X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fendgame.cpp;h=4ee515ade71cab5c856f3f6c547d1fd959a8820f;hp=869a36d76ceb5d0358765e7dd89ef639f240f6f6;hb=c0d3010438e9cec2d40dec9e92695b58514497bb;hpb=a646f74e6a62af756b2e51756a81ee983db4ff34 diff --git a/src/endgame.cpp b/src/endgame.cpp index 869a36d7..4ee515ad 100644 --- a/src/endgame.cpp +++ b/src/endgame.cpp @@ -82,8 +82,7 @@ namespace { // Get the material key of 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 do the work for us. Note that the - // FEN string could correspond to an illegal position. + // and then let a Position object do the work for us. Key key(const string& code, Color c) { assert(code.length() > 0 && code.length() < 8); @@ -94,8 +93,8 @@ namespace { std::transform(sides[c].begin(), sides[c].end(), sides[c].begin(), tolower); - string fen = sides[0] + char('0' + int(8 - code.length())) - + sides[1] + "/8/8/8/8/8/8/8 w - - 0 10"; + string fen = sides[0] + char(8 - sides[0].length() + '0') + "/8/8/8/8/8/8/" + + sides[1] + char(8 - sides[1].length() + '0') + " w - - 0 10"; return Position(fen, false, NULL).material_key(); } @@ -118,7 +117,6 @@ Endgames::Endgames() { add("KRKN"); add("KQKP"); add("KQKR"); - add("KBBKN"); add("KNPK"); add("KNPKB"); @@ -168,6 +166,7 @@ Value Endgame::operator()(const Position& pos) const { if ( pos.count(strongSide) || pos.count(strongSide) + ||(pos.count(strongSide) && pos.count(strongSide)) || pos.bishop_pair(strongSide)) result += VALUE_KNOWN_WIN; @@ -242,18 +241,18 @@ Value Endgame::operator()(const Position& pos) const { Square rsq = relative_square(strongSide, pos.list(strongSide)[0]); Square psq = relative_square(strongSide, pos.list(weakSide)[0]); - Square queeningSq = file_of(psq) | RANK_1; + Square queeningSq = make_square(file_of(psq), RANK_1); Value result; // If the stronger side's king is in front of the pawn, it's a win if (wksq < psq && file_of(wksq) == file_of(psq)) - result = RookValueEg - Value(square_distance(wksq, psq)); + result = RookValueEg - square_distance(wksq, psq); // If the weaker side's king is too far from the pawn and the rook, // it's a win. else if ( square_distance(bksq, psq) >= 3 + (pos.side_to_move() == weakSide) && square_distance(bksq, rsq) >= 3) - result = RookValueEg - Value(square_distance(wksq, psq)); + result = RookValueEg - square_distance(wksq, psq); // If the pawn is far advanced and supported by the defending king, // the position is drawish @@ -261,13 +260,12 @@ Value Endgame::operator()(const Position& pos) const { && square_distance(bksq, psq) == 1 && rank_of(wksq) >= RANK_4 && square_distance(wksq, psq) > 2 + (pos.side_to_move() == strongSide)) - result = Value(80 - square_distance(wksq, psq) * 8); + result = Value(80) - 8 * square_distance(wksq, psq); else - result = Value(200) - - Value(square_distance(wksq, psq + DELTA_S) * 8) - + Value(square_distance(bksq, psq + DELTA_S) * 8) - + Value(square_distance(psq, queeningSq) * 8); + result = Value(200) - 8 * ( square_distance(wksq, psq + DELTA_S) + - square_distance(bksq, psq + DELTA_S) + - square_distance(psq, queeningSq)); return strongSide == pos.side_to_move() ? result : -result; } @@ -348,32 +346,8 @@ Value Endgame::operator()(const Position& pos) const { } -/// KBB vs KN. This is almost always a win. We try to push the enemy king to a corner -/// and away from his knight. For a reference of this difficult endgame see: -/// en.wikipedia.org/wiki/Chess_endgame#Effect_of_tablebases_on_endgame_theory - -template<> -Value Endgame::operator()(const Position& pos) const { - - assert(verify_material(pos, strongSide, 2 * BishopValueMg, 0)); - assert(verify_material(pos, weakSide, KnightValueMg, 0)); - - Square winnerKSq = pos.king_square(strongSide); - Square loserKSq = pos.king_square(weakSide); - Square knightSq = pos.list(weakSide)[0]; - - Value result = VALUE_KNOWN_WIN - + PushToCorners[loserKSq] - + PushClose[square_distance(winnerKSq, loserKSq)] - + PushAway[square_distance(loserKSq, knightSq)]; - - return strongSide == pos.side_to_move() ? result : -result; -} - - /// Some cases of trivial draws template<> Value Endgame::operator()(const Position&) const { return VALUE_DRAW; } -template<> Value Endgame::operator()(const Position&) const { return VALUE_DRAW; } /// KB and one or more pawns vs K. It checks for draws with rook pawns and @@ -390,52 +364,27 @@ ScaleFactor Endgame::operator()(const Position& pos) const { // be detected even when the weaker side has some pawns. Bitboard pawns = pos.pieces(strongSide, PAWN); - File pawnFile = file_of(pos.list(strongSide)[0]); + File pawnsFile = file_of(lsb(pawns)); // All pawns are on a single rook file ? - if ( (pawnFile == FILE_A || pawnFile == FILE_H) - && !(pawns & ~file_bb(pawnFile))) + if ( (pawnsFile == FILE_A || pawnsFile == FILE_H) + && !(pawns & ~file_bb(pawnsFile))) { Square bishopSq = pos.list(strongSide)[0]; - Square queeningSq = relative_square(strongSide, pawnFile | RANK_8); + Square queeningSq = relative_square(strongSide, make_square(pawnsFile, RANK_8)); Square kingSq = pos.king_square(weakSide); + // If the bishop has the wrong color, and the defending king is on the file + // of the pawn(s) or the neighboring file, then it's potentially a draw. if ( opposite_colors(queeningSq, bishopSq) - && square_distance(queeningSq, kingSq) <= 1) - return SCALE_FACTOR_DRAW; - } - - // If all the pawns are on the same B or G file, then it's potentially a draw - if ( (pawnFile == FILE_B || pawnFile == FILE_G) - && !(pos.pieces(PAWN) & ~file_bb(pawnFile)) - && pos.non_pawn_material(weakSide) == 0 - && pos.count(weakSide) >= 1) - { - // Get weakSide pawn that is closest to the home rank - Square weakPawnSq = backmost_sq(weakSide, pos.pieces(weakSide, PAWN)); - - Square strongKingSq = pos.king_square(strongSide); - Square weakKingSq = pos.king_square(weakSide); - Square bishopSq = pos.list(strongSide)[0]; - - // There's potential for a draw if our pawn is blocked on the 7th rank, - // the bishop cannot attack it or they only have one pawn left - if ( relative_rank(strongSide, weakPawnSq) == RANK_7 - && (pos.pieces(strongSide, PAWN) & (weakPawnSq + pawn_push(weakSide))) - && (opposite_colors(bishopSq, weakPawnSq) || pos.count(strongSide) == 1)) + && file_distance(kingSq, lsb(pawns)) <= 1) { - int strongKingDist = square_distance(weakPawnSq, strongKingSq); - int weakKingDist = square_distance(weakPawnSq, weakKingSq); - - // It's a draw if the weak king is on its back two ranks, within 2 - // squares of the blocking pawn and the strong king is not - // closer. (I think this rule only fails in practically - // unreachable positions such as 5k1K/6p1/6P1/8/8/3B4/8/8 w - // and positions where qsearch will immediately correct the - // problem such as 8/4k1p1/6P1/1K6/3B4/8/8/8 w) - if ( relative_rank(strongSide, weakKingSq) >= RANK_7 - && weakKingDist <= 2 - && weakKingDist <= strongKingDist) + // If the defending king has distance <= 1 to the promotion square or + // is placed somewhere in front of the frontmost pawn, it's a draw. + Rank rank = relative_rank(strongSide, (frontmost_sq(strongSide, pawns))); + + if ( square_distance(kingSq, queeningSq) <= 1 + || relative_rank(strongSide, kingSq) >= rank) return SCALE_FACTOR_DRAW; } } @@ -489,7 +438,7 @@ ScaleFactor Endgame::operator()(const Position& pos) const { File f = file_of(wpsq); Rank r = rank_of(wpsq); - Square queeningSq = f | RANK_8; + Square queeningSq = make_square(f, RANK_8); int tempo = (pos.side_to_move() == strongSide); // If the pawn is not too far advanced and the defending king defends the @@ -747,12 +696,12 @@ ScaleFactor Endgame::operator()(const Position& pos) const { if (relative_rank(strongSide, psq1) > relative_rank(strongSide, psq2)) { blockSq1 = psq1 + pawn_push(strongSide); - blockSq2 = file_of(psq2) | rank_of(psq1); + blockSq2 = make_square(file_of(psq2), rank_of(psq1)); } else { blockSq1 = psq2 + pawn_push(strongSide); - blockSq2 = file_of(psq1) | rank_of(psq2); + blockSq2 = make_square(file_of(psq1), rank_of(psq2)); } switch (file_distance(psq1, psq2))