X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fendgame.cpp;h=44a34d607fb69676fd12b662f2b56f2c18e26003;hp=3258c6fc18ac02af42fbd474dbacd699a2de99dd;hb=b5d5646c840d63710552fdaf2521a054dd3b8a18;hpb=76024ac40ea45e44a8389cb4206d40b884e259a5 diff --git a/src/endgame.cpp b/src/endgame.cpp index 3258c6fc..44a34d60 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) 2008-2009 Marco Costalba + Copyright (C) 2008-2010 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 @@ -17,56 +17,15 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - #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 -EvaluationFunction EvaluateKXK(WHITE), EvaluateKKX(BLACK); - -// K and two minors vs K and one or two minors -EvaluationFunction EvaluateKmmKm(WHITE); - -EvaluationFunction EvaluateKBNK(WHITE), EvaluateKKBN(BLACK); // KBN vs K -EvaluationFunction EvaluateKPK(WHITE), EvaluateKKP(BLACK); // KP vs K -EvaluationFunction EvaluateKRKP(WHITE), EvaluateKPKR(BLACK); // KR vs KP -EvaluationFunction EvaluateKRKB(WHITE), EvaluateKBKR(BLACK); // KR vs KB -EvaluationFunction EvaluateKRKN(WHITE), EvaluateKNKR(BLACK); // KR vs KN -EvaluationFunction EvaluateKQKR(WHITE), EvaluateKRKQ(BLACK); // KQ vs KR -EvaluationFunction EvaluateKBBKN(WHITE), EvaluateKNKBB(BLACK); // KBB vs KN - - -/// Scaling functions - -ScalingFunction ScaleKBPK(WHITE), ScaleKKBP(BLACK); // KBP vs K -ScalingFunction ScaleKQKRP(WHITE), ScaleKRPKQ(BLACK); // KQ vs KRP -ScalingFunction ScaleKRPKR(WHITE), ScaleKRKRP(BLACK); // KRP vs KR -ScalingFunction ScaleKRPPKRP(WHITE), ScaleKRPKRPP(BLACK); // KRPP vs KRP -ScalingFunction ScaleKPsK(WHITE), ScaleKKPs(BLACK); // King and pawns vs king -ScalingFunction ScaleKBPKB(WHITE), ScaleKBKBP(BLACK); // KBP vs KB -ScalingFunction ScaleKBPPKB(WHITE), ScaleKBKBPP(BLACK); // KBPP vs KB -ScalingFunction ScaleKBPKN(WHITE), ScaleKNKBP(BLACK); // KBP vs KN -ScalingFunction ScaleKNPK(WHITE), ScaleKKNP(BLACK); // KNP vs K -ScalingFunction ScaleKPKPw(WHITE), ScaleKPKPb(BLACK); // KPKP - - -//// -//// Local definitions -//// +extern uint32_t probe_kpk_bitbase(Square wksq, Square wpsq, Square bksq, Color stm); namespace { @@ -100,9 +59,6 @@ namespace { // 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]; - // 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 }; @@ -124,25 +80,105 @@ namespace { return Value(KRKNKingKnightDistancePenalty[d]); } - // Function for probing the KP vs K bitbase - int probe_kpk(Square wksq, Square wpsq, Square bksq, Color stm); + // Build corresponding key for the opposite color: "KBPKN" -> "KNKBP" + const string swapColors(const string& keyCode) { + + size_t idx = keyCode.find('K', 1); + return keyCode.substr(idx) + keyCode.substr(0, idx); + } + + // Build up a fen string with the given pieces, note that the fen string + // could be of an illegal position. + Key buildKey(const string& keyCode) { + + assert(keyCode.length() > 0 && keyCode.length() < 8); + assert(keyCode[0] == 'K'); + + string fen; + bool upcase = false; + + for (size_t i = 0; i < keyCode.length(); i++) + { + if (keyCode[i] == 'K') + upcase = !upcase; + + fen += char(upcase ? toupper(keyCode[i]) : tolower(keyCode[i])); + } + fen += char(8 - keyCode.length() + '0'); + fen += "/8/8/8/8/8/8/8 w - -"; + return Position(fen, false, 0).get_material_key(); + } + + typedef EndgameBase EF; + typedef EndgameBase SF; + +} // namespace + + +/// Endgames member definitions + +template<> const Endgames::EFMap& Endgames::get() const { return maps.first; } +template<> const Endgames::SFMap& Endgames::get() const { return maps.second; } + +Endgames::Endgames() { + + add >("KNNK"); + add >("KPK"); + add >("KBNK"); + add >("KRKP"); + add >("KRKB"); + add >("KRKN"); + add >("KQKR"); + add >("KBBKN"); + + add >("KNPK"); + add >("KRPKR"); + add >("KBPKB"); + add >("KBPPKB"); + add >("KBPKN"); + add >("KRPPKRP"); +} + +Endgames::~Endgames() { + + for (EFMap::const_iterator it = get().begin(); it != get().end(); ++it) + delete it->second; + + for (SFMap::const_iterator it = get().begin(); it != get().end(); ++it) + delete it->second; +} + +template +void Endgames::add(const string& keyCode) { + + typedef typename T::Base F; + typedef std::map M; + const_cast(get()).insert(std::pair(buildKey(keyCode), new T(WHITE))); + const_cast(get()).insert(std::pair(buildKey(swapColors(keyCode)), new T(BLACK))); } +template +T* Endgames::get(Key key) const { + + typename std::map::const_iterator it = get().find(key); + return it != get().end() ? it->second : NULL; +} + +// Explicit template instantiations +template EF* Endgames::get(Key key) const; +template SF* Endgames::get(Key key) const; -//// -//// Functions -//// /// 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 EvaluationFunction::apply(const Position& pos) { +Value Endgame::apply(const Position& pos) const { - assert(pos.non_pawn_material(weakerSide) == Value(0)); - assert(pos.piece_count(weakerSide, PAWN) == 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); @@ -152,23 +188,23 @@ Value EvaluationFunction::apply(const Position& pos) { + mate_table(loserKSq) + distance_bonus(square_distance(winnerKSq, loserKSq)); - if ( pos.piece_count(strongerSide, QUEEN) > 0 - || pos.piece_count(strongerSide, ROOK) > 0 + 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 /// defending king towards a corner square of the right color. template<> -Value EvaluationFunction::apply(const Position& pos) { +Value Endgame::apply(const Position& pos) const { - assert(pos.non_pawn_material(weakerSide) == Value(0)); - assert(pos.piece_count(weakerSide, PAWN) == Value(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); @@ -178,7 +214,10 @@ Value EvaluationFunction::apply(const Position& pos) { Square loserKSq = pos.king_square(weakerSide); Square bishopSquare = pos.piece_list(strongerSide, BISHOP, 0); - if (square_color(bishopSquare) == BLACK) + // 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_color_squares(bishopSquare, SQ_A1)) { winnerKSq = flop_square(winnerKSq); loserKSq = flop_square(loserKSq); @@ -188,16 +227,16 @@ Value EvaluationFunction::apply(const Position& pos) { + distance_bonus(square_distance(winnerKSq, loserKSq)) + kbnk_mate_table(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. template<> -Value EvaluationFunction::apply(const Position& pos) { +Value Endgame::apply(const Position& pos) const { - assert(pos.non_pawn_material(strongerSide) == Value(0)); - assert(pos.non_pawn_material(weakerSide) == Value(0)); + 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); @@ -221,19 +260,19 @@ Value EvaluationFunction::apply(const Position& pos) { if (square_file(wpsq) >= FILE_E) { - wksq = flop_square(wksq); - bksq = flop_square(bksq); - wpsq = flop_square(wpsq); + wksq = flop_square(wksq); + bksq = flop_square(bksq); + wpsq = flop_square(wpsq); } - if (!probe_kpk(wksq, wpsq, bksq, stm)) + if (!probe_kpk_bitbase(wksq, wpsq, bksq, stm)) return VALUE_DRAW; Value result = VALUE_KNOWN_WIN + PawnValueEndgame + Value(square_rank(wpsq)); - return (strongerSide == pos.side_to_move() ? result : -result); + return strongerSide == pos.side_to_move() ? result : -result; } @@ -242,7 +281,7 @@ Value EvaluationFunction::apply(const Position& pos) { /// far advanced with support of the king, while the attacking king is far /// away. template<> -Value EvaluationFunction::apply(const Position& pos) { +Value Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -274,7 +313,7 @@ Value EvaluationFunction::apply(const Position& pos) { // 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 + else if ( square_distance(bksq, bpsq) - (tempo ^ 1) >= 3 && square_distance(bksq, wrsq) >= 3) result = RookValueEndgame - Value(square_distance(wksq, bpsq)); @@ -292,14 +331,14 @@ Value EvaluationFunction::apply(const Position& pos) { + 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 /// score is slightly bigger when the defending king is close to the edge. template<> -Value EvaluationFunction::apply(const Position& pos) { +Value Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -308,14 +347,14 @@ Value EvaluationFunction::apply(const Position& pos) { assert(pos.piece_count(weakerSide, BISHOP) == 1); Value result = mate_table(pos.king_square(weakerSide)); - return (pos.side_to_move() == strongerSide ? result : -result); + 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. template<> -Value EvaluationFunction::apply(const Position& pos) { +Value Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -326,10 +365,12 @@ Value EvaluationFunction::apply(const Position& pos) { Square defendingKSq = pos.king_square(weakerSide); Square nSq = pos.piece_list(weakerSide, KNIGHT, 0); - Value result = Value(10) + mate_table(defendingKSq) + - krkn_king_knight_distance_penalty(square_distance(defendingKSq, nSq)); + int d = square_distance(defendingKSq, nSq); + Value result = Value(10) + + mate_table(defendingKSq) + + krkn_king_knight_distance_penalty(d); - return (strongerSide == pos.side_to_move())? result : -result; + return strongerSide == pos.side_to_move() ? result : -result; } @@ -339,7 +380,7 @@ Value EvaluationFunction::apply(const Position& pos) { /// for the defending side in the search, this is usually sufficient to be /// able to win KQ vs KR. template<> -Value EvaluationFunction::apply(const Position& pos) { +Value Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -354,17 +395,17 @@ Value EvaluationFunction::apply(const Position& pos) { + mate_table(loserKSq) + distance_bonus(square_distance(winnerKSq, loserKSq)); - return (strongerSide == pos.side_to_move())? result : -result; + return strongerSide == pos.side_to_move() ? result : -result; } template<> -Value EvaluationFunction::apply(const Position& pos) { +Value Endgame::apply(const Position& pos) const { 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.pawns() == EmptyBoardBB); + assert(pos.pieces(PAWN) == EmptyBoardBB); Value result = BishopValueEndgame; Square wksq = pos.king_square(strongerSide); @@ -378,24 +419,31 @@ Value EvaluationFunction::apply(const Position& pos) { result += Value(square_distance(bksq, nsq) * 32); // Bonus for restricting the knight's mobility - result += Value((8 - count_1s_max_15(pos.piece_attacks(nsq))) * 8); + result += Value((8 - count_1s(pos.attacks_from(nsq))) * 8); - return (strongerSide == pos.side_to_move() ? result : -result); + return strongerSide == pos.side_to_move() ? result : -result; } + +/// 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); +Value Endgame::apply(const Position&) const { + return VALUE_DRAW; } +template<> +Value Endgame::apply(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, ScaleFactor(0) is +/// 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 /// will be used. template<> -ScaleFactor ScalingFunction::apply(const Position& pos) { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); assert(pos.piece_count(strongerSide, BISHOP) == 1); @@ -404,7 +452,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) { // 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.pawns(strongerSide); + Bitboard pawns = pos.pieces(PAWN, strongerSide); File pawnFile = square_file(pos.piece_list(strongerSide, PAWN, 0)); // All pawns are on a single rook file ? @@ -415,13 +463,12 @@ ScaleFactor ScalingFunction::apply(const Position& pos) { Square queeningSq = relative_square(strongerSide, make_square(pawnFile, RANK_8)); Square kingSq = pos.king_square(weakerSide); - if ( square_color(queeningSq) != square_color(bishopSq) - && file_distance(square_file(kingSq), pawnFile) <= 1) + if ( opposite_color_squares(queeningSq, bishopSq) + && abs(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) { @@ -430,15 +477,15 @@ ScaleFactor ScalingFunction::apply(const Position& pos) { } else { - for(rank = RANK_2; (rank_bb(rank) & pawns) == EmptyBoardBB; rank++) {} - rank = Rank(rank^7); // HACK to get the relative rank + for (rank = RANK_2; (rank_bb(rank) & pawns) == EmptyBoardBB; 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 ScaleFactor(0); + return SCALE_FACTOR_ZERO; } } return SCALE_FACTOR_NONE; @@ -450,7 +497,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) { /// It tests for fortress draws with a rook on the third rank defended by /// a pawn. template<> -ScaleFactor ScalingFunction::apply(const Position& pos) { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame); assert(pos.piece_count(strongerSide, QUEEN) == 1); @@ -461,13 +508,13 @@ ScaleFactor ScalingFunction::apply(const Position& pos) { 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))) + && (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.pawn_attacks(strongerSide, rsq) & pos.pawns(weakerSide)) - return ScaleFactor(0); + if (pos.attacks_from(rsq, strongerSide) & pos.pieces(PAWN, weakerSide)) + return SCALE_FACTOR_ZERO; } return SCALE_FACTOR_NONE; } @@ -481,7 +528,7 @@ ScaleFactor ScalingFunction::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. template<> -ScaleFactor ScalingFunction::apply(const Position &pos) { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 1); @@ -524,7 +571,7 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { && square_distance(bksq, queeningSq) <= 1 && wksq <= SQ_H5 && (square_rank(brsq) == RANK_6 || (r <= RANK_3 && square_rank(wrsq) != RANK_6))) - return ScaleFactor(0); + return SCALE_FACTOR_ZERO; // The defending side saves a draw by checking from behind in case the pawn // has advanced to the 6th rank with the king behind. @@ -532,13 +579,13 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { && 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); + return SCALE_FACTOR_ZERO; if ( r >= RANK_6 && bksq == queeningSq && square_rank(brsq) == RANK_1 && (!tempo || square_distance(wksq, wpsq) >= 2)) - return ScaleFactor(0); + return SCALE_FACTOR_ZERO; // 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. @@ -547,7 +594,7 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { && (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); + return SCALE_FACTOR_ZERO; // If the defending king blocks the pawn and the attacking king is too far // away, it's a draw. @@ -555,7 +602,7 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { && bksq == wpsq + DELTA_N && square_distance(wksq, wpsq) - tempo >= 2 && square_distance(wksq, brsq) - tempo >= 2) - return ScaleFactor(0); + return SCALE_FACTOR_ZERO; // 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, @@ -578,8 +625,8 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { || ( 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))); + - 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. @@ -599,7 +646,7 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { /// single pattern: If the stronger side has no pawns and the defending king /// is actively placed, the position is drawish. template<> -ScaleFactor ScalingFunction::apply(const Position &pos) { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 2); @@ -638,43 +685,35 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { /// 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. template<> -ScaleFactor ScalingFunction::apply(const Position &pos) { +ScaleFactor Endgame::apply(const Position& pos) const { - assert(pos.non_pawn_material(strongerSide) == Value(0)); + assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO); assert(pos.piece_count(strongerSide, PAWN) >= 2); - assert(pos.non_pawn_material(weakerSide) == Value(0)); + 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 ( square_distance(ksq, relative_square(strongerSide, SQ_A8)) <= 1 + || ( square_file(ksq) == FILE_A + && (in_front_bb(strongerSide, ksq) & pawns) == EmptyBoardBB)) + return SCALE_FACTOR_ZERO; } // Are all pawns on the 'h' file? else if ((pawns & ~FileHBB) == EmptyBoardBB) { // 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 + || ( square_file(ksq) == FILE_H + && (in_front_bb(strongerSide, ksq) & pawns) == EmptyBoardBB)) + return SCALE_FACTOR_ZERO; } - else - return SCALE_FACTOR_NONE; + return SCALE_FACTOR_NONE; } @@ -684,7 +723,7 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { /// it's a draw. If the two bishops have opposite color, it's almost always /// a draw. template<> -ScaleFactor ScalingFunction::apply(const Position &pos) { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); assert(pos.piece_count(strongerSide, BISHOP) == 1); @@ -701,12 +740,12 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { // 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) + && ( opposite_color_squares(weakerKingSq, strongerBishopSq) || relative_rank(strongerSide, weakerKingSq) <= RANK_6)) - return ScaleFactor(0); + return SCALE_FACTOR_ZERO; // Case 2: Opposite colored bishops - if (square_color(strongerBishopSq) != square_color(weakerBishopSq)) + if (opposite_color_squares(strongerBishopSq, weakerBishopSq)) { // We assume that the position is drawn in the following three situations: // @@ -719,15 +758,17 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { // reasonably well. if (relative_rank(strongerSide, pawnSq) <= RANK_5) - return ScaleFactor(0); + return SCALE_FACTOR_ZERO; 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); + Bitboard path = squares_in_front_of(strongerSide, pawnSq); + + if (path & pos.pieces(KING, weakerSide)) + return SCALE_FACTOR_ZERO; + + if ( (pos.attacks_from(weakerBishopSq) & path) + && square_distance(weakerBishopSq, pawnSq) >= 3) + return SCALE_FACTOR_ZERO; } } return SCALE_FACTOR_NONE; @@ -737,7 +778,7 @@ ScaleFactor ScalingFunction::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) { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); assert(pos.piece_count(strongerSide, BISHOP) == 1); @@ -749,8 +790,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) { 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 + if (!opposite_color_squares(wbsq, bbsq)) return SCALE_FACTOR_NONE; Square ksq = pos.king_square(weakerSide); @@ -778,8 +818,8 @@ ScaleFactor ScalingFunction::apply(const Position& pos) { // 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); + && opposite_color_squares(ksq, wbsq)) + return SCALE_FACTOR_ZERO; else return SCALE_FACTOR_NONE; @@ -788,16 +828,17 @@ ScaleFactor ScalingFunction::apply(const Position& pos) { // 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) + && opposite_color_squares(ksq, wbsq) && ( bbsq == blockSq2 - || (pos.piece_attacks(blockSq2) & pos.bishops(weakerSide)) - || rank_distance(r1, r2) >= 2)) - return ScaleFactor(0); + || (pos.attacks_from(blockSq2) & pos.pieces(BISHOP, weakerSide)) + || abs(r1 - r2) >= 2)) + return SCALE_FACTOR_ZERO; + else if ( ksq == blockSq2 - && square_color(ksq) != square_color(wbsq) + && opposite_color_squares(ksq, wbsq) && ( bbsq == blockSq1 - || (pos.piece_attacks(blockSq1) & pos.bishops(weakerSide)))) - return ScaleFactor(0); + || (pos.attacks_from(blockSq1) & pos.pieces(BISHOP, weakerSide)))) + return SCALE_FACTOR_ZERO; else return SCALE_FACTOR_NONE; @@ -813,7 +854,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) { /// square of the king is not of the same color as the stronger side's bishop, /// it's a draw. template<> -ScaleFactor ScalingFunction::apply(const Position &pos) { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); assert(pos.piece_count(strongerSide, BISHOP) == 1); @@ -828,9 +869,9 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { if ( square_file(weakerKingSq) == square_file(pawnSq) && relative_rank(strongerSide, pawnSq) < relative_rank(strongerSide, weakerKingSq) - && ( square_color(weakerKingSq) != square_color(strongerBishopSq) + && ( opposite_color_squares(weakerKingSq, strongerBishopSq) || relative_rank(strongerSide, weakerKingSq) <= RANK_6)) - return ScaleFactor(0); + return SCALE_FACTOR_ZERO; return SCALE_FACTOR_NONE; } @@ -840,12 +881,12 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { /// 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 ScalingFunction::apply(const Position &pos) { +ScaleFactor Endgame::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == KnightValueMidgame); assert(pos.piece_count(strongerSide, KNIGHT) == 1); assert(pos.piece_count(strongerSide, PAWN) == 1); - assert(pos.non_pawn_material(weakerSide) == Value(0)); + assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO); assert(pos.piece_count(weakerSide, PAWN) == 0); Square pawnSq = pos.piece_list(strongerSide, PAWN, 0); @@ -853,11 +894,11 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { if ( pawnSq == relative_square(strongerSide, SQ_A7) && square_distance(weakerKingSq, relative_square(strongerSide, SQ_A8)) <= 1) - return ScaleFactor(0); + return SCALE_FACTOR_ZERO; if ( pawnSq == relative_square(strongerSide, SQ_H7) && square_distance(weakerKingSq, relative_square(strongerSide, SQ_H8)) <= 1) - return ScaleFactor(0); + return SCALE_FACTOR_ZERO; return SCALE_FACTOR_NONE; } @@ -870,10 +911,10 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { /// 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 ScalingFunction::apply(const Position &pos) { +ScaleFactor Endgame::apply(const Position& pos) const { - assert(pos.non_pawn_material(strongerSide) == Value(0)); - assert(pos.non_pawn_material(weakerSide) == Value(0)); + 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); @@ -910,32 +951,5 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { // 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: - - 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)); - } + return probe_kpk_bitbase(wksq, wpsq, bksq, stm) ? SCALE_FACTOR_NONE : SCALE_FACTOR_ZERO; }