X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fendgame.cpp;h=53c9ec8364c4b6a010ff96fec56e1ebc6ac2a814;hp=6745ee2664c612689646c283f78833355d509dcf;hb=9690cd6295fbed93ee434e7b2e16181e475755ac;hpb=be5a2f015e45886e32867b4559ef51dd694a3cec diff --git a/src/endgame.cpp b/src/endgame.cpp index 6745ee26..53c9ec83 100644 --- a/src/endgame.cpp +++ b/src/endgame.cpp @@ -54,12 +54,9 @@ namespace { 4160, 4480, 4800, 5120, 5440, 5760, 6080, 6400 }; - // Tables used to drive a piece towards or away from another piece - constexpr int PushClose[8] = { 0, 0, 100, 80, 60, 40, 20, 10 }; - constexpr int PushAway [8] = { 0, 5, 20, 40, 60, 80, 90, 100 }; - - // Pawn Rank based scaling factors used in KRPPKRP endgame - constexpr int KRPPKRPScaleFactors[RANK_NB] = { 0, 9, 10, 14, 21, 44, 0, 0 }; + // Drive a piece close to or away from another piece + inline int push_close(Square s1, Square s2) { return 140 - 20 * distance(s1, s2); } + inline int push_away(Square s1, Square s2) { return 120 - push_close(s1, s2); } #ifndef NDEBUG bool verify_material(const Position& pos, Color c, Value npm, int pawnsCnt) { @@ -74,9 +71,9 @@ namespace { assert(pos.count(strongSide) == 1); if (file_of(pos.square(strongSide)) >= FILE_E) - sq = Square(int(sq) ^ 7); // Mirror SQ_H1 -> SQ_A1 + sq = flip_file(sq); - return strongSide == WHITE ? sq : ~sq; + return strongSide == WHITE ? sq : flip_rank(sq); } } // namespace @@ -130,7 +127,7 @@ Value Endgame::operator()(const Position& pos) const { Value result = pos.non_pawn_material(strongSide) + pos.count(strongSide) * PawnValueEg + PushToEdges[loserKSq] - + PushClose[distance(winnerKSq, loserKSq)]; + + push_close(winnerKSq, loserKSq); if ( pos.count(strongSide) || pos.count(strongSide) @@ -159,7 +156,7 @@ Value Endgame::operator()(const Position& pos) const { // to drive to opposite corners (A8/H1). Value result = VALUE_KNOWN_WIN - + PushClose[distance(winnerKSq, loserKSq)] + + push_close(winnerKSq, loserKSq) + PushToCorners[opposite_colors(bishopSq, SQ_A1) ? ~loserKSq : loserKSq]; assert(abs(result) < VALUE_TB_WIN_IN_MAX_PLY); @@ -258,7 +255,7 @@ Value Endgame::operator()(const Position& pos) const { Square bksq = pos.square(weakSide); Square bnsq = pos.square(weakSide); - Value result = Value(PushToEdges[bksq] + PushAway[distance(bksq, bnsq)]); + Value result = Value(PushToEdges[bksq] + push_away(bksq, bnsq)); return strongSide == pos.side_to_move() ? result : -result; } @@ -277,11 +274,11 @@ Value Endgame::operator()(const Position& pos) const { Square loserKSq = pos.square(weakSide); Square pawnSq = pos.square(weakSide); - Value result = Value(PushClose[distance(winnerKSq, loserKSq)]); + Value result = Value(push_close(winnerKSq, loserKSq)); if ( relative_rank(weakSide, pawnSq) != RANK_7 || distance(loserKSq, pawnSq) != 1 - || !((FileABB | FileCBB | FileFBB | FileHBB) & pawnSq)) + || ((FileBBB | FileDBB | FileEBB | FileGBB) & pawnSq)) result += QueenValueEg - PawnValueEg; return strongSide == pos.side_to_move() ? result : -result; @@ -304,22 +301,23 @@ Value Endgame::operator()(const Position& pos) const { Value result = QueenValueEg - RookValueEg + PushToEdges[loserKSq] - + PushClose[distance(winnerKSq, loserKSq)]; + + push_close(winnerKSq, loserKSq); return strongSide == pos.side_to_move() ? result : -result; } -/// KNN vs KP. Simply push the opposing king to the corner +/// KNN vs KP. Very drawish, but there are some mate opportunities if we can +// press the weakSide King to a corner before the pawn advances too much. template<> Value Endgame::operator()(const Position& pos) const { assert(verify_material(pos, strongSide, 2 * KnightValueMg, 0)); assert(verify_material(pos, weakSide, VALUE_ZERO, 1)); - Value result = 2 * KnightValueEg - - PawnValueEg - + PushToEdges[pos.square(weakSide)]; + Value result = PawnValueEg + + 2 * PushToEdges[pos.square(weakSide)] + - 10 * relative_rank(weakSide, pos.square(weakSide)); return strongSide == pos.side_to_move() ? result : -result; } @@ -342,29 +340,27 @@ ScaleFactor Endgame::operator()(const Position& pos) const { // No assertions about the material of weakSide, because we want draws to // be detected even when the weaker side has some pawns. - Bitboard pawns = pos.pieces(strongSide, PAWN); - File pawnsFile = file_of(lsb(pawns)); + Bitboard strongpawns = pos.pieces(strongSide, PAWN); + Bitboard allpawns = pos.pieces(PAWN); - // All pawns are on a single rook file? - if ( (pawnsFile == FILE_A || pawnsFile == FILE_H) - && !(pawns & ~file_bb(pawnsFile))) + // All strongSide pawns are on a single rook file? + if (!(strongpawns & ~FileABB) || !(strongpawns & ~FileHBB)) { Square bishopSq = pos.square(strongSide); - Square queeningSq = relative_square(strongSide, make_square(pawnsFile, RANK_8)); - Square kingSq = pos.square(weakSide); + Square queeningSq = relative_square(strongSide, make_square(file_of(lsb(strongpawns)), RANK_8)); + Square weakkingSq = pos.square(weakSide); if ( opposite_colors(queeningSq, bishopSq) - && distance(queeningSq, kingSq) <= 1) + && distance(queeningSq, weakkingSq) <= 1) return SCALE_FACTOR_DRAW; } // If all the pawns are on the same B or G file, then it's potentially a draw - if ( (pawnsFile == FILE_B || pawnsFile == FILE_G) - && !(pos.pieces(PAWN) & ~file_bb(pawnsFile)) + if ((!(allpawns & ~FileBBB) || !(allpawns & ~FileGBB)) && pos.non_pawn_material(weakSide) == 0 && pos.count(weakSide) >= 1) { - // Get weakSide pawn that is closest to the home rank + // Get the least advanced weakSide pawn Square weakPawnSq = frontmost_sq(strongSide, pos.pieces(weakSide, PAWN)); Square strongKingSq = pos.square(strongSide); @@ -374,8 +370,8 @@ ScaleFactor Endgame::operator()(const Position& pos) const { // 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)) + && (strongpawns & (weakPawnSq + pawn_push(weakSide))) + && (opposite_colors(bishopSq, weakPawnSq) || !more_than_one(strongpawns))) { int strongKingDist = distance(weakPawnSq, strongKingSq); int weakKingDist = distance(weakPawnSq, weakKingSq); @@ -588,7 +584,7 @@ ScaleFactor Endgame::operator()(const Position& pos) const { && relative_rank(strongSide, bksq) > r) { assert(r > RANK_1 && r < RANK_7); - return ScaleFactor(KRPPKRPScaleFactors[r]); + return ScaleFactor(7 * r); } return SCALE_FACTOR_NONE; }