X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fendgame.cpp;h=a868c0e82cb31405befb810a5a7bd19a995e9249;hp=366a02d1137458b80085034af0577b4a82903e18;hb=3ec94abcdb5f4ad81cc8829aece2d7fa64bb21db;hpb=d9e54ceaa1fb38cc16f2b9f68ea45eff85b7c0f5 diff --git a/src/endgame.cpp b/src/endgame.cpp index 366a02d1..a868c0e8 100644 --- a/src/endgame.cpp +++ b/src/endgame.cpp @@ -1,128 +1,51 @@ /* - Glaurung, a UCI chess playing engine. - Copyright (C) 2004-2008 Tord Romstad + Stockfish, a UCI chess playing engine derived from Glaurung 2.1 + Copyright (C) 2004-2008 Tord Romstad (Glaurung author) + Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad - Glaurung is free software: you can redistribute it and/or modify + 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. - - Glaurung is distributed in the hope that it will be useful, + + 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 . */ - -//// -//// Includes -//// - +#include #include -#include "bitbase.h" +#include "bitcount.h" #include "endgame.h" +#include "pawns.h" +using std::string; -//// -//// 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); - - -/// 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 -//// +extern uint32_t probe_kpk_bitbase(Square wksq, Square wpsq, Square bksq, Color stm); namespace { // Table used to drive the defending king towards the edge of the board - // in KX vs K and KQ vs KR endgames: - const uint8_t MateTable[64] = { + // in KX vs K and KQ vs KR endgames. + const int MateTable[64] = { 100, 90, 80, 70, 70, 80, 90, 100, - 90, 70, 60, 50, 50, 60, 70, 90, - 80, 60, 40, 30, 30, 40, 60, 80, - 70, 50, 30, 20, 20, 30, 50, 70, - 70, 50, 30, 20, 20, 30, 50, 70, - 80, 60, 40, 30, 30, 40, 60, 80, - 90, 70, 60, 50, 50, 60, 70, 90, + 90, 70, 60, 50, 50, 60, 70, 90, + 80, 60, 40, 30, 30, 40, 60, 80, + 70, 50, 30, 20, 20, 30, 50, 70, + 70, 50, 30, 20, 20, 30, 50, 70, + 80, 60, 40, 30, 30, 40, 60, 80, + 90, 70, 60, 50, 50, 60, 70, 90, 100, 90, 80, 70, 70, 80, 90, 100, }; // Table used to drive the defending king towards a corner square of the - // right color in KBN vs K endgames: - const uint8_t KBNKMateTable[64] = { + // right color in KBN vs K endgames. + const int KBNKMateTable[64] = { 200, 190, 180, 170, 160, 150, 140, 130, 190, 180, 170, 160, 150, 140, 130, 140, 180, 170, 155, 140, 140, 125, 140, 150, @@ -134,266 +57,270 @@ namespace { }; // The attacking side is given a descending bonus based on distance between - // the two kings in basic endgames: - const int DistanceBonus[8] = {0, 0, 100, 80, 60, 40, 20, 10}; + // the two kings in basic endgames. + const int DistanceBonus[8] = { 0, 0, 100, 80, 60, 40, 20, 10 }; - // Bitbase for KP vs K: - uint8_t KPKBitbase[24576]; + // Get the material key of a Position out of the given endgame key code + // like "KBPKN". The trick here is to first forge an ad-hoc fen string + // and then let a Position object to do the work for us. Note that the + // fen string could correspond to an illegal position. + Key key(const string& code, Color c) { - // Penalty for big distance between king and knight for the defending king - // and knight in KR vs KN endgames: - const int KRKNKingKnightDistancePenalty[8] = { 0, 0, 4, 10, 20, 32, 48, 70 }; + assert(code.length() > 0 && code.length() < 8); + assert(code[0] == 'K'); - // Various inline functions for accessing the above arrays: - - inline Value mate_table(Square s) { - return Value(MateTable[s]); - } + string sides[] = { code.substr(code.find('K', 1)), // Weaker + code.substr(0, code.find('K', 1)) }; // Stronger - inline Value kbnk_mate_table(Square s) { - return Value(KBNKMateTable[s]); - } + transform(sides[c].begin(), sides[c].end(), sides[c].begin(), tolower); - inline Value distance_bonus(int d) { - return Value(DistanceBonus[d]); - } + string fen = sides[0] + char('0' + int(8 - code.length())) + + sides[1] + "/8/8/8/8/8/8/8 w - - 0 10"; - inline Value krkn_king_knight_distance_penalty(int d) { - return Value(KRKNKingKnightDistancePenalty[d]); + return Position(fen, false, 0).material_key(); } - // Function for probing the KP vs K bitbase: - int probe_kpk(Square wksq, Square wpsq, Square bksq, Color stm); + template + void delete_endgame(const typename M::value_type& p) { delete p.second; } -} - +} // namespace -//// -//// Functions -//// -/// Constructors +/// Endgames members definitions -EndgameEvaluationFunction::EndgameEvaluationFunction(Color c) { - strongerSide = c; - weakerSide = opposite_color(strongerSide); -} +Endgames::Endgames() { + + add("KPK"); + add("KNNK"); + add("KBNK"); + add("KRKP"); + add("KRKB"); + add("KRKN"); + add("KQKR"); + add("KBBKN"); -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) { } + add("KNPK"); + add("KRPKR"); + add("KBPKB"); + add("KBPKN"); + add("KBPPKB"); + add("KRPPKRP"); +} +Endgames::~Endgames() { -ScalingFunction::ScalingFunction(Color c) { - strongerSide = c; - weakerSide = opposite_color(c); + for_each(m1.begin(), m1.end(), delete_endgame); + for_each(m2.begin(), m2.end(), delete_endgame); } -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) { } +template +void Endgames::add(const string& code) { + typedef typename eg_family::type T; -/// 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 + map((T*)0)[key(code, WHITE)] = new Endgame(WHITE); + map((T*)0)[key(code, BLACK)] = new Endgame(BLACK); +} + + +/// 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. +template<> +Value Endgame::operator()(const Position& pos) const { -Value KXKEvaluationFunction::apply(const Position &pos) { - - assert(pos.non_pawn_material(weakerSide) == Value(0)); - assert(pos.pawn_count(weakerSide) == Value(0)); + assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO); + assert(pos.piece_count(weakerSide, PAWN) == VALUE_ZERO); Square winnerKSq = pos.king_square(strongerSide); Square loserKSq = pos.king_square(weakerSide); - Value result = - pos.non_pawn_material(strongerSide) + - pos.pawn_count(strongerSide) * PawnValueEndgame + - mate_table(loserKSq) + - distance_bonus(square_distance(winnerKSq, loserKSq)); + Value result = pos.non_pawn_material(strongerSide) + + pos.piece_count(strongerSide, PAWN) * PawnValueEndgame + + MateTable[loserKSq] + + DistanceBonus[square_distance(winnerKSq, loserKSq)]; - if(pos.queen_count(strongerSide) > 0 || pos.rook_count(strongerSide) > 0 || - pos.bishop_count(strongerSide) > 1) - // TODO: check for two equal-colored bishops! - result += VALUE_KNOWN_WIN; + if ( pos.piece_count(strongerSide, QUEEN) + || pos.piece_count(strongerSide, ROOK) + || pos.piece_count(strongerSide, BISHOP) > 1) + // TODO: check for two equal-colored bishops! + result += VALUE_KNOWN_WIN; - return (strongerSide == pos.side_to_move())? result : -result; + return strongerSide == pos.side_to_move() ? result : -result; } -/// Mate with KBN vs K. This is similar to KX vs K, but we have to drive the +/// 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 Endgame::operator()(const Position& pos) const { - assert(pos.non_pawn_material(weakerSide) == Value(0)); - assert(pos.pawn_count(weakerSide) == Value(0)); - assert(pos.non_pawn_material(strongerSide) == - KnightValueMidgame + BishopValueMidgame); - assert(pos.bishop_count(strongerSide) == 1); - assert(pos.knight_count(strongerSide) == 1); - assert(pos.pawn_count(strongerSide) == 0); + assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO); + assert(pos.piece_count(weakerSide, PAWN) == VALUE_ZERO); + assert(pos.non_pawn_material(strongerSide) == KnightValueMidgame + BishopValueMidgame); + assert(pos.piece_count(strongerSide, BISHOP) == 1); + assert(pos.piece_count(strongerSide, KNIGHT) == 1); + assert(pos.piece_count(strongerSide, PAWN) == 0); Square winnerKSq = pos.king_square(strongerSide); Square loserKSq = pos.king_square(weakerSide); - Square bishopSquare = pos.bishop_list(strongerSide, 0); - - if(square_color(bishopSquare) == BLACK) { - winnerKSq = flop_square(winnerKSq); - loserKSq = flop_square(loserKSq); + Square bishopSquare = pos.piece_list(strongerSide, BISHOP)[0]; + + // kbnk_mate_table() tries to drive toward corners A1 or H8, + // if we have a bishop that cannot reach the above squares we + // mirror the kings so to drive enemy toward corners A8 or H1. + if (opposite_colors(bishopSquare, SQ_A1)) + { + winnerKSq = mirror(winnerKSq); + loserKSq = mirror(loserKSq); } - Value result = - VALUE_KNOWN_WIN + distance_bonus(square_distance(winnerKSq, loserKSq)) + - kbnk_mate_table(loserKSq); + Value result = VALUE_KNOWN_WIN + + DistanceBonus[square_distance(winnerKSq, loserKSq)] + + KBNKMateTable[loserKSq]; - return (strongerSide == pos.side_to_move())? result : -result; + return strongerSide == pos.side_to_move() ? result : -result; } -/// KP vs K. This endgame is evaluated with the help of a bitbase. +/// KP vs K. This endgame is evaluated with the help of a bitbase. +template<> +Value Endgame::operator()(const Position& pos) const { -Value KPKEvaluationFunction::apply(const Position &pos) { + assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO); + assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO); + assert(pos.piece_count(strongerSide, PAWN) == 1); + assert(pos.piece_count(weakerSide, PAWN) == 0); - assert(pos.non_pawn_material(strongerSide) == Value(0)); - assert(pos.non_pawn_material(weakerSide) == Value(0)); - assert(pos.pawn_count(strongerSide) == 1); - assert(pos.pawn_count(weakerSide) == 0); - Square wksq, bksq, wpsq; Color stm; - if(strongerSide == WHITE) { - wksq = pos.king_square(WHITE); - bksq = pos.king_square(BLACK); - wpsq = pos.pawn_list(WHITE, 0); - stm = pos.side_to_move(); + if (strongerSide == WHITE) + { + wksq = pos.king_square(WHITE); + bksq = pos.king_square(BLACK); + wpsq = pos.piece_list(WHITE, PAWN)[0]; + stm = pos.side_to_move(); } - else { - wksq = flip_square(pos.king_square(BLACK)); - bksq = flip_square(pos.king_square(WHITE)); - wpsq = flip_square(pos.pawn_list(BLACK, 0)); - stm = opposite_color(pos.side_to_move()); + else + { + wksq = ~pos.king_square(BLACK); + bksq = ~pos.king_square(WHITE); + wpsq = ~pos.piece_list(BLACK, PAWN)[0]; + stm = ~pos.side_to_move(); } - if(square_file(wpsq) >= FILE_E) { - wksq = flop_square(wksq); - bksq = flop_square(bksq); - wpsq = flop_square(wpsq); + if (file_of(wpsq) >= FILE_E) + { + wksq = mirror(wksq); + bksq = mirror(bksq); + wpsq = mirror(wpsq); } - if(probe_kpk(wksq, wpsq, bksq, stm)) { - Value result = - VALUE_KNOWN_WIN + PawnValueEndgame + Value(square_rank(wpsq)); - return (strongerSide == pos.side_to_move())? result : -result; - } + if (!probe_kpk_bitbase(wksq, wpsq, bksq, stm)) + return VALUE_DRAW; - return VALUE_DRAW; + Value result = VALUE_KNOWN_WIN + + PawnValueEndgame + + Value(rank_of(wpsq)); + + return strongerSide == pos.side_to_move() ? result : -result; } -/// KR vs KP. This is a somewhat tricky endgame to evaluate precisely without -/// a bitbase. The function below returns drawish scores when the pawn is +/// KR vs KP. This is a somewhat tricky endgame to evaluate precisely without +/// 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 Endgame::operator()(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); - assert(pos.pawn_count(strongerSide) == 0); + assert(pos.piece_count(strongerSide, PAWN) == 0); assert(pos.non_pawn_material(weakerSide) == 0); - assert(pos.pawn_count(weakerSide) == 1); + assert(pos.piece_count(weakerSide, PAWN) == 1); Square wksq, wrsq, bksq, bpsq; int tempo = (pos.side_to_move() == strongerSide); wksq = pos.king_square(strongerSide); - wrsq = pos.rook_list(strongerSide, 0); + wrsq = pos.piece_list(strongerSide, ROOK)[0]; bksq = pos.king_square(weakerSide); - bpsq = pos.pawn_list(weakerSide, 0); - - if(strongerSide == BLACK) { - wksq = flip_square(wksq); - wrsq = flip_square(wrsq); - bksq = flip_square(bksq); - bpsq = flip_square(bpsq); + bpsq = pos.piece_list(weakerSide, PAWN)[0]; + + if (strongerSide == BLACK) + { + wksq = ~wksq; + wrsq = ~wrsq; + bksq = ~bksq; + bpsq = ~bpsq; } - Square queeningSq = make_square(square_file(bpsq), RANK_1); + Square queeningSq = make_square(file_of(bpsq), RANK_1); Value result; - // If the stronger side's king is in front of the pawn, it's a win: - if(wksq < bpsq && square_file(wksq) == square_file(bpsq)) - result = RookValueEndgame - Value(square_distance(wksq, bpsq)); + // If the stronger side's king is in front of the pawn, it's a win + if (wksq < bpsq && file_of(wksq) == file_of(bpsq)) + result = RookValueEndgame - Value(square_distance(wksq, bpsq)); // If the weaker side's king is too far from the pawn and the rook, - // it's a win: - else if(square_distance(bksq, bpsq) - (tempo^1) >= 3 && - square_distance(bksq, wrsq) >= 3) - result = RookValueEndgame - Value(square_distance(wksq, bpsq)); + // it's a win + else if ( square_distance(bksq, bpsq) - (tempo ^ 1) >= 3 + && square_distance(bksq, wrsq) >= 3) + result = RookValueEndgame - Value(square_distance(wksq, bpsq)); // If the pawn is far advanced and supported by the defending king, - // the position is drawish: - else if(square_rank(bksq) <= RANK_3 && square_distance(bksq, bpsq) == 1 && - square_rank(wksq) >= RANK_4 && - square_distance(wksq, bpsq) - tempo > 2) - result = Value(80 - square_distance(wksq, bpsq) * 8); + // the position is drawish + else if ( rank_of(bksq) <= RANK_3 + && square_distance(bksq, bpsq) == 1 + && rank_of(wksq) >= RANK_4 + && square_distance(wksq, bpsq) - tempo > 2) + result = Value(80 - square_distance(wksq, bpsq) * 8); else - result = Value(200) - - Value(square_distance(wksq, bpsq + DELTA_S) * 8) - + Value(square_distance(bksq, bpsq + DELTA_S) * 8) - + Value(square_distance(bpsq, queeningSq) * 8); + result = Value(200) + - Value(square_distance(wksq, bpsq + DELTA_S) * 8) + + Value(square_distance(bksq, bpsq + DELTA_S) * 8) + + Value(square_distance(bpsq, queeningSq) * 8); - return (strongerSide == pos.side_to_move())? result : -result; + return strongerSide == pos.side_to_move() ? result : -result; } -/// KR vs KB. This is very simple, and always returns drawish scores. The +/// 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 Endgame::operator()(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); - assert(pos.pawn_count(strongerSide) == 0); + assert(pos.piece_count(strongerSide, PAWN) == 0); assert(pos.non_pawn_material(weakerSide) == BishopValueMidgame); - assert(pos.pawn_count(weakerSide) == 0); - assert(pos.bishop_count(weakerSide) == 1); + assert(pos.piece_count(weakerSide, PAWN) == 0); + assert(pos.piece_count(weakerSide, BISHOP) == 1); - Value result = mate_table(pos.king_square(weakerSide)); - return (pos.side_to_move() == strongerSide)? result : -result; + Value result = Value(MateTable[pos.king_square(weakerSide)]); + return strongerSide == pos.side_to_move() ? result : -result; } /// 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 Endgame::operator()(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); - assert(pos.pawn_count(strongerSide) == 0); + assert(pos.piece_count(strongerSide, PAWN) == 0); assert(pos.non_pawn_material(weakerSide) == KnightValueMidgame); - assert(pos.pawn_count(weakerSide) == 0); - assert(pos.knight_count(weakerSide) == 1); + assert(pos.piece_count(weakerSide, PAWN) == 0); + assert(pos.piece_count(weakerSide, KNIGHT) == 1); - Square defendingKSq = pos.king_square(weakerSide); - Square nSq = pos.knight_list(weakerSide, 0); + const int penalty[8] = { 0, 10, 14, 20, 30, 42, 58, 80 }; - Value result = Value(10) + mate_table(defendingKSq) + - krkn_king_knight_distance_penalty(square_distance(defendingKSq, nSq)); - - return (strongerSide == pos.side_to_move())? result : -result; + Square bksq = pos.king_square(weakerSide); + Square bnsq = pos.piece_list(weakerSide, KNIGHT)[0]; + Value result = Value(MateTable[bksq] + penalty[square_distance(bksq, bnsq)]); + return strongerSide == pos.side_to_move() ? result : -result; } @@ -402,466 +329,564 @@ 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. +template<> +Value Endgame::operator()(const Position& pos) const { -Value KQKREvaluationFunction::apply(const Position &pos) { assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame); - assert(pos.pawn_count(strongerSide) == 0); + assert(pos.piece_count(strongerSide, PAWN) == 0); assert(pos.non_pawn_material(weakerSide) == RookValueMidgame); - assert(pos.pawn_count(weakerSide) == 0); + assert(pos.piece_count(weakerSide, PAWN) == 0); Square winnerKSq = pos.king_square(strongerSide); Square loserKSq = pos.king_square(weakerSide); - - Value result = QueenValueEndgame - RookValueEndgame + - mate_table(loserKSq) + distance_bonus(square_distance(winnerKSq, loserKSq)); - return (strongerSide == pos.side_to_move())? result : -result; + Value result = QueenValueEndgame + - RookValueEndgame + + MateTable[loserKSq] + + DistanceBonus[square_distance(winnerKSq, loserKSq)]; + + return strongerSide == pos.side_to_move() ? result : -result; } +template<> +Value Endgame::operator()(const Position& pos) const { -/// 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. + assert(pos.piece_count(strongerSide, BISHOP) == 2); + assert(pos.non_pawn_material(strongerSide) == 2*BishopValueMidgame); + assert(pos.piece_count(weakerSide, KNIGHT) == 1); + assert(pos.non_pawn_material(weakerSide) == KnightValueMidgame); + assert(!pos.pieces(PAWN)); -ScaleFactor KBPKScalingFunction::apply(const Position &pos) { - assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); - assert(pos.bishop_count(strongerSide) == 1); - assert(pos.pawn_count(strongerSide) >= 1); + Value result = BishopValueEndgame; + Square wksq = pos.king_square(strongerSide); + Square bksq = pos.king_square(weakerSide); + Square nsq = pos.piece_list(weakerSide, KNIGHT)[0]; - // No assertions about the material of weakerSide, because we want draws to - // be detected even when the weaker side has some pawns. + // Bonus for attacking king close to defending king + result += Value(DistanceBonus[square_distance(wksq, bksq)]); - Bitboard pawns = pos.pawns(strongerSide); - File pawnFile = square_file(pos.pawn_list(strongerSide, 0)); + // Bonus for driving the defending king and knight apart + result += Value(square_distance(bksq, nsq) * 32); - if((pawnFile == FILE_A || pawnFile == FILE_H) && - (pawns & ~file_bb(pawnFile)) == EmptyBoardBB) { - // All pawns are on a single rook file. + // Bonus for restricting the knight's mobility + result += Value((8 - popcount(pos.attacks_from(nsq))) * 8); - Square bishopSq = pos.bishop_list(strongerSide, 0); - Square queeningSq = - relative_square(strongerSide, make_square(pawnFile, RANK_8)); - Square kingSq = pos.king_square(weakerSide); + return strongerSide == pos.side_to_move() ? result : -result; +} - if(square_color(queeningSq) != square_color(bishopSq) && - file_distance(square_file(kingSq), pawnFile) <= 1) { - // The bishop has the wrong color, and the defending king is on the - // file of the pawn(s) or the neighboring file. Find the rank of the - // frontmost pawn: - Rank rank; - if(strongerSide == WHITE) { - for(rank = RANK_7; (rank_bb(rank) & pawns) == EmptyBoardBB; rank--); - assert(rank >= RANK_2 && rank <= RANK_7); - } - else { - for(rank = RANK_2; (rank_bb(rank) & pawns) == EmptyBoardBB; rank++); - rank = Rank(rank^7); // HACK - assert(rank >= RANK_2 && rank <= RANK_7); +/// K and two minors vs K and one or two minors or K and two knights against +/// king alone are always draw. +template<> +Value Endgame::operator()(const Position&) const { + return VALUE_DRAW; +} + +template<> +Value Endgame::operator()(const Position&) const { + return VALUE_DRAW; +} + +/// K, bishop and one or more pawns vs K. It checks for draws with rook pawns and +/// a bishop of the wrong color. If such a draw is detected, SCALE_FACTOR_DRAW +/// is returned. If not, the return value is SCALE_FACTOR_NONE, i.e. no scaling +/// will be used. +template<> +ScaleFactor Endgame::operator()(const Position& pos) const { + + assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); + assert(pos.piece_count(strongerSide, BISHOP) == 1); + assert(pos.piece_count(strongerSide, PAWN) >= 1); + + // No assertions about the material of weakerSide, because we want draws to + // be detected even when the weaker side has some pawns. + + Bitboard pawns = pos.pieces(PAWN, strongerSide); + File pawnFile = file_of(pos.piece_list(strongerSide, PAWN)[0]); + + // All pawns are on a single rook file ? + if ( (pawnFile == FILE_A || pawnFile == FILE_H) + && !(pawns & ~file_bb(pawnFile))) + { + Square bishopSq = pos.piece_list(strongerSide, BISHOP)[0]; + Square queeningSq = relative_square(strongerSide, make_square(pawnFile, RANK_8)); + Square kingSq = pos.king_square(weakerSide); + + if ( opposite_colors(queeningSq, bishopSq) + && abs(file_of(kingSq) - pawnFile) <= 1) + { + // The bishop has the wrong color, and the defending king is on the + // file of the pawn(s) or the adjacent file. Find the rank of the + // frontmost pawn. + Rank rank; + if (strongerSide == WHITE) + { + for (rank = RANK_7; !(rank_bb(rank) & pawns); rank--) {} + assert(rank >= RANK_2 && rank <= RANK_7); + } + else + { + for (rank = RANK_2; !(rank_bb(rank) & pawns); rank++) {} + rank = Rank(rank ^ 7); // HACK to get the relative rank + assert(rank >= RANK_2 && rank <= RANK_7); + } + // If the defending king has distance 1 to the promotion square or + // is placed somewhere in front of the pawn, it's a draw. + if ( square_distance(kingSq, queeningSq) <= 1 + || relative_rank(strongerSide, kingSq) >= rank) + return SCALE_FACTOR_DRAW; } - // If the defending king has distance 1 to the promotion square or - // is placed somewhere in front of the pawn, it's a draw. - if(square_distance(kingSq, queeningSq) <= 1 || - relative_rank(strongerSide, kingSq) >= rank) - return ScaleFactor(0); - } } return SCALE_FACTOR_NONE; } -/// KQKRPScalingFunction scales endgames where the stronger side has only -/// 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. +/// K and queen vs K, rook and one or more pawns. It tests for fortress draws with +/// a rook on the third rank defended by a pawn. +template<> +ScaleFactor Endgame::operator()(const Position& pos) const { -ScaleFactor KQKRPScalingFunction::apply(const Position &pos) { assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame); - assert(pos.queen_count(strongerSide) == 1); - assert(pos.pawn_count(strongerSide) == 0); - assert(pos.rook_count(weakerSide) == 1); - assert(pos.pawn_count(weakerSide) >= 1); + assert(pos.piece_count(strongerSide, QUEEN) == 1); + assert(pos.piece_count(strongerSide, PAWN) == 0); + assert(pos.piece_count(weakerSide, ROOK) == 1); + assert(pos.piece_count(weakerSide, PAWN) >= 1); Square kingSq = pos.king_square(weakerSide); - if(relative_rank(weakerSide, kingSq) <= RANK_2 && - relative_rank(weakerSide, pos.king_square(strongerSide)) >= RANK_4 && - (pos.rooks(weakerSide) & relative_rank_bb(weakerSide, RANK_3)) && - (pos.pawns(weakerSide) & relative_rank_bb(weakerSide, RANK_2)) && - (pos.piece_attacks(kingSq) & pos.pawns(weakerSide))) { - Square rsq = pos.rook_list(weakerSide, 0); - if(pos.pawn_attacks(strongerSide, rsq) & pos.pawns(weakerSide)) - return ScaleFactor(0); + if ( relative_rank(weakerSide, kingSq) <= RANK_2 + && relative_rank(weakerSide, pos.king_square(strongerSide)) >= RANK_4 + && (pos.pieces(ROOK, weakerSide) & rank_bb(relative_rank(weakerSide, RANK_3))) + && (pos.pieces(PAWN, weakerSide) & rank_bb(relative_rank(weakerSide, RANK_2))) + && (pos.attacks_from(kingSq) & pos.pieces(PAWN, weakerSide))) + { + Square rsq = pos.piece_list(weakerSide, ROOK)[0]; + if (pos.attacks_from(rsq, strongerSide) & pos.pieces(PAWN, weakerSide)) + return SCALE_FACTOR_DRAW; } return SCALE_FACTOR_NONE; } -/// KRPKRScalingFunction scales KRP vs KR endgames. This function knows a -/// handful of the most important classes of drawn positions, but is far -/// from perfect. It would probably be a good idea to add more knowledge -/// in the future. +/// K, rook and one pawn vs K and a rook. This function knows a handful of the +/// most important classes of drawn positions, but is far from perfect. It would +/// probably be a good idea to add more knowledge in the future. /// /// 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. +template<> +ScaleFactor Endgame::operator()(const Position& pos) const { -ScaleFactor KRPKRScalingFunction::apply(const Position &pos) { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); - assert(pos.pawn_count(strongerSide) == 1); + assert(pos.piece_count(strongerSide, PAWN) == 1); assert(pos.non_pawn_material(weakerSide) == RookValueMidgame); - assert(pos.pawn_count(weakerSide) == 0); + assert(pos.piece_count(weakerSide, PAWN) == 0); Square wksq = pos.king_square(strongerSide); - Square wrsq = pos.rook_list(strongerSide, 0); - Square wpsq = pos.pawn_list(strongerSide, 0); + Square wrsq = pos.piece_list(strongerSide, ROOK)[0]; + Square wpsq = pos.piece_list(strongerSide, PAWN)[0]; Square bksq = pos.king_square(weakerSide); - Square brsq = pos.rook_list(weakerSide, 0); + Square brsq = pos.piece_list(weakerSide, ROOK)[0]; // Orient the board in such a way that the stronger side is white, and the - // pawn is on the left half of the board: - if(strongerSide == BLACK) { - wksq = flip_square(wksq); - wrsq = flip_square(wrsq); - wpsq = flip_square(wpsq); - bksq = flip_square(bksq); - brsq = flip_square(brsq); + // pawn is on the left half of the board. + if (strongerSide == BLACK) + { + wksq = ~wksq; + wrsq = ~wrsq; + wpsq = ~wpsq; + bksq = ~bksq; + brsq = ~brsq; } - if(square_file(wpsq) > FILE_D) { - wksq = flop_square(wksq); - wrsq = flop_square(wrsq); - wpsq = flop_square(wpsq); - bksq = flop_square(bksq); - brsq = flop_square(brsq); + if (file_of(wpsq) > FILE_D) + { + wksq = mirror(wksq); + wrsq = mirror(wrsq); + wpsq = mirror(wpsq); + bksq = mirror(bksq); + brsq = mirror(brsq); } - File f = square_file(wpsq); - Rank r = square_rank(wpsq); + File f = file_of(wpsq); + Rank r = rank_of(wpsq); Square queeningSq = make_square(f, RANK_8); int tempo = (pos.side_to_move() == strongerSide); // If the pawn is not too far advanced and the defending king defends the - // queening square, use the third-rank defence: - if(r <= RANK_5 && square_distance(bksq, queeningSq) <= 1 && wksq <= SQ_H5 && - (square_rank(brsq) == RANK_6 || (r <= RANK_3 && - square_rank(wrsq) != RANK_6))) - return ScaleFactor(0); + // queening square, use the third-rank defence. + if ( r <= RANK_5 + && square_distance(bksq, queeningSq) <= 1 + && wksq <= SQ_H5 + && (rank_of(brsq) == RANK_6 || (r <= RANK_3 && rank_of(wrsq) != RANK_6))) + return SCALE_FACTOR_DRAW; // The defending side saves a draw by checking from behind in case the pawn // has advanced to the 6th rank with the king behind. - if(r == RANK_6 && square_distance(bksq, queeningSq) <= 1 && - square_rank(wksq) + tempo <= RANK_6 && - (square_rank(brsq) == RANK_1 || - (!tempo && abs(square_file(brsq) - f) >= 3))) - return ScaleFactor(0); - - if(r >= RANK_6 && bksq == queeningSq && square_rank(brsq) == RANK_1 && - (!tempo || square_distance(wksq, wpsq) >= 2)) - return ScaleFactor(0); + if ( r == RANK_6 + && square_distance(bksq, queeningSq) <= 1 + && rank_of(wksq) + tempo <= RANK_6 + && (rank_of(brsq) == RANK_1 || (!tempo && abs(file_of(brsq) - f) >= 3))) + return SCALE_FACTOR_DRAW; + + if ( r >= RANK_6 + && bksq == queeningSq + && rank_of(brsq) == RANK_1 + && (!tempo || square_distance(wksq, wpsq) >= 2)) + return SCALE_FACTOR_DRAW; // White pawn on a7 and rook on a8 is a draw if black's king is on g7 or h7 // and the black rook is behind the pawn. - if(wpsq == SQ_A7 && wrsq == SQ_A8 && (bksq == SQ_H7 || bksq == SQ_G7) && - square_file(brsq) == FILE_A && - (square_rank(brsq) <= RANK_3 || square_file(wksq) >= FILE_D || - square_rank(wksq) <= RANK_5)) - return ScaleFactor(0); + if ( wpsq == SQ_A7 + && wrsq == SQ_A8 + && (bksq == SQ_H7 || bksq == SQ_G7) + && file_of(brsq) == FILE_A + && (rank_of(brsq) <= RANK_3 || file_of(wksq) >= FILE_D || rank_of(wksq) <= RANK_5)) + return SCALE_FACTOR_DRAW; // If the defending king blocks the pawn and the attacking king is too far // away, it's a draw. - if(r <= RANK_5 && bksq == wpsq + DELTA_N && - square_distance(wksq, wpsq) - tempo >= 2 && - square_distance(wksq, brsq) - tempo >= 2) - return ScaleFactor(0); + if ( r <= RANK_5 + && bksq == wpsq + DELTA_N + && square_distance(wksq, wpsq) - tempo >= 2 + && square_distance(wksq, brsq) - tempo >= 2) + return SCALE_FACTOR_DRAW; // Pawn on the 7th rank supported by the rook from behind usually wins if the // attacking king is closer to the queening square than the defending king, - // and the defending king cannot gain tempi by threatening the attacking - // rook. - if(r == RANK_7 && f != FILE_A && square_file(wrsq) == f - && wrsq != queeningSq - && (square_distance(wksq, queeningSq) < - square_distance(bksq, queeningSq) - 2 + tempo) - && (square_distance(wksq, queeningSq) < - square_distance(bksq, wrsq) + tempo)) - return ScaleFactor(SCALE_FACTOR_MAX - - 2 * square_distance(wksq, queeningSq)); - - // Similar to the above, but with the pawn further back: - if(f != FILE_A && square_file(wrsq) == f && wrsq < wpsq - && (square_distance(wksq, queeningSq) < - square_distance(bksq, queeningSq) - 2 + tempo) - && (square_distance(wksq, wpsq + DELTA_N) < - square_distance(bksq, wpsq + DELTA_N) - 2 + tempo) - && (square_distance(bksq, wrsq) + tempo >= 3 - || (square_distance(wksq, queeningSq) < - square_distance(bksq, wrsq) + tempo - && (square_distance(wksq, wpsq + DELTA_N) < - square_distance(bksq, wrsq) + tempo)))) - return - ScaleFactor(SCALE_FACTOR_MAX - - (8 * square_distance(wpsq, queeningSq) + - 2 * square_distance(wksq, queeningSq))); - + // and the defending king cannot gain tempi by threatening the attacking rook. + if ( r == RANK_7 + && f != FILE_A + && file_of(wrsq) == f + && wrsq != queeningSq + && (square_distance(wksq, queeningSq) < square_distance(bksq, queeningSq) - 2 + tempo) + && (square_distance(wksq, queeningSq) < square_distance(bksq, wrsq) + tempo)) + return ScaleFactor(SCALE_FACTOR_MAX - 2 * square_distance(wksq, queeningSq)); + + // Similar to the above, but with the pawn further back + if ( f != FILE_A + && file_of(wrsq) == f + && wrsq < wpsq + && (square_distance(wksq, queeningSq) < square_distance(bksq, queeningSq) - 2 + tempo) + && (square_distance(wksq, wpsq + DELTA_N) < square_distance(bksq, wpsq + DELTA_N) - 2 + tempo) + && ( square_distance(bksq, wrsq) + tempo >= 3 + || ( square_distance(wksq, queeningSq) < square_distance(bksq, wrsq) + tempo + && (square_distance(wksq, wpsq + DELTA_N) < square_distance(bksq, wrsq) + tempo)))) + return ScaleFactor( SCALE_FACTOR_MAX + - 8 * square_distance(wpsq, queeningSq) + - 2 * square_distance(wksq, queeningSq)); + + // If the pawn is not far advanced, and the defending king is somewhere in + // the pawn's path, it's probably a draw. + if (r <= RANK_4 && bksq > wpsq) + { + if (file_of(bksq) == file_of(wpsq)) + return ScaleFactor(10); + if ( abs(file_of(bksq) - file_of(wpsq)) == 1 + && square_distance(wksq, bksq) > 2) + return ScaleFactor(24 - 2 * square_distance(wksq, bksq)); + } return SCALE_FACTOR_NONE; } -/// KRPPKRPScalingFunction scales KRPP vs KRP endgames. There is only a -/// single pattern: If the stronger side has no pawns and the defending king +/// K, rook and two pawns vs K, rook and one pawn. There is only a single +/// pattern: If the stronger side has no passed pawns and the defending king /// is actively placed, the position is drawish. +template<> +ScaleFactor Endgame::operator()(const Position& pos) const { -ScaleFactor KRPPKRPScalingFunction::apply(const Position &pos) { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); - assert(pos.pawn_count(strongerSide) == 2); + assert(pos.piece_count(strongerSide, PAWN) == 2); assert(pos.non_pawn_material(weakerSide) == RookValueMidgame); - assert(pos.pawn_count(weakerSide) == 1); + assert(pos.piece_count(weakerSide, PAWN) == 1); - Square wpsq1 = pos.pawn_list(strongerSide, 0); - Square wpsq2 = pos.pawn_list(strongerSide, 1); + Square wpsq1 = pos.piece_list(strongerSide, PAWN)[0]; + Square wpsq2 = pos.piece_list(strongerSide, PAWN)[1]; Square bksq = pos.king_square(weakerSide); // Does the stronger side have a passed pawn? - if(pos.pawn_is_passed(strongerSide, wpsq1) || - pos.pawn_is_passed(strongerSide, wpsq2)) - return SCALE_FACTOR_NONE; - - Rank r = Max(relative_rank(strongerSide, wpsq1), relative_rank(strongerSide, wpsq2)); - - if(file_distance(bksq, wpsq1) <= 1 && file_distance(bksq, wpsq2) <= 1 - && relative_rank(strongerSide, bksq) > r) { - switch(r) { - - case RANK_2: return ScaleFactor(10); - case RANK_3: return ScaleFactor(10); - case RANK_4: return ScaleFactor(15); - case RANK_5: return ScaleFactor(20); - case RANK_6: return ScaleFactor(40); - default: assert(false); + if ( pos.pawn_is_passed(strongerSide, wpsq1) + || pos.pawn_is_passed(strongerSide, wpsq2)) + return SCALE_FACTOR_NONE; - } + Rank r = std::max(relative_rank(strongerSide, wpsq1), relative_rank(strongerSide, wpsq2)); + + if ( file_distance(bksq, wpsq1) <= 1 + && file_distance(bksq, wpsq2) <= 1 + && relative_rank(strongerSide, bksq) > r) + { + switch (r) { + case RANK_2: return ScaleFactor(10); + case RANK_3: return ScaleFactor(10); + case RANK_4: return ScaleFactor(15); + case RANK_5: return ScaleFactor(20); + case RANK_6: return ScaleFactor(40); + default: assert(false); + } } return SCALE_FACTOR_NONE; } -/// 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. +/// K and two or more pawns vs K. 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. +template<> +ScaleFactor Endgame::operator()(const Position& pos) const { -ScaleFactor KPsKScalingFunction::apply(const Position &pos) { - assert(pos.non_pawn_material(strongerSide) == Value(0)); - assert(pos.pawn_count(strongerSide) >= 2); - assert(pos.non_pawn_material(weakerSide) == Value(0)); - assert(pos.pawn_count(weakerSide) == 0); + assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO); + assert(pos.piece_count(strongerSide, PAWN) >= 2); + assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO); + assert(pos.piece_count(weakerSide, PAWN) == 0); - Bitboard pawns = pos.pawns(strongerSide); + Square ksq = pos.king_square(weakerSide); + Bitboard pawns = pos.pieces(PAWN, strongerSide); // Are all pawns on the 'a' file? - if((pawns & ~FileABB) == EmptyBoardBB) { - // Does the defending king block the pawns? - Square ksq = pos.king_square(weakerSide); - if(square_distance(ksq, relative_square(strongerSide, SQ_A8)) <= 1) - return ScaleFactor(0); - else if(square_file(ksq) == FILE_A && - (in_front_bb(strongerSide, ksq) & pawns) == EmptyBoardBB) - return ScaleFactor(0); - else - return SCALE_FACTOR_NONE; + if (!(pawns & ~FileABB)) + { + // Does the defending king block the pawns? + if ( square_distance(ksq, relative_square(strongerSide, SQ_A8)) <= 1 + || ( file_of(ksq) == FILE_A + && !in_front_bb(strongerSide, ksq) & pawns)) + return SCALE_FACTOR_DRAW; } // Are all pawns on the 'h' file? - else if((pawns & ~FileHBB) == EmptyBoardBB) { + else if (!(pawns & ~FileHBB)) + { // Does the defending king block the pawns? - Square ksq = pos.king_square(weakerSide); - if(square_distance(ksq, relative_square(strongerSide, SQ_H8)) <= 1) - return ScaleFactor(0); - else if(square_file(ksq) == FILE_H && - (in_front_bb(strongerSide, ksq) & pawns) == EmptyBoardBB) - return ScaleFactor(0); - else - return SCALE_FACTOR_NONE; + if ( square_distance(ksq, relative_square(strongerSide, SQ_H8)) <= 1 + || ( file_of(ksq) == FILE_H + && !in_front_bb(strongerSide, ksq) & pawns)) + return SCALE_FACTOR_DRAW; } - else - return SCALE_FACTOR_NONE; + return SCALE_FACTOR_NONE; } -/// KBPKBScalingFunction scales KBP vs KB endgames. There are two rules: -/// 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. If the two bishops have opposite color, it's almost always -/// a draw. +/// K, bishop and a pawn vs K and a bishop. There are two rules: 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. If the two +/// bishops have opposite color, it's almost always a draw. +template<> +ScaleFactor Endgame::operator()(const Position& pos) const { -ScaleFactor KBPKBScalingFunction::apply(const Position &pos) { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); - assert(pos.bishop_count(strongerSide) == 1); - assert(pos.pawn_count(strongerSide) == 1); + assert(pos.piece_count(strongerSide, BISHOP) == 1); + assert(pos.piece_count(strongerSide, PAWN) == 1); assert(pos.non_pawn_material(weakerSide) == BishopValueMidgame); - assert(pos.bishop_count(weakerSide) == 1); - assert(pos.pawn_count(weakerSide) == 0); + assert(pos.piece_count(weakerSide, BISHOP) == 1); + assert(pos.piece_count(weakerSide, PAWN) == 0); - Square pawnSq = pos.pawn_list(strongerSide, 0); - Square strongerBishopSq = pos.bishop_list(strongerSide, 0); - Square weakerBishopSq = pos.bishop_list(weakerSide, 0); + Square pawnSq = pos.piece_list(strongerSide, PAWN)[0]; + Square strongerBishopSq = pos.piece_list(strongerSide, BISHOP)[0]; + Square weakerBishopSq = pos.piece_list(weakerSide, BISHOP)[0]; Square weakerKingSq = pos.king_square(weakerSide); - // Case 1: Defending king blocks the pawn, and cannot be driven away. - if(square_file(weakerKingSq) == square_file(pawnSq) - && relative_rank(strongerSide, pawnSq) < relative_rank(strongerSide, weakerKingSq) - && (square_color(weakerKingSq) != square_color(strongerBishopSq) - || relative_rank(strongerSide, weakerKingSq) <= RANK_6)) - return ScaleFactor(0); - - // Case 2: Opposite colored bishops. - if(square_color(strongerBishopSq) != square_color(weakerBishopSq)) { - - // We assume that the position is drawn in the following three situations: - // - // a. The pawn is on rank 5 or further back. - // b. The defending king is somewhere in the pawn's path. - // c. The defending bishop attacks some square along the pawn's path, - // and is at least three squares away from the pawn. - // - // These rules are probably not perfect, but in practice they work - // reasonably well. - - if(relative_rank(strongerSide, pawnSq) <= RANK_5) - return ScaleFactor(0); - else { - Bitboard ray = - ray_bb(pawnSq, (strongerSide == WHITE)? SIGNED_DIR_N : SIGNED_DIR_S); - if(ray & pos.kings(weakerSide)) - return ScaleFactor(0); - if((pos.piece_attacks(weakerBishopSq) & ray) - && square_distance(weakerBishopSq, pawnSq) >= 3) - return ScaleFactor(0); - } + // Case 1: Defending king blocks the pawn, and cannot be driven away + if ( file_of(weakerKingSq) == file_of(pawnSq) + && relative_rank(strongerSide, pawnSq) < relative_rank(strongerSide, weakerKingSq) + && ( opposite_colors(weakerKingSq, strongerBishopSq) + || relative_rank(strongerSide, weakerKingSq) <= RANK_6)) + return SCALE_FACTOR_DRAW; + + // Case 2: Opposite colored bishops + if (opposite_colors(strongerBishopSq, weakerBishopSq)) + { + // We assume that the position is drawn in the following three situations: + // + // a. The pawn is on rank 5 or further back. + // b. The defending king is somewhere in the pawn's path. + // c. The defending bishop attacks some square along the pawn's path, + // and is at least three squares away from the pawn. + // + // These rules are probably not perfect, but in practice they work + // reasonably well. + + if (relative_rank(strongerSide, pawnSq) <= RANK_5) + return SCALE_FACTOR_DRAW; + else + { + Bitboard path = squares_in_front_of(strongerSide, pawnSq); + + if (path & pos.pieces(KING, weakerSide)) + return SCALE_FACTOR_DRAW; + + if ( (pos.attacks_from(weakerBishopSq) & path) + && square_distance(weakerBishopSq, pawnSq) >= 3) + return SCALE_FACTOR_DRAW; + } } 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. +/// K, bishop and two pawns vs K and bishop. It detects a few basic draws with +/// opposite-colored bishops. +template<> +ScaleFactor Endgame::operator()(const Position& pos) const { + + 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 (!opposite_colors(wbsq, bbsq)) + 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 = rank_of(psq1); + Rank r2 = rank_of(psq2); + Square blockSq1, blockSq2; + + if (relative_rank(strongerSide, psq1) > relative_rank(strongerSide, psq2)) + { + blockSq1 = psq1 + pawn_push(strongerSide); + blockSq2 = make_square(file_of(psq2), rank_of(psq1)); + } + else + { + blockSq1 = psq2 + pawn_push(strongerSide); + blockSq2 = make_square(file_of(psq1), rank_of(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 ( file_of(ksq) == file_of(blockSq1) + && relative_rank(strongerSide, ksq) >= relative_rank(strongerSide, blockSq1) + && opposite_colors(ksq, wbsq)) + return SCALE_FACTOR_DRAW; + else + return SCALE_FACTOR_NONE; + + case 1: + // Pawns on adjacent 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 + && opposite_colors(ksq, wbsq) + && ( bbsq == blockSq2 + || (pos.attacks_from(blockSq2) & pos.pieces(BISHOP, weakerSide)) + || abs(r1 - r2) >= 2)) + return SCALE_FACTOR_DRAW; + + else if ( ksq == blockSq2 + && opposite_colors(ksq, wbsq) + && ( bbsq == blockSq1 + || (pos.attacks_from(blockSq1) & pos.pieces(BISHOP, weakerSide)))) + return SCALE_FACTOR_DRAW; + else + return SCALE_FACTOR_NONE; + + default: + // The pawns are not on the same file or adjacent files. No scaling. + return SCALE_FACTOR_NONE; + } +} + + +/// K, bisop and a pawn vs K and knight. 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. +template<> +ScaleFactor Endgame::operator()(const Position& pos) const { -ScaleFactor KBPKNScalingFunction::apply(const Position &pos) { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); - assert(pos.bishop_count(strongerSide) == 1); - assert(pos.pawn_count(strongerSide) == 1); + assert(pos.piece_count(strongerSide, BISHOP) == 1); + assert(pos.piece_count(strongerSide, PAWN) == 1); assert(pos.non_pawn_material(weakerSide) == KnightValueMidgame); - assert(pos.knight_count(weakerSide) == 1); - assert(pos.pawn_count(weakerSide) == 0); + assert(pos.piece_count(weakerSide, KNIGHT) == 1); + assert(pos.piece_count(weakerSide, PAWN) == 0); - Square pawnSq = pos.pawn_list(strongerSide, 0); - Square strongerBishopSq = pos.bishop_list(strongerSide, 0); + Square pawnSq = pos.piece_list(strongerSide, PAWN)[0]; + Square strongerBishopSq = pos.piece_list(strongerSide, BISHOP)[0]; Square weakerKingSq = pos.king_square(weakerSide); - - if(square_file(weakerKingSq) == square_file(pawnSq) - && relative_rank(strongerSide, pawnSq) < relative_rank(strongerSide, weakerKingSq) - && (square_color(weakerKingSq) != square_color(strongerBishopSq) - || relative_rank(strongerSide, weakerKingSq) <= RANK_6)) - return ScaleFactor(0); + + if ( file_of(weakerKingSq) == file_of(pawnSq) + && relative_rank(strongerSide, pawnSq) < relative_rank(strongerSide, weakerKingSq) + && ( opposite_colors(weakerKingSq, strongerBishopSq) + || relative_rank(strongerSide, weakerKingSq) <= RANK_6)) + return SCALE_FACTOR_DRAW; return SCALE_FACTOR_NONE; } -/// 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. +/// K, knight and a pawn vs K. 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. +template<> +ScaleFactor Endgame::operator()(const Position& pos) const { -ScaleFactor KNPKScalingFunction::apply(const Position &pos) { assert(pos.non_pawn_material(strongerSide) == KnightValueMidgame); - assert(pos.knight_count(strongerSide) == 1); - assert(pos.pawn_count(strongerSide) == 1); - assert(pos.non_pawn_material(weakerSide) == Value(0)); - assert(pos.pawn_count(weakerSide) == 0); + assert(pos.piece_count(strongerSide, KNIGHT) == 1); + assert(pos.piece_count(strongerSide, PAWN) == 1); + assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO); + assert(pos.piece_count(weakerSide, PAWN) == 0); - Square pawnSq = pos.pawn_list(strongerSide, 0); + Square pawnSq = pos.piece_list(strongerSide, PAWN)[0]; Square weakerKingSq = pos.king_square(weakerSide); - if(pawnSq == relative_square(strongerSide, SQ_A7) && - square_distance(weakerKingSq, relative_square(strongerSide, SQ_A8)) <= 1) - return ScaleFactor(0); + if ( pawnSq == relative_square(strongerSide, SQ_A7) + && square_distance(weakerKingSq, relative_square(strongerSide, SQ_A8)) <= 1) + return SCALE_FACTOR_DRAW; - if(pawnSq == relative_square(strongerSide, SQ_H7) && - square_distance(weakerKingSq, relative_square(strongerSide, SQ_H8)) <= 1) - return ScaleFactor(0); + if ( pawnSq == relative_square(strongerSide, SQ_H7) + && square_distance(weakerKingSq, relative_square(strongerSide, SQ_H8)) <= 1) + return SCALE_FACTOR_DRAW; return SCALE_FACTOR_NONE; } -/// KPKPScalingFunction scales KP vs KP endgames. This is done by removing -/// the weakest side's pawn and probing the KP vs K bitbase: If the weakest -/// side has a draw without the pawn, she probably has at least a draw with -/// 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) { - assert(pos.non_pawn_material(strongerSide) == Value(0)); - assert(pos.non_pawn_material(weakerSide) == Value(0)); - assert(pos.pawn_count(WHITE) == 1); - assert(pos.pawn_count(BLACK) == 1); +/// K and a pawn vs K and a pawn. This is done by removing the weakest side's +/// pawn and probing the KP vs K bitbase: If the weakest side has a draw without +/// the pawn, she probably has at least a draw with 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). +template<> +ScaleFactor Endgame::operator()(const Position& pos) const { - Square wksq, bksq, wpsq; - Color stm; + assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO); + assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO); + assert(pos.piece_count(WHITE, PAWN) == 1); + assert(pos.piece_count(BLACK, PAWN) == 1); - if(strongerSide == WHITE) { - wksq = pos.king_square(WHITE); - bksq = pos.king_square(BLACK); - wpsq = pos.pawn_list(WHITE, 0); - stm = pos.side_to_move(); - } - else { - wksq = flip_square(pos.king_square(BLACK)); - bksq = flip_square(pos.king_square(WHITE)); - wpsq = flip_square(pos.pawn_list(BLACK, 0)); - stm = opposite_color(pos.side_to_move()); + Square wksq = pos.king_square(strongerSide); + Square bksq = pos.king_square(weakerSide); + Square wpsq = pos.piece_list(strongerSide, PAWN)[0]; + Color stm = pos.side_to_move(); + + if (strongerSide == BLACK) + { + wksq = ~wksq; + bksq = ~bksq; + wpsq = ~wpsq; + stm = ~stm; } - if(square_file(wpsq) >= FILE_E) { - wksq = flop_square(wksq); - bksq = flop_square(bksq); - wpsq = flop_square(wpsq); + if (file_of(wpsq) >= FILE_E) + { + wksq = mirror(wksq); + bksq = mirror(bksq); + wpsq = mirror(wpsq); } // If the pawn has advanced to the fifth rank or further, and is not a // rook pawn, it's too dangerous to assume that it's at least a draw. - if(square_rank(wpsq) >= RANK_5 && square_file(wpsq) != FILE_A) - return SCALE_FACTOR_NONE; - - // Probe the KPK bitbase with the weakest side's pawn removed. If it's a - // draw, it's probably at least a draw even with the pawn. - if(probe_kpk(wksq, wpsq, bksq, stm)) - return SCALE_FACTOR_NONE; - else - return ScaleFactor(0); -} - - -/// init_bitbases() is called during program initialization, and simply loads -/// bitbases from disk into memory. At the moment, there is only the bitbase -/// for KP vs K, but we may decide to add other bitbases later. - -void init_bitbases() { - generate_kpk_bitbase(KPKBitbase); -} - - -namespace { - - // Probe the KP vs K bitbase: + if ( rank_of(wpsq) >= RANK_5 + && file_of(wpsq) != FILE_A) + return SCALE_FACTOR_NONE; - int probe_kpk(Square wksq, Square wpsq, Square bksq, Color stm) { - int wp = int(square_file(wpsq)) + (int(square_rank(wpsq)) - 1) * 4; - int index = int(stm) + 2*int(bksq) + 128*int(wksq) + 8192*wp; - - assert(index >= 0 && index < 24576*8); - return KPKBitbase[index/8] & (1 << (index&7)); - } - + // Probe the KPK bitbase with the weakest side's pawn removed. If it's a draw, + // it's probably at least a draw even with the pawn. + return probe_kpk_bitbase(wksq, wpsq, bksq, stm) ? SCALE_FACTOR_NONE : SCALE_FACTOR_DRAW; }