X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=93c42291b658d6d90ec9236d2a8642c3073c6037;hp=ec54da9e9e3161b382120acfaadfe7c9866129fd;hb=3e40bd0648ab69c04e37da50fd3f3d4beb072df2;hpb=1f97b48a31cd60d71c5fb63541cbf3991a094443 diff --git a/src/position.cpp b/src/position.cpp index ec54da9e..93c42291 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 Marco Costalba + Copyright (C) 2008-2009 Marco Costalba Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -35,13 +35,13 @@ #include "san.h" #include "ucioption.h" +using std::string; + //// //// Variables //// -extern SearchStack EmptySearchStack; - int Position::castleRightsMask[64]; Key Position::zobrist[2][8][64]; @@ -65,7 +65,7 @@ Position::Position(const Position& pos) { copy(pos); } -Position::Position(const std::string& fen) { +Position::Position(const string& fen) { from_fen(fen); } @@ -74,9 +74,9 @@ Position::Position(const std::string& fen) { /// string. This function is not very robust - make sure that input FENs are /// correct (this is assumed to be the responsibility of the GUI). -void Position::from_fen(const std::string& fen) { +void Position::from_fen(const string& fen) { - static const std::string pieceLetters = "KQRBNPkqrbnp"; + static const string pieceLetters = "KQRBNPkqrbnp"; static const Piece pieces[] = { WK, WQ, WR, WB, WN, WP, BK, BQ, BR, BB, BN, BP }; clear(); @@ -100,7 +100,7 @@ void Position::from_fen(const std::string& fen) { continue; } size_t idx = pieceLetters.find(fen[i]); - if (idx == std::string::npos) + if (idx == string::npos) { std::cout << "Error in FEN at character " << i << std::endl; return; @@ -190,7 +190,7 @@ void Position::from_fen(const std::string& fen) { i++; // En passant square - if ( i < fen.length() - 2 + if ( i <= fen.length() - 2 && (fen[i] >= 'a' && fen[i] <= 'h') && (fen[i+1] == '3' || fen[i+1] == '6')) st->epSquare = square_from_string(fen.substr(i, 2)); @@ -207,25 +207,24 @@ void Position::from_fen(const std::string& fen) { castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO; find_checkers(); - find_hidden_checks(); st->key = compute_key(); st->pawnKey = compute_pawn_key(); st->materialKey = compute_material_key(); st->mgValue = compute_value(); st->egValue = compute_value(); - npMaterial[WHITE] = compute_non_pawn_material(WHITE); - npMaterial[BLACK] = compute_non_pawn_material(BLACK); + st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); + st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); } /// Position::to_fen() converts the position object to a FEN string. This is /// probably only useful for debugging. -const std::string Position::to_fen() const { +const string Position::to_fen() const { - static const std::string pieceLetters = " PNBRQK pnbrqk"; - std::string fen; + static const string pieceLetters = " PNBRQK pnbrqk"; + string fen; int skip; for (Rank rank = RANK_8; rank >= RANK_1; rank--) @@ -275,7 +274,7 @@ const std::string Position::to_fen() const { void Position::print(Move m) const { - static const std::string pieceLetters = " PNBRQK PNBRQK ."; + static const string pieceLetters = " PNBRQK PNBRQK ."; // Check for reentrancy, as example when called from inside // MovePicker that is used also here in move_to_san() @@ -287,7 +286,7 @@ void Position::print(Move m) const { std::cout << std::endl; if (m != MOVE_NONE) { - std::string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : ""); + string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : ""); std::cout << "Move is: " << col << move_to_san(*this, m) << std::endl; } for (Rank rank = RANK_8; rank >= RANK_1; rank--) @@ -321,56 +320,64 @@ void Position::copy(const Position &pos) { } -/// Position:hidden_checks<>() returns a bitboard of all pinned (against the +/// Position:hidden_checkers<>() returns a bitboard of all pinned (against the /// king) pieces for the given color and for the given pinner type. Or, when -/// template parameter FindPinned is false, the pinned pieces of opposite color -/// that are, indeed, the pieces candidate for a discovery check. +/// template parameter FindPinned is false, the pieces of the given color +/// candidate for a discovery check against the enemy king. /// Note that checkersBB bitboard must be already updated. -template -Bitboard Position::hidden_checks(Color c, Square ksq, Bitboard& pinners) const { - Square s; - Bitboard sliders, result = EmptyBoardBB; +template +Bitboard Position::hidden_checkers(Color c) const { - if (Piece == ROOK) // Resolved at compile time - sliders = rooks_and_queens(FindPinned ? opposite_color(c) : c) & RookPseudoAttacks[ksq]; - else - sliders = bishops_and_queens(FindPinned ? opposite_color(c) : c) & BishopPseudoAttacks[ksq]; + Bitboard pinners, result = EmptyBoardBB; + + // Pinned pieces protect our king, dicovery checks attack + // the enemy king. + Square ksq = king_square(FindPinned ? c : opposite_color(c)); - if (sliders && (!FindPinned || (sliders & ~st->checkersBB))) + // Pinners are sliders, not checkers, that give check when + // candidate pinned is removed. + pinners = (rooks_and_queens(FindPinned ? opposite_color(c) : c) & RookPseudoAttacks[ksq]) + | (bishops_and_queens(FindPinned ? opposite_color(c) : c) & BishopPseudoAttacks[ksq]); + + if (FindPinned && pinners) + pinners &= ~st->checkersBB; + + while (pinners) { - // King blockers are candidate pinned pieces - Bitboard candidate_pinned = piece_attacks(ksq) & pieces_of_color(c); - - // Pinners are sliders, not checkers, that give check when - // candidate pinned are removed. - pinners = (FindPinned ? sliders & ~st->checkersBB : sliders); - - if (Piece == ROOK) - pinners &= rook_attacks_bb(ksq, occupied_squares() ^ candidate_pinned); - else - pinners &= bishop_attacks_bb(ksq, occupied_squares() ^ candidate_pinned); - - // Finally for each pinner find the corresponding pinned piece (if same color of king) - // or discovery checker (if opposite color) among the candidates. - Bitboard p = pinners; - while (p) - { - s = pop_1st_bit(&p); - result |= (squares_between(s, ksq) & candidate_pinned); - } - } - else - pinners = EmptyBoardBB; + Square s = pop_1st_bit(&pinners); + Bitboard b = squares_between(s, ksq) & occupied_squares(); + assert(b); + + if ( !(b & (b - 1)) // Only one bit set? + && (b & pieces_of_color(c))) // Is an our piece? + result |= b; + } return result; } +/// Position:pinned_pieces() returns a bitboard of all pinned (against the +/// king) pieces for the given color. + +Bitboard Position::pinned_pieces(Color c) const { + + return hidden_checkers(c); +} + + +/// Position:discovered_check_candidates() returns a bitboard containing all +/// pieces for the given side which are candidates for giving a discovered +/// check. + +Bitboard Position::discovered_check_candidates(Color c) const { + + return hidden_checkers(c); +} + /// Position::attacks_to() computes a bitboard containing all pieces which -/// attacks a given square. There are two versions of this function: One -/// which finds attackers of both colors, and one which only finds the -/// attackers for one side. +/// attacks a given square. Bitboard Position::attacks_to(Square s) const { @@ -446,50 +453,28 @@ void Position::find_checkers() { st->checkersBB = attacks_to(king_square(us), opposite_color(us)); } -/// Position:find_hidden_checks() computes the pinned, pinners and dcCandidates -/// bitboards. There are two versions of this function. One takes a color and -/// computes bitboards relative to that color only, the other computes both -/// colors. Bitboard checkersBB must be already updated. - -void Position::find_hidden_checks(Color us, unsigned int types) { - Bitboard p1, p2; - Color them = opposite_color(us); - Square ksq = king_square(them); - if (types & Pinned) - { - st->pinned[them] = hidden_checks(them, ksq, p1) | hidden_checks(them, ksq, p2); - st->pinners[them] = p1 | p2; - } - if (types & DcCandidates) - st->dcCandidates[us] = hidden_checks(us, ksq, p1) | hidden_checks(us, ksq, p2); -} +/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal -void Position::find_hidden_checks() { +bool Position::pl_move_is_legal(Move m) const { - for (Color c = WHITE; c <= BLACK; c++) - find_hidden_checks(c, Pinned | DcCandidates); + // If we're in check, all pseudo-legal moves are legal, because our + // check evasion generator only generates true legal moves. + return is_check() || pl_move_is_legal(m, pinned_pieces(side_to_move())); } - -/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal - -bool Position::pl_move_is_legal(Move m) const { +bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { assert(is_ok()); assert(move_is_ok(m)); - - // If we're in check, all pseudo-legal moves are legal, because our - // check evasion generator only generates true legal moves. - if (is_check()) - return true; + assert(pinned == pinned_pieces(side_to_move())); + assert(!is_check()); // Castling moves are checked for legality during move generation. if (move_is_castle(m)) return true; Color us = side_to_move(); - Color them = opposite_color(us); Square from = move_from(m); Square ksq = king_square(us); @@ -501,6 +486,7 @@ bool Position::pl_move_is_legal(Move m) const { // after the move is made if (move_is_ep(m)) { + Color them = opposite_color(us); Square to = move_to(m); Square capsq = make_square(square_file(to), square_rank(from)); Bitboard b = occupied_squares(); @@ -521,11 +507,12 @@ bool Position::pl_move_is_legal(Move m) const { // If the moving piece is a king, check whether the destination // square is attacked by the opponent. if (from == ksq) - return !(square_is_attacked(move_to(m), them)); + return !(square_is_attacked(move_to(m), opposite_color(us))); // A non-king move is legal if and only if it is not pinned or it // is moving along the ray towards or away from the king. - return ( !bit_is_set(pinned_pieces(us), from) + return ( !pinned + || !bit_is_set(pinned, from) || (direction_between_squares(from, ksq) == direction_between_squares(move_to(m), ksq))); } @@ -534,15 +521,21 @@ bool Position::pl_move_is_legal(Move m) const { bool Position::move_is_check(Move m) const { + Bitboard dc = discovered_check_candidates(side_to_move()); + return move_is_check(m, dc); +} + +bool Position::move_is_check(Move m, Bitboard dcCandidates) const { + assert(is_ok()); assert(move_is_ok(m)); + assert(dcCandidates == discovered_check_candidates(side_to_move())); Color us = side_to_move(); Color them = opposite_color(us); Square from = move_from(m); Square to = move_to(m); Square ksq = king_square(them); - Bitboard dcCandidates = discovered_check_candidates(us); assert(color_of_piece_on(from) == us); assert(piece_on(ksq) == piece_of_color_and_type(them, KING)); @@ -555,7 +548,8 @@ bool Position::move_is_check(Move m) const { if (bit_is_set(pawn_attacks(them, ksq), to)) // Normal check? return true; - if ( bit_is_set(dcCandidates, from) // Discovered check? + if ( dcCandidates // Discovered check? + && bit_is_set(dcCandidates, from) && (direction_between_squares(from, ksq) != direction_between_squares(to, ksq))) return true; @@ -594,22 +588,24 @@ bool Position::move_is_check(Move m) const { } return false; + // Test discovered check and normal check according to piece type case KNIGHT: - return bit_is_set(dcCandidates, from) // Discovered check? - || bit_is_set(piece_attacks(ksq), to); // Normal check? + return (dcCandidates && bit_is_set(dcCandidates, from)) + || bit_is_set(piece_attacks(ksq), to); case BISHOP: - return bit_is_set(dcCandidates, from) // Discovered check? - || bit_is_set(piece_attacks(ksq), to); // Normal check? + return (dcCandidates && bit_is_set(dcCandidates, from)) + || (direction_is_diagonal(ksq, to) && bit_is_set(piece_attacks(ksq), to)); case ROOK: - return bit_is_set(dcCandidates, from) // Discovered check? - || bit_is_set(piece_attacks(ksq), to); // Normal check? + return (dcCandidates && bit_is_set(dcCandidates, from)) + || (direction_is_straight(ksq, to) && bit_is_set(piece_attacks(ksq), to)); case QUEEN: // Discovered checks are impossible! assert(!bit_is_set(dcCandidates, from)); - return bit_is_set(piece_attacks(ksq), to); // Normal check? + return ( (direction_is_straight(ksq, to) && bit_is_set(piece_attacks(ksq), to)) + || (direction_is_diagonal(ksq, to) && bit_is_set(piece_attacks(ksq), to))); case KING: // Discovered check? @@ -649,20 +645,6 @@ bool Position::move_is_check(Move m) const { } -/// Position::move_is_capture() tests whether a move from the current -/// position is a capture. Move must not be MOVE_NONE. - -bool Position::move_is_capture(Move m) const { - - assert(m != MOVE_NONE); - - return ( !square_is_empty(move_to(m)) - && (color_of_piece_on(move_to(m)) != color_of_piece_on(move_from(m))) - ) - || move_is_ep(m); -} - - /// Position::update_checkers() udpates chekers info given the move. It is called /// in do_move() and is faster then find_checkers(). @@ -670,9 +652,22 @@ template inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square from, Square to, Bitboard dcCandidates) { - if (Piece != KING && bit_is_set(piece_attacks(ksq), to)) + const bool Bishop = (Piece == QUEEN || Piece == BISHOP); + const bool Rook = (Piece == QUEEN || Piece == ROOK); + const bool Slider = Bishop || Rook; + + // Direct checks + if ( ( (Bishop && bit_is_set(BishopPseudoAttacks[ksq], to)) + || (Rook && bit_is_set(RookPseudoAttacks[ksq], to))) + && bit_is_set(piece_attacks(ksq), to)) // slow, try to early skip + set_bit(pCheckersBB, to); + + else if ( Piece != KING + && !Slider + && bit_is_set(piece_attacks(ksq), to)) set_bit(pCheckersBB, to); + // Discovery checks if (Piece != QUEEN && bit_is_set(dcCandidates, from)) { if (Piece != ROOK) @@ -684,78 +679,32 @@ inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square } -/// Position::update_hidden_checks() udpates pinned, pinners and dcCandidates -/// bitboards incrementally, given the move. It is called in do_move and is -/// faster then find_hidden_checks(). - -void Position::update_hidden_checks(Square from, Square to) { - - Color us = sideToMove; - Color them = opposite_color(us); - Square ksq = king_square(opposite_color(us)); - - Bitboard moveSquares = EmptyBoardBB; - set_bit(&moveSquares, from); - set_bit(&moveSquares, to); - - // Our moving piece could have been a possible pinner or hidden checker behind a dcCandidates? - bool checkerMoved = (st->dcCandidates[us] | st->pinners[them]) && (moveSquares & sliders()); - - // If we are moving from/to an opponent king attack direction and we was a possible hidden checker - // or there exsist some possible hidden checker on that line then recalculate the position - // otherwise skip because our dcCandidates and opponent pinned pieces are not changed. - if ( (moveSquares & RookPseudoAttacks[ksq]) && (checkerMoved || (rooks_and_queens(us) & RookPseudoAttacks[ksq])) - || (moveSquares & BishopPseudoAttacks[ksq]) && (checkerMoved || (bishops_and_queens(us) & BishopPseudoAttacks[ksq]))) - find_hidden_checks(us, Pinned | DcCandidates); - - ksq = king_square(us); - - if (ksq == to) - { - find_hidden_checks(them, Pinned | DcCandidates); - return; - } - - // It is possible that we have captured an opponent hidden checker? - Bitboard checkerCaptured = st->capture && (st->dcCandidates[them] || bit_is_set(st->pinners[us], to)); - - // If we are moving from/to an our king attack direction and there was/is some possible - // opponent hidden checker then calculate the position otherwise skip because opponent - // dcCandidates and our pinned pieces are not changed. - if ( (moveSquares & RookPseudoAttacks[ksq]) && (checkerCaptured || (rooks_and_queens(them) & RookPseudoAttacks[ksq])) - || (moveSquares & BishopPseudoAttacks[ksq]) && (checkerCaptured || (bishops_and_queens(them) & BishopPseudoAttacks[ksq]))) - { - - // If we don't have opponent dc candidates and we are moving in the - // attack line then won't be dc candidates also after the move. - if ( st->dcCandidates[them] - || bit_is_set(RookPseudoAttacks[ksq], from) - || bit_is_set(BishopPseudoAttacks[ksq], from)) - - find_hidden_checks(them, Pinned | DcCandidates); - else - find_hidden_checks(them, Pinned); - } -} - - /// Position::do_move() makes a move, and saves all information necessary /// to a StateInfo object. The move is assumed to be legal. /// Pseudo-legal moves should be filtered out before this function is called. void Position::do_move(Move m, StateInfo& newSt) { + do_move(m, newSt, discovered_check_candidates(side_to_move())); +} + +void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) { + assert(is_ok()); assert(move_is_ok(m)); - // Get now the current (before to move) dc candidates that we will use - // in update_checkers(). - Bitboard oldDcCandidates = discovered_check_candidates(side_to_move()); + // Copy some fields of old state to our new StateInfo object except the + // ones which are recalculated from scratch anyway, then switch our state + // pointer to point to the new, ready to be updated, state. + struct ReducedStateInfo { + Key key, pawnKey, materialKey; + int castleRights, rule50; + Square epSquare; + Value mgValue, egValue; + Value npMaterial[2]; + }; - // Copy some fields of old state to our new StateInfo object (except the - // captured piece, which is taken care of later) and switch state pointer - // to point to the new, ready to be updated, state. - newSt = *st; + memcpy(&newSt, st, sizeof(ReducedStateInfo)); newSt.capture = NO_PIECE_TYPE; newSt.previous = st; st = &newSt; @@ -789,15 +738,14 @@ void Position::do_move(Move m, StateInfo& newSt) { st->capture = type_of_piece_on(to); if (st->capture) - do_capture_move(m, st->capture, them, to); + do_capture_move(st->capture, them, to); // Move the piece - clear_bit(&(byColorBB[us]), from); - clear_bit(&(byTypeBB[piece]), from); - clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares - set_bit(&(byColorBB[us]), to); - set_bit(&(byTypeBB[piece]), to); - set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares + Bitboard move_bb = make_move_bb(from, to); + do_move_bb(&(byColorBB[us]), move_bb); + do_move_bb(&(byTypeBB[piece]), move_bb); + do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares + board[to] = board[from]; board[from] = EMPTY; @@ -857,16 +805,14 @@ void Position::do_move(Move m, StateInfo& newSt) { Square ksq = king_square(them); switch (piece) { - case PAWN: update_checkers(&st->checkersBB, ksq, from, to, oldDcCandidates); break; - case KNIGHT: update_checkers(&st->checkersBB, ksq, from, to, oldDcCandidates); break; - case BISHOP: update_checkers(&st->checkersBB, ksq, from, to, oldDcCandidates); break; - case ROOK: update_checkers(&st->checkersBB, ksq, from, to, oldDcCandidates); break; - case QUEEN: update_checkers(&st->checkersBB, ksq, from, to, oldDcCandidates); break; - case KING: update_checkers(&st->checkersBB, ksq, from, to, oldDcCandidates); break; + case PAWN: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; + case KNIGHT: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; + case BISHOP: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; + case ROOK: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; + case QUEEN: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; + case KING: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; default: assert(false); break; } - - update_hidden_checks(from, to); } // Finish @@ -884,13 +830,14 @@ void Position::do_move(Move m, StateInfo& newSt) { /// Position::do_capture_move() is a private method used to update captured /// piece info. It is called from the main Position::do_move function. -void Position::do_capture_move(Move m, PieceType capture, Color them, Square to) { +void Position::do_capture_move(PieceType capture, Color them, Square to) { assert(capture != KING); // Remove captured piece clear_bit(&(byColorBB[them]), to); clear_bit(&(byTypeBB[capture]), to); + clear_bit(&(byTypeBB[0]), to); // Update hash key st->key ^= zobrist[them][capture][to]; @@ -903,11 +850,9 @@ void Position::do_capture_move(Move m, PieceType capture, Color them, Square to) st->mgValue -= pst(them, capture, to); st->egValue -= pst(them, capture, to); - assert(!move_promotion(m) || capture != PAWN); - // Update material if (capture != PAWN) - npMaterial[them] -= piece_value_midgame(capture); + st->npMaterial[them] -= piece_value_midgame(capture); // Update material hash key st->materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]]; @@ -1018,9 +963,6 @@ void Position::do_castle_move(Move m) { // Update checkers BB st->checkersBB = attacks_to(king_square(them), us); - - // Update hidden checks - find_hidden_checks(); } @@ -1049,7 +991,7 @@ void Position::do_promotion_move(Move m) { st->capture = type_of_piece_on(to); if (st->capture) - do_capture_move(m, st->capture, them, to); + do_capture_move(st->capture, them, to); // Remove pawn clear_bit(&(byColorBB[us]), from); @@ -1092,7 +1034,7 @@ void Position::do_promotion_move(Move m) { st->egValue += pst(us, promotion, to); // Update material - npMaterial[us] += piece_value_midgame(promotion); + st->npMaterial[us] += piece_value_midgame(promotion); // Clear the en passant square if (st->epSquare != SQ_NONE) @@ -1111,9 +1053,6 @@ void Position::do_promotion_move(Move m) { // Update checkers BB st->checkersBB = attacks_to(king_square(them), us); - - // Update hidden checks - find_hidden_checks(); } @@ -1196,9 +1135,6 @@ void Position::do_ep_move(Move m) { // Update checkers BB st->checkersBB = attacks_to(king_square(them), us); - - // Update hidden checks - find_hidden_checks(); } @@ -1234,17 +1170,13 @@ void Position::undo_move(Move m) { assert(color_of_piece_on(to) == us); // Put the piece back at the source square + Bitboard move_bb = make_move_bb(to, from); piece = type_of_piece_on(to); - set_bit(&(byColorBB[us]), from); - set_bit(&(byTypeBB[piece]), from); - set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares + do_move_bb(&(byColorBB[us]), move_bb); + do_move_bb(&(byTypeBB[piece]), move_bb); + do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares board[from] = piece_of_color_and_type(us, piece); - // Clear the destination square - clear_bit(&(byColorBB[us]), to); - clear_bit(&(byTypeBB[piece]), to); - clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - // If the moving piece was a king, update the king square if (piece == KING) kingSquare[us] = from; @@ -1257,16 +1189,12 @@ void Position::undo_move(Move m) { { assert(st->capture != KING); - // Replace the captured piece + // Restore the captured piece set_bit(&(byColorBB[them]), to); set_bit(&(byTypeBB[st->capture]), to); set_bit(&(byTypeBB[0]), to); board[to] = piece_of_color_and_type(them, st->capture); - // Update material - if (st->capture != PAWN) - npMaterial[them] += piece_value_midgame(st->capture); - // Update piece list pieceList[them][st->capture][pieceCount[them][st->capture]] = to; index[to] = pieceCount[them][st->capture]; @@ -1277,7 +1205,7 @@ void Position::undo_move(Move m) { board[to] = EMPTY; } - // Finally point out state pointer back to the previous state + // Finally point our state pointer back to the previous state st = st->previous; assert(is_ok()); @@ -1388,9 +1316,6 @@ void Position::undo_promotion_move(Move m) { set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares board[from] = piece_of_color_and_type(us, PAWN); - // Update material - npMaterial[us] -= piece_value_midgame(promotion); - // Update piece list pieceList[us][PAWN][pieceCount[us][PAWN]] = from; index[from] = pieceCount[us][PAWN]; @@ -1412,11 +1337,6 @@ void Position::undo_promotion_move(Move m) { set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares board[to] = piece_of_color_and_type(them, st->capture); - // Update material. Because the move is a promotion move, we know - // that the captured piece cannot be a pawn. - assert(st->capture != PAWN); - npMaterial[them] += piece_value_midgame(st->capture); - // Update piece list pieceList[them][st->capture][pieceCount[them][st->capture]] = to; index[to] = pieceCount[them][st->capture]; @@ -1469,13 +1389,13 @@ void Position::undo_ep_move(Move m) { set_bit(&(byTypeBB[0]), from); board[from] = piece_of_color_and_type(us, PAWN); - // Update piece list: + // Update piece list pieceList[us][PAWN][index[to]] = from; index[from] = index[to]; pieceList[them][PAWN][pieceCount[them][PAWN]] = capsq; index[capsq] = pieceCount[them][PAWN]; - // Update piece count: + // Update piece count pieceCount[them][PAWN]++; } @@ -1483,18 +1403,21 @@ void Position::undo_ep_move(Move m) { /// Position::do_null_move makes() a "null move": It switches the side to move /// and updates the hash key without executing any move on the board. -void Position::do_null_move(StateInfo& newSt) { +void Position::do_null_move(StateInfo& backupSt) { assert(is_ok()); assert(!is_check()); // Back up the information necessary to undo the null move to the supplied - // StateInfo object. In the case of a null move, the only thing we need to - // remember is the last move made and the en passant square. - newSt.lastMove = st->lastMove; - newSt.epSquare = st->epSquare; - newSt.previous = st->previous; - st->previous = &newSt; + // StateInfo object. + // Note that differently from normal case here backupSt is actually used as + // a backup storage not as a new state to be used. + backupSt.epSquare = st->epSquare; + backupSt.key = st->key; + backupSt.mgValue = st->mgValue; + backupSt.egValue = st->egValue; + backupSt.previous = st->previous; + st->previous = &backupSt; // Save the current key to the history[] array, in order to be able to // detect repetition draws. @@ -1524,22 +1447,17 @@ void Position::undo_null_move() { assert(is_ok()); assert(!is_check()); - // Restore information from the our StateInfo object - st->lastMove = st->previous->lastMove; + // Restore information from the our backup StateInfo object st->epSquare = st->previous->epSquare; + st->key = st->previous->key; + st->mgValue = st->previous->mgValue; + st->egValue = st->previous->egValue; st->previous = st->previous->previous; - if (st->epSquare != SQ_NONE) - st->key ^= zobEp[st->epSquare]; - // Update the necessary information sideToMove = opposite_color(sideToMove); st->rule50--; gamePly--; - st->key ^= zobSideToMove; - - st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; assert(is_ok()); } @@ -1574,7 +1492,7 @@ int Position::see(Square from, Square to) const { 0, 0 }; - Bitboard attackers, occ, b; + Bitboard attackers, stmAttackers, occ, b; assert(square_is_ok(from) || from == SQ_NONE); assert(square_is_ok(to)); @@ -1583,11 +1501,6 @@ int Position::see(Square from, Square to) const { Color us = (from != SQ_NONE ? color_of_piece_on(from) : opposite_color(color_of_piece_on(to))); Color them = opposite_color(us); - // Initialize pinned and pinners bitboards - Bitboard pinned[2], pinners[2]; - pinned[us] = pinned_pieces(us, pinners[us]); - pinned[them] = pinned_pieces(them, pinners[them]); - // Initialize pieces Piece piece = piece_on(from); Piece capture = piece_on(to); @@ -1603,7 +1516,6 @@ int Position::see(Square from, Square to) const { Square capQq = (side_to_move() == WHITE)? (to - DELTA_N) : (to - DELTA_S); capture = piece_on(capQq); - assert(type_of_piece_on(capQq) == PAWN); // Remove the captured pawn @@ -1620,17 +1532,6 @@ int Position::see(Square from, Square to) const { | (pawn_attacks(WHITE, to) & pawns(BLACK)) | (pawn_attacks(BLACK, to) & pawns(WHITE)); - // Remove our pinned pieces from attacks if the captured piece is not - // a pinner, otherwise we could remove a valid "capture the pinner" attack. - if (pinned[us] != EmptyBoardBB && !bit_is_set(pinners[us], to)) - attackers &= ~pinned[us]; - - // Remove opponent pinned pieces from attacks if the moving piece is not - // a pinner, otherwise we could remove a piece that is no more pinned - // due to our pinner piece is moving away. - if (pinned[them] != EmptyBoardBB && !bit_is_set(pinners[them], from)) - attackers &= ~pinned[them]; - if (from != SQ_NONE) break; @@ -1649,7 +1550,8 @@ int Position::see(Square from, Square to) const { } // If the opponent has no attackers we are finished - if ((attackers & pieces_of_color(them)) == EmptyBoardBB) + stmAttackers = attackers & pieces_of_color(them); + if (!stmAttackers) return seeValues[capture]; attackers &= occ; // Remove the moving piece @@ -1671,13 +1573,13 @@ int Position::see(Square from, Square to) const { // Locate the least valuable attacker for the side to move. The loop // below looks like it is potentially infinite, but it isn't. We know // that the side to move still has at least one attacker left. - for (pt = PAWN; !(attackers & pieces_of_color_and_type(c, pt)); pt++) + for (pt = PAWN; !(stmAttackers & pieces_of_type(pt)); pt++) assert(pt < KING); // Remove the attacker we just found from the 'attackers' bitboard, // and scan for new X-ray attacks behind the attacker. - b = attackers & pieces_of_color_and_type(c, pt); - occ ^= (b & -b); + b = stmAttackers & pieces_of_type(pt); + occ ^= (b & (~b + 1)); attackers |= (rook_attacks_bb(to, occ) & rooks_and_queens()) | (bishop_attacks_bb(to, occ) & bishops_and_queens()); @@ -1692,21 +1594,16 @@ int Position::see(Square from, Square to) const { // before beginning the next iteration lastCapturingPieceValue = seeValues[pt]; c = opposite_color(c); - - // Remove pinned pieces from attackers - if ( pinned[c] != EmptyBoardBB - && !bit_is_set(pinners[c], to) - && !(pinners[c] & attackers)) - attackers &= ~pinned[c]; + stmAttackers = attackers & pieces_of_color(c); // Stop after a king capture - if (pt == KING && (attackers & pieces_of_color(c))) + if (pt == KING && stmAttackers) { assert(n < 32); swapList[n++] = 100; break; } - } while (attackers & pieces_of_color(c)); + } 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 @@ -1919,15 +1816,14 @@ Value Position::compute_value() const { Value Position::compute_non_pawn_material(Color c) const { Value result = Value(0); - Square s; for (PieceType pt = KNIGHT; pt <= QUEEN; pt++) { Bitboard b = pieces_of_color_and_type(c, pt); - while(b) + while (b) { - s = pop_1st_bit(&b); - assert(piece_on(s) == piece_of_color_and_type(c, pt)); + assert(piece_on(first_1(b)) == piece_of_color_and_type(c, pt)); + pop_1st_bit(&b); result += piece_value_midgame(pt); } } @@ -1935,21 +1831,6 @@ Value Position::compute_non_pawn_material(Color c) const { } -/// Position::is_mate() returns true or false depending on whether the -/// side to move is checkmated. Note that this function is currently very -/// slow, and shouldn't be used frequently inside the search. - -bool Position::is_mate() const { - - if (is_check()) - { - MovePicker mp = MovePicker(*this, false, MOVE_NONE, EmptySearchStack, Depth(0)); - return mp.get_next_move() == MOVE_NONE; - } - return false; -} - - /// Position::is_draw() tests whether the position is drawn by material, /// repetition, or the 50 moves rule. It does not detect stalemates, this /// must be done by the search. @@ -1974,21 +1855,25 @@ bool Position::is_draw() const { } +/// Position::is_mate() returns true or false depending on whether the +/// side to move is checkmated. + +bool Position::is_mate() const { + + MoveStack moves[256]; + + return is_check() && !generate_evasions(*this, moves, pinned_pieces(sideToMove)); +} + + /// Position::has_mate_threat() tests whether a given color has a mate in one -/// from the current position. This function is quite slow, but it doesn't -/// matter, because it is currently only called from PV nodes, which are rare. +/// from the current position. bool Position::has_mate_threat(Color c) { StateInfo st1, st2; Color stm = side_to_move(); - // The following lines are useless and silly, but prevents gcc from - // emitting a stupid warning stating that u1.lastMove and u1.epSquare might - // be used uninitialized. - st1.lastMove = st->lastMove; - st1.epSquare = st->epSquare; - if (is_check()) return false; @@ -1999,18 +1884,26 @@ bool Position::has_mate_threat(Color c) { MoveStack mlist[120]; int count; bool result = false; + Bitboard dc = discovered_check_candidates(sideToMove); + Bitboard pinned = pinned_pieces(sideToMove); - // Generate legal moves - count = generate_legal_moves(*this, mlist); + // Generate pseudo-legal non-capture and capture check moves + count = generate_non_capture_checks(*this, mlist, dc); + count += generate_captures(*this, mlist + count); // Loop through the moves, and see if one of them is mate for (int i = 0; i < count; i++) { - do_move(mlist[i].move, st2); + Move move = mlist[i].move; + + if (!pl_move_is_legal(move, pinned)) + continue; + + do_move(move, st2); if (is_mate()) result = true; - undo_move(mlist[i].move); + undo_move(move); } // Undo null move, if necessary @@ -2131,8 +2024,8 @@ void Position::flipped_copy(const Position &pos) { st->egValue = compute_value(); // Material - npMaterial[WHITE] = compute_non_pawn_material(WHITE); - npMaterial[BLACK] = compute_non_pawn_material(BLACK); + st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); + st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); assert(is_ok()); } @@ -2268,10 +2161,10 @@ bool Position::is_ok(int* failedStep) const { if (failedStep) (*failedStep)++; if (debugNonPawnMaterial) { - if (npMaterial[WHITE] != compute_non_pawn_material(WHITE)) + if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE)) return false; - if (npMaterial[BLACK] != compute_non_pawn_material(BLACK)) + if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK)) return false; }