X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmaterial.cpp;h=a14e3370cad9c4a69afd507c193d09b52801b2c1;hp=068d88e702092a67259ae312165bb33683cb101e;hb=94dd204c3b10ebe0e6c8df5d7c98de5ba4906cad;hpb=3ed86ed3f95f712587bea62f4a7fc474812db458 diff --git a/src/material.cpp b/src/material.cpp index 068d88e7..a14e3370 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) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2014 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 @@ -27,29 +27,23 @@ using namespace std; namespace { - // Values modified by Joona Kiiski - const Value MidgameLimit = Value(15581); - const Value EndgameLimit = Value(3998); - - // Scale factors used when one side has no more pawns - const int NoPawnsSF[4] = { 6, 12, 32 }; - // Polynomial material balance parameters - // pair pawn knight bishop rook queen - const int LinearCoefficients[6] = { 1852, -162, -1122, -183, 249, -52 }; + // pair pawn knight bishop rook queen + const int Linear[6] = { 1852, -162, -1122, -183, 249, -154 }; - const int QuadraticCoefficientsSameColor[][PIECE_TYPE_NB] = { + const int QuadraticSameSide[][PIECE_TYPE_NB] = { + // OUR PIECES // pair pawn knight bishop rook queen { 0 }, // Bishop pair { 39, 2 }, // Pawn - { 35, 271, -4 }, // Knight + { 35, 271, -4 }, // Knight OUR PIECES { 0, 105, 4, 0 }, // Bishop { -27, -2, 46, 100, -141 }, // Rook - { 58, 29, 83, 148, -163, 0 } // Queen + {-177, 25, 129, 142, -137, 0 } // Queen }; - const int QuadraticCoefficientsOppositeColor[][PIECE_TYPE_NB] = { + const int QuadraticOppositeSide[][PIECE_TYPE_NB] = { // THEIR PIECES // pair pawn knight bishop rook queen { 0 }, // Bishop pair @@ -57,12 +51,11 @@ namespace { { 10, 62, 0 }, // Knight OUR PIECES { 57, 64, 39, 0 }, // Bishop { 50, 40, 23, -22, 0 }, // Rook - { 106, 101, 3, 151, 171, 0 } // Queen + { 98, 105, -39, 141, 274, 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 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) }; @@ -73,8 +66,7 @@ namespace { // 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 + return !more_than_one(pos.pieces(Them)) && pos.non_pawn_material(Us) >= RookValueMg; } @@ -93,7 +85,7 @@ namespace { && pos.count(Them) >= 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 @@ -101,25 +93,24 @@ namespace { const Color Them = (Us == WHITE ? BLACK : WHITE); - int pt1, pt2, pc, v; - int value = 0; + int bonus = 0; // Second-degree polynomial material imbalance by Tord Romstad - for (pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; ++pt1) + 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 = Linear[pt1]; - 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 += QuadraticSameSide[pt1][pt2] * pieceCount[Us][pt2] + + QuadraticOppositeSide[pt1][pt2] * pieceCount[Them][pt2]; - value += pc * v; + bonus += pieceCount[Us][pt1] * v; } - return value; + + return bonus; } } // namespace @@ -145,11 +136,11 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { 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); + e->gamePhase = pos.game_phase(); - // 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. + // 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 (endgames.probe(key, e->evaluationFunction)) return e; @@ -165,21 +156,6 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { 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) - { - 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? // @@ -193,8 +169,8 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { return e; } - // Generic scaling functions that refer to more then one material - // distribution. Should be probed after the specialized ones. + // Generic scaling functions that refer to more than one material + // distribution. They 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]; @@ -211,7 +187,7 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { Value npm_w = pos.non_pawn_material(WHITE); Value npm_b = pos.non_pawn_material(BLACK); - if (npm_w + npm_b == VALUE_ZERO) + if (npm_w + npm_b == VALUE_ZERO && pos.pieces(PAWN)) { if (!pos.count(BLACK)) { @@ -233,18 +209,19 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { } // No pawns makes it difficult to win, even with a material advantage. This - // catches some trivial draws like KK, KBK and KNK + // catches some trivial draws like KK, KBK and KNK and gives a very 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 : 12); 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)]); - } + e->factor[BLACK] = uint8_t(npm_b < RookValueMg ? SCALE_FACTOR_DRAW : npm_w <= BishopValueMg ? 4 : 12); + + if (pos.count(WHITE) == 1 && npm_w - npm_b <= BishopValueMg) + e->factor[WHITE] = (uint8_t) SCALE_FACTOR_ONEPAWN; + + if (pos.count(BLACK) == 1 && npm_b - npm_w <= BishopValueMg) + e->factor[BLACK] = (uint8_t) SCALE_FACTOR_ONEPAWN; // Compute the space weight if (npm_w + npm_b >= 2 * QueenValueMg + 4 * RookValueMg + 2 * KnightValueMg) @@ -256,7 +233,7 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { } // 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), @@ -268,18 +245,4 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { 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