X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovegen.cpp;h=be9309d127368192e299e979589f79237b5a784c;hp=abcafc00b5b0c6379f475eef5fd34d0c386e3609;hb=9fbe9af0a09bd88b96955474f294a945b1bb6773;hpb=f56af8e84db25c0d26fe762fbe171ec5518177bb diff --git a/src/movegen.cpp b/src/movegen.cpp index abcafc00..be9309d1 100644 --- a/src/movegen.cpp +++ b/src/movegen.cpp @@ -1,17 +1,18 @@ /* - Glaurung, a UCI chess playing engine. - Copyright (C) 2004-2008 Tord Romstad + 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 - Glaurung is free software: you can redistribute it and/or modify + Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. - - Glaurung is distributed in the hope that it will be useful, + + Stockfish is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. - + You should have received a copy of the GNU General Public License along with this program. If not, see . */ @@ -25,1214 +26,926 @@ #include "movegen.h" +// Simple macro to wrap a very common while loop, no facny, no flexibility, +// hardcoded list name 'mlist' and from square 'from'. +#define SERIALIZE_MOVES(b) while (b) (*mlist++).move = make_move(from, pop_1st_bit(&b)) //// //// Local definitions //// namespace { - - int generate_white_pawn_captures(const Position &pos, MoveStack *mlist); - int generate_black_pawn_captures(const Position &pos, MoveStack *mlist); - int generate_white_pawn_noncaptures(const Position &pos, MoveStack *mlist); - int generate_black_pawn_noncaptures(const Position &pos, MoveStack *mlist); - int generate_knight_moves(const Position &pos, MoveStack *mlist, - Color side, Bitboard target); - int generate_bishop_moves(const Position &pos, MoveStack *mlist, - Color side, Bitboard target); - int generate_rook_moves(const Position &pos, MoveStack *mlist, - Color side, Bitboard target); - int generate_queen_moves(const Position &pos, MoveStack *mlist, - Color side, Bitboard target); - int generate_king_moves(const Position &pos, MoveStack *mlist, - Square from, Bitboard target); - int generate_castle_moves(const Position &pos, MoveStack *mlist, Color us); - -} + enum CastlingSide { + KING_SIDE, + QUEEN_SIDE + }; -//// -//// Functions -//// + enum MoveType { + CAPTURE, + NON_CAPTURE + }; + // Functions + bool castling_is_check(const Position&, CastlingSide); -/// generate_captures generates() all pseudo-legal captures and queen -/// promotions. The return value is the number of moves generated. + // Helper templates + template + MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist); -int generate_captures(const Position &pos, MoveStack *mlist) { - Color us = pos.side_to_move(); - Bitboard target = pos.pieces_of_color(opposite_color(us)); - int n = 0; + template + MoveStack* generate_pawn_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*); - assert(pos.is_ok()); - assert(!pos.is_check()); + template + MoveStack* generate_pawn_captures(const Position& pos, MoveStack* mlist); - if(us == WHITE) - n += generate_white_pawn_captures(pos, mlist); - else - n += generate_black_pawn_captures(pos, mlist); - n += generate_knight_moves(pos, mlist+n, us, target); - n += generate_bishop_moves(pos, mlist+n, us, target); - n += generate_rook_moves(pos, mlist+n, us, target); - n += generate_queen_moves(pos, mlist+n, us, target); - n += generate_king_moves(pos, mlist+n, pos.king_square(us), target); + template + MoveStack* generate_pawn_captures_diagonal(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces); - return n; -} + template + MoveStack* generate_pawn_noncaptures(const Position& pos, MoveStack* mlist); + template + MoveStack* generate_pawn_checks(const Position&, Bitboard, Square, MoveStack*); -/// generate_noncaptures() generates all pseudo-legal non-captures and -/// underpromotions. The return value is the number of moves generated. + template + inline Bitboard move_pawns(Bitboard p) { -int generate_noncaptures(const Position &pos, MoveStack *mlist) { - Color us = pos.side_to_move(); - Bitboard target = pos.empty_squares(); - int n = 0; + if (Direction == DELTA_N) + return Us == WHITE ? p << 8 : p >> 8; + else if (Direction == DELTA_NE) + return Us == WHITE ? p << 9 : p >> 7; + else if (Direction == DELTA_NW) + return Us == WHITE ? p << 7 : p >> 9; + else + return p; + } - assert(pos.is_ok()); - assert(!pos.is_check()); + // Template generate_piece_checks() with specializations + template + MoveStack* generate_piece_checks(const Position&, MoveStack*, Color, Bitboard, Square); - if(us == WHITE) - n += generate_white_pawn_noncaptures(pos, mlist); - else - n += generate_black_pawn_noncaptures(pos, mlist); - n += generate_knight_moves(pos, mlist+n, us, target); - n += generate_bishop_moves(pos, mlist+n, us, target); - n += generate_rook_moves(pos, mlist+n, us, target); - n += generate_queen_moves(pos, mlist+n, us, target); - n += generate_king_moves(pos, mlist+n, pos.king_square(us), target); - n += generate_castle_moves(pos, mlist+n, us); + template<> + inline MoveStack* generate_piece_checks(const Position& p, MoveStack* m, Color us, Bitboard dc, Square ksq) { - return n; -} + return (us == WHITE ? generate_pawn_checks(p, dc, ksq, m) + : generate_pawn_checks(p, dc, ksq, m)); + } + // Template generate_piece_moves() with specializations and overloads + template + MoveStack* generate_piece_moves(const Position&, MoveStack*, Color us, Bitboard); -/// generate_checks() generates all pseudo-legal non-capturing, non-promoting -/// checks, except castling moves (will add this later). It returns the -/// number of generated moves. + template<> + MoveStack* generate_piece_moves(const Position&, MoveStack*, Color, Bitboard); -int generate_checks(const Position &pos, MoveStack *mlist, Bitboard dc) { - Color us, them; - Square ksq, from, to; - Bitboard empty, checkSqs, b1, b2, b3; - int n = 0; + template + inline MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us) { - assert(pos.is_ok()); - assert(!pos.is_check()); + assert(Piece == PAWN); - us = pos.side_to_move(); - them = opposite_color(us); + if (Type == CAPTURE) + return (us == WHITE ? generate_pawn_captures(p, m) + : generate_pawn_captures(p, m)); + else + return (us == WHITE ? generate_pawn_noncaptures(p, m) + : generate_pawn_noncaptures(p, m)); + } - ksq = pos.king_square(them); - assert(pos.piece_on(ksq) == king_of_color(them)); + template + MoveStack* generate_piece_moves(const Position&, MoveStack*, Color us, Bitboard, Bitboard); - dc = pos.discovered_check_candidates(us); - empty = pos.empty_squares(); - - // Pawn moves. This is somewhat messy, and we use separate code for white - // and black, because we can't shift by negative numbers in C/C++. :-( + template<> + inline MoveStack* generate_piece_moves(const Position& p, MoveStack* m, + Color us, Bitboard t, Bitboard pnd) { + if (us == WHITE) + return generate_pawn_blocking_evasions(p, pnd, t, m); + else + return generate_pawn_blocking_evasions(p, pnd, t, m); + } +} - if(us == WHITE) { - // Pawn moves which give discovered check. This is possible only if the - // pawn is not on the same file as the enemy king, because we don't - // generate captures. - // Find all friendly pawns not on the enemy king's file: - b1 = pos.pawns(us) & ~file_bb(ksq); +//// +//// Functions +//// - // Discovered checks, single pawn pushes: - b2 = b3 = ((b1 & dc) << 8) & ~Rank8BB & empty; - while(b3) { - to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - DELTA_N, to); - } - // Discovered checks, double pawn pushes: - b3 = ((b2 & Rank3BB) << 8) & empty; - while(b3) { - to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to); - } +/// generate_captures generates() all pseudo-legal captures and queen +/// promotions. The return value is the number of moves generated. - // Direct checks. These are possible only for pawns on neighboring files - // of the enemy king: +int generate_captures(const Position& pos, MoveStack* mlist) { - b1 &= (~dc & neighboring_files_bb(ksq)); + assert(pos.is_ok()); + assert(!pos.is_check()); - // Direct checks, single pawn pushes: - b2 = (b1 << 8) & empty; - b3 = b2 & pos.black_pawn_attacks(ksq); - while(b3) { - to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - DELTA_N, to); - } + Color us = pos.side_to_move(); + Bitboard target = pos.pieces_of_color(opposite_color(us)); + MoveStack* mlist_start = mlist; + + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us); + mlist = generate_piece_moves(pos, mlist, us, target); + return int(mlist - mlist_start); +} - // Direct checks, double pawn pushes: - b3 = ((b2 & Rank3BB) << 8) & empty & pos.black_pawn_attacks(ksq); - while(b3) { - to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to); - } - } - else { // (us == BLACK) - // Pawn moves which give discovered check. This is possible only if the - // pawn is not on the same file as the enemy king, because we don't - // generate captures. +/// generate_noncaptures() generates all pseudo-legal non-captures and +/// underpromotions. The return value is the number of moves generated. - // Find all friendly pawns not on the enemy king's file: - b1 = pos.pawns(us) & ~file_bb(ksq); +int generate_noncaptures(const Position& pos, MoveStack* mlist) { - // Discovered checks, single pawn pushes: - b2 = b3 = ((b1 & dc) >> 8) & ~Rank1BB & empty; - while(b3) { - to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - DELTA_S, to); - } + assert(pos.is_ok()); + assert(!pos.is_check()); - // Discovered checks, double pawn pushes: - b3 = ((b2 & Rank6BB) >> 8) & empty; - while(b3) { - to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to); - } + Color us = pos.side_to_move(); + Bitboard target = pos.empty_squares(); + MoveStack* mlist_start = mlist; + + mlist = generate_piece_moves(pos, mlist, us); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_castle_moves(pos, mlist); + mlist = generate_castle_moves(pos, mlist); + return int(mlist - mlist_start); +} - // Direct checks. These are possible only for pawns on neighboring files - // of the enemy king: - b1 &= (~dc & neighboring_files_bb(ksq)); +/// generate_non_capture_checks() generates all pseudo-legal non-capturing, +/// non-promoting checks. It returns the number of generated moves. - // Direct checks, single pawn pushes: - b2 = (b1 >> 8) & empty; - b3 = b2 & pos.white_pawn_attacks(ksq); - while(b3) { - to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - DELTA_S, to); - } +int generate_non_capture_checks(const Position& pos, MoveStack* mlist, Bitboard dc) { - // Direct checks, double pawn pushes: - b3 = ((b2 & Rank6BB) >> 8) & empty & pos.black_pawn_attacks(ksq); - while(b3) { - to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to); - } - } + assert(pos.is_ok()); + assert(!pos.is_check()); - // Knight moves - b1 = pos.knights(us); - if(b1) { - // Discovered knight checks: - b2 = b1 & dc; - while(b2) { - from = pop_1st_bit(&b2); - b3 = pos.knight_attacks(from) & empty; - while(b3) { - to = pop_1st_bit(&b3); - mlist[n++].move = make_move(from, to); - } - } - - // Direct knight checks: - b2 = b1 & ~dc; - checkSqs = pos.knight_attacks(ksq) & empty; - while(b2) { - from = pop_1st_bit(&b2); - b3 = pos.knight_attacks(from) & checkSqs; - while(b3) { - to = pop_1st_bit(&b3); - mlist[n++].move = make_move(from, to); - } - } - } + Color us = pos.side_to_move(); + Square ksq = pos.king_square(opposite_color(us)); + MoveStack* mlist_start = mlist; + + assert(pos.piece_on(ksq) == piece_of_color_and_type(opposite_color(us), KING)); + + // Pieces moves + mlist = generate_piece_checks(pos, mlist, us, dc, ksq); + mlist = generate_piece_checks(pos, mlist, us, dc, ksq); + mlist = generate_piece_checks(pos, mlist, us, dc, ksq); + mlist = generate_piece_checks(pos, mlist, us, dc, ksq); + mlist = generate_piece_checks(pos, mlist, us, dc, ksq); + mlist = generate_piece_checks(pos, mlist, us, dc, ksq); + + // Castling moves that give check. Very rare but nice to have! + if ( pos.can_castle_queenside(us) + && (square_rank(ksq) == square_rank(pos.king_square(us)) || square_file(ksq) == FILE_D) + && castling_is_check(pos, QUEEN_SIDE)) + mlist = generate_castle_moves(pos, mlist); + + if ( pos.can_castle_kingside(us) + && (square_rank(ksq) == square_rank(pos.king_square(us)) || square_file(ksq) == FILE_F) + && castling_is_check(pos, KING_SIDE)) + mlist = generate_castle_moves(pos, mlist); + + return int(mlist - mlist_start); +} - // Bishop moves - b1 = pos.bishops(us); - if(b1) { - // Discovered bishop checks: - b2 = b1 & dc; - while(b2) { - from = pop_1st_bit(&b2); - b3 = pos.bishop_attacks(from) & empty; - while(b3) { - to = pop_1st_bit(&b3); - mlist[n++].move = make_move(from, to); - } - } - - // Direct bishop checks: - b2 = b1 & ~dc; - checkSqs = pos.bishop_attacks(ksq) & empty; - while(b2) { - from = pop_1st_bit(&b2); - b3 = pos.bishop_attacks(from) & checkSqs; - while(b3) { - to = pop_1st_bit(&b3); - mlist[n++].move = make_move(from, to); - } - } - } - // Rook moves - b1 = pos.rooks(us); - if(b1) { - // Discovered rook checks: - b2 = b1 & dc; - while(b2) { - from = pop_1st_bit(&b2); - b3 = pos.rook_attacks(from) & empty; - while(b3) { - to = pop_1st_bit(&b3); - mlist[n++].move = make_move(from, to); - } - } - - // Direct rook checks: - b2 = b1 & ~dc; - checkSqs = pos.rook_attacks(ksq) & empty; - while(b2) { - from = pop_1st_bit(&b2); - b3 = pos.rook_attacks(from) & checkSqs; - while(b3) { - to = pop_1st_bit(&b3); - mlist[n++].move = make_move(from, to); - } - } - } +/// generate_evasions() generates all check evasions when the side to move is +/// in check. Unlike the other move generation functions, this one generates +/// only legal moves. It returns the number of generated moves. - // Queen moves - b1 = pos.queens(us); - if(b1) { - // Discovered queen checks are impossible! - - // Direct queen checks: - checkSqs = pos.queen_attacks(ksq) & empty; - while(b1) { - from = pop_1st_bit(&b1); - b2 = pos.queen_attacks(from) & checkSqs; - while(b2) { - to = pop_1st_bit(&b2); - mlist[n++].move = make_move(from, to); - } - } - } +int generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pinned) { - // King moves - from = pos.king_square(us); - if(bit_is_set(dc, from)) { - b1 = pos.king_attacks(from) & empty & ~QueenPseudoAttacks[ksq]; - while(b1) { - to = pop_1st_bit(&b1); - mlist[n++].move = make_move(from, to); - } - } + assert(pos.is_ok()); + assert(pos.is_check()); - // TODO: Castling moves! - - return n; -} + Square from, to; + Color us = pos.side_to_move(); + Color them = opposite_color(us); + Square ksq = pos.king_square(us); + MoveStack* mlist_start = mlist; + assert(pos.piece_on(ksq) == piece_of_color_and_type(us, KING)); -/// generate_evasions() generates all check evasions when the side to move is -/// in check. Unlike the other move generation functions, this one generates -/// only legal moves. It returns the number of generated moves. This -/// function is very ugly, and needs cleaning up some time later. FIXME + // The bitboard of occupied pieces without our king + Bitboard b_noKing = pos.occupied_squares(); + clear_bit(&b_noKing, ksq); -int generate_evasions(const Position &pos, MoveStack *mlist) { - Color us, them; + // Find squares attacked by slider checkers, we will + // remove them from king evasions set so to avoid a couple + // of cycles in the slow king evasions legality check loop + // and to be able to use square_is_attacked(). Bitboard checkers = pos.checkers(); - Bitboard pinned, b1, b2; - Square ksq, from, to; - int n = 0; - - assert(pos.is_ok()); - assert(pos.is_check()); + Bitboard checkersAttacks = EmptyBoardBB; + Bitboard b = checkers & (pos.queens() | pos.bishops()); + while (b) + { + from = pop_1st_bit(&b); + checkersAttacks |= bishop_attacks_bb(from, b_noKing); + } - us = pos.side_to_move(); - them = opposite_color(us); - - ksq = pos.king_square(us); - assert(pos.piece_on(ksq) == king_of_color(us)); - - // Generate evasions for king: - b1 = pos.king_attacks(ksq) & ~pos.pieces_of_color(us); - b2 = pos.occupied_squares(); - clear_bit(&b2, ksq); - while(b1) { - to = pop_1st_bit(&b1); - - // Make sure to is not attacked by the other side. This is a bit ugly, - // because we can't use Position::square_is_attacked. Instead we use - // the low-level bishop_attacks_bb and rook_attacks_bb with the bitboard - // b2 (the occupied squares with the king removed) in order to test whether - // the king will remain in check on the destination square. - if(((pos.pawn_attacks(us, to) & pos.pawns(them)) == EmptyBoardBB) && - ((pos.knight_attacks(to) & pos.knights(them)) == EmptyBoardBB) && - ((pos.king_attacks(to) & pos.kings(them)) == EmptyBoardBB) && - ((bishop_attacks_bb(to, b2) & pos.bishops_and_queens(them)) - == EmptyBoardBB) && - ((rook_attacks_bb(to, b2) & pos.rooks_and_queens(them)) == EmptyBoardBB)) - mlist[n++].move = make_move(ksq, to); + b = checkers & (pos.queens() | pos.rooks()); + while (b) + { + from = pop_1st_bit(&b); + checkersAttacks |= rook_attacks_bb(from, b_noKing); } + // Generate evasions for king + Bitboard b1 = pos.piece_attacks(ksq) & ~pos.pieces_of_color(us) & ~checkersAttacks; + while (b1) + { + to = pop_1st_bit(&b1); + // Note that we can use square_is_attacked() only because we + // have already removed slider checkers. + if (!pos.square_is_attacked(to, them)) + (*mlist++).move = make_move(ksq, to); + } - // Generate evasions for other pieces only if not double check. We use a + // Generate evasions for other pieces only if not double check. We use a // simple bit twiddling hack here rather than calling count_1s in order to // save some time (we know that pos.checkers() has at most two nonzero bits). - if(!(checkers & (checkers - 1))) { - Square checksq = first_1(checkers); - assert(pos.color_of_piece_on(checksq) == them); - - // Find pinned pieces: - pinned = pos.pinned_pieces(us); - - // Generate captures of the checking piece: - - // Pawn captures: - b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & ~pinned; - while(b1) { - from = pop_1st_bit(&b1); - if(relative_rank(us, checksq) == RANK_8) { - mlist[n++].move = make_promotion_move(from, checksq, QUEEN); - mlist[n++].move = make_promotion_move(from, checksq, ROOK); - mlist[n++].move = make_promotion_move(from, checksq, BISHOP); - mlist[n++].move = make_promotion_move(from, checksq, KNIGHT); + if (!(checkers & (checkers - 1))) // Only one bit set? + { + Square checksq = first_1(checkers); + + assert(pos.color_of_piece_on(checksq) == them); + + // Generate captures of the checking piece + + // Pawn captures + b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & ~pinned; + while (b1) + { + from = pop_1st_bit(&b1); + if (relative_rank(us, checksq) == RANK_8) + { + (*mlist++).move = make_promotion_move(from, checksq, QUEEN); + (*mlist++).move = make_promotion_move(from, checksq, ROOK); + (*mlist++).move = make_promotion_move(from, checksq, BISHOP); + (*mlist++).move = make_promotion_move(from, checksq, KNIGHT); + } else + (*mlist++).move = make_move(from, checksq); } - else - mlist[n++].move = make_move(from, checksq); - } - - // Knight captures: - b1 = pos.knight_attacks(checksq) & pos.knights(us) & ~pinned; - while(b1) { - from = pop_1st_bit(&b1); - mlist[n++].move = make_move(from, checksq); - } - // Bishop and queen captures: - b1 = pos.bishop_attacks(checksq) & pos.bishops_and_queens(us) - & ~pinned; - while(b1) { - from = pop_1st_bit(&b1); - mlist[n++].move = make_move(from, checksq); - } + // Pieces captures + b1 = ( (pos.piece_attacks(checksq) & pos.knights(us)) + | (pos.piece_attacks(checksq) & pos.bishops_and_queens(us)) + | (pos.piece_attacks(checksq) & pos.rooks_and_queens(us)) ) & ~pinned; - // Rook and queen captures: - b1 = pos.rook_attacks(checksq) & pos.rooks_and_queens(us) - & ~pinned; - while(b1) { - from = pop_1st_bit(&b1); - mlist[n++].move = make_move(from, checksq); - } - - // Blocking check evasions are possible only if the checking piece is - // a slider: - if(checkers & pos.sliders()) { - Bitboard blockSquares = squares_between(checksq, ksq); - assert((pos.occupied_squares() & blockSquares) == EmptyBoardBB); - - // Pawn moves. Because a blocking evasion can never be a capture, we - // only generate pawn pushes. As so often, the code for pawns is a bit - // ugly, and uses separate clauses for white and black pawns. :-( - if(us == WHITE) { - // Find non-pinned pawns: - b1 = pos.pawns(WHITE) & ~pinned; - - // Single pawn pushes. We don't have to AND with empty squares here, - // because the blocking squares will always be empty. - b2 = (b1 << 8) & blockSquares; - while(b2) { - to = pop_1st_bit(&b2); - assert(pos.piece_on(to) == EMPTY); - if(square_rank(to) == RANK_8) { - mlist[n++].move = make_promotion_move(to - DELTA_N, to, QUEEN); - mlist[n++].move = make_promotion_move(to - DELTA_N, to, ROOK); - mlist[n++].move = make_promotion_move(to - DELTA_N, to, BISHOP); - mlist[n++].move = make_promotion_move(to - DELTA_N, to, KNIGHT); - } - else - mlist[n++].move = make_move(to - DELTA_N, to); - } - // Double pawn pushes. - b2 = (((b1 << 8) & pos.empty_squares() & Rank3BB) << 8) & blockSquares; - while(b2) { - to = pop_1st_bit(&b2); - assert(pos.piece_on(to) == EMPTY); - assert(square_rank(to) == RANK_4); - mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to); - } - } - else { // (us == BLACK) - // Find non-pinned pawns: - b1 = pos.pawns(BLACK) & ~pinned; - - // Single pawn pushes. We don't have to AND with empty squares here, - // because the blocking squares will always be empty. - b2 = (b1 >> 8) & blockSquares; - while(b2) { - to = pop_1st_bit(&b2); - assert(pos.piece_on(to) == EMPTY); - if(square_rank(to) == RANK_1) { - mlist[n++].move = make_promotion_move(to - DELTA_S, to, QUEEN); - mlist[n++].move = make_promotion_move(to - DELTA_S, to, ROOK); - mlist[n++].move = make_promotion_move(to - DELTA_S, to, BISHOP); - mlist[n++].move = make_promotion_move(to - DELTA_S, to, KNIGHT); - } - else - mlist[n++].move = make_move(to - DELTA_S, to); - } - // Double pawn pushes. - b2 = (((b1 >> 8) & pos.empty_squares() & Rank6BB) >> 8) & blockSquares; - while(b2) { - to = pop_1st_bit(&b2); - assert(pos.piece_on(to) == EMPTY); - assert(square_rank(to) == RANK_5); - mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to); - } + while (b1) + { + from = pop_1st_bit(&b1); + (*mlist++).move = make_move(from, checksq); } - // Knight moves - b1 = pos.knights(us) & ~pinned; - while(b1) { - from = pop_1st_bit(&b1); - b2 = pos.knight_attacks(from) & blockSquares; - while(b2) { - to = pop_1st_bit(&b2); - mlist[n++].move = make_move(from, to); - } - } - - // Bishop moves - b1 = pos.bishops(us) & ~pinned; - while(b1) { - from = pop_1st_bit(&b1); - b2 = pos.bishop_attacks(from) & blockSquares; - while(b2) { - to = pop_1st_bit(&b2); - mlist[n++].move = make_move(from, to); - } - } - - // Rook moves - b1 = pos.rooks(us) & ~pinned; - while(b1) { - from = pop_1st_bit(&b1); - b2 = pos.rook_attacks(from) & blockSquares; - while(b2) { - to = pop_1st_bit(&b2); - mlist[n++].move = make_move(from, to); - } - } - - // Queen moves - b1 = pos.queens(us) & ~pinned; - while(b1) { - from = pop_1st_bit(&b1); - b2 = pos.queen_attacks(from) & blockSquares; - while(b2) { - to = pop_1st_bit(&b2); - mlist[n++].move = make_move(from, to); - } + // Blocking check evasions are possible only if the checking piece is + // a slider. + if (checkers & pos.sliders()) + { + Bitboard blockSquares = squares_between(checksq, ksq); + + assert((pos.occupied_squares() & blockSquares) == EmptyBoardBB); + + if (blockSquares != EmptyBoardBB) + { + mlist = generate_piece_moves(pos, mlist, us, blockSquares, pinned); + mlist = generate_piece_moves(pos, mlist, us, blockSquares, pinned); + mlist = generate_piece_moves(pos, mlist, us, blockSquares, pinned); + mlist = generate_piece_moves(pos, mlist, us, blockSquares, pinned); + mlist = generate_piece_moves(pos, mlist, us, blockSquares, pinned); + } } - } - // Finally, the ugly special case of en passant captures. An en passant - // capture can only be a check evasion if the check is not a discovered - // check. If pos.ep_square() is set, the last move made must have been - // a double pawn push. If, furthermore, the checking piece is a pawn, - // an en passant check evasion may be possible. - if(pos.ep_square() != SQ_NONE && (checkers & pos.pawns(them))) { - to = pos.ep_square(); - b1 = pos.pawn_attacks(them, to) & pos.pawns(us); - assert(b1 != EmptyBoardBB); - b1 &= ~pinned; - while(b1) { - from = pop_1st_bit(&b1); - - // Before generating the move, we have to make sure it is legal. - // This is somewhat tricky, because the two disappearing pawns may - // cause new "discovered checks". We test this by removing the - // two relevant bits from the occupied squares bitboard, and using - // the low-level bitboard functions for bishop and rook attacks. - b2 = pos.occupied_squares(); - clear_bit(&b2, from); - clear_bit(&b2, checksq); - if(((bishop_attacks_bb(ksq, b2) & pos.bishops_and_queens(them)) - == EmptyBoardBB) && - ((rook_attacks_bb(ksq, b2) & pos.rooks_and_queens(them)) - == EmptyBoardBB)) - mlist[n++].move = make_ep_move(from, to); + // Finally, the special case of en passant captures. An en passant + // capture can only be a check evasion if the check is not a discovered + // check. If pos.ep_square() is set, the last move made must have been + // a double pawn push. If, furthermore, the checking piece is a pawn, + // an en passant check evasion may be possible. + if (pos.ep_square() != SQ_NONE && (checkers & pos.pawns(them))) + { + to = pos.ep_square(); + b1 = pos.pawn_attacks(them, to) & pos.pawns(us); + + // The checking pawn cannot be a discovered (bishop) check candidate + // otherwise we were in check also before last double push move. + assert(!bit_is_set(pos.discovered_check_candidates(them), checksq)); + assert(count_1s(b1) == 1 || count_1s(b1) == 2); + + b1 &= ~pinned; + while (b1) + { + from = pop_1st_bit(&b1); + // Move is always legal because checking pawn is not a discovered + // check candidate and our capturing pawn has been already tested + // against pinned pieces. + (*mlist++).move = make_ep_move(from, to); + } } - } } - - return n; + return int(mlist - mlist_start); } /// generate_legal_moves() computes a complete list of legal moves in the -/// current position. This function is not very fast, and should be used -/// only in situations where performance is unimportant. It wouldn't be +/// current position. This function is not very fast, and should be used +/// only in situations where performance is unimportant. It wouldn't be /// very hard to write an efficient legal move generator, but for the moment /// we don't need it. -int generate_legal_moves(const Position &pos, MoveStack *mlist) { +int generate_legal_moves(const Position& pos, MoveStack* mlist) { + assert(pos.is_ok()); - if(pos.is_check()) - return generate_evasions(pos, mlist); - else { - int i, n; - Bitboard pinned = pos.pinned_pieces(pos.side_to_move()); + Bitboard pinned = pos.pinned_pieces(pos.side_to_move()); - // Generate pseudo-legal moves: - n = generate_captures(pos, mlist); - n += generate_noncaptures(pos, mlist + n); + if (pos.is_check()) + return generate_evasions(pos, mlist, pinned); - // Remove illegal moves from the list: - for(i = 0; i < n; i++) { - if(!pos.move_is_legal(mlist[i].move, pinned)) - mlist[i--].move = mlist[--n].move; - } + // Generate pseudo-legal moves + int n = generate_captures(pos, mlist); + n += generate_noncaptures(pos, mlist + n); - return n; - } + // Remove illegal moves from the list + for (int i = 0; i < n; i++) + if (!pos.pl_move_is_legal(mlist[i].move, pinned)) + mlist[i--].move = mlist[--n].move; + + return n; } -/// generate_move_if_legal() takes a position and a (not necessarily -/// pseudo-legal) move and a pinned pieces bitboard as input, and tests -/// whether the move is legal. If the move is legal, the move itself is -/// returned. If not, the function returns MOVE_NONE. This function must +/// move_is_legal() takes a position and a (not necessarily pseudo-legal) +/// move and a pinned pieces bitboard as input, and tests whether +/// the move is legal. If the move is legal, the move itself is +/// returned. If not, the function returns false. This function must /// only be used when the side to move is not in check. -Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) { - Color us, them; - Square from, to; - Piece pc; +bool move_is_legal(const Position& pos, const Move m, Bitboard pinned) { assert(pos.is_ok()); assert(!pos.is_check()); assert(move_is_ok(m)); + assert(pinned == pos.pinned_pieces(pos.side_to_move())); - us = pos.side_to_move(); - them = opposite_color(us); - from = move_from(m); - pc = pos.piece_on(from); + Color us = pos.side_to_move(); + Color them = opposite_color(us); + Square from = move_from(m); + Piece pc = pos.piece_on(from); // If the from square is not occupied by a piece belonging to the side to // move, the move is obviously not legal. - if(color_of_piece(pc) != us ) - return MOVE_NONE; - - to = move_to(m); + if (color_of_piece(pc) != us) + return false; - // En passant moves: - if(move_is_ep(m)) { + Square to = move_to(m); - // The piece must be a pawn: - if(type_of_piece(pc) != PAWN) - return MOVE_NONE; + // En passant moves + if (move_is_ep(m)) + { + // The piece must be a pawn and destination square must be the + // en passant square. + if ( type_of_piece(pc) != PAWN + || to != pos.ep_square()) + return false; - // The destination square must be the en passant square: - if(to != pos.ep_square()) - return MOVE_NONE; + assert(pos.square_is_empty(to)); + assert(pos.piece_on(to - pawn_push(us)) == piece_of_color_and_type(them, PAWN)); - assert(pos.square_is_empty(to)); - assert(pos.piece_on(to - pawn_push(us)) == pawn_of_color(them)); - - // The move is pseudo-legal. If it is legal, return it. - if(pos.move_is_legal(m)) - return m; - else - return MOVE_NONE; + // The move is pseudo-legal, check if it is also legal + return pos.pl_move_is_legal(m, pinned); } - // Castling moves: - else if(move_is_short_castle(m)) { - - // The piece must be a king: - if(type_of_piece(pc) != KING) - return MOVE_NONE; - - // The side to move must still have the right to castle kingside: - if(!pos.can_castle_kingside(us)) - return MOVE_NONE; + // Castling moves + if (move_is_short_castle(m)) + { + // The piece must be a king and side to move must still have + // the right to castle kingside. + if ( type_of_piece(pc) != KING + ||!pos.can_castle_kingside(us)) + return false; + + assert(from == pos.king_square(us)); + assert(to == pos.initial_kr_square(us)); + assert(pos.piece_on(to) == piece_of_color_and_type(us, ROOK)); + + Square g1 = relative_square(us, SQ_G1); + Square f1 = relative_square(us, SQ_F1); + Square s; + bool illegal = false; + + // Check if any of the squares between king and rook + // is occupied or under attack. + for (s = Min(from, g1); s <= Max(from, g1); s++) + if ( (s != from && s != to && !pos.square_is_empty(s)) + || pos.square_is_attacked(s, them)) + illegal = true; + + // Check if any of the squares between king and rook + // is occupied. + for (s = Min(to, f1); s <= Max(to, f1); s++) + if (s != from && s != to && !pos.square_is_empty(s)) + illegal = true; + + return !illegal; + } - assert(from == pos.king_square(us)); - assert(to == pos.initial_kr_square(us)); - assert(pos.piece_on(to) == rook_of_color(us)); + if (move_is_long_castle(m)) + { + // The piece must be a king and side to move must still have + // the right to castle kingside. + if ( type_of_piece(pc) != KING + ||!pos.can_castle_queenside(us)) + return false; + + assert(from == pos.king_square(us)); + assert(to == pos.initial_qr_square(us)); + assert(pos.piece_on(to) == piece_of_color_and_type(us, ROOK)); + + Square c1 = relative_square(us, SQ_C1); + Square d1 = relative_square(us, SQ_D1); + Square s; + bool illegal = false; + + for (s = Min(from, c1); s <= Max(from, c1); s++) + if( (s != from && s != to && !pos.square_is_empty(s)) + || pos.square_is_attacked(s, them)) + illegal = true; - Square g1 = relative_square(us, SQ_G1); - Square f1 = relative_square(us, SQ_F1); - Square s; - bool illegal = false; + for (s = Min(to, d1); s <= Max(to, d1); s++) + if(s != from && s != to && !pos.square_is_empty(s)) + illegal = true; - for(s = Min(from, g1); s <= Max(from, g1); s++) - if((s != from && s != to && !pos.square_is_empty(s)) || - pos.square_is_attacked(s, them)) - illegal = true; - for(s = Min(to, f1); s <= Max(to, f1); s++) - if(s != from && s != to && !pos.square_is_empty(s)) - illegal = true; + if ( square_file(to) == FILE_B + && ( pos.piece_on(to + DELTA_W) == piece_of_color_and_type(them, ROOK) + || pos.piece_on(to + DELTA_W) == piece_of_color_and_type(them, QUEEN))) + illegal = true; - if(!illegal) - return m; - else - return MOVE_NONE; - } - else if(move_is_long_castle(m)) { - - // The piece must be a king: - if(type_of_piece(pc) != KING) - return MOVE_NONE; - - // The side to move must still have the right to castle kingside: - if(!pos.can_castle_queenside(us)) - return MOVE_NONE; - - assert(from == pos.king_square(us)); - assert(to == pos.initial_qr_square(us)); - assert(pos.piece_on(to) == rook_of_color(us)); - - Square c1 = relative_square(us, SQ_C1); - Square d1 = relative_square(us, SQ_D1); - Square s; - bool illegal = false; - - for(s = Min(from, c1); s <= Max(from, c1); s++) - if((s != from && s != to && !pos.square_is_empty(s)) || - pos.square_is_attacked(s, them)) - illegal = true; - for(s = Min(to, d1); s <= Max(to, d1); s++) - if(s != from && s != to && !pos.square_is_empty(s)) - illegal = true; - if(square_file(to) == FILE_B && - (pos.piece_on(to + DELTA_W) == rook_of_color(them) || - pos.piece_on(to + DELTA_W) == queen_of_color(them))) - illegal = true; - - if(!illegal) - return m; - else - return MOVE_NONE; + return !illegal; } // Normal moves - else { - - // The destination square cannot be occupied by a friendly piece: - if(pos.color_of_piece_on(to) == us) - return MOVE_NONE; - - // Proceed according to the type of the moving piece. - switch(type_of_piece(pc)) { - - case PAWN: - // Pawn moves, as usual, are somewhat messy. - if(us == WHITE) { - // If the destination square is on the 8th rank, the move must be a - // promotion. - if(square_rank(to) == RANK_8 && !move_promotion(m)) - return MOVE_NONE; - - // Proceed according to the square delta between the source and - // destionation squares. - switch(to - from) { - - case DELTA_NW: case DELTA_NE: - // Capture. The destination square must be occupied by an enemy piece - // (en passant captures was handled earlier). - if(pos.color_of_piece_on(to) != them) - return MOVE_NONE; - break; - case DELTA_N: - // Pawn push. The destination square must be empty. - if(!pos.square_is_empty(to)) - return MOVE_NONE; + // The destination square cannot be occupied by a friendly piece + if (pos.color_of_piece_on(to) == us) + return false; + + // Proceed according to the type of the moving piece. + if (type_of_piece(pc) == PAWN) + { + // Move direction must be compatible with pawn color + int direction = to - from; + if ((us == WHITE) != (direction > 0)) + return false; + + // If the destination square is on the 8/1th rank, the move must + // be a promotion. + if ( ( (square_rank(to) == RANK_8 && us == WHITE) + ||(square_rank(to) == RANK_1 && us != WHITE)) + && !move_promotion(m)) + return false; + + // Proceed according to the square delta between the source and + // destionation squares. + switch (direction) + { + case DELTA_NW: + case DELTA_NE: + case DELTA_SW: + case DELTA_SE: + // Capture. The destination square must be occupied by an enemy + // piece (en passant captures was handled earlier). + if (pos.color_of_piece_on(to) != them) + return false; break; - case DELTA_NN: - // Double pawn push. The destination square must be on the fourth - // rank, and both the destination square and the square between the - // source and destination squares must be empty. - if(square_rank(to) != RANK_4 || !pos.square_is_empty(to) || - !pos.square_is_empty(from + DELTA_N)) - return MOVE_NONE; - break; - - default: - return MOVE_NONE; - } - } - else { // (us == BLACK) - // If the destination square is on the 1st rank, the move must be a - // promotion. - if(square_rank(to) == RANK_1 && !move_promotion(m)) - return MOVE_NONE; - - // Proceed according to the square delta between the source and - // destionation squares. - switch(to - from) { - - case DELTA_SW: case DELTA_SE: - // Capture. The destination square must be occupied by an enemy piece - // (en passant captures was handled earlier). - if(pos.color_of_piece_on(to) != them) - return MOVE_NONE; - break; - - case DELTA_S: - // Pawn push. The destination square must be empty. - if(!pos.square_is_empty(to)) - return MOVE_NONE; + case DELTA_N: + case DELTA_S: + // Pawn push. The destination square must be empty. + if (!pos.square_is_empty(to)) + return false; break; - - case DELTA_SS: - // Double pawn push. The destination square must be on the fifth - // rank, and both the destination square and the square between the - // source and destination squares must be empty. - if(square_rank(to) != RANK_5 || !pos.square_is_empty(to) || - !pos.square_is_empty(from + DELTA_S)) - return MOVE_NONE; - break; - - default: - return MOVE_NONE; - } - } - // The move is pseudo-legal. Return it if it is legal. - if(pos.move_is_legal(m)) - return m; - else - return MOVE_NONE; - break; - case KNIGHT: - if(pos.knight_attacks_square(from, to) && pos.move_is_legal(m) && - !move_promotion(m)) - return m; - else - return MOVE_NONE; - break; - - case BISHOP: - if(pos.bishop_attacks_square(from, to) && pos.move_is_legal(m) && - !move_promotion(m)) - return m; - else - return MOVE_NONE; - break; - - case ROOK: - if(pos.rook_attacks_square(from, to) && pos.move_is_legal(m) && - !move_promotion(m)) - return m; - else - return MOVE_NONE; - break; - - case QUEEN: - if(pos.queen_attacks_square(from, to) && pos.move_is_legal(m) && - !move_promotion(m)) - return m; - else - return MOVE_NONE; - break; + case DELTA_NN: + // Double white pawn push. The destination square must be on the fourth + // rank, and both the destination square and the square between the + // source and destination squares must be empty. + if ( square_rank(to) != RANK_4 + || !pos.square_is_empty(to) + || !pos.square_is_empty(from + DELTA_N)) + return false; + break; - case KING: - if(pos.king_attacks_square(from, to) && pos.move_is_legal(m) && - !move_promotion(m)) - return m; - else - return MOVE_NONE; - break; + case DELTA_SS: + // Double black pawn push. The destination square must be on the fifth + // rank, and both the destination square and the square between the + // source and destination squares must be empty. + if ( square_rank(to) != RANK_5 + || !pos.square_is_empty(to) + || !pos.square_is_empty(from + DELTA_S)) + return false; + break; - default: - assert(false); - } + default: + return false; + } + // The move is pseudo-legal, check if it is also legal + return pos.pl_move_is_legal(m, pinned); } - assert(false); - return MOVE_NONE; + // Luckly we can handle all the other pieces in one go + return ( pos.piece_attacks_square(pos.piece_on(from), from, to) + && pos.pl_move_is_legal(m, pinned) + && !move_promotion(m)); } namespace { - int generate_white_pawn_captures(const Position &pos, MoveStack *mlist) { - Bitboard pawns = pos.pawns(WHITE); - Bitboard enemyPieces = pos.pieces_of_color(BLACK); - Bitboard b1, b2; - Square sq; - int n = 0; - - // Captures in the a1-h8 direction: - b1 = (pawns << 9) & ~FileABB & enemyPieces; + template + MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) { - // Promotions: - b2 = b1 & Rank8BB; - while(b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_promotion_move(sq - DELTA_NE, sq, QUEEN); - } + Square from; + Bitboard b; - // Non-promotions: - b2 = b1 & ~Rank8BB; - while(b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - DELTA_NE, sq); + for (int i = 0, e = pos.piece_count(us, Piece); i < e; i++) + { + from = pos.piece_list(us, Piece, i); + b = pos.piece_attacks(from) & target; + SERIALIZE_MOVES(b); } + return mlist; + } - // Captures in the h1-a8 direction: - b1 = (pawns << 7) & ~FileHBB & enemyPieces; + template + MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, + Color us, Bitboard target, Bitboard pinned) { + Square from; + Bitboard b; - // Promotions: - b2 = b1 & Rank8BB; - while(b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_promotion_move(sq - DELTA_NW, sq, QUEEN); - } + for (int i = 0, e = pos.piece_count(us, Piece); i < e; i++) + { + from = pos.piece_list(us, Piece, i); + if (pinned && bit_is_set(pinned, from)) + continue; - // Non-promotions: - b2 = b1 & ~Rank8BB; - while(b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - DELTA_NW, sq); + b = pos.piece_attacks(from) & target; + SERIALIZE_MOVES(b); } + return mlist; + } - // Non-capturing promotions: - b1 = (pawns << 8) & pos.empty_squares() & Rank8BB; - while(b1) { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_promotion_move(sq - DELTA_N, sq, QUEEN); - } + template<> + MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) { - // En passant captures: - if(pos.ep_square() != SQ_NONE) { - assert(square_rank(pos.ep_square()) == RANK_6); - b1 = pawns & pos.black_pawn_attacks(pos.ep_square()); - assert(b1 != EmptyBoardBB); - while(b1) { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_ep_move(sq, pos.ep_square()); - } - } + Bitboard b; + Square from = pos.king_square(us); - return n; + b = pos.piece_attacks(from) & target; + SERIALIZE_MOVES(b); + return mlist; } + template + MoveStack* generate_pawn_captures_diagonal(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces) { - int generate_black_pawn_captures(const Position &pos, MoveStack *mlist) { - Bitboard pawns = pos.pawns(BLACK); - Bitboard enemyPieces = pos.pieces_of_color(WHITE); - Bitboard b1, b2; - Square sq; - int n = 0; + // Calculate our parametrized parameters at compile time + const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB); + const Bitboard TFileABB = (Diagonal == DELTA_NE ? FileABB : FileHBB); + const SquareDelta TDELTA_NE = (Us == WHITE ? DELTA_NE : DELTA_SE); + const SquareDelta TDELTA_NW = (Us == WHITE ? DELTA_NW : DELTA_SW); + const SquareDelta TTDELTA_NE = (Diagonal == DELTA_NE ? TDELTA_NE : TDELTA_NW); - // Captures in the a8-h1 direction: - b1 = (pawns >> 7) & ~FileABB & enemyPieces; + Square to; - // Promotions: - b2 = b1 & Rank1BB; - while(b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_promotion_move(sq - DELTA_SE, sq, QUEEN); - } + // Captures in the a1-h8 (a8-h1 for black) diagonal or in the h1-a8 (h8-a1 for black) + Bitboard b1 = move_pawns(pawns) & ~TFileABB & enemyPieces; - // Non-promotions: - b2 = b1 & ~Rank1BB; - while(b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - DELTA_SE, sq); + // Capturing promotions + Bitboard b2 = b1 & TRank8BB; + while (b2) + { + to = pop_1st_bit(&b2); + (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, QUEEN); } - // Captures in the h8-a1 direction: - b1 = (pawns >> 9) & ~FileHBB & enemyPieces; - - // Promotions: - b2 = b1 & Rank1BB; - while(b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_promotion_move(sq - DELTA_SW, sq, QUEEN); + // Capturing non-promotions + b2 = b1 & ~TRank8BB; + while (b2) + { + to = pop_1st_bit(&b2); + (*mlist++).move = make_move(to - TTDELTA_NE, to); } + return mlist; + } - // Non-promotions: - b2 = b1 & ~Rank1BB; - while(b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - DELTA_SW, sq); - } + template + MoveStack* generate_pawn_captures(const Position& pos, MoveStack* mlist) { - // Non-capturing promotions: - b1 = (pawns >> 8) & pos.empty_squares() & Rank1BB; - while(b1) { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_promotion_move(sq - DELTA_S, sq, QUEEN); - } + // Calculate our parametrized parameters at compile time + const Color Them = (Us == WHITE ? BLACK : WHITE); + const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB); + const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S); - // En passant captures: - if(pos.ep_square() != SQ_NONE) { - assert(square_rank(pos.ep_square()) == RANK_3); - b1 = pawns & pos.white_pawn_attacks(pos.ep_square()); - assert(b1 != EmptyBoardBB); - while(b1) { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_ep_move(sq, pos.ep_square()); - } + Square to; + Bitboard pawns = pos.pawns(Us); + Bitboard enemyPieces = pos.pieces_of_color(opposite_color(Us)); + + // Standard captures and capturing promotions in both directions + mlist = generate_pawn_captures_diagonal(mlist, pawns, enemyPieces); + mlist = generate_pawn_captures_diagonal(mlist, pawns, enemyPieces); + + // Non-capturing promotions + Bitboard b1 = move_pawns(pawns) & pos.empty_squares() & TRank8BB; + while (b1) + { + to = pop_1st_bit(&b1); + (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN); + } + + // En passant captures + if (pos.ep_square() != SQ_NONE) + { + assert(Us != WHITE || square_rank(pos.ep_square()) == RANK_6); + assert(Us != BLACK || square_rank(pos.ep_square()) == RANK_3); + + b1 = pawns & pos.pawn_attacks(Them, pos.ep_square()); + assert(b1 != EmptyBoardBB); + + while (b1) + { + to = pop_1st_bit(&b1); + (*mlist++).move = make_ep_move(to, pos.ep_square()); + } } - - return n; + return mlist; } - - int generate_white_pawn_noncaptures(const Position &pos, MoveStack *mlist) { - Bitboard pawns = pos.pawns(WHITE); - Bitboard enemyPieces = pos.pieces_of_color(BLACK); - Bitboard emptySquares = pos.empty_squares(); - Bitboard b1, b2; - Square sq; - int n = 0; - - // Underpromotion captures in the a1-h8 direction: - b1 = (pawns << 9) & ~FileABB & enemyPieces & Rank8BB; - while(b1) { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_promotion_move(sq - DELTA_NE, sq, ROOK); - mlist[n++].move = make_promotion_move(sq - DELTA_NE, sq, BISHOP); - mlist[n++].move = make_promotion_move(sq - DELTA_NE, sq, KNIGHT); - } + template + MoveStack* generate_pawn_noncaptures(const Position& pos, MoveStack* mlist) { - // Underpromotion captures in the h1-a8 direction: - b1 = (pawns << 7) & ~FileHBB & enemyPieces & Rank8BB; - while(b1) { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_promotion_move(sq - DELTA_NW, sq, ROOK); - mlist[n++].move = make_promotion_move(sq - DELTA_NW, sq, BISHOP); - mlist[n++].move = make_promotion_move(sq - DELTA_NW, sq, KNIGHT); - } + // Calculate our parametrized parameters at compile time + const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB); + const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB); + const SquareDelta TDELTA_NE = (Us == WHITE ? DELTA_NE : DELTA_SE); + const SquareDelta TDELTA_NW = (Us == WHITE ? DELTA_NW : DELTA_SW); + const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S); + + Bitboard b1, b2; + Square to; + Bitboard pawns = pos.pawns(Us); + Bitboard enemyPieces = pos.pieces_of_color(opposite_color(Us)); + Bitboard emptySquares = pos.empty_squares(); - // Single pawn pushes: - b1 = (pawns << 8) & emptySquares; - b2 = b1 & Rank8BB; - while(b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_promotion_move(sq - DELTA_N, sq, ROOK); - mlist[n++].move = make_promotion_move(sq - DELTA_N, sq, BISHOP); - mlist[n++].move = make_promotion_move(sq - DELTA_N, sq, KNIGHT); + // Underpromotion captures in the a1-h8 (a8-h1 for black) direction + b1 = move_pawns(pawns) & ~FileABB & enemyPieces & TRank8BB; + while (b1) + { + to = pop_1st_bit(&b1); + (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, ROOK); + (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, BISHOP); + (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, KNIGHT); + } + + // Underpromotion captures in the h1-a8 (h8-a1 for black) direction + b1 = move_pawns(pawns) & ~FileHBB & enemyPieces & TRank8BB; + while (b1) + { + to = pop_1st_bit(&b1); + (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, ROOK); + (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, BISHOP); + (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, KNIGHT); + } + + // Single pawn pushes + b1 = move_pawns(pawns) & emptySquares; + b2 = b1 & TRank8BB; + while (b2) + { + to = pop_1st_bit(&b2); + (*mlist++).move = make_promotion_move(to - TDELTA_N, to, ROOK); + (*mlist++).move = make_promotion_move(to - TDELTA_N, to, BISHOP); + (*mlist++).move = make_promotion_move(to - TDELTA_N, to, KNIGHT); } - b2 = b1 & ~Rank8BB; - while(b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - DELTA_N, sq); + b2 = b1 & ~TRank8BB; + while (b2) + { + to = pop_1st_bit(&b2); + (*mlist++).move = make_move(to - TDELTA_N, to); } - // Double pawn pushes: - b2 = ((b1 & Rank3BB) << 8) & emptySquares; - while(b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - DELTA_N - DELTA_N, sq); + // Double pawn pushes + b2 = move_pawns(b1 & TRank3BB) & emptySquares; + while (b2) + { + to = pop_1st_bit(&b2); + (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to); } - - return n; + return mlist; } - int generate_black_pawn_noncaptures(const Position &pos, MoveStack *mlist) { - Bitboard pawns = pos.pawns(BLACK); - Bitboard enemyPieces = pos.pieces_of_color(WHITE); - Bitboard emptySquares = pos.empty_squares(); - Bitboard b1, b2; - Square sq; - int n = 0; - - // Underpromotion captures in the a8-h1 direction: - b1 = (pawns >> 7) & ~FileABB & enemyPieces & Rank1BB; - while(b1) { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_promotion_move(sq - DELTA_SE, sq, ROOK); - mlist[n++].move = make_promotion_move(sq - DELTA_SE, sq, BISHOP); - mlist[n++].move = make_promotion_move(sq - DELTA_SE, sq, KNIGHT); - } + template + MoveStack* generate_pawn_checks(const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist) + { + // Calculate our parametrized parameters at compile time + const Color Them = (Us == WHITE ? BLACK : WHITE); + const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB); + const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB); + const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S); + + Bitboard b1, b2, b3; + Bitboard empty = pos.empty_squares(); + Bitboard pawns = pos.pawns(Us); + + if (dc & pawns) + { + // Pawn moves which gives discovered check. This is possible only if the + // pawn is not on the same file as the enemy king, because we don't + // generate captures. + b1 = pawns & ~file_bb(ksq); + + // Discovered checks, single pawn pushes, no promotions + b2 = b3 = move_pawns(b1 & dc) & empty & ~TRank8BB; + while (b3) + { + Square to = pop_1st_bit(&b3); + (*mlist++).move = make_move(to - TDELTA_N, to); + } - // Underpromotion captures in the h8-a1 direction: - b1 = (pawns >> 9) & ~FileHBB & enemyPieces & Rank1BB; - while(b1) { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_promotion_move(sq - DELTA_SW, sq, ROOK); - mlist[n++].move = make_promotion_move(sq - DELTA_SW, sq, BISHOP); - mlist[n++].move = make_promotion_move(sq - DELTA_SW, sq, KNIGHT); + // Discovered checks, double pawn pushes + b3 = move_pawns(b2 & TRank3BB) & empty; + while (b3) + { + Square to = pop_1st_bit(&b3); + (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to); + } } - // Single pawn pushes: - b1 = (pawns >> 8) & emptySquares; - b2 = b1 & Rank1BB; - while(b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_promotion_move(sq - DELTA_S, sq, ROOK); - mlist[n++].move = make_promotion_move(sq - DELTA_S, sq, BISHOP); - mlist[n++].move = make_promotion_move(sq - DELTA_S, sq, KNIGHT); - } - b2 = b1 & ~Rank1BB; - while(b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - DELTA_S, sq); - } - - // Double pawn pushes: - b2 = ((b1 & Rank6BB) >> 8) & emptySquares; - while(b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - DELTA_S - DELTA_S, sq); - } + // Direct checks. These are possible only for pawns on neighboring files + // of the enemy king. + b1 = pawns & neighboring_files_bb(ksq) & ~dc; - return n; - } + // Direct checks, single pawn pushes + b2 = move_pawns(b1) & empty; + b3 = b2 & pos.pawn_attacks(Them, ksq); + while (b3) + { + Square to = pop_1st_bit(&b3); + (*mlist++).move = make_move(to - TDELTA_N, to); + } - - int generate_knight_moves(const Position &pos, MoveStack *mlist, - Color side, Bitboard target) { - Square from, to; - Bitboard b; - int i, n = 0; - - for(i = 0; i < pos.knight_count(side); i++) { - from = pos.knight_list(side, i); - b = pos.knight_attacks(from) & target; - while(b) { - to = pop_1st_bit(&b); - mlist[n++].move = make_move(from, to); - } + // Direct checks, double pawn pushes + b3 = move_pawns(b2 & TRank3BB) & empty & pos.pawn_attacks(Them, ksq); + while (b3) + { + Square to = pop_1st_bit(&b3); + (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to); } - return n; + return mlist; } + template + MoveStack* generate_piece_checks(const Position& pos, MoveStack* mlist, Color us, + Bitboard dc, Square ksq) { - int generate_bishop_moves(const Position &pos, MoveStack *mlist, - Color side, Bitboard target) { - Square from, to; - Bitboard b; - int i, n = 0; - - for(i = 0; i < pos.bishop_count(side); i++) { - from = pos.bishop_list(side, i); - b = pos.bishop_attacks(from) & target; - while(b) { - to = pop_1st_bit(&b); - mlist[n++].move = make_move(from, to); - } - } - return n; - } + Bitboard target = pos.pieces_of_color_and_type(us, Piece); + // Discovered checks + Bitboard b = target & dc; + while (b) + { + Square from = pop_1st_bit(&b); + Bitboard bb = pos.piece_attacks(from) & pos.empty_squares(); + if (Piece == KING) + bb &= ~QueenPseudoAttacks[ksq]; - int generate_rook_moves(const Position &pos, MoveStack *mlist, - Color side, Bitboard target) { - Square from, to; - Bitboard b; - int i, n = 0; - - for(i = 0; i < pos.rook_count(side); i++) { - from = pos.rook_list(side, i); - b = pos.rook_attacks(from) & target; - while(b) { - to = pop_1st_bit(&b); - mlist[n++].move = make_move(from, to); - } + SERIALIZE_MOVES(bb); } - return n; - } + // Direct checks + b = target & ~dc; + if (Piece == KING || !b) + return mlist; - int generate_queen_moves(const Position &pos, MoveStack *mlist, - Color side, Bitboard target) { - Square from, to; - Bitboard b; - int i, n = 0; - - for(i = 0; i < pos.queen_count(side); i++) { - from = pos.queen_list(side, i); - b = pos.queen_attacks(from) & target; - while(b) { - to = pop_1st_bit(&b); - mlist[n++].move = make_move(from, to); - } + Bitboard checkSqs = pos.piece_attacks(ksq) & pos.empty_squares(); + if (!checkSqs) + return mlist; + + while (b) + { + Square from = pop_1st_bit(&b); + if ( (Piece == QUEEN && !(QueenPseudoAttacks[from] & checkSqs)) + || (Piece == ROOK && !(RookPseudoAttacks[from] & checkSqs)) + || (Piece == BISHOP && !(BishopPseudoAttacks[from] & checkSqs))) + continue; + + Bitboard bb = pos.piece_attacks(from) & checkSqs; + SERIALIZE_MOVES(bb); } - return n; + return mlist; } - - int generate_king_moves(const Position &pos, MoveStack *mlist, - Square from, Bitboard target) { + template + MoveStack* generate_pawn_blocking_evasions(const Position& pos, Bitboard pinned, + Bitboard blockSquares, MoveStack* mlist) { Square to; - Bitboard b; - int n = 0; - - b = pos.king_attacks(from) & target; - while(b) { - to = pop_1st_bit(&b); - mlist[n++].move = make_move(from, to); + + // Find non-pinned pawns and push them one square + Bitboard b1 = move_pawns(pos.pawns(Us) & ~pinned); + + // We don't have to AND with empty squares here, + // because the blocking squares will always be empty. + Bitboard b2 = b1 & blockSquares; + while (b2) + { + to = pop_1st_bit(&b2); + + assert(pos.piece_on(to) == EMPTY); + + if (square_rank(to) == TRANK_8) + { + (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN); + (*mlist++).move = make_promotion_move(to - TDELTA_N, to, ROOK); + (*mlist++).move = make_promotion_move(to - TDELTA_N, to, BISHOP); + (*mlist++).move = make_promotion_move(to - TDELTA_N, to, KNIGHT); + } else + (*mlist++).move = make_move(to - TDELTA_N, to); } - return n; - } + // Double pawn pushes + b2 = b1 & pos.empty_squares() & TRank3BB; + b2 = move_pawns(b2) & blockSquares; + while (b2) + { + to = pop_1st_bit(&b2); - int generate_castle_moves(const Position &pos, MoveStack *mlist, Color us) { - int n = 0; + assert(pos.piece_on(to) == EMPTY); + assert(Us != WHITE || square_rank(to) == RANK_4); + assert(Us != BLACK || square_rank(to) == RANK_5); - if(pos.can_castle(us)) { - Color them = opposite_color(us); - Square ksq = pos.king_square(us); - assert(pos.piece_on(ksq) == king_of_color(us)); - - if(pos.can_castle_kingside(us)) { - Square rsq = pos.initial_kr_square(us); - Square g1 = relative_square(us, SQ_G1); - Square f1 = relative_square(us, SQ_F1); - Square s; - bool illegal = false; + (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to); + } + return mlist; + } - assert(pos.piece_on(rsq) == rook_of_color(us)); + template + MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist) { - for(s = Min(ksq, g1); s <= Max(ksq, g1); s++) - if((s != ksq && s != rsq && pos.square_is_occupied(s)) - || pos.square_is_attacked(s, them)) - illegal = true; - for(s = Min(rsq, f1); s <= Max(rsq, f1); s++) - if(s != ksq && s != rsq && pos.square_is_occupied(s)) - illegal = true; + Color us = pos.side_to_move(); - if(!illegal) - mlist[n++].move = make_castle_move(ksq, rsq); - } + if ( (Side == KING_SIDE && pos.can_castle_kingside(us)) + ||(Side == QUEEN_SIDE && pos.can_castle_queenside(us))) + { + Color them = opposite_color(us); + Square ksq = pos.king_square(us); + + assert(pos.piece_on(ksq) == piece_of_color_and_type(us, KING)); - if(pos.can_castle_queenside(us)) { - Square rsq = pos.initial_qr_square(us); - Square c1 = relative_square(us, SQ_C1); - Square d1 = relative_square(us, SQ_D1); + Square rsq = (Side == KING_SIDE ? pos.initial_kr_square(us) : pos.initial_qr_square(us)); + Square s1 = relative_square(us, Side == KING_SIDE ? SQ_G1 : SQ_C1); + Square s2 = relative_square(us, Side == KING_SIDE ? SQ_F1 : SQ_D1); Square s; bool illegal = false; - assert(pos.piece_on(rsq) == rook_of_color(us)); + assert(pos.piece_on(rsq) == piece_of_color_and_type(us, ROOK)); - for(s = Min(ksq, c1); s <= Max(ksq, c1); s++) - if((s != ksq && s != rsq && pos.square_is_occupied(s)) - || pos.square_is_attacked(s, them)) - illegal = true; - for(s = Min(rsq, d1); s <= Max(rsq, d1); s++) - if(s != ksq && s != rsq && pos.square_is_occupied(s)) + // It is a bit complicated to correctly handle Chess960 + for (s = Min(ksq, s1); s <= Max(ksq, s1); s++) + if ( (s != ksq && s != rsq && pos.square_is_occupied(s)) + || pos.square_is_attacked(s, them)) + illegal = true; + + for (s = Min(rsq, s2); s <= Max(rsq, s2); s++) + if (s != ksq && s != rsq && pos.square_is_occupied(s)) + illegal = true; + + if ( Side == QUEEN_SIDE + && square_file(rsq) == FILE_B + && ( pos.piece_on(relative_square(us, SQ_A1)) == piece_of_color_and_type(them, ROOK) + || pos.piece_on(relative_square(us, SQ_A1)) == piece_of_color_and_type(them, QUEEN))) illegal = true; - if(square_file(rsq) == FILE_B && - (pos.piece_on(relative_square(us, SQ_A1)) == rook_of_color(them) || - pos.piece_on(relative_square(us, SQ_A1)) == queen_of_color(them))) - illegal = true; - - if(!illegal) - mlist[n++].move = make_castle_move(ksq, rsq); - } + + if (!illegal) + (*mlist++).move = make_castle_move(ksq, rsq); } + return mlist; + } + + bool castling_is_check(const Position& pos, CastlingSide side) { + + // After castling opponent king is attacked by the castled rook? + File rookFile = (side == QUEEN_SIDE ? FILE_D : FILE_F); + Color us = pos.side_to_move(); + Square ksq = pos.king_square(us); + Bitboard occ = pos.occupied_squares(); - return n; + clear_bit(&occ, ksq); // Remove our king from the board + Square rsq = make_square(rookFile, square_rank(ksq)); + return bit_is_set(rook_attacks_bb(rsq, occ), pos.king_square(opposite_color(us))); } - }