2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2009 Marco Costalba
6 Stockfish is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 Stockfish is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
30 // Simple macro to wrap a very common while loop, no facny, no flexibility,
31 // hardcoded list name 'mlist' and from square 'from'.
32 #define SERIALIZE_MOVES(b) while (b) (*mlist++).move = make_move(from, pop_1st_bit(&b))
34 // Version used for pawns, where the 'from' square is given as a delta from the 'to' square
35 #define SERIALIZE_MOVES_D(b, d) while (b) { to = pop_1st_bit(&b); (*mlist++).move = make_move(to + (d), to); }
38 //// Local definitions
56 bool castling_is_check(const Position&, CastlingSide);
59 template<CastlingSide Side>
60 MoveStack* generate_castle_moves(const Position&, MoveStack*);
62 template<Color Us, SquareDelta Diagonal>
63 MoveStack* generate_pawn_captures_diagonal(MoveStack*, Bitboard, Bitboard, bool);
65 template<Color Us, MoveType Type>
66 MoveStack* generate_pawn_moves(const Position&, MoveStack*, Bitboard = EmptyBoardBB,
67 Square = SQ_NONE, Bitboard = EmptyBoardBB);
69 template<Color Us, SquareDelta Direction>
70 inline Bitboard move_pawns(Bitboard p) {
72 if (Direction == DELTA_N)
73 return Us == WHITE ? p << 8 : p >> 8;
74 else if (Direction == DELTA_NE)
75 return Us == WHITE ? p << 9 : p >> 7;
76 else if (Direction == DELTA_NW)
77 return Us == WHITE ? p << 7 : p >> 9;
82 // Template generate_piece_checks() with specializations
84 MoveStack* generate_piece_checks(const Position&, MoveStack*, Color, Bitboard, Square);
87 inline MoveStack* generate_piece_checks<PAWN>(const Position& p, MoveStack* m, Color us, Bitboard dc, Square ksq) {
89 return (us == WHITE ? generate_pawn_moves<WHITE, CHECK>(p, m, dc, ksq)
90 : generate_pawn_moves<BLACK, CHECK>(p, m, dc, ksq));
93 // Template generate_piece_moves() with specializations and overloads
95 MoveStack* generate_piece_moves(const Position&, MoveStack*, Color, Bitboard);
98 MoveStack* generate_piece_moves<KING>(const Position&, MoveStack*, Color, Bitboard);
100 template<PieceType Piece, MoveType Type>
101 inline MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us) {
103 assert(Piece == PAWN);
104 assert(Type == CAPTURE || Type == NON_CAPTURE);
106 return (us == WHITE ? generate_pawn_moves<WHITE, Type>(p, m)
107 : generate_pawn_moves<BLACK, Type>(p, m));
111 MoveStack* generate_piece_moves(const Position&, MoveStack*, Color, Bitboard, Bitboard);
114 inline MoveStack* generate_piece_moves<PAWN>(const Position& p, MoveStack* m,
115 Color us, Bitboard t, Bitboard pnd) {
117 return (us == WHITE ? generate_pawn_moves<WHITE, EVASION>(p, m, pnd, SQ_NONE, t)
118 : generate_pawn_moves<BLACK, EVASION>(p, m, pnd, SQ_NONE, t));
128 /// generate_captures() generates all pseudo-legal captures and queen
129 /// promotions. Returns a pointer to the end of the move list.
131 MoveStack* generate_captures(const Position& pos, MoveStack* mlist) {
134 assert(!pos.is_check());
136 Color us = pos.side_to_move();
137 Bitboard target = pos.pieces_of_color(opposite_color(us));
139 mlist = generate_piece_moves<QUEEN>(pos, mlist, us, target);
140 mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
141 mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
142 mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
143 mlist = generate_piece_moves<PAWN, CAPTURE>(pos, mlist, us);
144 return generate_piece_moves<KING>(pos, mlist, us, target);
148 /// generate_noncaptures() generates all pseudo-legal non-captures and
149 /// underpromotions. Returns a pointer to the end of the move list.
151 MoveStack* generate_noncaptures(const Position& pos, MoveStack* mlist) {
154 assert(!pos.is_check());
156 Color us = pos.side_to_move();
157 Bitboard target = pos.empty_squares();
159 mlist = generate_piece_moves<PAWN, NON_CAPTURE>(pos, mlist, us);
160 mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
161 mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
162 mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
163 mlist = generate_piece_moves<QUEEN>(pos, mlist, us, target);
164 mlist = generate_piece_moves<KING>(pos, mlist, us, target);
165 mlist = generate_castle_moves<KING_SIDE>(pos, mlist);
166 return generate_castle_moves<QUEEN_SIDE>(pos, mlist);
170 /// generate_non_capture_checks() generates all pseudo-legal non-captures and
171 /// underpromotions that give check. Returns a pointer to the end of the move list.
173 MoveStack* generate_non_capture_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
176 assert(!pos.is_check());
178 Color us = pos.side_to_move();
179 Square ksq = pos.king_square(opposite_color(us));
181 assert(pos.piece_on(ksq) == piece_of_color_and_type(opposite_color(us), KING));
184 mlist = generate_piece_checks<PAWN>(pos, mlist, us, dc, ksq);
185 mlist = generate_piece_checks<KNIGHT>(pos, mlist, us, dc, ksq);
186 mlist = generate_piece_checks<BISHOP>(pos, mlist, us, dc, ksq);
187 mlist = generate_piece_checks<ROOK>(pos, mlist, us, dc, ksq);
188 mlist = generate_piece_checks<QUEEN>(pos, mlist, us, dc, ksq);
189 mlist = generate_piece_checks<KING>(pos, mlist, us, dc, ksq);
191 // Castling moves that give check. Very rare but nice to have!
192 if ( pos.can_castle_queenside(us)
193 && (square_rank(ksq) == square_rank(pos.king_square(us)) || square_file(ksq) == FILE_D)
194 && castling_is_check(pos, QUEEN_SIDE))
195 mlist = generate_castle_moves<QUEEN_SIDE>(pos, mlist);
197 if ( pos.can_castle_kingside(us)
198 && (square_rank(ksq) == square_rank(pos.king_square(us)) || square_file(ksq) == FILE_F)
199 && castling_is_check(pos, KING_SIDE))
200 mlist = generate_castle_moves<KING_SIDE>(pos, mlist);
206 /// generate_evasions() generates all check evasions when the side to move is
207 /// in check. Unlike the other move generation functions, this one generates
208 /// only legal moves. Returns a pointer to the end of the move list.
210 MoveStack* generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pinned) {
213 assert(pos.is_check());
216 Color us = pos.side_to_move();
217 Color them = opposite_color(us);
218 Square ksq = pos.king_square(us);
219 Bitboard sliderAttacks = EmptyBoardBB;
220 Bitboard checkers = pos.checkers();
222 assert(pos.piece_on(ksq) == piece_of_color_and_type(us, KING));
224 // The bitboard of occupied pieces without our king
225 Bitboard b_noKing = pos.occupied_squares();
226 clear_bit(&b_noKing, ksq);
228 // Find squares attacked by slider checkers, we will remove
229 // them from the king evasions set so to avoid a couple
230 // of cycles in the slow king evasions legality check loop
231 // and to be able to use attackers_to().
232 Bitboard b = checkers & pos.pieces(BISHOP, QUEEN);
235 from = pop_1st_bit(&b);
236 sliderAttacks |= bishop_attacks_bb(from, b_noKing);
239 b = checkers & pos.pieces(ROOK, QUEEN);
242 from = pop_1st_bit(&b);
243 sliderAttacks |= rook_attacks_bb(from, b_noKing);
246 // Generate evasions for king, capture and non capture moves
247 Bitboard enemy = pos.pieces_of_color(them);
248 Bitboard b1 = pos.attacks_from<KING>(ksq) & ~pos.pieces_of_color(us) & ~sliderAttacks;
251 // Note that we can use attackers_to() only because we have already
252 // removed from b1 the squares attacked by slider checkers.
253 to = pop_1st_bit(&b1);
254 if (!(pos.attackers_to(to) & enemy))
255 (*mlist++).move = make_move(ksq, to);
258 // Generate evasions for other pieces only if not double check. We use a
259 // simple bit twiddling hack here rather than calling count_1s in order to
260 // save some time (we know that pos.checkers() has at most two nonzero bits).
261 if (!(checkers & (checkers - 1))) // Only one bit set?
263 Square checksq = first_1(checkers);
265 assert(pos.color_of_piece_on(checksq) == them);
267 // Generate captures of the checking piece
270 b1 = pos.attacks_from<PAWN>(checksq, them) & pos.pieces(PAWN, us) & ~pinned;
273 from = pop_1st_bit(&b1);
274 if (relative_rank(us, checksq) == RANK_8)
276 (*mlist++).move = make_promotion_move(from, checksq, QUEEN);
277 (*mlist++).move = make_promotion_move(from, checksq, ROOK);
278 (*mlist++).move = make_promotion_move(from, checksq, BISHOP);
279 (*mlist++).move = make_promotion_move(from, checksq, KNIGHT);
281 (*mlist++).move = make_move(from, checksq);
285 b1 = ( (pos.attacks_from<KNIGHT>(checksq) & pos.pieces(KNIGHT, us))
286 | (pos.attacks_from<BISHOP>(checksq) & pos.pieces(BISHOP, QUEEN, us))
287 | (pos.attacks_from<ROOK>(checksq) & pos.pieces(ROOK, QUEEN, us)) ) & ~pinned;
291 from = pop_1st_bit(&b1);
292 (*mlist++).move = make_move(from, checksq);
295 // Blocking check evasions are possible only if the checking piece is a slider
298 Bitboard blockSquares = squares_between(checksq, ksq);
300 assert((pos.occupied_squares() & blockSquares) == EmptyBoardBB);
304 mlist = generate_piece_moves<PAWN>(pos, mlist, us, blockSquares, pinned);
305 mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, blockSquares, pinned);
306 mlist = generate_piece_moves<BISHOP>(pos, mlist, us, blockSquares, pinned);
307 mlist = generate_piece_moves<ROOK>(pos, mlist, us, blockSquares, pinned);
308 mlist = generate_piece_moves<QUEEN>(pos, mlist, us, blockSquares, pinned);
312 // Finally, the special case of en passant captures. An en passant
313 // capture can only be a check evasion if the check is not a discovered
314 // check. If pos.ep_square() is set, the last move made must have been
315 // a double pawn push. If, furthermore, the checking piece is a pawn,
316 // an en passant check evasion may be possible.
317 if (pos.ep_square() != SQ_NONE && (checkers & pos.pieces(PAWN, them)))
319 to = pos.ep_square();
320 b1 = pos.attacks_from<PAWN>(to, them) & pos.pieces(PAWN, us);
322 // The checking pawn cannot be a discovered (bishop) check candidate
323 // otherwise we were in check also before last double push move.
324 assert(!bit_is_set(pos.discovered_check_candidates(them), checksq));
325 assert(count_1s(b1) == 1 || count_1s(b1) == 2);
330 from = pop_1st_bit(&b1);
331 // Move is always legal because checking pawn is not a discovered
332 // check candidate and our capturing pawn has been already tested
333 // against pinned pieces.
334 (*mlist++).move = make_ep_move(from, to);
342 /// generate_moves() computes a complete list of legal or pseudo-legal moves in
343 /// the current position. This function is not very fast, and should be used
344 /// only in non time-critical paths.
346 MoveStack* generate_moves(const Position& pos, MoveStack* mlist, bool pseudoLegal) {
350 Bitboard pinned = pos.pinned_pieces(pos.side_to_move());
353 return generate_evasions(pos, mlist, pinned);
355 // Generate pseudo-legal moves
356 MoveStack* last = generate_captures(pos, mlist);
357 last = generate_noncaptures(pos, last);
361 // Remove illegal moves from the list
362 for (MoveStack* cur = mlist; cur != last; cur++)
363 if (!pos.pl_move_is_legal(cur->move, pinned))
365 cur->move = (--last)->move;
372 /// move_is_legal() takes a position and a (not necessarily pseudo-legal)
373 /// move and tests whether the move is legal. This version is not very fast
374 /// and should be used only in non time-critical paths.
376 bool move_is_legal(const Position& pos, const Move m) {
378 MoveStack mlist[256];
379 MoveStack* last = generate_moves(pos, mlist, true);
380 for (MoveStack* cur = mlist; cur != last; cur++)
382 return pos.pl_move_is_legal(m);
388 /// Fast version of move_is_legal() that takes a position a move and a
389 /// bitboard of pinned pieces as input, and tests whether the move is legal.
390 /// This version must only be used when the side to move is not in check.
392 bool move_is_legal(const Position& pos, const Move m, Bitboard pinned) {
395 assert(!pos.is_check());
396 assert(move_is_ok(m));
397 assert(pinned == pos.pinned_pieces(pos.side_to_move()));
399 // Use a slower but simpler function for uncommon cases
400 if (move_is_ep(m) || move_is_castle(m))
401 return move_is_legal(pos, m);
403 Color us = pos.side_to_move();
404 Color them = opposite_color(us);
405 Square from = move_from(m);
406 Square to = move_to(m);
407 Piece pc = pos.piece_on(from);
409 // If the from square is not occupied by a piece belonging to the side to
410 // move, the move is obviously not legal.
411 if (color_of_piece(pc) != us)
414 // The destination square cannot be occupied by a friendly piece
415 if (pos.color_of_piece_on(to) == us)
418 // Handle the special case of a pawn move
419 if (type_of_piece(pc) == PAWN)
421 // Move direction must be compatible with pawn color
422 int direction = to - from;
423 if ((us == WHITE) != (direction > 0))
426 // A pawn move is a promotion iff the destination square is
427 // on the 8/1th rank.
428 if (( (square_rank(to) == RANK_8 && us == WHITE)
429 ||(square_rank(to) == RANK_1 && us != WHITE)) != bool(move_is_promotion(m)))
432 // Proceed according to the square delta between the origin and
433 // destination squares.
440 // Capture. The destination square must be occupied by an enemy
441 // piece (en passant captures was handled earlier).
442 if (pos.color_of_piece_on(to) != them)
448 // Pawn push. The destination square must be empty.
449 if (!pos.square_is_empty(to))
454 // Double white pawn push. The destination square must be on the fourth
455 // rank, and both the destination square and the square between the
456 // source and destination squares must be empty.
457 if ( square_rank(to) != RANK_4
458 || !pos.square_is_empty(to)
459 || !pos.square_is_empty(from + DELTA_N))
464 // Double black pawn push. The destination square must be on the fifth
465 // rank, and both the destination square and the square between the
466 // source and destination squares must be empty.
467 if ( square_rank(to) != RANK_5
468 || !pos.square_is_empty(to)
469 || !pos.square_is_empty(from + DELTA_S))
476 // The move is pseudo-legal, check if it is also legal
477 return pos.pl_move_is_legal(m, pinned);
480 // Luckly we can handle all the other pieces in one go
481 return ( bit_is_set(pos.attacks_from(pc, from), to)
482 && pos.pl_move_is_legal(m, pinned)
483 && !move_is_promotion(m));
489 template<PieceType Piece>
490 MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
495 for (int i = 0, e = pos.piece_count(us, Piece); i < e; i++)
497 from = pos.piece_list(us, Piece, i);
498 b = pos.attacks_from<Piece>(from) & target;
505 MoveStack* generate_piece_moves<KING>(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
508 Square from = pos.king_square(us);
510 b = pos.attacks_from<KING>(from) & target;
515 template<PieceType Piece>
516 MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist,
517 Color us, Bitboard target, Bitboard pinned) {
521 for (int i = 0, e = pos.piece_count(us, Piece); i < e; i++)
523 from = pos.piece_list(us, Piece, i);
524 if (pinned && bit_is_set(pinned, from))
527 b = pos.attacks_from<Piece>(from) & target;
533 template<Color Us, SquareDelta Diagonal>
534 MoveStack* generate_pawn_captures_diagonal(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces, bool promotion) {
536 // Calculate our parametrized parameters at compile time
537 const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
538 const Bitboard TFileABB = (Diagonal == DELTA_NE ? FileABB : FileHBB);
539 const SquareDelta TDELTA_NE = (Us == WHITE ? DELTA_NE : DELTA_SE);
540 const SquareDelta TDELTA_NW = (Us == WHITE ? DELTA_NW : DELTA_SW);
541 const SquareDelta TTDELTA_NE = (Diagonal == DELTA_NE ? TDELTA_NE : TDELTA_NW);
545 // Captures in the a1-h8 (a8-h1 for black) diagonal or in the h1-a8 (h8-a1 for black)
546 Bitboard b1 = move_pawns<Us, Diagonal>(pawns) & ~TFileABB & enemyPieces;
548 // Capturing promotions
551 Bitboard b2 = b1 & TRank8BB;
555 to = pop_1st_bit(&b2);
556 (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, QUEEN);
560 // Capturing non-promotions
561 SERIALIZE_MOVES_D(b1, -TTDELTA_NE);
565 template<Color Us, MoveType Type>
566 MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard dcp,
567 Square ksq, Bitboard blockSquares) {
569 // Calculate our parametrized parameters at compile time
570 const Color Them = (Us == WHITE ? BLACK : WHITE);
571 const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
572 const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
573 const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
574 const SquareDelta TDELTA_NE = (Us == WHITE ? DELTA_NE : DELTA_SE);
575 const SquareDelta TDELTA_NW = (Us == WHITE ? DELTA_NW : DELTA_SW);
576 const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
578 Bitboard b1, b2, dcPawns1, dcPawns2;
580 Bitboard pawns = (Type != EVASION ? pos.pieces(PAWN, Us) : pos.pieces(PAWN, Us) & ~dcp);
581 Bitboard emptySquares = pos.empty_squares();
582 bool possiblePromotion = (pawns & TRank7BB);
586 // Standard captures and capturing promotions in both directions
587 Bitboard enemyPieces = pos.pieces_of_color(opposite_color(Us));
588 mlist = generate_pawn_captures_diagonal<Us, DELTA_NE>(mlist, pawns, enemyPieces, possiblePromotion);
589 mlist = generate_pawn_captures_diagonal<Us, DELTA_NW>(mlist, pawns, enemyPieces, possiblePromotion);
592 if (possiblePromotion)
594 // When generating checks consider under-promotion moves (both captures
595 // and non captures) only if can give a discovery check. Note that dcp
596 // is dc bitboard or pinned bitboard when Type == EVASION.
597 Bitboard pp = (Type == CHECK ? pawns & dcp : pawns);
599 if (Type != EVASION && Type != CAPTURE)
601 Bitboard enemyPieces = pos.pieces_of_color(opposite_color(Us));
603 // Underpromotion captures in the a1-h8 (a8-h1 for black) direction
604 b1 = move_pawns<Us, DELTA_NE>(pp) & ~FileABB & enemyPieces & TRank8BB;
607 to = pop_1st_bit(&b1);
608 (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, ROOK);
609 (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, BISHOP);
610 (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, KNIGHT);
613 // Underpromotion captures in the h1-a8 (h8-a1 for black) direction
614 b1 = move_pawns<Us, DELTA_NW>(pp) & ~FileHBB & enemyPieces & TRank8BB;
617 to = pop_1st_bit(&b1);
618 (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, ROOK);
619 (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, BISHOP);
620 (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, KNIGHT);
624 // Underpromotion pawn pushes. Also promotion for evasions and captures.
625 b1 = move_pawns<Us, DELTA_N>(pp) & TRank8BB;
626 b1 &= (Type == EVASION ? blockSquares : emptySquares);
630 to = pop_1st_bit(&b1);
631 if (Type == EVASION || Type == CAPTURE)
632 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN);
636 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, ROOK);
637 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, BISHOP);
638 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, KNIGHT);
645 // En passant captures
646 if (pos.ep_square() != SQ_NONE)
648 assert(Us != WHITE || square_rank(pos.ep_square()) == RANK_6);
649 assert(Us != BLACK || square_rank(pos.ep_square()) == RANK_3);
651 Bitboard b1 = pawns & pos.attacks_from<PAWN>(pos.ep_square(), Them);
652 assert(b1 != EmptyBoardBB);
656 to = pop_1st_bit(&b1);
657 (*mlist++).move = make_ep_move(to, pos.ep_square());
663 dcPawns1 = dcPawns2 = EmptyBoardBB;
664 if (Type == CHECK && (pawns & dcp))
666 // Pawn moves which gives discovered check. This is possible only if the
667 // pawn is not on the same file as the enemy king, because we don't
668 // generate captures.
669 dcPawns1 = move_pawns<Us, DELTA_N>(pawns & dcp & ~file_bb(ksq)) & emptySquares & ~TRank8BB;
670 dcPawns2 = move_pawns<Us, DELTA_N>(dcPawns1 & TRank3BB) & emptySquares;
673 // Single pawn pushes
674 b1 = move_pawns<Us, DELTA_N>(pawns) & emptySquares & ~TRank8BB;
675 b2 = (Type == CHECK ? (b1 & pos.attacks_from<PAWN>(ksq, Them)) | dcPawns1 :
676 (Type == EVASION ? b1 & blockSquares : b1));
677 SERIALIZE_MOVES_D(b2, -TDELTA_N);
679 // Double pawn pushes
680 b1 = move_pawns<Us, DELTA_N>(b1 & TRank3BB) & emptySquares;
681 b2 = (Type == CHECK ? (b1 & pos.attacks_from<PAWN>(ksq, Them)) | dcPawns2 :
682 (Type == EVASION ? b1 & blockSquares : b1));
683 SERIALIZE_MOVES_D(b2, -TDELTA_N -TDELTA_N);
687 template<PieceType Piece>
688 MoveStack* generate_piece_checks(const Position& pos, MoveStack* mlist, Color us,
689 Bitboard dc, Square ksq) {
691 Bitboard target = pos.pieces(Piece, us);
693 // Discovered non-capture checks
694 Bitboard b = target & dc;
696 assert(Piece != QUEEN || !b);
700 Square from = pop_1st_bit(&b);
701 Bitboard bb = pos.attacks_from<Piece>(from) & pos.empty_squares();
703 bb &= ~QueenPseudoAttacks[ksq];
708 // Direct non-capture checks
710 Bitboard checkSqs = pos.attacks_from<Piece>(ksq) & pos.empty_squares();
711 if (Piece == KING || !checkSqs)
716 Square from = pop_1st_bit(&b);
717 if ( (Piece == QUEEN && !(QueenPseudoAttacks[from] & checkSqs))
718 || (Piece == ROOK && !(RookPseudoAttacks[from] & checkSqs))
719 || (Piece == BISHOP && !(BishopPseudoAttacks[from] & checkSqs)))
722 Bitboard bb = pos.attacks_from<Piece>(from) & checkSqs;
728 template<CastlingSide Side>
729 MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist) {
731 Color us = pos.side_to_move();
733 if ( (Side == KING_SIDE && pos.can_castle_kingside(us))
734 ||(Side == QUEEN_SIDE && pos.can_castle_queenside(us)))
736 Color them = opposite_color(us);
737 Square ksq = pos.king_square(us);
739 assert(pos.piece_on(ksq) == piece_of_color_and_type(us, KING));
741 Square rsq = (Side == KING_SIDE ? pos.initial_kr_square(us) : pos.initial_qr_square(us));
742 Square s1 = relative_square(us, Side == KING_SIDE ? SQ_G1 : SQ_C1);
743 Square s2 = relative_square(us, Side == KING_SIDE ? SQ_F1 : SQ_D1);
745 bool illegal = false;
747 assert(pos.piece_on(rsq) == piece_of_color_and_type(us, ROOK));
749 // It is a bit complicated to correctly handle Chess960
750 for (s = Min(ksq, s1); s <= Max(ksq, s1); s++)
751 if ( (s != ksq && s != rsq && pos.square_is_occupied(s))
752 ||(pos.attackers_to(s) & pos.pieces_of_color(them)))
755 for (s = Min(rsq, s2); s <= Max(rsq, s2); s++)
756 if (s != ksq && s != rsq && pos.square_is_occupied(s))
759 if ( Side == QUEEN_SIDE
760 && square_file(rsq) == FILE_B
761 && ( pos.piece_on(relative_square(us, SQ_A1)) == piece_of_color_and_type(them, ROOK)
762 || pos.piece_on(relative_square(us, SQ_A1)) == piece_of_color_and_type(them, QUEEN)))
766 (*mlist++).move = make_castle_move(ksq, rsq);
771 bool castling_is_check(const Position& pos, CastlingSide side) {
773 // After castling opponent king is attacked by the castled rook?
774 File rookFile = (side == QUEEN_SIDE ? FILE_D : FILE_F);
775 Color us = pos.side_to_move();
776 Square ksq = pos.king_square(us);
777 Bitboard occ = pos.occupied_squares();
779 clear_bit(&occ, ksq); // Remove our king from the board
780 Square rsq = make_square(rookFile, square_rank(ksq));
781 return bit_is_set(rook_attacks_bb(rsq, occ), pos.king_square(opposite_color(us)));