X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fmovegen.cpp;h=258f9c710616a208339b055599f999c0817b382a;hb=7ae3c05795e79c9bd945607cdcfb08198f4c4b45;hp=259d276b3d79f122de26a1ad4c826fd671498bf4;hpb=d9e54ceaa1fb38cc16f2b9f68ea45eff85b7c0f5;p=stockfish diff --git a/src/movegen.cpp b/src/movegen.cpp index 259d276b..6a3cdc24 100644 --- a/src/movegen.cpp +++ b/src/movegen.cpp @@ -1,909 +1,420 @@ /* - 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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad - 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 . */ - -//// -//// Includes -//// - #include #include "movegen.h" - - -//// -//// Local definitions -//// +#include "position.h" namespace { - inline Bitboard forward_white(Bitboard b) { return b << 8; } - inline Bitboard forward_right_white(Bitboard b) { return b << 9; } - inline Bitboard forward_left_white(Bitboard b) { return b << 7; } - - inline Bitboard forward_black(Bitboard b) { return b >> 8; } - inline Bitboard forward_right_black(Bitboard b) { return b >> 7; } - inline Bitboard forward_left_black(Bitboard b) { return b >> 9; } - - struct PawnOffsets { - - Bitboard Rank3BB, Rank8BB; - Rank RANK_8; - SquareDelta DELTA_N, DELTA_NE, DELTA_NW; - Color us, them; - typedef Bitboard (*Shift_fn)(Bitboard b); - Shift_fn forward, forward_left, forward_right; - }; - - const PawnOffsets WhitePawnOffsets = { Rank3BB, Rank8BB, RANK_8, DELTA_N, DELTA_NE, DELTA_NW, WHITE, BLACK, - &forward_white, forward_left_white, forward_right_white }; + template + ExtMove* generate_castling(const Position& pos, ExtMove* moveList, Color us) { - const PawnOffsets BlackPawnOffsets = { Rank6BB, Rank1BB, RANK_1, DELTA_S, DELTA_SE, DELTA_SW, BLACK, WHITE, - &forward_black, &forward_left_black, &forward_right_black }; - - int generate_pawn_captures(const PawnOffsets&, const Position&, MoveStack*); - int generate_pawn_noncaptures(const PawnOffsets&, const Position&, MoveStack*); - int generate_pawn_checks(const PawnOffsets&, const Position&, Bitboard, Square, MoveStack*, int); - int generate_castle_moves(const Position&, MoveStack*, Color); - int generate_pawn_blocking_evasions(const PawnOffsets&, const Position&, Bitboard, Bitboard, MoveStack*, int); + static const bool KingSide = (Cr == WHITE_OO || Cr == BLACK_OO); - template - int generate_piece_moves(const Position&, MoveStack*, Color, Bitboard); + if (pos.castling_impeded(Cr) || !pos.can_castle(Cr)) + return moveList; - template - int generate_piece_checks(const Position&, Bitboard, Bitboard, Square, MoveStack*, int); + // After castling, the rook and king final positions are the same in Chess960 + // as they would be in standard chess. + Square kfrom = pos.square(us); + Square rfrom = pos.castling_rook_square(Cr); + Square kto = relative_square(us, KingSide ? SQ_G1 : SQ_C1); + Bitboard enemies = pos.pieces(~us); - template - int generate_piece_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*, int); -} - - -//// -//// Functions -//// + assert(!pos.checkers()); + const Square K = Chess960 ? kto > kfrom ? WEST : EAST + : KingSide ? WEST : EAST; -/// generate_captures generates() all pseudo-legal captures and queen -/// promotions. The return value is the number of moves generated. + for (Square s = kto; s != kfrom; s += K) + if (pos.attackers_to(s) & enemies) + return moveList; -int generate_captures(const Position& pos, MoveStack* mlist) { + // Because we generate only legal castling moves we need to verify that + // when moving the castling rook we do not discover some hidden checker. + // For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1. + if (Chess960 && (attacks_bb(kto, pos.pieces() ^ rfrom) & pos.pieces(~us, ROOK, QUEEN))) + return moveList; - assert(pos.is_ok()); - assert(!pos.is_check()); + Move m = make(kfrom, rfrom); - Color us = pos.side_to_move(); - Bitboard target = pos.pieces_of_color(opposite_color(us)); - int n; - - if (us == WHITE) - n = generate_pawn_captures(WhitePawnOffsets, pos, mlist); - else - n = generate_pawn_captures(BlackPawnOffsets, pos, mlist); - - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - return n; -} + if (Checks && !pos.gives_check(m)) + return moveList; + *moveList++ = m; + return moveList; + } -/// generate_noncaptures() generates all pseudo-legal non-captures and -/// underpromotions. The return value is the number of moves generated. -int generate_noncaptures(const Position& pos, MoveStack *mlist) { + template + ExtMove* make_promotions(ExtMove* moveList, Square to, Square ksq) { - assert(pos.is_ok()); - assert(!pos.is_check()); + if (Type == CAPTURES || Type == EVASIONS || Type == NON_EVASIONS) + *moveList++ = make(to - D, to, QUEEN); - Color us = pos.side_to_move(); - Bitboard target = pos.empty_squares(); - int n; - - if (us == WHITE) - n = generate_pawn_noncaptures(WhitePawnOffsets, pos, mlist); - else - n = generate_pawn_noncaptures(BlackPawnOffsets, pos, mlist); - - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - - n += generate_castle_moves(pos, mlist+n, us); - return n; -} + if (Type == QUIETS || Type == EVASIONS || Type == NON_EVASIONS) + { + *moveList++ = make(to - D, to, ROOK); + *moveList++ = make(to - D, to, BISHOP); + *moveList++ = make(to - D, to, KNIGHT); + } + // Knight promotion is the only promotion that can give a direct check + // that's not already included in the queen promotion. + if (Type == QUIET_CHECKS && (StepAttacksBB[W_KNIGHT][to] & ksq)) + *moveList++ = make(to - D, to, KNIGHT); + else + (void)ksq; // Silence a warning under MSVC -/// 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. + return moveList; + } -int generate_checks(const Position& pos, MoveStack* mlist, Bitboard dc) { - assert(pos.is_ok()); - assert(!pos.is_check()); + template + ExtMove* generate_pawn_moves(const Position& pos, ExtMove* moveList, Bitboard target) { - int n; - Color us = pos.side_to_move(); - Square ksq = pos.king_square(opposite_color(us)); + // Compute our parametrized parameters at compile time, named according to + // the point of view of white side. + const Color Them = (Us == WHITE ? BLACK : WHITE); + const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB); + const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB); + const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB); + const Square Up = (Us == WHITE ? NORTH : SOUTH); + const Square Right = (Us == WHITE ? NORTH_EAST : SOUTH_WEST); + const Square Left = (Us == WHITE ? NORTH_WEST : SOUTH_EAST); - assert(pos.piece_on(ksq) == king_of_color(opposite_color(us))); + Bitboard emptySquares; - dc = pos.discovered_check_candidates(us); + Bitboard pawnsOn7 = pos.pieces(Us, PAWN) & TRank7BB; + Bitboard pawnsNotOn7 = pos.pieces(Us, PAWN) & ~TRank7BB; - // Pawn moves - if (us == WHITE) - n = generate_pawn_checks(WhitePawnOffsets, pos, dc, ksq, mlist, 0); - else - n = generate_pawn_checks(BlackPawnOffsets, pos, dc, ksq, mlist, 0); + Bitboard enemies = (Type == EVASIONS ? pos.pieces(Them) & target: + Type == CAPTURES ? target : pos.pieces(Them)); - // Pieces moves - Bitboard b = pos.knights(us); - if (b) - n = generate_piece_checks(pos, b, dc, ksq, mlist, n); + // Single and double pawn pushes, no promotions + if (Type != CAPTURES) + { + emptySquares = (Type == QUIETS || Type == QUIET_CHECKS ? target : ~pos.pieces()); - b = pos.bishops(us); - if (b) - n = generate_piece_checks(pos, b, dc, ksq, mlist, n); + Bitboard b1 = shift(pawnsNotOn7) & emptySquares; + Bitboard b2 = shift(b1 & TRank3BB) & emptySquares; - b = pos.rooks(us); - if (b) - n = generate_piece_checks(pos, b, dc, ksq, mlist, n); + if (Type == EVASIONS) // Consider only blocking squares + { + b1 &= target; + b2 &= target; + } - b = pos.queens(us); - if (b) - n = generate_piece_checks(pos, b, dc, ksq, mlist, n); + if (Type == QUIET_CHECKS) + { + Square ksq = pos.square(Them); + + b1 &= pos.attacks_from(ksq, Them); + b2 &= pos.attacks_from(ksq, Them); + + // Add pawn pushes 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. Note that a possible discovery check + // promotion has been already generated amongst the captures. + Bitboard dcCandidates = pos.discovered_check_candidates(); + if (pawnsNotOn7 & dcCandidates) + { + Bitboard dc1 = shift(pawnsNotOn7 & dcCandidates) & emptySquares & ~file_bb(ksq); + Bitboard dc2 = shift(dc1 & TRank3BB) & emptySquares; + + b1 |= dc1; + b2 |= dc2; + } + } - // King moves - Square from = pos.king_square(us); - if (bit_is_set(dc, from)) - { - b = pos.piece_attacks(from) & pos.empty_squares() & ~QueenPseudoAttacks[ksq]; - while (b) - { - Square to = pop_1st_bit(&b); - mlist[n++].move = make_move(from, to); - } - } + while (b1) + { + Square to = pop_lsb(&b1); + *moveList++ = make_move(to - Up, to); + } - // TODO: Castling moves! - - return n; -} + while (b2) + { + Square to = pop_lsb(&b2); + *moveList++ = make_move(to - Up - Up, to); + } + } + // Promotions and underpromotions + if (pawnsOn7 && (Type != EVASIONS || (target & TRank8BB))) + { + if (Type == CAPTURES) + emptySquares = ~pos.pieces(); -/// 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 + if (Type == EVASIONS) + emptySquares &= target; -int generate_evasions(const Position& pos, MoveStack* mlist) { + Bitboard b1 = shift(pawnsOn7) & enemies; + Bitboard b2 = shift(pawnsOn7) & enemies; + Bitboard b3 = shift(pawnsOn7) & emptySquares; - assert(pos.is_ok()); - assert(pos.is_check()); + Square ksq = pos.square(Them); - Color us = pos.side_to_move(); - Color them = opposite_color(us); - Square ksq = pos.king_square(us); - Square from, to; - int n = 0; - - assert(pos.piece_on(ksq) == king_of_color(us)); - - // Generate evasions for king - Bitboard b1 = pos.piece_attacks(ksq) & ~pos.pieces_of_color(us); - Bitboard b2 = pos.occupied_squares(); - clear_bit(&b2, ksq); - - while (b1) - { - Square 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 (!( (bishop_attacks_bb(to, b2) & pos.bishops_and_queens(them)) - || (rook_attacks_bb(to, b2) & pos.rooks_and_queens(them)) - || (pos.piece_attacks(to) & pos.knights(them)) - || (pos.pawn_attacks(us, to) & pos.pawns(them)) - || (pos.piece_attacks(to) & pos.kings(them)))) - - mlist[n++].move = make_move(ksq, to); - } + while (b1) + moveList = make_promotions(moveList, pop_lsb(&b1), ksq); - // 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). - Bitboard checkers = pos.checkers(); + while (b2) + moveList = make_promotions(moveList, pop_lsb(&b2), ksq); - if (!(checkers & (checkers - 1))) // Only one bit set? - { - Square checksq = first_1(checkers); - - assert(pos.color_of_piece_on(checksq) == them); - - // Find pinned pieces - Bitboard not_pinned = ~pos.pinned_pieces(us); - - // Generate captures of the checking piece - - // Pawn captures - b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & not_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); - } else - 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)) ) & not_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. - if (us == WHITE) - n = generate_pawn_blocking_evasions(WhitePawnOffsets, pos, not_pinned, blockSquares, mlist, n); - else - n = generate_pawn_blocking_evasions(BlackPawnOffsets, pos, not_pinned, blockSquares, mlist, n); - - // Pieces moves - b1 = pos.knights(us) & not_pinned; - if (b1) - n = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist, n); - - b1 = pos.bishops(us) & not_pinned; - if (b1) - n = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist, n); - - b1 = pos.rooks(us) & not_pinned; - if (b1) - n = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist, n); - - b1 = pos.queens(us) & not_pinned; - if (b1) - n = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist, n); + while (b3) + moveList = make_promotions(moveList, pop_lsb(&b3), ksq); } - // 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))) + // Standard and en-passant captures + if (Type == CAPTURES || Type == EVASIONS || Type == NON_EVASIONS) { - to = pos.ep_square(); - b1 = pos.pawn_attacks(them, to) & pos.pawns(us); + Bitboard b1 = shift(pawnsNotOn7) & enemies; + Bitboard b2 = shift(pawnsNotOn7) & enemies; - assert(b1 != EmptyBoardBB); - - b1 &= not_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)) - ||(rook_attacks_bb(ksq, b2) & pos.rooks_and_queens(them)))) - - mlist[n++].move = make_ep_move(from, to); + Square to = pop_lsb(&b1); + *moveList++ = make_move(to - Right, to); } - } - } - return n; -} - - -/// 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 -/// 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) { - - assert(pos.is_ok()); - - if (pos.is_check()) - return generate_evasions(pos, mlist); - - // Generate pseudo-legal moves: - int n = generate_captures(pos, mlist); - n += generate_noncaptures(pos, mlist + n); - - Bitboard pinned = pos.pinned_pieces(pos.side_to_move()); - - // Remove illegal moves from the list: - for (int i = 0; i < n; i++) - if (!pos.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 -/// only be used when the side to move is not in check. - -Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) { - assert(pos.is_ok()); - assert(!pos.is_check()); - assert(move_is_ok(m)); - - 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; + while (b2) + { + Square to = pop_lsb(&b2); + *moveList++ = make_move(to - Left, to); + } - Square to = move_to(m); + if (pos.ep_square() != SQ_NONE) + { + assert(rank_of(pos.ep_square()) == relative_rank(Us, RANK_6)); - // 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 MOVE_NONE; + // An en passant capture can be an evasion only if the checking piece + // is the double pushed pawn and so is in the target. Otherwise this + // is a discovery check and we are forced to do otherwise. + if (Type == EVASIONS && !(target & (pos.ep_square() - Up))) + return moveList; - assert(pos.square_is_empty(to)); - assert(pos.piece_on(to - pawn_push(us)) == pawn_of_color(them)); + b1 = pawnsNotOn7 & pos.attacks_from(pos.ep_square(), Them); - // The move is pseudo-legal. If it is legal, return it. - return (pos.move_is_legal(m) ? m : MOVE_NONE); - } + assert(b1); - // 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 MOVE_NONE; - - assert(from == pos.king_square(us)); - assert(to == pos.initial_kr_square(us)); - assert(pos.piece_on(to) == rook_of_color(us)); - - 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 ? m : MOVE_NONE); - } - - 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 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; - - return (!illegal ? m : MOVE_NONE); - } + while (b1) + *moveList++ = make(pop_lsb(&b1), pos.ep_square()); + } + } - // Normal moves - - // 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. - if (type_of_piece(pc) == PAWN) - { - // 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 MOVE_NONE; - - // Proceed according to the square delta between the source and - // destionation squares. - switch (to - from) - { - 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 MOVE_NONE; - break; - - case DELTA_N: - case DELTA_S: - // Pawn push. The destination square must be empty. - if (!pos.square_is_empty(to)) - 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 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 MOVE_NONE; - break; - - default: - return MOVE_NONE; - } - // The move is pseudo-legal. Return it if it is legal. - return (pos.move_is_legal(m) ? m : MOVE_NONE); + return moveList; } - // Luckly we can handle all the other pieces in one go - return ( pos.piece_attacks_square(from, to) - && pos.move_is_legal(m) - && !move_promotion(m) ? m : MOVE_NONE); -} - - -namespace { - int generate_pawn_captures(const PawnOffsets& ofs, const Position& pos, MoveStack* mlist) { + template + ExtMove* generate_moves(const Position& pos, ExtMove* moveList, Color us, + Bitboard target) { - Bitboard pawns = pos.pawns(ofs.us); - Bitboard enemyPieces = pos.pieces_of_color(ofs.them); - Square sq; - int n = 0; + assert(Pt != KING && Pt != PAWN); - // Captures in the a1-h8 (a8-h1 for black) direction - Bitboard b1 = (ofs.forward_right)(pawns) & ~FileABB & enemyPieces; + const Square* pl = pos.squares(us); - // Capturing promotions - Bitboard b2 = b1 & ofs.Rank8BB; - while (b2) + for (Square from = *pl; from != SQ_NONE; from = *++pl) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, QUEEN); - } - - // Capturing non-promotions - b2 = b1 & ~ofs.Rank8BB; - while (b2) - { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - ofs.DELTA_NE, sq); - } + if (Checks) + { + if ( (Pt == BISHOP || Pt == ROOK || Pt == QUEEN) + && !(PseudoAttacks[Pt][from] & target & pos.check_squares(Pt))) + continue; - // Captures in the h1-a8 (h8-a1 for black) direction - b1 = (ofs.forward_left)(pawns) & ~FileHBB & enemyPieces; + if (pos.discovered_check_candidates() & from) + continue; + } - // Capturing promotions - b2 = b1 & ofs.Rank8BB; - while (b2) - { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, QUEEN); - } + Bitboard b = pos.attacks_from(from) & target; - // Capturing non-promotions - b2 = b1 & ~ofs.Rank8BB; - while (b2) - { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - ofs.DELTA_NW, sq); - } + if (Checks) + b &= pos.check_squares(Pt); - // Non-capturing promotions - b1 = (ofs.forward)(pawns) & pos.empty_squares() & Rank8BB; - while (b1) - { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, QUEEN); + while (b) + *moveList++ = make_move(from, pop_lsb(&b)); } - // En passant captures - if (pos.ep_square() != SQ_NONE) - { - assert(ofs.us != WHITE || square_rank(pos.ep_square()) == RANK_6); - assert(ofs.us != BLACK || square_rank(pos.ep_square()) == RANK_3); - - b1 = pawns & pos.pawn_attacks(ofs.them, pos.ep_square()); - assert(b1 != EmptyBoardBB); - - while (b1) - { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_ep_move(sq, pos.ep_square()); - } - } - return n; + return moveList; } - int generate_pawn_noncaptures(const PawnOffsets& ofs, const Position& pos, MoveStack* mlist) { + template + ExtMove* generate_all(const Position& pos, ExtMove* moveList, Bitboard target) { - Bitboard pawns = pos.pawns(ofs.us); - Bitboard enemyPieces = pos.pieces_of_color(ofs.them); - Bitboard emptySquares = pos.empty_squares(); - Bitboard b1, b2; - Square sq; - int n = 0; + const bool Checks = Type == QUIET_CHECKS; - // Underpromotion captures in the a1-h8 (a8-h1 for black) direction - b1 = ofs.forward_right(pawns) & ~FileABB & enemyPieces & ofs.Rank8BB; - while (b1) - { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, ROOK); - mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, BISHOP); - mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, KNIGHT); - } + moveList = generate_pawn_moves(pos, moveList, target); + moveList = generate_moves(pos, moveList, Us, target); + moveList = generate_moves(pos, moveList, Us, target); + moveList = generate_moves< ROOK, Checks>(pos, moveList, Us, target); + moveList = generate_moves< QUEEN, Checks>(pos, moveList, Us, target); - // Underpromotion captures in the h1-a8 (h8-a1 for black) direction - b1 = ofs.forward_left(pawns) & ~FileHBB & enemyPieces & ofs.Rank8BB; - while (b1) + if (Type != QUIET_CHECKS && Type != EVASIONS) { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, ROOK); - mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, BISHOP); - mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, KNIGHT); + Square ksq = pos.square(Us); + Bitboard b = pos.attacks_from(ksq) & target; + while (b) + *moveList++ = make_move(ksq, pop_lsb(&b)); } - // Single pawn pushes - b1 = ofs.forward(pawns) & emptySquares; - b2 = b1 & ofs.Rank8BB; - while (b2) + if (Type != CAPTURES && Type != EVASIONS && pos.can_castle(Us)) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, ROOK); - mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, BISHOP); - mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, KNIGHT); - } - b2 = b1 & ~ofs.Rank8BB; - while (b2) - { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - ofs.DELTA_N, sq); + if (pos.is_chess960()) + { + moveList = generate_castling::right, Checks, true>(pos, moveList, Us); + moveList = generate_castling::right, Checks, true>(pos, moveList, Us); + } + else + { + moveList = generate_castling::right, Checks, false>(pos, moveList, Us); + moveList = generate_castling::right, Checks, false>(pos, moveList, Us); + } } - // Double pawn pushes - b2 = (ofs.forward(b1 & ofs.Rank3BB)) & emptySquares; - while (b2) - { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - ofs.DELTA_N - ofs.DELTA_N, sq); - } - return n; + return moveList; } +} // namespace - template - int generate_piece_moves(const Position &pos, MoveStack *mlist, - Color side, Bitboard target) { - Square from, to; - Bitboard b; - int n = 0; +/// generate generates all pseudo-legal captures and queen +/// promotions. Returns a pointer to the end of the move list. +/// +/// generate generates all pseudo-legal non-captures and +/// underpromotions. Returns a pointer to the end of the move list. +/// +/// generate generates all pseudo-legal captures and +/// non-captures. Returns a pointer to the end of the move list. - for (int i = 0; i < pos.piece_count(side, Piece); i++) - { - from = pos.piece_list(side, Piece, i); - b = pos.piece_attacks(from) & target; - while (b) - { - to = pop_1st_bit(&b); - mlist[n++].move = make_move(from, to); - } - } - return n; - } +template +ExtMove* generate(const Position& pos, ExtMove* moveList) { + assert(Type == CAPTURES || Type == QUIETS || Type == NON_EVASIONS); + assert(!pos.checkers()); - int generate_castle_moves(const Position &pos, MoveStack *mlist, Color us) { + Color us = pos.side_to_move(); - int n = 0; + Bitboard target = Type == CAPTURES ? pos.pieces(~us) + : Type == QUIETS ? ~pos.pieces() + : Type == NON_EVASIONS ? ~pos.pieces(us) : 0; - if (pos.can_castle(us)) - { - Color them = opposite_color(us); - Square ksq = pos.king_square(us); + return us == WHITE ? generate_all(pos, moveList, target) + : generate_all(pos, moveList, target); +} - assert(pos.piece_on(ksq) == king_of_color(us)); +// Explicit template instantiations +template ExtMove* generate(const Position&, ExtMove*); +template ExtMove* generate(const Position&, ExtMove*); +template ExtMove* generate(const Position&, ExtMove*); - 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; - - assert(pos.piece_on(rsq) == rook_of_color(us)); - - 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; - - if (!illegal) - mlist[n++].move = make_castle_move(ksq, rsq); - } - - 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 s; - bool illegal = false; - - assert(pos.piece_on(rsq) == rook_of_color(us)); - - 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)) - 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); - } - } - return n; - } - template - int generate_piece_checks(const Position& pos, Bitboard target, Bitboard dc, - Square ksq, MoveStack* mlist, int n) { +/// generate generates all pseudo-legal non-captures and knight +/// underpromotions that give check. Returns a pointer to the end of the move list. +template<> +ExtMove* generate(const Position& pos, ExtMove* moveList) { - // Discovered checks - Bitboard b = target & dc; - while (b) - { - Square from = pop_1st_bit(&b); - Bitboard bb = pos.piece_attacks(from) & pos.empty_squares(); - while (bb) - { - Square to = pop_1st_bit(&bb); - mlist[n++].move = make_move(from, to); - } - } + assert(!pos.checkers()); - // Direct checks - b = target & ~dc; - Bitboard checkSqs = pos.piece_attacks(ksq) & pos.empty_squares(); - while (b) - { - Square from = pop_1st_bit(&b); - Bitboard bb = pos.piece_attacks(from) & checkSqs; - while (bb) - { - Square to = pop_1st_bit(&bb); - mlist[n++].move = make_move(from, to); - } - } - return n; - } + Color us = pos.side_to_move(); + Bitboard dc = pos.discovered_check_candidates(); - int generate_pawn_checks(const PawnOffsets& ofs, const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist, int n) + while (dc) { - // 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. - Bitboard empty = pos.empty_squares(); + Square from = pop_lsb(&dc); + PieceType pt = type_of(pos.piece_on(from)); - // Find all friendly pawns not on the enemy king's file - Bitboard b1 = pos.pawns(pos.side_to_move()) & ~file_bb(ksq), b2, b3; + if (pt == PAWN) + continue; // Will be generated together with direct checks - // Discovered checks, single pawn pushes - b2 = b3 = (ofs.forward)(b1 & dc) & ~ofs.Rank8BB & empty; - while (b3) - { - Square to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - ofs.DELTA_N, to); - } + Bitboard b = pos.attacks_from(Piece(pt), from) & ~pos.pieces(); - // Discovered checks, double pawn pushes - b3 = (ofs.forward)(b2 & ofs.Rank3BB) & empty; - while (b3) - { - Square to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to); - } + if (pt == KING) + b &= ~PseudoAttacks[QUEEN][pos.square(~us)]; - // Direct checks. These are possible only for pawns on neighboring files - // of the enemy king + while (b) + *moveList++ = make_move(from, pop_lsb(&b)); + } - b1 &= (~dc & neighboring_files_bb(ksq)); // FIXME why ~dc ?? + return us == WHITE ? generate_all(pos, moveList, ~pos.pieces()) + : generate_all(pos, moveList, ~pos.pieces()); +} - // Direct checks, single pawn pushes - b2 = (ofs.forward)(b1) & empty; - b3 = b2 & pos.pawn_attacks(ofs.them, ksq); - while (b3) - { - Square to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - ofs.DELTA_N, to); - } - // Direct checks, double pawn pushes - b3 = (ofs.forward)(b2 & ofs.Rank3BB) & empty & pos.pawn_attacks(ofs.them, ksq); - while (b3) - { - Square to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to); - } - return n; - } +/// generate generates all pseudo-legal check evasions when the side +/// to move is in check. Returns a pointer to the end of the move list. +template<> +ExtMove* generate(const Position& pos, ExtMove* moveList) { + assert(pos.checkers()); - template - int generate_piece_blocking_evasions(const Position& pos, Bitboard b, - Bitboard blockSquares, MoveStack* mlist, int n) { - while (b) - { - Square from = pop_1st_bit(&b); - Bitboard bb = pos.piece_attacks(from) & blockSquares; - while (bb) - { - Square to = pop_1st_bit(&bb); - mlist[n++].move = make_move(from, to); - } - } - return n; + Color us = pos.side_to_move(); + Square ksq = pos.square(us); + Bitboard sliderAttacks = 0; + Bitboard sliders = pos.checkers() & ~pos.pieces(KNIGHT, PAWN); + + // Find all the squares attacked by slider checkers. We will remove them from + // the king evasions in order to skip known illegal moves, which avoids any + // useless legality checks later on. + while (sliders) + { + Square checksq = pop_lsb(&sliders); + sliderAttacks |= LineBB[checksq][ksq] ^ checksq; } + // Generate evasions for king, capture and non capture moves + Bitboard b = pos.attacks_from(ksq) & ~pos.pieces(us) & ~sliderAttacks; + while (b) + *moveList++ = make_move(ksq, pop_lsb(&b)); - int generate_pawn_blocking_evasions(const PawnOffsets& ofs, const Position& pos, Bitboard not_pinned, - Bitboard blockSquares, MoveStack* mlist, int n) { - // Find non-pinned pawns - Bitboard b1 = pos.pawns(ofs.us) & not_pinned; + if (more_than_one(pos.checkers())) + return moveList; // Double check, only a king move can save the day - // Single pawn pushes. We don't have to AND with empty squares here, - // because the blocking squares will always be empty. - Bitboard b2 = (ofs.forward)(b1) & blockSquares; - while (b2) - { - Square to = pop_1st_bit(&b2); + // Generate blocking evasions or captures of the checking piece + Square checksq = lsb(pos.checkers()); + Bitboard target = between_bb(checksq, ksq) | checksq; - assert(pos.piece_on(to) == EMPTY); + return us == WHITE ? generate_all(pos, moveList, target) + : generate_all(pos, moveList, target); +} - if (square_rank(to) == ofs.RANK_8) - { - mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, QUEEN); - mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, ROOK); - mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, BISHOP); - mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, KNIGHT); - } else - mlist[n++].move = make_move(to - ofs.DELTA_N, to); - } - // Double pawn pushes - b2 = (ofs.forward)((ofs.forward)(b1) & pos.empty_squares() & ofs.Rank3BB) & blockSquares; - while (b2) - { - Square to = pop_1st_bit(&b2); +/// generate generates all the legal moves in the given position - assert(pos.piece_on(to) == EMPTY); - assert(ofs.us != WHITE || square_rank(to) == RANK_4); - assert(ofs.us != BLACK || square_rank(to) == RANK_5); +template<> +ExtMove* generate(const Position& pos, ExtMove* moveList) { - mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to); - } - return n; - } + Bitboard pinned = pos.pinned_pieces(pos.side_to_move()); + Square ksq = pos.square(pos.side_to_move()); + ExtMove* cur = moveList; + + moveList = pos.checkers() ? generate(pos, moveList) + : generate(pos, moveList); + while (cur != moveList) + if ( (pinned || from_sq(*cur) == ksq || type_of(*cur) == ENPASSANT) + && !pos.legal(*cur)) + *cur = (--moveList)->move; + else + ++cur; + + return moveList; }