/* Glaurung, a UCI chess playing engine. Copyright (C) 2004-2008 Tord Romstad Glaurung 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, 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 //// 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); } //// //// Functions //// /// generate_captures generates() all pseudo-legal captures and queen /// promotions. The return value is the number of moves generated. 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; assert(pos.is_ok()); assert(!pos.is_check()); 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); return n; } /// 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) { Color us = pos.side_to_move(); Bitboard target = pos.empty_squares(); int n = 0; assert(pos.is_ok()); assert(!pos.is_check()); 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); return n; } /// 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. 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; assert(pos.is_ok()); assert(!pos.is_check()); us = pos.side_to_move(); them = opposite_color(us); ksq = pos.king_square(them); assert(pos.piece_on(ksq) == king_of_color(them)); 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++. :-( 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); // 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); } // Direct checks. These are possible only for pawns on neighboring files // of the enemy king: b1 &= (~dc & neighboring_files_bb(ksq)); // 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); } // 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. // Find all friendly pawns not on the enemy king's file: b1 = pos.pawns(us) & ~file_bb(ksq); // 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); } // 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); } // Direct checks. These are possible only for pawns on neighboring files // of the enemy king: b1 &= (~dc & neighboring_files_bb(ksq)); // 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); } // 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); } } // 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); } } } // 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); } } } // 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); } } } // 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); } } // TODO: Castling moves! return n; } /// 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 int generate_evasions(const Position &pos, MoveStack *mlist) { Color us, them; Bitboard checkers = pos.checkers(); Bitboard pinned, b1, b2; Square ksq, from, to; int n = 0; assert(pos.is_ok()); assert(pos.is_check()); 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); } // 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(pawn_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); } // 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); } // 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); } } // 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); } } } // 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); } } } 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); else { int i, n; Bitboard pinned = pos.pinned_pieces(pos.side_to_move()); // Generate pseudo-legal moves: n = generate_captures(pos, mlist); n += generate_noncaptures(pos, mlist + n); // 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; } 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) { Color us, them; Square from, to; Piece pc; assert(pos.is_ok()); assert(!pos.is_check()); assert(move_is_ok(m)); us = pos.side_to_move(); them = opposite_color(us); from = move_from(m); 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); // En passant moves: if(move_is_ep(m)) { // The piece must be a pawn: if(type_of_piece(pc) != PAWN) return MOVE_NONE; // 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)) == 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; } // 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; 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; 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(!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; } // 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; 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; 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 KING: if(pos.king_attacks_square(from, to) && pos.move_is_legal(m) && !move_promotion(m)) return m; else return MOVE_NONE; break; default: assert(false); } } assert(false); return MOVE_NONE; } 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; // Promotions: b2 = b1 & Rank8BB; while(b2) { sq = pop_1st_bit(&b2); mlist[n++].move = make_promotion_move(sq - DELTA_NE, sq, QUEEN); } // Non-promotions: b2 = b1 & ~Rank8BB; while(b2) { sq = pop_1st_bit(&b2); mlist[n++].move = make_move(sq - DELTA_NE, sq); } // Captures in the h1-a8 direction: b1 = (pawns << 7) & ~FileHBB & enemyPieces; // Promotions: b2 = b1 & Rank8BB; while(b2) { sq = pop_1st_bit(&b2); mlist[n++].move = make_promotion_move(sq - DELTA_NW, sq, QUEEN); } // Non-promotions: b2 = b1 & ~Rank8BB; while(b2) { sq = pop_1st_bit(&b2); mlist[n++].move = make_move(sq - DELTA_NW, sq); } // 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); } // 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()); } } return n; } 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; // Captures in the a8-h1 direction: b1 = (pawns >> 7) & ~FileABB & enemyPieces; // Promotions: b2 = b1 & Rank1BB; while(b2) { sq = pop_1st_bit(&b2); mlist[n++].move = make_promotion_move(sq - DELTA_SE, sq, QUEEN); } // Non-promotions: b2 = b1 & ~Rank1BB; while(b2) { sq = pop_1st_bit(&b2); mlist[n++].move = make_move(sq - DELTA_SE, sq); } // 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); } // Non-promotions: b2 = b1 & ~Rank1BB; while(b2) { sq = pop_1st_bit(&b2); mlist[n++].move = make_move(sq - DELTA_SW, sq); } // 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); } // 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()); } } return n; } 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); } // 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); } // 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); } b2 = b1 & ~Rank8BB; while(b2) { sq = pop_1st_bit(&b2); mlist[n++].move = make_move(sq - DELTA_N, sq); } // 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); } return n; } 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); } // 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); } // 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); } return n; } 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); } } return n; } 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; } 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); } } return n; } 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); } } return n; } int generate_king_moves(const Position &pos, MoveStack *mlist, Square from, Bitboard target) { 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); } return n; } int generate_castle_moves(const Position &pos, MoveStack *mlist, Color us) { int n = 0; 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; 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; } }