X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmaterial.cpp;h=11d4c687dfe7066ee1abda9b2d933c70f34b24c6;hp=22953cff6d8d4328706cb1ffe4299d46214d2c05;hb=aec918a2b6ee931826ef19db1726950976da7ffe;hpb=4ede49cd850392f28bc9da9537c111d2c3f0b297 diff --git a/src/material.cpp b/src/material.cpp index 22953cff..11d4c687 100644 --- a/src/material.cpp +++ b/src/material.cpp @@ -1,7 +1,8 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, 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 @@ -17,218 +18,169 @@ along with this program. If not, see . */ -#include // For std::min #include -#include +#include // For std::memset #include "material.h" +#include "thread.h" using namespace std; namespace { - // Values modified by Joona Kiiski - const Value MidgameLimit = Value(15581); - const Value EndgameLimit = Value(3998); + // Polynomial material imbalance parameters - // Scale factors used when one side has no more pawns - const int NoPawnsSF[4] = { 6, 12, 32 }; - - // Polynomial material balance parameters - const Value RedundantQueen = Value(320); - const Value RedundantRook = Value(554); - - // pair pawn knight bishop rook queen - const int LinearCoefficients[6] = { 1617, -162, -1172, -190, 105, 26 }; - - const int QuadraticCoefficientsSameColor[][PIECE_TYPE_NB] = { + constexpr int QuadraticOurs[][PIECE_TYPE_NB] = { + // OUR PIECES // pair pawn knight bishop rook queen - { 7 }, // Bishop pair - { 39, 2 }, // Pawn - { 35, 271, -4 }, // Knight - { 7, 105, 4, 7 }, // Bishop - { -27, -2, 46, 100, 56 }, // Rook - { 58, 29, 83, 148, -3, -25 } // Queen + {1438 }, // Bishop pair + { 40, 38 }, // Pawn + { 32, 255, -62 }, // Knight OUR PIECES + { 0, 104, 4, 0 }, // Bishop + { -26, -2, 47, 105, -208 }, // Rook + {-189, 24, 117, 133, -134, -6 } // Queen }; - const int QuadraticCoefficientsOppositeColor[][PIECE_TYPE_NB] = { + constexpr int QuadraticTheirs[][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 + { 0 }, // Bishop pair + { 36, 0 }, // Pawn + { 9, 63, 0 }, // Knight OUR PIECES + { 59, 65, 42, 0 }, // Bishop + { 46, 39, 24, -24, 0 }, // Rook + { 97, 100, -42, 137, 268, 0 } // Queen }; - // 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 evaluation and scaling functions are accessed directly and not through + // the function maps because they correspond to more than one material hash key. + 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.count(Them) - && pos.non_pawn_material(Them) == VALUE_ZERO - && pos.non_pawn_material(Us) >= RookValueMg; + // Helper used to detect a given material distribution + bool is_KXK(const Position& pos, Color us) { + return !more_than_one(pos.pieces(~us)) + && pos.non_pawn_material(us) >= RookValueMg; } - template bool is_KBPsKs(const Position& pos) { - return pos.non_pawn_material(Us) == BishopValueMg - && pos.count(Us) == 1 - && pos.count(Us) >= 1; + bool is_KBPsK(const Position& pos, Color us) { + return pos.non_pawn_material(us) == BishopValueMg + && pos.count(us) >= 1; } - template bool is_KQKRPs(const Position& pos) { - const Color Them = (Us == WHITE ? BLACK : WHITE); - return !pos.count(Us) - && pos.non_pawn_material(Us) == QueenValueMg - && pos.count(Us) == 1 - && pos.count(Them) == 1 - && pos.count(Them) >= 1; + bool is_KQKRPs(const Position& pos, Color us) { + return !pos.count(us) + && pos.non_pawn_material(us) == QueenValueMg + && pos.count(~us) == 1 + && pos.count(~us) >= 1; } - /// imbalance() calculates imbalance comparing piece count of each + /// imbalance() calculates the imbalance by comparing the piece count of each /// piece type for both colors. - template int imbalance(const int pieceCount[][PIECE_TYPE_NB]) { - const Color Them = (Us == WHITE ? BLACK : WHITE); - - int pt1, pt2, pc, v; - int value = 0; + constexpr Color Them = (Us == WHITE ? BLACK : WHITE); - // Redundancy of major pieces, formula based on Kaufman's paper - // "The Evaluation of Material Imbalances in Chess" - if (pieceCount[Us][ROOK] > 0) - value -= RedundantRook * (pieceCount[Us][ROOK] - 1) - + RedundantQueen * pieceCount[Us][QUEEN]; + int bonus = 0; - // Second-degree polynomial material imbalance by Tord Romstad - for (pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; pt1++) + // Second-degree polynomial material imbalance, by Tord Romstad + for (int pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; ++pt1) { - pc = pieceCount[Us][pt1]; - if (!pc) + if (!pieceCount[Us][pt1]) continue; - v = LinearCoefficients[pt1]; + int v = 0; - for (pt2 = NO_PIECE_TYPE; pt2 <= pt1; pt2++) - v += QuadraticCoefficientsSameColor[pt1][pt2] * pieceCount[Us][pt2] - + QuadraticCoefficientsOppositeColor[pt1][pt2] * pieceCount[Them][pt2]; + for (int pt2 = NO_PIECE_TYPE; pt2 <= pt1; ++pt2) + v += QuadraticOurs[pt1][pt2] * pieceCount[Us][pt2] + + QuadraticTheirs[pt1][pt2] * pieceCount[Them][pt2]; - value += pc * v; + bonus += pieceCount[Us][pt1] * v; } - return value; + + return bonus; } } // namespace namespace Material { -/// 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. +/// Material::probe() looks up the current position's material configuration in +/// the material hash table. It returns a pointer to the Entry if the position +/// is found. Otherwise a new Entry is computed and stored there, so we don't +/// have to recompute all when the same material configuration occurs again. -Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { +Entry* probe(const Position& pos) { Key key = pos.material_key(); - Entry* e = entries[key]; + Entry* e = pos.this_thread()->materialTable[key]; - // 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 (e->key == key) return e; std::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. First we look for a fixed - // configuration one, then a generic one if previous search failed. - if (endgames.probe(key, e->evaluationFunction)) - return e; + Value npm_w = pos.non_pawn_material(WHITE); + Value npm_b = pos.non_pawn_material(BLACK); + Value npm = clamp(npm_w + npm_b, EndgameLimit, MidgameLimit); - if (is_KXK(pos)) - { - e->evaluationFunction = &EvaluateKXK[WHITE]; - return e; - } + // Map total non-pawn material into [PHASE_ENDGAME, PHASE_MIDGAME] + e->gamePhase = Phase(((npm - EndgameLimit) * PHASE_MIDGAME) / (MidgameLimit - EndgameLimit)); - if (is_KXK(pos)) - { - e->evaluationFunction = &EvaluateKXK[BLACK]; + // Let's look if we have a specialized evaluation function for this particular + // material configuration. Firstly we look for a fixed configuration one, then + // for a generic one if the previous search failed. + if ((e->evaluationFunction = Endgames::probe(key)) != nullptr) return e; - } - - if (!pos.pieces(PAWN) && !pos.pieces(ROOK) && !pos.pieces(QUEEN)) - { - // 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.count(WHITE) + pos.count(WHITE) <= 2 - && pos.count(BLACK) + pos.count(BLACK) <= 2) + for (Color c : { WHITE, BLACK }) + if (is_KXK(pos, c)) { - e->evaluationFunction = &EvaluateKmmKm[pos.side_to_move()]; + e->evaluationFunction = &EvaluateKXK[c]; return e; } - } - // OK, we didn't find any special evaluation function for the current - // material configuration. Is there a suitable scaling function? - // - // We face problems when there are several conflicting applicable - // scaling functions and we need to decide which one to use. - EndgameBase* sf; + // OK, we didn't find any special evaluation function for the current material + // configuration. Is there a suitable specialized scaling function? + const auto* sf = Endgames::probe(key); - if (endgames.probe(key, sf)) + if (sf) { - e->scalingFunction[sf->color()] = sf; + e->scalingFunction[sf->strongSide] = sf; // Only strong color assigned return e; } - // 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]; + // We didn't find any specialized scaling function, so fall back on generic + // ones that refer to more than one material distribution. Note that in this + // case we don't return after setting the function. + for (Color c : { WHITE, BLACK }) + { + if (is_KBPsK(pos, c)) + e->scalingFunction[c] = &ScaleKBPsK[c]; - Value npm_w = pos.non_pawn_material(WHITE); - Value npm_b = pos.non_pawn_material(BLACK); + else if (is_KQKRPs(pos, c)) + e->scalingFunction[c] = &ScaleKQKRPs[c]; + } - if (npm_w + npm_b == VALUE_ZERO) + if (npm_w + npm_b == VALUE_ZERO && pos.pieces(PAWN)) // Only pawns on the board { if (!pos.count(BLACK)) { assert(pos.count(WHITE) >= 2); + e->scalingFunction[WHITE] = &ScaleKPsK[WHITE]; } else if (!pos.count(WHITE)) { assert(pos.count(BLACK) >= 2); + e->scalingFunction[BLACK] = &ScaleKPsK[BLACK]; } else if (pos.count(WHITE) == 1 && pos.count(BLACK) == 1) @@ -240,30 +192,19 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { } } - // No pawns makes it difficult to win, even with a material advantage + // Zero or just one pawn makes it difficult to win, even with a small material + // advantage. This catches some trivial draws like KK, KBK and KNK and gives a + // drawish scale factor for cases such as KRKBP and KmmKm (except for KBBKN). if (!pos.count(WHITE) && npm_w - npm_b <= BishopValueMg) - { - e->factor[WHITE] = (uint8_t) - (npm_w == npm_b || npm_w < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count(WHITE), 2)]); - } + e->factor[WHITE] = uint8_t(npm_w < RookValueMg ? SCALE_FACTOR_DRAW : + npm_b <= BishopValueMg ? 4 : 14); if (!pos.count(BLACK) && npm_b - npm_w <= BishopValueMg) - { - e->factor[BLACK] = (uint8_t) - (npm_w == npm_b || npm_b < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count(BLACK), 2)]); - } - - // Compute the space weight - if (npm_w + npm_b >= 2 * QueenValueMg + 4 * RookValueMg + 2 * KnightValueMg) - { - int minorPieceCount = pos.count(WHITE) + pos.count(WHITE) - + pos.count(BLACK) + pos.count(BLACK); - - e->spaceWeight = minorPieceCount * minorPieceCount; - } + e->factor[BLACK] = uint8_t(npm_b < RookValueMg ? SCALE_FACTOR_DRAW : + npm_w <= BishopValueMg ? 4 : 14); // 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 + // for the bishop pair "extended piece", which allows us to be more flexible // in defining bishop pair bonuses. const int pieceCount[COLOR_NB][PIECE_TYPE_NB] = { { pos.count(WHITE) > 1, pos.count(WHITE), pos.count(WHITE), @@ -271,22 +212,8 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { { pos.count(BLACK) > 1, pos.count(BLACK), pos.count(BLACK), pos.count(BLACK) , pos.count(BLACK), pos.count(BLACK) } }; - e->value = (int16_t)((imbalance(pieceCount) - imbalance(pieceCount)) / 16); + e->value = int16_t((imbalance(pieceCount) - imbalance(pieceCount)) / 16); return e; } - -/// 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