X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmaterial.cpp;h=9cc8eeadc470b7e2f20a9f91a9c5ee8a4c1f9568;hp=3b1ead6dafcd22ed40706b666819e8ad3441d23c;hb=70d20326b0d53a39bbfa32f7c2b749e7dbebb985;hpb=5e906ea10e100cdad2f65d49e8212c14a1d65050 diff --git a/src/material.cpp b/src/material.cpp index 3b1ead6d..9cc8eead 100644 --- a/src/material.cpp +++ b/src/material.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008 Marco Costalba + Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -17,297 +17,276 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - +#include // For std::min #include -#include +#include #include "material.h" - -//// -//// Local definitions -//// +using namespace std; namespace { - const Value BishopPairMidgameBonus = Value(100); - const Value BishopPairEndgameBonus = Value(100); - - Key KNNKMaterialKey, KKNNMaterialKey; + // Values modified by Joona Kiiski + const Value MidgameLimit = Value(15581); + const Value EndgameLimit = Value(3998); - struct ScalingInfo - { - Color col; - ScalingFunction* fun; - }; + // Scale factors used when one side has no more pawns + const int NoPawnsSF[4] = { 6, 12, 32 }; - std::map EEFmap; - std::map ESFmap; + // Polynomial material balance parameters + const Value RedundantQueenPenalty = Value(320); + const Value RedundantRookPenalty = Value(554); - void add(Key k, EndgameEvaluationFunction* f) { + // pair pawn knight bishop rook queen + const int LinearCoefficients[6] = { 1617, -162, -1172, -190, 105, 26 }; - EEFmap.insert(std::pair(k, f)); - } + const int QuadraticCoefficientsSameColor[][PIECE_TYPE_NB] = { + // pair pawn knight bishop rook queen + { 7 }, // Bishop pair + { 39, 2 }, // Pawn + { 35, 271, -4 }, // Knight + { 7, 25, 4, 7 }, // Bishop + { -27, -2, 46, 100, 56 }, // Rook + { 58, 29, 83, 148, -3, -25 } // Queen + }; - void add(Key k, Color c, ScalingFunction* f) { + const int QuadraticCoefficientsOppositeColor[][PIECE_TYPE_NB] = { + // THEIR PIECES + // pair pawn knight bishop rook queen + { 41 }, // Bishop pair + { 37, 41 }, // Pawn + { 10, 62, 41 }, // Knight OUR PIECES + { 57, 64, 39, 41 }, // Bishop + { 50, 40, 23, -22, 41 }, // Rook + { 106, 101, 3, 151, 171, 41 } // Queen + }; - ScalingInfo s = {c, f}; - ESFmap.insert(std::pair(k, s)); + // Endgame evaluation and scaling functions accessed direcly and not through + // the function maps because correspond to more then one material hash key. + Endgame EvaluateKmmKm[] = { Endgame(WHITE), Endgame(BLACK) }; + Endgame EvaluateKXK[] = { Endgame(WHITE), Endgame(BLACK) }; + + Endgame ScaleKBPsK[] = { Endgame(WHITE), Endgame(BLACK) }; + Endgame ScaleKQKRPs[] = { Endgame(WHITE), Endgame(BLACK) }; + Endgame ScaleKPsK[] = { Endgame(WHITE), Endgame(BLACK) }; + Endgame ScaleKPKP[] = { Endgame(WHITE), Endgame(BLACK) }; + + // Helper templates used to detect a given material distribution + template bool is_KXK(const Position& pos) { + const Color Them = (Us == WHITE ? BLACK : WHITE); + return pos.non_pawn_material(Them) == VALUE_ZERO + && pos.piece_count(Them, PAWN) == 0 + && pos.non_pawn_material(Us) >= RookValueMg; } -} - - -//// -//// Functions -//// - -/// MaterialInfo::init() is called during program initialization. It -/// precomputes material hash keys for a few basic endgames, in order -/// to make it easy to recognize such endgames when they occur. - -void MaterialInfo::init() { - - typedef Key ZM[2][8][16]; - const ZM& z = Position::zobMaterial; - - static const Color W = WHITE; - static const Color B = BLACK; + template bool is_KBPsKs(const Position& pos) { + return pos.non_pawn_material(Us) == BishopValueMg + && pos.piece_count(Us, BISHOP) == 1 + && pos.piece_count(Us, PAWN) >= 1; + } - KNNKMaterialKey = z[W][KNIGHT][1] ^ z[W][KNIGHT][2]; - KKNNMaterialKey = z[B][KNIGHT][1] ^ z[B][KNIGHT][2]; + template bool is_KQKRPs(const Position& pos) { + const Color Them = (Us == WHITE ? BLACK : WHITE); + return pos.piece_count(Us, PAWN) == 0 + && pos.non_pawn_material(Us) == QueenValueMg + && pos.piece_count(Us, QUEEN) == 1 + && pos.piece_count(Them, ROOK) == 1 + && pos.piece_count(Them, PAWN) >= 1; + } - add(z[W][PAWN][1], &EvaluateKPK); - add(z[B][PAWN][1], &EvaluateKKP); + /// imbalance() calculates imbalance comparing piece count of each + /// piece type for both colors. - 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); + template + int imbalance(const int pieceCount[][PIECE_TYPE_NB]) { - add(z[W][KNIGHT][1] ^ z[W][PAWN][1], W, &ScaleKNPK); - add(z[B][KNIGHT][1] ^ z[B][PAWN][1], B, &ScaleKKNP); + const Color Them = (Us == WHITE ? BLACK : WHITE); - 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); + int pt1, pt2, pc, v; + int value = 0; - 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); -} + // Redundancy of major pieces, formula based on Kaufman's paper + // "The Evaluation of Material Imbalances in Chess" + if (pieceCount[Us][ROOK] > 0) + value -= RedundantRookPenalty * (pieceCount[Us][ROOK] - 1) + + RedundantQueenPenalty * pieceCount[Us][QUEEN]; + // Second-degree polynomial material imbalance by Tord Romstad + for (pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; pt1++) + { + pc = pieceCount[Us][pt1]; + if (!pc) + continue; -/// Constructor for the MaterialInfoTable class + v = LinearCoefficients[pt1]; -MaterialInfoTable::MaterialInfoTable(unsigned int numOfEntries) { + for (pt2 = NO_PIECE_TYPE; pt2 <= pt1; pt2++) + v += QuadraticCoefficientsSameColor[pt1][pt2] * pieceCount[Us][pt2] + + QuadraticCoefficientsOppositeColor[pt1][pt2] * pieceCount[Them][pt2]; - size = numOfEntries; - entries = new MaterialInfo[size]; - if (!entries) - { - std::cerr << "Failed to allocate " << (numOfEntries * sizeof(MaterialInfo)) - << " bytes for material hash table." << std::endl; - exit(EXIT_FAILURE); + value += pc * v; + } + return value; } - clear(); -} - -/// Destructor for the MaterialInfoTable class - -MaterialInfoTable::~MaterialInfoTable() { - - delete [] entries; -} - - -/// MaterialInfoTable::clear() clears a material hash table by setting -/// all entries to 0. - -void MaterialInfoTable::clear() { - - memset(entries, 0, size * sizeof(MaterialInfo)); -} +} // namespace +namespace Material { -/// 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. +/// Material::probe() takes a position object as input, looks up a MaterialEntry +/// object, and returns a pointer to it. If the material configuration is not +/// already present in the table, it is computed and 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) { +Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { - Key key = pos.get_material_key(); - int index = key & (size - 1); - MaterialInfo* mi = entries + index; + Key key = pos.material_key(); + Entry* e = entries[key]; - // If mi->key matches the position's material hash key, it means that we + // If e->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; + // return the information we found the last time instead of recomputing it. + if (e->key == key) + return e; - // 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; - } + memset(e, 0, sizeof(Entry)); + e->key = key; + e->factor[WHITE] = e->factor[BLACK] = (uint8_t)SCALE_FACTOR_NORMAL; + e->gamePhase = game_phase(pos); // Let's look if we have a specialized evaluation function for this - // particular material configuration - if (EEFmap.find(key) != EEFmap.end()) + // particular material configuration. First we look for a fixed + // configuration one, then a generic one if previous search failed. + if (endgames.probe(key, e->evaluationFunction)) + return e; + + if (is_KXK(pos)) { - mi->evaluationFunction = EEFmap[key]; - return mi; + e->evaluationFunction = &EvaluateKXK[WHITE]; + return e; } - else if ( pos.non_pawn_material(BLACK) == Value(0) - && pos.piece_count(BLACK, PAWN) == 0 - && pos.non_pawn_material(WHITE) >= RookValueEndgame) + + if (is_KXK(pos)) { - mi->evaluationFunction = &EvaluateKXK; - return mi; + e->evaluationFunction = &EvaluateKXK[BLACK]; + return e; } - else if ( pos.non_pawn_material(WHITE) == Value(0) - && pos.piece_count(WHITE, PAWN) == 0 - && pos.non_pawn_material(BLACK) >= RookValueEndgame) + + if (!pos.pieces(PAWN) && !pos.pieces(ROOK) && !pos.pieces(QUEEN)) { - mi->evaluationFunction = &EvaluateKKX; - return mi; + // Minor piece endgame with at least one minor piece per side and + // no pawns. Note that the case KmmK is already handled by KXK. + assert((pos.pieces(WHITE, KNIGHT) | pos.pieces(WHITE, BISHOP))); + assert((pos.pieces(BLACK, KNIGHT) | pos.pieces(BLACK, BISHOP))); + + if ( pos.piece_count(WHITE, BISHOP) + pos.piece_count(WHITE, KNIGHT) <= 2 + && pos.piece_count(BLACK, BISHOP) + pos.piece_count(BLACK, KNIGHT) <= 2) + { + e->evaluationFunction = &EvaluateKmmKm[pos.side_to_move()]; + return e; + } } // 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. + // We face problems when there are several conflicting applicable + // scaling functions and we need to decide which one to use. + EndgameBase* sf; - if (ESFmap.find(key) != ESFmap.end()) + if (endgames.probe(key, sf)) { - mi->scalingFunction[ESFmap[key].col] = ESFmap[key].fun; - return mi; + e->scalingFunction[sf->color()] = sf; + return e; } - 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)) + // Generic scaling functions that refer to more then one material + // distribution. Should be probed after the specialized ones. + // Note that these ones don't return after setting the function. + if (is_KBPsKs(pos)) + e->scalingFunction[WHITE] = &ScaleKBPsK[WHITE]; + + if (is_KBPsKs(pos)) + e->scalingFunction[BLACK] = &ScaleKBPsK[BLACK]; + + if (is_KQKRPs(pos)) + e->scalingFunction[WHITE] = &ScaleKQKRPs[WHITE]; + + else if (is_KQKRPs(pos)) + e->scalingFunction[BLACK] = &ScaleKQKRPs[BLACK]; + + Value npm_w = pos.non_pawn_material(WHITE); + Value npm_b = pos.non_pawn_material(BLACK); + + if (npm_w + npm_b == VALUE_ZERO) { if (pos.piece_count(BLACK, PAWN) == 0) { assert(pos.piece_count(WHITE, PAWN) >= 2); - mi->scalingFunction[WHITE] = &ScaleKPsK; + e->scalingFunction[WHITE] = &ScaleKPsK[WHITE]; } else if (pos.piece_count(WHITE, PAWN) == 0) { assert(pos.piece_count(BLACK, PAWN) >= 2); - mi->scalingFunction[BLACK] = &ScaleKKPs; + e->scalingFunction[BLACK] = &ScaleKPsK[BLACK]; } else if (pos.piece_count(WHITE, PAWN) == 1 && pos.piece_count(BLACK, PAWN) == 1) { - mi->scalingFunction[WHITE] = &ScaleKPKPw; - mi->scalingFunction[BLACK] = &ScaleKPKPb; + // This is a special case because we set scaling functions + // for both colors instead of only one. + e->scalingFunction[WHITE] = &ScaleKPKP[WHITE]; + e->scalingFunction[BLACK] = &ScaleKPKP[BLACK]; } } - // Evaluate the material balance + // No pawns makes it difficult to win, even with a material advantage + if (pos.piece_count(WHITE, PAWN) == 0 && npm_w - npm_b <= BishopValueMg) + { + e->factor[WHITE] = (uint8_t) + (npm_w == npm_b || npm_w < RookValueMg ? 0 : NoPawnsSF[std::min(pos.piece_count(WHITE, BISHOP), 2)]); + } - Color c; - int sign; - Value egValue = Value(0); - Value mgValue = Value(0); + if (pos.piece_count(BLACK, PAWN) == 0 && npm_b - npm_w <= BishopValueMg) + { + e->factor[BLACK] = (uint8_t) + (npm_w == npm_b || npm_b < RookValueMg ? 0 : NoPawnsSF[std::min(pos.piece_count(BLACK, BISHOP), 2)]); + } - for (c = WHITE, sign = 1; c <= BLACK; c++, sign = -sign) + // Compute the space weight + if (npm_w + npm_b >= 2 * QueenValueMg + 4 * RookValueMg + 2 * KnightValueMg) { - // 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; - } - } - } + int minorPieceCount = pos.piece_count(WHITE, KNIGHT) + pos.piece_count(WHITE, BISHOP) + + pos.piece_count(BLACK, KNIGHT) + pos.piece_count(BLACK, BISHOP); - // Bishop pair - if (pos.piece_count(c, BISHOP) >= 2) - { - mgValue += sign * BishopPairMidgameBonus; - egValue += sign * BishopPairEndgameBonus; - } + e->spaceWeight = minorPieceCount * minorPieceCount; + } - // 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); + // Evaluate the material imbalance. We use PIECE_TYPE_NONE as a place holder + // for the bishop pair "extended piece", this allow us to be more flexible + // in defining bishop pair bonuses. + const int pieceCount[COLOR_NB][PIECE_TYPE_NB] = { + { pos.piece_count(WHITE, BISHOP) > 1, pos.piece_count(WHITE, PAWN), pos.piece_count(WHITE, KNIGHT), + pos.piece_count(WHITE, BISHOP) , pos.piece_count(WHITE, ROOK), pos.piece_count(WHITE, QUEEN) }, + { pos.piece_count(BLACK, BISHOP) > 1, pos.piece_count(BLACK, PAWN), pos.piece_count(BLACK, KNIGHT), + pos.piece_count(BLACK, BISHOP) , pos.piece_count(BLACK, ROOK), pos.piece_count(BLACK, QUEEN) } }; + + e->value = (int16_t)((imbalance(pieceCount) - imbalance(pieceCount)) / 16); + return e; +} - // 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; +/// Material::game_phase() calculates the phase given the current +/// position. Because the phase is strictly a function of the material, it +/// is stored in MaterialEntry. + +Phase game_phase(const Position& pos) { + + Value npm = pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK); + + return npm >= MidgameLimit ? PHASE_MIDGAME + : npm <= EndgameLimit ? PHASE_ENDGAME + : Phase(((npm - EndgameLimit) * 128) / (MidgameLimit - EndgameLimit)); } + +} // namespace Material