X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fendgame.cpp;h=abbb0876c64bd35b77be6f919ca66b793d02c4cb;hp=9fafb042d86452f56006f23732f64c7b51bd436f;hb=aa925a0e2905042a978860a75798398cb79b2600;hpb=82bf08e4f20509b1e8e284833cd508dea7e3c145 diff --git a/src/endgame.cpp b/src/endgame.cpp index 9fafb042..abbb0876 100644 --- a/src/endgame.cpp +++ b/src/endgame.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) 2008-2009 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 @@ -25,90 +25,10 @@ #include #include "bitbase.h" +#include "bitcount.h" #include "endgame.h" -//// -//// Constants and variables -//// - -/// Evaluation functions - -// Generic "mate lone king" eval -KXKEvaluationFunction EvaluateKXK = KXKEvaluationFunction(WHITE); -KXKEvaluationFunction EvaluateKKX = KXKEvaluationFunction(BLACK); - -// KBN vs K -KBNKEvaluationFunction EvaluateKBNK = KBNKEvaluationFunction(WHITE); -KBNKEvaluationFunction EvaluateKKBN = KBNKEvaluationFunction(BLACK); - -// KP vs K -KPKEvaluationFunction EvaluateKPK = KPKEvaluationFunction(WHITE); -KPKEvaluationFunction EvaluateKKP = KPKEvaluationFunction(BLACK); - -// KR vs KP -KRKPEvaluationFunction EvaluateKRKP = KRKPEvaluationFunction(WHITE); -KRKPEvaluationFunction EvaluateKPKR = KRKPEvaluationFunction(BLACK); - -// KR vs KB -KRKBEvaluationFunction EvaluateKRKB = KRKBEvaluationFunction(WHITE); -KRKBEvaluationFunction EvaluateKBKR = KRKBEvaluationFunction(BLACK); - -// KR vs KN -KRKNEvaluationFunction EvaluateKRKN = KRKNEvaluationFunction(WHITE); -KRKNEvaluationFunction EvaluateKNKR = KRKNEvaluationFunction(BLACK); - -// KQ vs KR -KQKREvaluationFunction EvaluateKQKR = KQKREvaluationFunction(WHITE); -KQKREvaluationFunction EvaluateKRKQ = KQKREvaluationFunction(BLACK); - -// KBB vs KN -KBBKNEvaluationFunction EvaluateKBBKN = KBBKNEvaluationFunction(WHITE); -KBBKNEvaluationFunction EvaluateKNKBB = KBBKNEvaluationFunction(BLACK); - -// K and two minors vs K and one or two minors -KmmKmEvaluationFunction EvaluateKmmKm = KmmKmEvaluationFunction(WHITE); - - -/// Scaling functions - -// KBP vs K -KBPKScalingFunction ScaleKBPK = KBPKScalingFunction(WHITE); -KBPKScalingFunction ScaleKKBP = KBPKScalingFunction(BLACK); - -// KQ vs KRP -KQKRPScalingFunction ScaleKQKRP = KQKRPScalingFunction(WHITE); -KQKRPScalingFunction ScaleKRPKQ = KQKRPScalingFunction(BLACK); - -// KRP vs KR -KRPKRScalingFunction ScaleKRPKR = KRPKRScalingFunction(WHITE); -KRPKRScalingFunction ScaleKRKRP = KRPKRScalingFunction(BLACK); - -// KRPP vs KRP -KRPPKRPScalingFunction ScaleKRPPKRP = KRPPKRPScalingFunction(WHITE); -KRPPKRPScalingFunction ScaleKRPKRPP = KRPPKRPScalingFunction(BLACK); - -// King and pawns vs king -KPsKScalingFunction ScaleKPsK = KPsKScalingFunction(WHITE); -KPsKScalingFunction ScaleKKPs = KPsKScalingFunction(BLACK); - -// KBP vs KB -KBPKBScalingFunction ScaleKBPKB = KBPKBScalingFunction(WHITE); -KBPKBScalingFunction ScaleKBKBP = KBPKBScalingFunction(BLACK); - -// KBP vs KN -KBPKNScalingFunction ScaleKBPKN = KBPKNScalingFunction(WHITE); -KBPKNScalingFunction ScaleKNKBP = KBPKNScalingFunction(BLACK); - -// KNP vs K -KNPKScalingFunction ScaleKNPK = KNPKScalingFunction(WHITE); -KNPKScalingFunction ScaleKKNP = KNPKScalingFunction(BLACK); - -// KPKP -KPKPScalingFunction ScaleKPKPw = KPKPScalingFunction(WHITE); -KPKPScalingFunction ScaleKPKPb = KPKPScalingFunction(BLACK); - - //// //// Local definitions //// @@ -179,44 +99,12 @@ namespace { //// Functions //// -/// Constructors - -EndgameEvaluationFunction::EndgameEvaluationFunction(Color c) : strongerSide(c) { - weakerSide = opposite_color(strongerSide); -} - -KXKEvaluationFunction::KXKEvaluationFunction(Color c) : EndgameEvaluationFunction(c) {} -KBNKEvaluationFunction::KBNKEvaluationFunction(Color c) : EndgameEvaluationFunction(c) {} -KPKEvaluationFunction::KPKEvaluationFunction(Color c) : EndgameEvaluationFunction(c) {} -KRKPEvaluationFunction::KRKPEvaluationFunction(Color c) : EndgameEvaluationFunction(c) {} -KRKBEvaluationFunction::KRKBEvaluationFunction(Color c) : EndgameEvaluationFunction(c) {} -KRKNEvaluationFunction::KRKNEvaluationFunction(Color c) : EndgameEvaluationFunction(c) {} -KQKREvaluationFunction::KQKREvaluationFunction(Color c) : EndgameEvaluationFunction(c) {} -KBBKNEvaluationFunction::KBBKNEvaluationFunction(Color c) : EndgameEvaluationFunction(c) {} -KmmKmEvaluationFunction::KmmKmEvaluationFunction(Color c) : EndgameEvaluationFunction(c) {} - - -ScalingFunction::ScalingFunction(Color c) : strongerSide(c) { - weakerSide = opposite_color(c); -} - -KBPKScalingFunction::KBPKScalingFunction(Color c) : ScalingFunction(c) {} -KQKRPScalingFunction::KQKRPScalingFunction(Color c) : ScalingFunction(c) {} -KRPKRScalingFunction::KRPKRScalingFunction(Color c) : ScalingFunction(c) {} -KRPPKRPScalingFunction::KRPPKRPScalingFunction(Color c) : ScalingFunction(c) {} -KPsKScalingFunction::KPsKScalingFunction(Color c) : ScalingFunction(c) {} -KBPKBScalingFunction::KBPKBScalingFunction(Color c) : ScalingFunction(c) {} -KBPKNScalingFunction::KBPKNScalingFunction(Color c) : ScalingFunction(c) {} -KNPKScalingFunction::KNPKScalingFunction(Color c) : ScalingFunction(c) {} -KPKPScalingFunction::KPKPScalingFunction(Color c) : ScalingFunction(c) {} - - /// Mate with KX vs K. This function is used to evaluate positions with /// King and plenty of material vs a lone king. It simply gives the /// attacking side a bonus for driving the defending king towards the edge /// of the board, and for keeping the distance between the two kings small. - -Value KXKEvaluationFunction::apply(const Position& pos) { +template<> +Value EvaluationFunction::apply(const Position& pos) { assert(pos.non_pawn_material(weakerSide) == Value(0)); assert(pos.piece_count(weakerSide, PAWN) == Value(0)); @@ -241,8 +129,8 @@ Value KXKEvaluationFunction::apply(const Position& pos) { /// Mate with KBN vs K. This is similar to KX vs K, but we have to drive the /// defending king towards a corner square of the right color. - -Value KBNKEvaluationFunction::apply(const Position& pos) { +template<> +Value EvaluationFunction::apply(const Position& pos) { assert(pos.non_pawn_material(weakerSide) == Value(0)); assert(pos.piece_count(weakerSide, PAWN) == Value(0)); @@ -270,8 +158,8 @@ Value KBNKEvaluationFunction::apply(const Position& pos) { /// KP vs K. This endgame is evaluated with the help of a bitbase. - -Value KPKEvaluationFunction::apply(const Position& pos) { +template<> +Value EvaluationFunction::apply(const Position& pos) { assert(pos.non_pawn_material(strongerSide) == Value(0)); assert(pos.non_pawn_material(weakerSide) == Value(0)); @@ -318,8 +206,8 @@ Value KPKEvaluationFunction::apply(const Position& pos) { /// a bitbase. The function below returns drawish scores when the pawn is /// far advanced with support of the king, while the attacking king is far /// away. - -Value KRKPEvaluationFunction::apply(const Position& pos) { +template<> +Value EvaluationFunction::apply(const Position& pos) { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -375,8 +263,8 @@ Value KRKPEvaluationFunction::apply(const Position& pos) { /// KR vs KB. This is very simple, and always returns drawish scores. The /// score is slightly bigger when the defending king is close to the edge. - -Value KRKBEvaluationFunction::apply(const Position& pos) { +template<> +Value EvaluationFunction::apply(const Position& pos) { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -391,8 +279,8 @@ Value KRKBEvaluationFunction::apply(const Position& pos) { /// KR vs KN. The attacking side has slightly better winning chances than /// in KR vs KB, particularly if the king and the knight are far apart. - -Value KRKNEvaluationFunction::apply(const Position& pos) { +template<> +Value EvaluationFunction::apply(const Position& pos) { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -415,8 +303,8 @@ Value KRKNEvaluationFunction::apply(const Position& pos) { /// defending king towards the edge. If we also take care to avoid null move /// for the defending side in the search, this is usually sufficient to be /// able to win KQ vs KR. - -Value KQKREvaluationFunction::apply(const Position& pos) { +template<> +Value EvaluationFunction::apply(const Position& pos) { assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -434,8 +322,8 @@ Value KQKREvaluationFunction::apply(const Position& pos) { return (strongerSide == pos.side_to_move())? result : -result; } - -Value KBBKNEvaluationFunction::apply(const Position& pos) { +template<> +Value EvaluationFunction::apply(const Position& pos) { assert(pos.piece_count(strongerSide, BISHOP) == 2); assert(pos.non_pawn_material(strongerSide) == 2*BishopValueMidgame); @@ -461,18 +349,25 @@ Value KBBKNEvaluationFunction::apply(const Position& pos) { } -Value KmmKmEvaluationFunction::apply(const Position &pos) { +/// K and two minors vs K and one or two minors or K and two knights against +/// king alone are always draw. +template<> +Value EvaluationFunction::apply(const Position&) { return Value(0); } +template<> +Value EvaluationFunction::apply(const Position&) { + return Value(0); +} /// KBPKScalingFunction scales endgames where the stronger side has king, /// bishop and one or more pawns. It checks for draws with rook pawns and a /// bishop of the wrong color. If such a draw is detected, ScaleFactor(0) is /// returned. If not, the return value is SCALE_FACTOR_NONE, i.e. no scaling /// will be used. - -ScaleFactor KBPKScalingFunction::apply(const Position& pos) { +template<> +ScaleFactor ScalingFunction::apply(const Position& pos) { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); assert(pos.piece_count(strongerSide, BISHOP) == 1); @@ -526,8 +421,8 @@ ScaleFactor KBPKScalingFunction::apply(const Position& pos) { /// king and queen, while the weaker side has at least a rook and a pawn. /// It tests for fortress draws with a rook on the third rank defended by /// a pawn. - -ScaleFactor KQKRPScalingFunction::apply(const Position& pos) { +template<> +ScaleFactor ScalingFunction::apply(const Position& pos) { assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame); assert(pos.piece_count(strongerSide, QUEEN) == 1); @@ -557,8 +452,8 @@ ScaleFactor KQKRPScalingFunction::apply(const Position& pos) { /// /// It would also be nice to rewrite the actual code for this function, /// which is mostly copied from Glaurung 1.x, and not very pretty. - -ScaleFactor KRPKRScalingFunction::apply(const Position &pos) { +template<> +ScaleFactor ScalingFunction::apply(const Position &pos) { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 1); @@ -675,8 +570,8 @@ ScaleFactor KRPKRScalingFunction::apply(const Position &pos) { /// KRPPKRPScalingFunction scales KRPP vs KRP endgames. There is only a /// single pattern: If the stronger side has no pawns and the defending king /// is actively placed, the position is drawish. - -ScaleFactor KRPPKRPScalingFunction::apply(const Position &pos) { +template<> +ScaleFactor ScalingFunction::apply(const Position &pos) { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 2); @@ -714,8 +609,8 @@ ScaleFactor KRPPKRPScalingFunction::apply(const Position &pos) { /// KPsKScalingFunction scales endgames with king and two or more pawns /// against king. There is just a single rule here: If all pawns are on /// the same rook file and are blocked by the defending king, it's a draw. - -ScaleFactor KPsKScalingFunction::apply(const Position &pos) { +template<> +ScaleFactor ScalingFunction::apply(const Position &pos) { assert(pos.non_pawn_material(strongerSide) == Value(0)); assert(pos.piece_count(strongerSide, PAWN) >= 2); @@ -760,8 +655,8 @@ ScaleFactor KPsKScalingFunction::apply(const Position &pos) { /// square of the king is not of the same color as the stronger side's bishop, /// it's a draw. If the two bishops have opposite color, it's almost always /// a draw. - -ScaleFactor KBPKBScalingFunction::apply(const Position &pos) { +template<> +ScaleFactor ScalingFunction::apply(const Position &pos) { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); assert(pos.piece_count(strongerSide, BISHOP) == 1); @@ -811,12 +706,86 @@ ScaleFactor KBPKBScalingFunction::apply(const Position &pos) { } +/// KBPPKBScalingFunction scales KBPP vs KB endgames. It detects a few basic +/// draws with opposite-colored bishops. +template<> +ScaleFactor ScalingFunction::apply(const Position& pos) { + + assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); + assert(pos.piece_count(strongerSide, BISHOP) == 1); + assert(pos.piece_count(strongerSide, PAWN) == 2); + assert(pos.non_pawn_material(weakerSide) == BishopValueMidgame); + assert(pos.piece_count(weakerSide, BISHOP) == 1); + assert(pos.piece_count(weakerSide, PAWN) == 0); + + Square wbsq = pos.piece_list(strongerSide, BISHOP, 0); + Square bbsq = pos.piece_list(weakerSide, BISHOP, 0); + + if (square_color(wbsq) == square_color(bbsq)) + // Not opposite-colored bishops, no scaling + return SCALE_FACTOR_NONE; + + Square ksq = pos.king_square(weakerSide); + Square psq1 = pos.piece_list(strongerSide, PAWN, 0); + Square psq2 = pos.piece_list(strongerSide, PAWN, 1); + Rank r1 = square_rank(psq1); + Rank r2 = square_rank(psq2); + Square blockSq1, blockSq2; + + if (relative_rank(strongerSide, psq1) > relative_rank(strongerSide, psq2)) + { + blockSq1 = psq1 + pawn_push(strongerSide); + blockSq2 = make_square(square_file(psq2), square_rank(psq1)); + } + else + { + blockSq1 = psq2 + pawn_push(strongerSide); + blockSq2 = make_square(square_file(psq1), square_rank(psq2)); + } + + switch (file_distance(psq1, psq2)) + { + case 0: + // Both pawns are on the same file. Easy draw if defender firmly controls + // some square in the frontmost pawn's path. + if ( square_file(ksq) == square_file(blockSq1) + && relative_rank(strongerSide, ksq) >= relative_rank(strongerSide, blockSq1) + && square_color(ksq) != square_color(wbsq)) + return ScaleFactor(0); + else + return SCALE_FACTOR_NONE; + + case 1: + // Pawns on neighboring files. Draw if defender firmly controls the square + // in front of the frontmost pawn's path, and the square diagonally behind + // this square on the file of the other pawn. + if ( ksq == blockSq1 + && square_color(ksq) != square_color(wbsq) + && ( bbsq == blockSq2 + || (pos.piece_attacks(blockSq2) & pos.bishops(weakerSide)) + || rank_distance(r1, r2) >= 2)) + return ScaleFactor(0); + else if ( ksq == blockSq2 + && square_color(ksq) != square_color(wbsq) + && ( bbsq == blockSq1 + || (pos.piece_attacks(blockSq1) & pos.bishops(weakerSide)))) + return ScaleFactor(0); + else + return SCALE_FACTOR_NONE; + + default: + // The pawns are not on the same file or adjacent files. No scaling. + return SCALE_FACTOR_NONE; + } +} + + /// KBPKNScalingFunction scales KBP vs KN endgames. There is a single rule: /// If the defending king is somewhere along the path of the pawn, and the /// square of the king is not of the same color as the stronger side's bishop, /// it's a draw. - -ScaleFactor KBPKNScalingFunction::apply(const Position &pos) { +template<> +ScaleFactor ScalingFunction::apply(const Position &pos) { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); assert(pos.piece_count(strongerSide, BISHOP) == 1); @@ -842,8 +811,8 @@ ScaleFactor KBPKNScalingFunction::apply(const Position &pos) { /// KNPKScalingFunction scales KNP vs K endgames. There is a single rule: /// If the pawn is a rook pawn on the 7th rank and the defending king prevents /// the pawn from advancing, the position is drawn. - -ScaleFactor KNPKScalingFunction::apply(const Position &pos) { +template<> +ScaleFactor ScalingFunction::apply(const Position &pos) { assert(pos.non_pawn_material(strongerSide) == KnightValueMidgame); assert(pos.piece_count(strongerSide, KNIGHT) == 1); @@ -872,8 +841,8 @@ ScaleFactor KNPKScalingFunction::apply(const Position &pos) { /// the pawn as well. The exception is when the stronger side's pawn is far /// advanced and not on a rook file; in this case it is often possible to win /// (e.g. 8/4k3/3p4/3P4/6K1/8/8/8 w - - 0 1). - -ScaleFactor KPKPScalingFunction::apply(const Position &pos) { +template<> +ScaleFactor ScalingFunction::apply(const Position &pos) { assert(pos.non_pawn_material(strongerSide) == Value(0)); assert(pos.non_pawn_material(weakerSide) == Value(0));