X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fposition.cpp;h=78fccbb2891d8fb70b1d7e5d406ba985c88daccf;hb=7b0a2f2a90b63d9e5e092786fbfb54cd8ad3d8e5;hp=982befa35dacf71960f2d1bea539c7eccd2eb297;hpb=431c3ac485386cc10413fc8a3c7d338dcc71602d;p=stockfish diff --git a/src/position.cpp b/src/position.cpp index 982befa3..78fccbb2 100644 --- a/src/position.cpp +++ b/src/position.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) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2014 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 @@ -411,11 +411,14 @@ const string Position::pretty(Move move) const { } -/// Position:hidden_checkers() returns a bitboard of all pinned / discovered check -/// pieces, according to the call parameters. Pinned pieces protect our king and -/// discovered check pieces attack the enemy king. +/// Position::check_blockers() returns a bitboard of all the pieces with color +/// 'c' that are blocking check on the king with color 'kingColor'. A piece +/// blocks a check if removing that piece from the board would result in a +/// position where the king is in check. A check blocking piece can be either a +/// pinned or a discovered check piece, according if its color 'c' is the same +/// or the opposite of 'kingColor'. -Bitboard Position::hidden_checkers(Color c, Color kingColor) const { +Bitboard Position::check_blockers(Color c, Color kingColor) const { Bitboard b, pinners, result = 0; Square ksq = king_square(kingColor); @@ -614,7 +617,7 @@ bool Position::pseudo_legal(const Move m) const { } -/// Position::move_gives_check() tests whether a pseudo-legal move gives a check +/// Position::gives_check() tests whether a pseudo-legal move gives a check bool Position::gives_check(Move m, const CheckInfo& ci) const { @@ -633,20 +636,17 @@ bool Position::gives_check(Move m, const CheckInfo& ci) const { // Is there a discovered check? if ( unlikely(ci.dcCandidates) && (ci.dcCandidates & from) - && !aligned(from, to, king_square(~sideToMove))) + && !aligned(from, to, ci.ksq)) return true; // Can we skip the ugly special cases? if (type_of(m) == NORMAL) return false; - Color us = sideToMove; - Square ksq = king_square(~us); - switch (type_of(m)) { case PROMOTION: - return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & ksq; + return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & ci.ksq; // En passant capture with check? We have already handled the case // of direct checks and ordinary discovered check, so the only case we @@ -657,18 +657,18 @@ bool Position::gives_check(Move m, const CheckInfo& ci) const { Square capsq = file_of(to) | rank_of(from); Bitboard b = (pieces() ^ from ^ capsq) | to; - return (attacks_bb< ROOK>(ksq, b) & pieces(us, QUEEN, ROOK)) - | (attacks_bb(ksq, b) & pieces(us, QUEEN, BISHOP)); + return (attacks_bb< ROOK>(ci.ksq, b) & pieces(sideToMove, QUEEN, ROOK)) + | (attacks_bb(ci.ksq, b) & pieces(sideToMove, QUEEN, BISHOP)); } case CASTLING: { Square kfrom = from; Square rfrom = to; // Castling is encoded as 'King captures the rook' - Square kto = relative_square(us, rfrom > kfrom ? SQ_G1 : SQ_C1); - Square rto = relative_square(us, rfrom > kfrom ? SQ_F1 : SQ_D1); + Square kto = relative_square(sideToMove, rfrom > kfrom ? SQ_G1 : SQ_C1); + Square rto = relative_square(sideToMove, rfrom > kfrom ? SQ_F1 : SQ_D1); - return (PseudoAttacks[ROOK][rto] & ksq) - && (attacks_bb(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ksq); + return (PseudoAttacks[ROOK][rto] & ci.ksq) + && (attacks_bb(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ci.ksq); } default: assert(false); @@ -1011,12 +1011,9 @@ void Position::undo_null_move() { /// Position::see() is a static exchange evaluator: It tries to estimate the -/// material gain or loss resulting from a move. Parameter 'asymmThreshold' takes -/// tempi into account. If the side who initiated the capturing sequence does the -/// last capture, he loses a tempo and if the result is below 'asymmThreshold' -/// the capturing sequence is considered bad. +/// material gain or loss resulting from a move. -int Position::see_sign(Move m) const { +Value Position::see_sign(Move m) const { assert(is_ok(m)); @@ -1024,16 +1021,17 @@ int Position::see_sign(Move m) const { // is not less then capturing one. Note that king moves always return // here because king midgame value is set to 0. if (PieceValue[MG][moved_piece(m)] <= PieceValue[MG][piece_on(to_sq(m))]) - return 1; + return VALUE_KNOWN_WIN; return see(m); } -int Position::see(Move m, int asymmThreshold) const { +Value Position::see(Move m) const { Square from, to; Bitboard occupied, attackers, stmAttackers; - int swapList[32], slIndex = 1; + Value swapList[32]; + int slIndex = 1; PieceType captured; Color stm; @@ -1049,7 +1047,7 @@ int Position::see(Move m, int asymmThreshold) const { // handled correctly. Simply return 0 that is always the correct value // unless in the rare case the rook ends up under attack. if (type_of(m) == CASTLING) - return 0; + return VALUE_ZERO; if (type_of(m) == ENPASSANT) { @@ -1080,30 +1078,24 @@ int Position::see(Move m, int asymmThreshold) const { // Add the new entry to the swap list swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured]; - ++slIndex; // Locate and remove the next least valuable attacker captured = min_attacker(byTypeBB, to, stmAttackers, occupied, attackers); - stm = ~stm; - stmAttackers = attackers & pieces(stm); // Stop before processing a king capture - if (captured == KING && stmAttackers) + if (captured == KING) { - swapList[slIndex++] = QueenValueMg * 16; + if (stmAttackers == attackers) + ++slIndex; + break; } - } while (stmAttackers); + stm = ~stm; + stmAttackers = attackers & pieces(stm); + ++slIndex; - // If we are doing asymmetric SEE evaluation and the same side does the first - // and the last capture, it loses a tempo and gain must be at least worth - // 'asymmThreshold', otherwise we replace the score with a very low value, - // before negamaxing. - if (asymmThreshold) - for (int i = 0; i < slIndex; i += 2) - if (swapList[i] < asymmThreshold) - swapList[i] = - QueenValueMg * 16; + } while (stmAttackers); // Having built the swap list, we negamax through it to find the best // achievable score from the point of view of the side to move. @@ -1185,7 +1177,7 @@ Key Position::compute_material_key() const { Key k = 0; for (Color c = WHITE; c <= BLACK; ++c) - for (PieceType pt = PAWN; pt <= QUEEN; ++pt) + for (PieceType pt = PAWN; pt <= KING; ++pt) for (int cnt = 0; cnt < pieceCount[c][pt]; ++cnt) k ^= Zobrist::psq[c][pt][cnt];