
-//// Includes
-////
-
-#include <cassert>
-#include <cstring>
-#include <map>
-
-#include "material.h"
-
-
-////
-//// Local definitions
-////
-
-namespace {
-
- const Value BishopPairMidgameBonus = Value(100);
- const Value BishopPairEndgameBonus = Value(100);
-
- Key KNNKMaterialKey, KKNNMaterialKey;
-
-}
-
-////
-//// Classes
-////
-
-
-/// See header for a class description. It is declared here to avoid
-/// to include <map> in the header file.
-
-class EndgameFunctions {
-
-public:
- EndgameFunctions();
- EndgameEvaluationFunction* getEEF(Key key) const;
- ScalingFunction* getESF(Key key, Color* c) const;
-
-private:
- void add(Key k, EndgameEvaluationFunction* f);
- void add(Key k, Color c, ScalingFunction* f);
-
- struct ScalingInfo
- {
- Color col;
- ScalingFunction* fun;
- };
-
- std::map<Key, EndgameEvaluationFunction*> EEFmap;
- std::map<Key, ScalingInfo> ESFmap;
-};
-
-
-////
-//// Functions
-////
-
-
-/// Constructor for the MaterialInfoTable class
-
-MaterialInfoTable::MaterialInfoTable(unsigned int numOfEntries) {
-
- size = numOfEntries;
- entries = new MaterialInfo[size];
- funcs = new EndgameFunctions();
- if (!entries || !funcs)
- {
- std::cerr << "Failed to allocate " << (numOfEntries * sizeof(MaterialInfo))
- << " bytes for material hash table." << std::endl;
- exit(EXIT_FAILURE);
- }
- clear();
-}
-
-
-/// Destructor for the MaterialInfoTable class
-
-MaterialInfoTable::~MaterialInfoTable() {
-
- delete [] entries;
- delete funcs;
-}
-
-
-/// MaterialInfoTable::clear() clears a material hash table by setting
-/// all entries to 0.
-
-void MaterialInfoTable::clear() {
-
- memset(entries, 0, size * sizeof(MaterialInfo));
-}
-
-
-/// MaterialInfoTable::get_material_info() takes a position object as input,
-/// computes or looks up a MaterialInfo object, and returns a pointer to it.
-/// If the material configuration is not already present in the table, it
-/// is stored there, so we don't have to recompute everything when the
-/// same material configuration occurs again.
-
-MaterialInfo* MaterialInfoTable::get_material_info(const Position& pos) {
-
- Key key = pos.get_material_key();
- int index = key & (size - 1);
- MaterialInfo* mi = entries + index;
-
- // If mi->key matches the position's material hash key, it means that we
- // have analysed this material configuration before, and we can simply
- // return the information we found the last time instead of recomputing it.
- if (mi->key == key)
- return mi;
-
- // Clear the MaterialInfo object, and set its key
- mi->clear();
- mi->key = key;
-
- // A special case before looking for a specialized evaluation function
- // KNN vs K is a draw.
- if (key == KNNKMaterialKey || key == KKNNMaterialKey)
- {
- mi->factor[WHITE] = mi->factor[BLACK] = 0;
- return mi;
- }
-
- // Let's look if we have a specialized evaluation function for this
- // particular material configuration. First we look for a fixed
- // configuration one, then a generic one if previous search failed.
- if ((mi->evaluationFunction = funcs->getEEF(key)) != NULL)
- return mi;
-
- else if ( pos.non_pawn_material(BLACK) == Value(0)
- && pos.piece_count(BLACK, PAWN) == 0
- && pos.non_pawn_material(WHITE) >= RookValueEndgame)
- {
- mi->evaluationFunction = &EvaluateKXK;
- return mi;
- }
- else if ( pos.non_pawn_material(WHITE) == Value(0)
- && pos.piece_count(WHITE, PAWN) == 0
- && pos.non_pawn_material(BLACK) >= RookValueEndgame)
- {
- mi->evaluationFunction = &EvaluateKKX;
- return mi;
- }
- else if ( pos.pawns() == EmptyBoardBB
- && pos.rooks() == EmptyBoardBB
- && pos.queens() == EmptyBoardBB)
- {
- // Minor piece endgame with at least one minor piece per side,
- // and no pawns.
- assert(pos.knights(WHITE) | pos.bishops(WHITE));
- assert(pos.knights(BLACK) | pos.bishops(BLACK));
-
- if ( pos.piece_count(WHITE, BISHOP) + pos.piece_count(WHITE, KNIGHT) <= 2
- && pos.piece_count(BLACK, BISHOP) + pos.piece_count(BLACK, KNIGHT) <= 2)
- {
- mi->evaluationFunction = &EvaluateKmmKm;
- return mi;
- }
- }
-
- // OK, we didn't find any special evaluation function for the current
- // material configuration. Is there a suitable scaling function?
- //
- // The code below is rather messy, and it could easily get worse later,
- // if we decide to add more special cases. We face problems when there
- // are several conflicting applicable scaling functions and we need to
- // decide which one to use.
- Color c;
- ScalingFunction* sf;
-
- if ((sf = funcs->getESF(key, &c)) != NULL)
- {
- mi->scalingFunction[c] = sf;
- return mi;
- }
-
- if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
- && pos.piece_count(WHITE, BISHOP) == 1
- && pos.piece_count(WHITE, PAWN) >= 1)
- mi->scalingFunction[WHITE] = &ScaleKBPK;
-
- if ( pos.non_pawn_material(BLACK) == BishopValueMidgame
- && pos.piece_count(BLACK, BISHOP) == 1
- && pos.piece_count(BLACK, PAWN) >= 1)
- mi->scalingFunction[BLACK] = &ScaleKKBP;
-
- if ( pos.piece_count(WHITE, PAWN) == 0
- && pos.non_pawn_material(WHITE) == QueenValueMidgame
- && pos.piece_count(WHITE, QUEEN) == 1
- && pos.piece_count(BLACK, ROOK) == 1
- && pos.piece_count(BLACK, PAWN) >= 1)
- mi->scalingFunction[WHITE] = &ScaleKQKRP;
-
- else if ( pos.piece_count(BLACK, PAWN) == 0
- && pos.non_pawn_material(BLACK) == QueenValueMidgame
- && pos.piece_count(BLACK, QUEEN) == 1
- && pos.piece_count(WHITE, ROOK) == 1
- && pos.piece_count(WHITE, PAWN) >= 1)
- mi->scalingFunction[BLACK] = &ScaleKRPKQ;
-
- if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) == Value(0))
- {
- if (pos.piece_count(BLACK, PAWN) == 0)
- {
- assert(pos.piece_count(WHITE, PAWN) >= 2);
- mi->scalingFunction[WHITE] = &ScaleKPsK;
- }
- else if (pos.piece_count(WHITE, PAWN) == 0)
- {
- assert(pos.piece_count(BLACK, PAWN) >= 2);
- mi->scalingFunction[BLACK] = &ScaleKKPs;
- }
- else if (pos.piece_count(WHITE, PAWN) == 1 && pos.piece_count(BLACK, PAWN) == 1)
- {
- mi->scalingFunction[WHITE] = &ScaleKPKPw;
- mi->scalingFunction[BLACK] = &ScaleKPKPb;
- }
- }
-
- // Compute the space weight
- if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >=
- 2*QueenValueMidgame + 4*RookValueMidgame + 2*KnightValueMidgame)
- {
- int minorPieceCount = pos.piece_count(WHITE, KNIGHT)
- + pos.piece_count(BLACK, KNIGHT)
- + pos.piece_count(WHITE, BISHOP)
- + pos.piece_count(BLACK, BISHOP);
-
- mi->spaceWeight = minorPieceCount * minorPieceCount;
- }
-
- // Evaluate the material balance
-
- int sign;
- Value egValue = Value(0);
- Value mgValue = Value(0);
-
- for (c = WHITE, sign = 1; c <= BLACK; c++, sign = -sign)
- {
- // No pawns makes it difficult to win, even with a material advantage
- if ( pos.piece_count(c, PAWN) == 0
- && pos.non_pawn_material(c) - pos.non_pawn_material(opposite_color(c)) <= BishopValueMidgame)
- {
- if ( pos.non_pawn_material(c) == pos.non_pawn_material(opposite_color(c))
- || pos.non_pawn_material(c) < RookValueMidgame)
- mi->factor[c] = 0;
- else
- {
- switch (pos.piece_count(c, BISHOP)) {
- case 2:
- mi->factor[c] = 32;
- break;
- case 1:
- mi->factor[c] = 12;
- break;
- case 0:
- mi->factor[c] = 6;
- break;
- }
- }
- }
-
- // Bishop pair
- if (pos.piece_count(c, BISHOP) >= 2)
- {
- mgValue += sign * BishopPairMidgameBonus;
- egValue += sign * BishopPairEndgameBonus;
- }
-
- // Knights are stronger when there are many pawns on the board. The
- // formula is taken from Larry Kaufman's paper "The Evaluation of Material
- // Imbalances in Chess":
- // http://mywebpages.comcast.net/danheisman/Articles/evaluation_of_material_imbalance.htm
- mgValue += sign * Value(pos.piece_count(c, KNIGHT)*(pos.piece_count(c, PAWN)-5)*16);
- egValue += sign * Value(pos.piece_count(c, KNIGHT)*(pos.piece_count(c, PAWN)-5)*16);
-
- // Redundancy of major pieces, again based on Kaufman's paper:
- if (pos.piece_count(c, ROOK) >= 1)
- {
- Value v = Value((pos.piece_count(c, ROOK) - 1) * 32 + pos.piece_count(c, QUEEN) * 16);
- mgValue -= sign * v;
- egValue -= sign * v;
- }
- }
- mi->mgValue = int16_t(mgValue);
- mi->egValue = int16_t(egValue);
- return mi;
-}
-
-
-/// EndgameFunctions member definitions. This class is used to store the maps
-/// of end game and scaling functions that MaterialInfoTable will query for
-/// each key. The maps are constant and are populated only at construction,
-/// but are per-thread instead of globals to avoid expensive locks.
-
-EndgameFunctions::EndgameFunctions() {
-
- typedef Key ZM[2][8][16];
- const ZM& z = Position::zobMaterial;
-
- static const Color W = WHITE;
- static const Color B = BLACK;
-
- KNNKMaterialKey = z[W][KNIGHT][1] ^ z[W][KNIGHT][2];
- KKNNMaterialKey = z[B][KNIGHT][1] ^ z[B][KNIGHT][2];
-
- add(z[W][PAWN][1], &EvaluateKPK);
- add(z[B][PAWN][1], &EvaluateKKP);
-
- add(z[W][BISHOP][1] ^ z[W][KNIGHT][1], &EvaluateKBNK);
- add(z[B][BISHOP][1] ^ z[B][KNIGHT][1], &EvaluateKKBN);
- add(z[W][ROOK][1] ^ z[B][PAWN][1], &EvaluateKRKP);
- add(z[W][PAWN][1] ^ z[B][ROOK][1], &EvaluateKPKR);
- add(z[W][ROOK][1] ^ z[B][BISHOP][1], &EvaluateKRKB);
- add(z[W][BISHOP][1] ^ z[B][ROOK][1], &EvaluateKBKR);
- add(z[W][ROOK][1] ^ z[B][KNIGHT][1], &EvaluateKRKN);
- add(z[W][KNIGHT][1] ^ z[B][ROOK][1], &EvaluateKNKR);
- add(z[W][QUEEN][1] ^ z[B][ROOK][1], &EvaluateKQKR);
- add(z[W][ROOK][1] ^ z[B][QUEEN][1], &EvaluateKRKQ);
- add(z[W][BISHOP][2] ^ z[B][KNIGHT][1], &EvaluateKBBKN);
- add(z[W][KNIGHT][1] ^ z[B][BISHOP][2], &EvaluateKNKBB);
-
- add(z[W][KNIGHT][1] ^ z[W][PAWN][1], W, &ScaleKNPK);
- add(z[B][KNIGHT][1] ^ z[B][PAWN][1], B, &ScaleKKNP);
-
- add(z[W][ROOK][1] ^ z[W][PAWN][1] ^ z[B][ROOK][1] , W, &ScaleKRPKR);
- add(z[W][ROOK][1] ^ z[B][ROOK][1] ^ z[B][PAWN][1] , B, &ScaleKRKRP);
- add(z[W][BISHOP][1] ^ z[W][PAWN][1] ^ z[B][BISHOP][1], W, &ScaleKBPKB);
- add(z[W][BISHOP][1] ^ z[B][BISHOP][1] ^ z[B][PAWN][1] , B, &ScaleKBKBP);
- add(z[W][BISHOP][1] ^ z[W][PAWN][1] ^ z[B][KNIGHT][1], W, &ScaleKBPKN);
- add(z[W][KNIGHT][1] ^ z[B][BISHOP][1] ^ z[B][PAWN][1] , B, &ScaleKNKBP);
-
- add(z[W][ROOK][1] ^ z[W][PAWN][1] ^ z[W][PAWN][2] ^ z[B][ROOK][1] ^ z[B][PAWN][1], W, &ScaleKRPPKRP);
- add(z[W][ROOK][1] ^ z[W][PAWN][1] ^ z[B][ROOK][1] ^ z[B][PAWN][1] ^ z[B][PAWN][2], B, &ScaleKRPKRPP);
-}
-
-void EndgameFunctions::add(Key k, EndgameEvaluationFunction* f) {
-
- EEFmap.insert(std::pair<Key, EndgameEvaluationFunction*>(k, f));
-}
-
-void EndgameFunctions::add(Key k, Color c, ScalingFunction* f) {
-
- ScalingInfo s = {c, f};
- ESFmap.insert(std::pair<Key, ScalingInfo>(k, s));
-}
-
-EndgameEvaluationFunction* EndgameFunctions::getEEF(Key key) const {
-
- std::map<Key, EndgameEvaluationFunction*>::const_iterator it(EEFmap.find(key));
- return (it != EEFmap.end() ? it->second : NULL);
-}
-
-ScalingFunction* EndgameFunctions::getESF(Key key, Color* c) const {
-
- std::map<Key, ScalingInfo>::const_iterator it(ESFmap.find(key));
- if (it == ESFmap.end())
- return NULL;
-
- *c = it->second.col;
- return it->second.fun;
-}