X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fendgame.cpp;h=65f0f409de3df7daa8b38ae0636f3dc69323c236;hp=3082f56911680242678158b046df3e991e691e82;hb=e1919384a23fe728422f995369161efa192380db;hpb=98352a5e84096c906d5ecc1aeb2fca8745e173c2 diff --git a/src/endgame.cpp b/src/endgame.cpp index 3082f569..65f0f409 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) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -17,12 +17,12 @@ along with this program. If not, see . */ -#include #include +#include #include "bitcount.h" #include "endgame.h" -#include "pawns.h" +#include "movegen.h" using std::string; @@ -60,47 +60,33 @@ namespace { // the two kings in basic endgames. const int DistanceBonus[8] = { 0, 0, 100, 80, 60, 40, 20, 10 }; - // 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 }; - - // Build corresponding key code for the opposite color: "KBPKN" -> "KNKBP" - const string swap_colors(const string& keyCode) { - - size_t idx = keyCode.find('K', 1); - return keyCode.substr(idx) + keyCode.substr(0, idx); - } - - // Get the material key of a position out of the given endgame key code - // like "KBPKN". The trick here is to first build up a 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 mat_key(const string& keyCode) { + // 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) { - assert(keyCode.length() > 0 && keyCode.length() < 8); - assert(keyCode[0] == 'K'); + assert(code.length() > 0 && code.length() < 8); + assert(code[0] == 'K'); - string fen; - size_t i = 0; + string sides[] = { code.substr(code.find('K', 1)), // Weaker + code.substr(0, code.find('K', 1)) }; // Stronger - // First add white and then black pieces - do fen += keyCode[i]; while (keyCode[++i] != 'K'); - do fen += char(tolower(keyCode[i])); while (++i < keyCode.length()); + transform(sides[c].begin(), sides[c].end(), sides[c].begin(), tolower); - // Add file padding and remaining empty ranks - fen += string(1, '0' + int(8 - keyCode.length())) + "/8/8/8/8/8/8/8 w - - 0 10"; + string fen = sides[0] + char('0' + int(8 - code.length())) + + sides[1] + "/8/8/8/8/8/8/8 w - - 0 10"; - // Build a Position out of the fen string and get its material key - return Position(fen, false, 0).get_material_key(); + return Position(fen, false).material_key(); } -} // namespace + template + void delete_endgame(const typename M::value_type& p) { delete p.second; } +} // namespace -/// Endgames member definitions -template<> const Endgames::M1& Endgames::map() const { return m1; } -template<> const Endgames::M2& Endgames::map() const { return m2; } +/// Endgames members definitions Endgames::Endgames() { @@ -123,21 +109,15 @@ Endgames::Endgames() { Endgames::~Endgames() { - for (M1::const_iterator it = m1.begin(); it != m1.end(); ++it) - delete it->second; - - for (M2::const_iterator it = m2.begin(); it != m2.end(); ++it) - delete it->second; + for_each(m1.begin(), m1.end(), delete_endgame); + for_each(m2.begin(), m2.end(), delete_endgame); } template -void Endgames::add(const string& keyCode) { - - typedef typename eg_family::type T; - typedef typename Map::type M; +void Endgames::add(const string& code) { - const_cast(map()).insert(std::make_pair(mat_key(keyCode), new Endgame(WHITE))); - const_cast(map()).insert(std::make_pair(mat_key(swap_colors(keyCode)), new Endgame(BLACK))); + map((Endgame*)0)[key(code, WHITE)] = new Endgame(WHITE); + map((Endgame*)0)[key(code, BLACK)] = new Endgame(BLACK); } @@ -151,6 +131,13 @@ Value Endgame::operator()(const Position& pos) const { assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO); assert(pos.piece_count(weakerSide, PAWN) == VALUE_ZERO); + // Stalemate detection with lone king + if ( pos.side_to_move() == weakerSide + && !pos.in_check() + && !MoveList(pos).size()) { + return VALUE_DRAW; + } + Square winnerKSq = pos.king_square(strongerSide); Square loserKSq = pos.king_square(weakerSide); @@ -161,9 +148,9 @@ Value Endgame::operator()(const Position& pos) const { 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; + || pos.bishop_pair(strongerSide)) { + result += VALUE_KNOWN_WIN; + } return strongerSide == pos.side_to_move() ? result : -result; } @@ -223,10 +210,10 @@ Value Endgame::operator()(const Position& pos) const { } else { - wksq = flip(pos.king_square(BLACK)); - bksq = flip(pos.king_square(WHITE)); - wpsq = flip(pos.piece_list(BLACK, PAWN)[0]); - stm = flip(pos.side_to_move()); + wksq = ~pos.king_square(BLACK); + bksq = ~pos.king_square(WHITE); + wpsq = ~pos.piece_list(BLACK, PAWN)[0]; + stm = ~pos.side_to_move(); } if (file_of(wpsq) >= FILE_E) @@ -269,10 +256,10 @@ Value Endgame::operator()(const Position& pos) const { if (strongerSide == BLACK) { - wksq = flip(wksq); - wrsq = flip(wrsq); - bksq = flip(bksq); - bpsq = flip(bpsq); + wksq = ~wksq; + wrsq = ~wrsq; + bksq = ~bksq; + bpsq = ~bpsq; } Square queeningSq = make_square(file_of(bpsq), RANK_1); @@ -333,14 +320,11 @@ Value Endgame::operator()(const Position& pos) const { assert(pos.piece_count(weakerSide, PAWN) == 0); assert(pos.piece_count(weakerSide, KNIGHT) == 1); - Square defendingKSq = pos.king_square(weakerSide); - Square nSq = pos.piece_list(weakerSide, KNIGHT)[0]; - - int d = square_distance(defendingKSq, nSq); - Value result = Value(10) - + MateTable[defendingKSq] - + KRKNKingKnightDistancePenalty[d]; + const int penalty[8] = { 0, 10, 14, 20, 30, 42, 58, 80 }; + 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; } @@ -390,7 +374,7 @@ Value Endgame::operator()(const Position& pos) const { result += Value(square_distance(bksq, nsq) * 32); // Bonus for restricting the knight's mobility - result += Value((8 - count_1s(pos.attacks_from(nsq))) * 8); + result += Value((8 - popcount(pos.attacks_from(nsq))) * 8); return strongerSide == pos.side_to_move() ? result : -result; } @@ -408,10 +392,9 @@ Value Endgame::operator()(const Position&) const { return VALUE_DRAW; } -/// 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, SCALE_FACTOR_ZERO is -/// returned. If not, the return value is SCALE_FACTOR_NONE, i.e. no scaling +/// 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 { @@ -438,7 +421,7 @@ ScaleFactor Endgame::operator()(const Position& pos) const { && 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 neighboring file. Find the rank of the + // file of the pawn(s) or the adjacent file. Find the rank of the // frontmost pawn. Rank rank; if (strongerSide == WHITE) @@ -456,17 +439,15 @@ ScaleFactor Endgame::operator()(const Position& pos) const { // 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_ZERO; + return SCALE_FACTOR_DRAW; } } 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 { @@ -485,16 +466,15 @@ ScaleFactor Endgame::operator()(const Position& pos) const { { Square rsq = pos.piece_list(weakerSide, ROOK)[0]; if (pos.attacks_from(rsq, strongerSide) & pos.pieces(PAWN, weakerSide)) - return SCALE_FACTOR_ZERO; + 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. @@ -516,11 +496,11 @@ ScaleFactor Endgame::operator()(const Position& pos) const { // pawn is on the left half of the board. if (strongerSide == BLACK) { - wksq = flip(wksq); - wrsq = flip(wrsq); - wpsq = flip(wpsq); - bksq = flip(bksq); - brsq = flip(brsq); + wksq = ~wksq; + wrsq = ~wrsq; + wpsq = ~wpsq; + bksq = ~bksq; + brsq = ~brsq; } if (file_of(wpsq) > FILE_D) { @@ -542,7 +522,7 @@ ScaleFactor Endgame::operator()(const Position& pos) const { && square_distance(bksq, queeningSq) <= 1 && wksq <= SQ_H5 && (rank_of(brsq) == RANK_6 || (r <= RANK_3 && rank_of(wrsq) != RANK_6))) - return SCALE_FACTOR_ZERO; + 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. @@ -550,13 +530,13 @@ ScaleFactor Endgame::operator()(const Position& pos) const { && 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_ZERO; + return SCALE_FACTOR_DRAW; if ( r >= RANK_6 && bksq == queeningSq && rank_of(brsq) == RANK_1 && (!tempo || square_distance(wksq, wpsq) >= 2)) - return SCALE_FACTOR_ZERO; + 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. @@ -565,7 +545,7 @@ ScaleFactor Endgame::operator()(const Position& pos) const { && (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_ZERO; + return SCALE_FACTOR_DRAW; // If the defending king blocks the pawn and the attacking king is too far // away, it's a draw. @@ -573,7 +553,7 @@ ScaleFactor Endgame::operator()(const Position& pos) const { && bksq == wpsq + DELTA_N && square_distance(wksq, wpsq) - tempo >= 2 && square_distance(wksq, brsq) - tempo >= 2) - return SCALE_FACTOR_ZERO; + 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, @@ -613,8 +593,8 @@ ScaleFactor Endgame::operator()(const Position& pos) const { } -/// 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 { @@ -652,9 +632,8 @@ ScaleFactor Endgame::operator()(const Position& pos) const { } -/// 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 { @@ -673,7 +652,7 @@ ScaleFactor Endgame::operator()(const Position& pos) const { if ( square_distance(ksq, relative_square(strongerSide, SQ_A8)) <= 1 || ( file_of(ksq) == FILE_A && !in_front_bb(strongerSide, ksq) & pawns)) - return SCALE_FACTOR_ZERO; + return SCALE_FACTOR_DRAW; } // Are all pawns on the 'h' file? else if (!(pawns & ~FileHBB)) @@ -682,17 +661,16 @@ ScaleFactor Endgame::operator()(const Position& pos) const { if ( square_distance(ksq, relative_square(strongerSide, SQ_H8)) <= 1 || ( file_of(ksq) == FILE_H && !in_front_bb(strongerSide, ksq) & pawns)) - return SCALE_FACTOR_ZERO; + return SCALE_FACTOR_DRAW; } 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 { @@ -713,7 +691,7 @@ ScaleFactor Endgame::operator()(const Position& pos) const { && relative_rank(strongerSide, pawnSq) < relative_rank(strongerSide, weakerKingSq) && ( opposite_colors(weakerKingSq, strongerBishopSq) || relative_rank(strongerSide, weakerKingSq) <= RANK_6)) - return SCALE_FACTOR_ZERO; + return SCALE_FACTOR_DRAW; // Case 2: Opposite colored bishops if (opposite_colors(strongerBishopSq, weakerBishopSq)) @@ -729,25 +707,25 @@ ScaleFactor Endgame::operator()(const Position& pos) const { // reasonably well. if (relative_rank(strongerSide, pawnSq) <= RANK_5) - return SCALE_FACTOR_ZERO; + return SCALE_FACTOR_DRAW; else { Bitboard path = squares_in_front_of(strongerSide, pawnSq); if (path & pos.pieces(KING, weakerSide)) - return SCALE_FACTOR_ZERO; + return SCALE_FACTOR_DRAW; if ( (pos.attacks_from(weakerBishopSq) & path) && square_distance(weakerBishopSq, pawnSq) >= 3) - return SCALE_FACTOR_ZERO; + return SCALE_FACTOR_DRAW; } } return SCALE_FACTOR_NONE; } -/// KBPPKBScalingFunction scales KBPP vs KB endgames. It detects a few basic -/// draws with opposite-colored bishops. +/// 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 { @@ -790,12 +768,12 @@ ScaleFactor Endgame::operator()(const Position& pos) const { if ( file_of(ksq) == file_of(blockSq1) && relative_rank(strongerSide, ksq) >= relative_rank(strongerSide, blockSq1) && opposite_colors(ksq, wbsq)) - return SCALE_FACTOR_ZERO; + return SCALE_FACTOR_DRAW; else return SCALE_FACTOR_NONE; case 1: - // Pawns on neighboring files. Draw if defender firmly controls the square + // 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 @@ -803,13 +781,13 @@ ScaleFactor Endgame::operator()(const Position& pos) const { && ( bbsq == blockSq2 || (pos.attacks_from(blockSq2) & pos.pieces(BISHOP, weakerSide)) || abs(r1 - r2) >= 2)) - return SCALE_FACTOR_ZERO; + 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_ZERO; + return SCALE_FACTOR_DRAW; else return SCALE_FACTOR_NONE; @@ -820,10 +798,9 @@ ScaleFactor Endgame::operator()(const Position& pos) const { } -/// 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, 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 { @@ -842,15 +819,15 @@ ScaleFactor Endgame::operator()(const Position& pos) const { && relative_rank(strongerSide, pawnSq) < relative_rank(strongerSide, weakerKingSq) && ( opposite_colors(weakerKingSq, strongerBishopSq) || relative_rank(strongerSide, weakerKingSq) <= RANK_6)) - return SCALE_FACTOR_ZERO; + 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 { @@ -865,22 +842,21 @@ ScaleFactor Endgame::operator()(const Position& pos) const { if ( pawnSq == relative_square(strongerSide, SQ_A7) && square_distance(weakerKingSq, relative_square(strongerSide, SQ_A8)) <= 1) - return SCALE_FACTOR_ZERO; + return SCALE_FACTOR_DRAW; if ( pawnSq == relative_square(strongerSide, SQ_H7) && square_distance(weakerKingSq, relative_square(strongerSide, SQ_H8)) <= 1) - return SCALE_FACTOR_ZERO; + 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). +/// 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 { @@ -889,22 +865,17 @@ ScaleFactor Endgame::operator()(const Position& pos) const { assert(pos.piece_count(WHITE, PAWN) == 1); assert(pos.piece_count(BLACK, PAWN) == 1); - Square wksq, bksq, wpsq; - Color stm; + 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 == WHITE) - { - wksq = pos.king_square(WHITE); - bksq = pos.king_square(BLACK); - wpsq = pos.piece_list(WHITE, PAWN)[0]; - stm = pos.side_to_move(); - } - else + if (strongerSide == BLACK) { - wksq = flip(pos.king_square(BLACK)); - bksq = flip(pos.king_square(WHITE)); - wpsq = flip(pos.piece_list(BLACK, PAWN)[0]); - stm = flip(pos.side_to_move()); + wksq = ~wksq; + bksq = ~bksq; + wpsq = ~wpsq; + stm = ~stm; } if (file_of(wpsq) >= FILE_E) @@ -920,7 +891,7 @@ ScaleFactor Endgame::operator()(const Position& pos) const { && file_of(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. - return probe_kpk_bitbase(wksq, wpsq, bksq, stm) ? SCALE_FACTOR_NONE : SCALE_FACTOR_ZERO; + // 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; }