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
54 bool castling_is_check(const Position&, CastlingSide);
57 template<CastlingSide Side>
58 MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist);
61 MoveStack* generate_pawn_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*);
64 MoveStack* generate_pawn_captures(const Position& pos, MoveStack* mlist);
66 template<Color Us, SquareDelta Diagonal>
67 MoveStack* generate_pawn_captures_diagonal(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces, bool promotion);
70 MoveStack* generate_pawn_noncaptures(const Position& pos, MoveStack* mlist);
73 MoveStack* generate_pawn_checks(const Position&, Bitboard, Square, MoveStack*);
75 template<Color Us, SquareDelta Direction>
76 inline Bitboard move_pawns(Bitboard p) {
78 if (Direction == DELTA_N)
79 return Us == WHITE ? p << 8 : p >> 8;
80 else if (Direction == DELTA_NE)
81 return Us == WHITE ? p << 9 : p >> 7;
82 else if (Direction == DELTA_NW)
83 return Us == WHITE ? p << 7 : p >> 9;
88 // Template generate_piece_checks() with specializations
90 MoveStack* generate_piece_checks(const Position&, MoveStack*, Color, Bitboard, Square);
93 inline MoveStack* generate_piece_checks<PAWN>(const Position& p, MoveStack* m, Color us, Bitboard dc, Square ksq) {
95 return (us == WHITE ? generate_pawn_checks<WHITE>(p, dc, ksq, m)
96 : generate_pawn_checks<BLACK>(p, dc, ksq, m));
99 // Template generate_piece_moves() with specializations and overloads
101 MoveStack* generate_piece_moves(const Position&, MoveStack*, Color us, Bitboard);
104 MoveStack* generate_piece_moves<KING>(const Position&, MoveStack*, Color, Bitboard);
106 template<PieceType Piece, MoveType Type>
107 inline MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us) {
109 assert(Piece == PAWN);
112 return (us == WHITE ? generate_pawn_captures<WHITE>(p, m)
113 : generate_pawn_captures<BLACK>(p, m));
115 return (us == WHITE ? generate_pawn_noncaptures<WHITE>(p, m)
116 : generate_pawn_noncaptures<BLACK>(p, m));
120 MoveStack* generate_piece_moves(const Position&, MoveStack*, Color us, Bitboard, Bitboard);
123 inline MoveStack* generate_piece_moves<PAWN>(const Position& p, MoveStack* m,
124 Color us, Bitboard t, Bitboard pnd) {
126 return (us == WHITE ? generate_pawn_blocking_evasions<WHITE>(p, pnd, t, m)
127 : generate_pawn_blocking_evasions<BLACK>(p, pnd, t, m));
137 /// generate_captures generates() all pseudo-legal captures and queen
138 /// promotions. Returns a pointer to the end of the move list.
140 MoveStack* generate_captures(const Position& pos, MoveStack* mlist) {
143 assert(!pos.is_check());
145 Color us = pos.side_to_move();
146 Bitboard target = pos.pieces_of_color(opposite_color(us));
148 mlist = generate_piece_moves<QUEEN>(pos, mlist, us, target);
149 mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
150 mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
151 mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
152 mlist = generate_piece_moves<PAWN, CAPTURE>(pos, mlist, us);
153 return generate_piece_moves<KING>(pos, mlist, us, target);
157 /// generate_noncaptures() generates all pseudo-legal non-captures and
158 /// underpromotions. Returns a pointer to the end of the move list.
160 MoveStack* generate_noncaptures(const Position& pos, MoveStack* mlist) {
163 assert(!pos.is_check());
165 Color us = pos.side_to_move();
166 Bitboard target = pos.empty_squares();
168 mlist = generate_piece_moves<PAWN, NON_CAPTURE>(pos, mlist, us);
169 mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
170 mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
171 mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
172 mlist = generate_piece_moves<QUEEN>(pos, mlist, us, target);
173 mlist = generate_piece_moves<KING>(pos, mlist, us, target);
174 mlist = generate_castle_moves<KING_SIDE>(pos, mlist);
175 return generate_castle_moves<QUEEN_SIDE>(pos, mlist);
179 /// generate_non_capture_checks() generates all pseudo-legal non-capturing,
180 /// non-promoting checks. Returns a pointer to the end of the move list.
182 MoveStack* generate_non_capture_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
185 assert(!pos.is_check());
187 Color us = pos.side_to_move();
188 Square ksq = pos.king_square(opposite_color(us));
190 assert(pos.piece_on(ksq) == piece_of_color_and_type(opposite_color(us), KING));
193 mlist = generate_piece_checks<PAWN>(pos, mlist, us, dc, ksq);
194 mlist = generate_piece_checks<KNIGHT>(pos, mlist, us, dc, ksq);
195 mlist = generate_piece_checks<BISHOP>(pos, mlist, us, dc, ksq);
196 mlist = generate_piece_checks<ROOK>(pos, mlist, us, dc, ksq);
197 mlist = generate_piece_checks<QUEEN>(pos, mlist, us, dc, ksq);
198 mlist = generate_piece_checks<KING>(pos, mlist, us, dc, ksq);
200 // Castling moves that give check. Very rare but nice to have!
201 if ( pos.can_castle_queenside(us)
202 && (square_rank(ksq) == square_rank(pos.king_square(us)) || square_file(ksq) == FILE_D)
203 && castling_is_check(pos, QUEEN_SIDE))
204 mlist = generate_castle_moves<QUEEN_SIDE>(pos, mlist);
206 if ( pos.can_castle_kingside(us)
207 && (square_rank(ksq) == square_rank(pos.king_square(us)) || square_file(ksq) == FILE_F)
208 && castling_is_check(pos, KING_SIDE))
209 mlist = generate_castle_moves<KING_SIDE>(pos, mlist);
215 /// generate_evasions() generates all check evasions when the side to move is
216 /// in check. Unlike the other move generation functions, this one generates
217 /// only legal moves. Returns a pointer to the end of the move list.
219 MoveStack* generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pinned) {
222 assert(pos.is_check());
225 Color us = pos.side_to_move();
226 Color them = opposite_color(us);
227 Square ksq = pos.king_square(us);
229 assert(pos.piece_on(ksq) == piece_of_color_and_type(us, KING));
231 // The bitboard of occupied pieces without our king
232 Bitboard b_noKing = pos.occupied_squares();
233 clear_bit(&b_noKing, ksq);
235 // Find squares attacked by slider checkers, we will
236 // remove them from king evasions set so to avoid a couple
237 // of cycles in the slow king evasions legality check loop
238 // and to be able to use attackers_to().
239 Bitboard checkers = pos.checkers();
240 Bitboard checkersAttacks = EmptyBoardBB;
241 Bitboard b = checkers & pos.pieces(BISHOP, QUEEN);
244 from = pop_1st_bit(&b);
245 checkersAttacks |= bishop_attacks_bb(from, b_noKing);
248 b = checkers & pos.pieces(ROOK, QUEEN);
251 from = pop_1st_bit(&b);
252 checkersAttacks |= rook_attacks_bb(from, b_noKing);
255 // Generate evasions for king
256 Bitboard b1 = pos.attacks_from<KING>(ksq) & ~pos.pieces_of_color(us) & ~checkersAttacks;
257 Bitboard enemy = pos.pieces_of_color(them);
260 to = pop_1st_bit(&b1);
261 // Note that we can use attackers_to() only because we
262 // have already removed slider checkers.
263 if (!(pos.attackers_to(to) & enemy))
264 (*mlist++).move = make_move(ksq, to);
267 // Generate evasions for other pieces only if not double check. We use a
268 // simple bit twiddling hack here rather than calling count_1s in order to
269 // save some time (we know that pos.checkers() has at most two nonzero bits).
270 if (!(checkers & (checkers - 1))) // Only one bit set?
272 Square checksq = first_1(checkers);
274 assert(pos.color_of_piece_on(checksq) == them);
276 // Generate captures of the checking piece
279 b1 = pos.attacks_from<PAWN>(checksq, them) & pos.pieces(PAWN, us) & ~pinned;
282 from = pop_1st_bit(&b1);
283 if (relative_rank(us, checksq) == RANK_8)
285 (*mlist++).move = make_promotion_move(from, checksq, QUEEN);
286 (*mlist++).move = make_promotion_move(from, checksq, ROOK);
287 (*mlist++).move = make_promotion_move(from, checksq, BISHOP);
288 (*mlist++).move = make_promotion_move(from, checksq, KNIGHT);
290 (*mlist++).move = make_move(from, checksq);
294 b1 = ( (pos.attacks_from<KNIGHT>(checksq) & pos.pieces(KNIGHT, us))
295 | (pos.attacks_from<BISHOP>(checksq) & pos.pieces(BISHOP, QUEEN, us))
296 | (pos.attacks_from<ROOK>(checksq) & pos.pieces(ROOK, QUEEN, us)) ) & ~pinned;
300 from = pop_1st_bit(&b1);
301 (*mlist++).move = make_move(from, checksq);
304 // Blocking check evasions are possible only if the checking piece is
306 if (checkers & (pos.pieces(BISHOP) | pos.pieces(ROOK) | pos.pieces(QUEEN)))
308 Bitboard blockSquares = squares_between(checksq, ksq);
310 assert((pos.occupied_squares() & blockSquares) == EmptyBoardBB);
312 if (blockSquares != EmptyBoardBB)
314 mlist = generate_piece_moves<PAWN>(pos, mlist, us, blockSquares, pinned);
315 mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, blockSquares, pinned);
316 mlist = generate_piece_moves<BISHOP>(pos, mlist, us, blockSquares, pinned);
317 mlist = generate_piece_moves<ROOK>(pos, mlist, us, blockSquares, pinned);
318 mlist = generate_piece_moves<QUEEN>(pos, mlist, us, blockSquares, pinned);
322 // Finally, the special case of en passant captures. An en passant
323 // capture can only be a check evasion if the check is not a discovered
324 // check. If pos.ep_square() is set, the last move made must have been
325 // a double pawn push. If, furthermore, the checking piece is a pawn,
326 // an en passant check evasion may be possible.
327 if (pos.ep_square() != SQ_NONE && (checkers & pos.pieces(PAWN, them)))
329 to = pos.ep_square();
330 b1 = pos.attacks_from<PAWN>(to, them) & pos.pieces(PAWN, us);
332 // The checking pawn cannot be a discovered (bishop) check candidate
333 // otherwise we were in check also before last double push move.
334 assert(!bit_is_set(pos.discovered_check_candidates(them), checksq));
335 assert(count_1s(b1) == 1 || count_1s(b1) == 2);
340 from = pop_1st_bit(&b1);
341 // Move is always legal because checking pawn is not a discovered
342 // check candidate and our capturing pawn has been already tested
343 // against pinned pieces.
344 (*mlist++).move = make_ep_move(from, to);
352 /// generate_legal_moves() computes a complete list of legal moves in the
353 /// current position. This function is not very fast, and should be used
354 /// only in situations where performance is unimportant. It wouldn't be
355 /// very hard to write an efficient legal move generator, but for the moment
356 /// we don't need it.
358 MoveStack* generate_legal_moves(const Position& pos, MoveStack* mlist) {
362 Bitboard pinned = pos.pinned_pieces(pos.side_to_move());
365 return generate_evasions(pos, mlist, pinned);
367 // Generate pseudo-legal moves
368 MoveStack* last = generate_captures(pos, mlist);
369 last = generate_noncaptures(pos, last);
371 // Remove illegal moves from the list
372 for (MoveStack* cur = mlist; cur != last; cur++)
373 if (!pos.pl_move_is_legal(cur->move, pinned))
375 cur->move = (--last)->move;
382 /// move_is_legal() takes a position and a (not necessarily pseudo-legal)
383 /// move and a pinned pieces bitboard as input, and tests whether
384 /// the move is legal. If the move is legal, the move itself is
385 /// returned. If not, the function returns false. This function must
386 /// only be used when the side to move is not in check.
388 bool move_is_legal(const Position& pos, const Move m, Bitboard pinned) {
391 assert(!pos.is_check());
392 assert(move_is_ok(m));
393 assert(pinned == pos.pinned_pieces(pos.side_to_move()));
395 Color us = pos.side_to_move();
396 Square from = move_from(m);
397 Piece pc = pos.piece_on(from);
399 // If the from square is not occupied by a piece belonging to the side to
400 // move, the move is obviously not legal.
401 if (color_of_piece(pc) != us)
404 Color them = opposite_color(us);
405 Square to = move_to(m);
410 // The piece must be a pawn and destination square must be the
411 // en passant square.
412 if ( type_of_piece(pc) != PAWN
413 || to != pos.ep_square())
416 assert(pos.square_is_empty(to));
417 assert(pos.piece_on(to - pawn_push(us)) == piece_of_color_and_type(them, PAWN));
419 // The move is pseudo-legal, check if it is also legal
420 return pos.pl_move_is_legal(m, pinned);
424 if (move_is_short_castle(m))
426 // The piece must be a king and side to move must still have
427 // the right to castle kingside.
428 if ( type_of_piece(pc) != KING
429 ||!pos.can_castle_kingside(us))
432 assert(from == pos.king_square(us));
433 assert(to == pos.initial_kr_square(us));
434 assert(pos.piece_on(to) == piece_of_color_and_type(us, ROOK));
436 Square g1 = relative_square(us, SQ_G1);
437 Square f1 = relative_square(us, SQ_F1);
439 bool illegal = false;
441 // Check if any of the squares between king and rook
442 // is occupied or under attack.
443 for (s = Min(from, g1); s <= Max(from, g1); s++)
444 if ( (s != from && s != to && !pos.square_is_empty(s))
445 ||(pos.attackers_to(s) & pos.pieces_of_color(them)))
448 // Check if any of the squares between king and rook
450 for (s = Min(to, f1); s <= Max(to, f1); s++)
451 if (s != from && s != to && !pos.square_is_empty(s))
457 if (move_is_long_castle(m))
459 // The piece must be a king and side to move must still have
460 // the right to castle kingside.
461 if ( type_of_piece(pc) != KING
462 ||!pos.can_castle_queenside(us))
465 assert(from == pos.king_square(us));
466 assert(to == pos.initial_qr_square(us));
467 assert(pos.piece_on(to) == piece_of_color_and_type(us, ROOK));
469 Square c1 = relative_square(us, SQ_C1);
470 Square d1 = relative_square(us, SQ_D1);
472 bool illegal = false;
474 for (s = Min(from, c1); s <= Max(from, c1); s++)
475 if( (s != from && s != to && !pos.square_is_empty(s))
476 ||(pos.attackers_to(s) & pos.pieces_of_color(them)))
479 for (s = Min(to, d1); s <= Max(to, d1); s++)
480 if(s != from && s != to && !pos.square_is_empty(s))
483 if ( square_file(to) == FILE_B
484 && ( pos.piece_on(to + DELTA_W) == piece_of_color_and_type(them, ROOK)
485 || pos.piece_on(to + DELTA_W) == piece_of_color_and_type(them, QUEEN)))
493 // The destination square cannot be occupied by a friendly piece
494 if (pos.color_of_piece_on(to) == us)
497 // Proceed according to the type of the moving piece.
498 if (type_of_piece(pc) == PAWN)
500 // Move direction must be compatible with pawn color
501 int direction = to - from;
502 if ((us == WHITE) != (direction > 0))
505 // If the destination square is on the 8/1th rank, the move must
507 if ( ( (square_rank(to) == RANK_8 && us == WHITE)
508 ||(square_rank(to) == RANK_1 && us != WHITE))
509 && !move_is_promotion(m))
512 // Proceed according to the square delta between the source and
513 // destionation squares.
520 // Capture. The destination square must be occupied by an enemy
521 // piece (en passant captures was handled earlier).
522 if (pos.color_of_piece_on(to) != them)
528 // Pawn push. The destination square must be empty.
529 if (!pos.square_is_empty(to))
534 // Double white pawn push. The destination square must be on the fourth
535 // rank, and both the destination square and the square between the
536 // source and destination squares must be empty.
537 if ( square_rank(to) != RANK_4
538 || !pos.square_is_empty(to)
539 || !pos.square_is_empty(from + DELTA_N))
544 // Double black pawn push. The destination square must be on the fifth
545 // rank, and both the destination square and the square between the
546 // source and destination squares must be empty.
547 if ( square_rank(to) != RANK_5
548 || !pos.square_is_empty(to)
549 || !pos.square_is_empty(from + DELTA_S))
556 // The move is pseudo-legal, check if it is also legal
557 return pos.pl_move_is_legal(m, pinned);
560 // Luckly we can handle all the other pieces in one go
561 return ( bit_is_set(pos.attacks_from(pc, from), to)
562 && pos.pl_move_is_legal(m, pinned)
563 && !move_is_promotion(m));
567 /// Another version of move_is_legal(), which takes only a position and a move
568 /// as input. This function does not require that the side to move is not in
569 /// check. It is not optimized for speed, and is only used for verifying move
570 /// legality when building a PV from the transposition table.
572 bool move_is_legal(const Position& pos, const Move m) {
574 Bitboard pinned = pos.pinned_pieces(pos.side_to_move());
576 return move_is_legal(pos, m, pinned);
581 MoveStack* last = generate_evasions(p, mlist, pinned);
582 for (MoveStack* cur = mlist; cur != last; cur++)
593 template<PieceType Piece>
594 MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
599 for (int i = 0, e = pos.piece_count(us, Piece); i < e; i++)
601 from = pos.piece_list(us, Piece, i);
602 b = pos.attacks_from<Piece>(from) & target;
608 template<PieceType Piece>
609 MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist,
610 Color us, Bitboard target, Bitboard pinned) {
614 for (int i = 0, e = pos.piece_count(us, Piece); i < e; i++)
616 from = pos.piece_list(us, Piece, i);
617 if (pinned && bit_is_set(pinned, from))
620 b = pos.attacks_from<Piece>(from) & target;
627 MoveStack* generate_piece_moves<KING>(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
630 Square from = pos.king_square(us);
632 b = pos.attacks_from<KING>(from) & target;
637 template<Color Us, SquareDelta Diagonal>
638 MoveStack* generate_pawn_captures_diagonal(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces, bool promotion) {
640 // Calculate our parametrized parameters at compile time
641 const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
642 const Bitboard TFileABB = (Diagonal == DELTA_NE ? FileABB : FileHBB);
643 const SquareDelta TDELTA_NE = (Us == WHITE ? DELTA_NE : DELTA_SE);
644 const SquareDelta TDELTA_NW = (Us == WHITE ? DELTA_NW : DELTA_SW);
645 const SquareDelta TTDELTA_NE = (Diagonal == DELTA_NE ? TDELTA_NE : TDELTA_NW);
649 // Captures in the a1-h8 (a8-h1 for black) diagonal or in the h1-a8 (h8-a1 for black)
650 Bitboard b1 = move_pawns<Us, Diagonal>(pawns) & ~TFileABB & enemyPieces;
652 // Capturing promotions
655 Bitboard b2 = b1 & TRank8BB;
659 to = pop_1st_bit(&b2);
660 (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, QUEEN);
664 // Capturing non-promotions
665 SERIALIZE_MOVES_D(b1, -TTDELTA_NE);
670 MoveStack* generate_pawn_captures(const Position& pos, MoveStack* mlist) {
672 // Calculate our parametrized parameters at compile time
673 const Color Them = (Us == WHITE ? BLACK : WHITE);
674 const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
675 const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
676 const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
679 Bitboard pawns = pos.pieces(PAWN, Us);
680 Bitboard enemyPieces = pos.pieces_of_color(opposite_color(Us));
681 bool possiblePromotion = (pawns & TRank7BB);
683 // Standard captures and capturing promotions in both directions
684 mlist = generate_pawn_captures_diagonal<Us, DELTA_NE>(mlist, pawns, enemyPieces, possiblePromotion);
685 mlist = generate_pawn_captures_diagonal<Us, DELTA_NW>(mlist, pawns, enemyPieces, possiblePromotion);
687 // Non-capturing promotions
688 if (possiblePromotion)
690 Bitboard b1 = move_pawns<Us, DELTA_N>(pawns) & pos.empty_squares() & TRank8BB;
693 to = pop_1st_bit(&b1);
694 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN);
698 // En passant captures
699 if (pos.ep_square() != SQ_NONE)
701 assert(Us != WHITE || square_rank(pos.ep_square()) == RANK_6);
702 assert(Us != BLACK || square_rank(pos.ep_square()) == RANK_3);
704 Bitboard b1 = pawns & pos.attacks_from<PAWN>(pos.ep_square(), Them);
705 assert(b1 != EmptyBoardBB);
709 to = pop_1st_bit(&b1);
710 (*mlist++).move = make_ep_move(to, pos.ep_square());
717 MoveStack* generate_pawn_noncaptures(const Position& pos, MoveStack* mlist) {
719 // Calculate our parametrized parameters at compile time
720 const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
721 const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
722 const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
723 const SquareDelta TDELTA_NE = (Us == WHITE ? DELTA_NE : DELTA_SE);
724 const SquareDelta TDELTA_NW = (Us == WHITE ? DELTA_NW : DELTA_SW);
725 const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
729 Bitboard pawns = pos.pieces(PAWN, Us);
730 Bitboard emptySquares = pos.empty_squares();
732 if (pawns & TRank7BB) // There is some promotion candidate ?
734 Bitboard enemyPieces = pos.pieces_of_color(opposite_color(Us));
736 // Underpromotion captures in the a1-h8 (a8-h1 for black) direction
737 b1 = move_pawns<Us, DELTA_NE>(pawns) & ~FileABB & enemyPieces & TRank8BB;
740 to = pop_1st_bit(&b1);
741 (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, ROOK);
742 (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, BISHOP);
743 (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, KNIGHT);
746 // Underpromotion captures in the h1-a8 (h8-a1 for black) direction
747 b1 = move_pawns<Us, DELTA_NW>(pawns) & ~FileHBB & enemyPieces & TRank8BB;
750 to = pop_1st_bit(&b1);
751 (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, ROOK);
752 (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, BISHOP);
753 (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, KNIGHT);
756 // Underpromotion pawn pushes
757 b1 = move_pawns<Us, DELTA_N>(pawns) & emptySquares & TRank8BB;
760 to = pop_1st_bit(&b1);
761 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, ROOK);
762 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, BISHOP);
763 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, KNIGHT);
767 // Single pawn pushes
768 b2 = b1 = move_pawns<Us, DELTA_N>(pawns) & emptySquares & ~TRank8BB;
769 SERIALIZE_MOVES_D(b2, -TDELTA_N);
771 // Double pawn pushes
772 b2 = move_pawns<Us, DELTA_N>(b1 & TRank3BB) & emptySquares;
773 SERIALIZE_MOVES_D(b2, -TDELTA_N -TDELTA_N);
779 MoveStack* generate_pawn_checks(const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist)
781 // Calculate our parametrized parameters at compile time
782 const Color Them = (Us == WHITE ? BLACK : WHITE);
783 const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
784 const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
785 const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
786 const SquareDelta TDELTA_S = (Us == WHITE ? DELTA_S : DELTA_N);
790 Bitboard pawns = pos.pieces(PAWN, Us);
794 Bitboard empty = pos.empty_squares();
796 // Pawn moves which gives discovered check. This is possible only if the
797 // pawn is not on the same file as the enemy king, because we don't
798 // generate captures.
799 b1 = pawns & ~file_bb(ksq);
801 // Discovered checks, single pawn pushes, no promotions
802 b2 = b3 = move_pawns<Us, DELTA_N>(b1 & dc) & empty & ~TRank8BB;
803 SERIALIZE_MOVES_D(b3, -TDELTA_N);
805 // Discovered checks, double pawn pushes
806 b3 = move_pawns<Us, DELTA_N>(b2 & TRank3BB) & empty;
807 SERIALIZE_MOVES_D(b3, -TDELTA_N -TDELTA_N);
810 // Direct checks. These are possible only for pawns on neighboring files
811 // and in the two ranks that, after the push, are in front of the enemy king.
812 b1 = pawns & neighboring_files_bb(ksq) & ~dc;
814 // We can get false positives if (ksq + x) is not in [0,63] range but
815 // is not a problem, they will be filtered out later.
816 b2 = b1 & (rank_bb(ksq + 2 * TDELTA_S) | rank_bb(ksq + 3 * TDELTA_S));
820 // Direct checks, single pawn pushes
821 Bitboard empty = pos.empty_squares();
822 b2 = move_pawns<Us, DELTA_N>(b1) & empty;
823 b3 = b2 & pos.attacks_from<PAWN>(ksq, Them);
824 SERIALIZE_MOVES_D(b3, -TDELTA_N);
826 // Direct checks, double pawn pushes
827 b3 = move_pawns<Us, DELTA_N>(b2 & TRank3BB) & empty & pos.attacks_from<PAWN>(ksq, Them);
828 SERIALIZE_MOVES_D(b3, -TDELTA_N -TDELTA_N);
832 template<PieceType Piece>
833 MoveStack* generate_piece_checks(const Position& pos, MoveStack* mlist, Color us,
834 Bitboard dc, Square ksq) {
836 Bitboard target = pos.pieces(Piece, us);
839 Bitboard b = target & dc;
842 Square from = pop_1st_bit(&b);
843 Bitboard bb = pos.attacks_from<Piece>(from) & pos.empty_squares();
845 bb &= ~QueenPseudoAttacks[ksq];
852 if (Piece != KING || b)
854 Bitboard checkSqs = pos.attacks_from<Piece>(ksq) & pos.empty_squares();
860 Square from = pop_1st_bit(&b);
861 if ( (Piece == QUEEN && !(QueenPseudoAttacks[from] & checkSqs))
862 || (Piece == ROOK && !(RookPseudoAttacks[from] & checkSqs))
863 || (Piece == BISHOP && !(BishopPseudoAttacks[from] & checkSqs)))
866 Bitboard bb = pos.attacks_from<Piece>(from) & checkSqs;
874 MoveStack* generate_pawn_blocking_evasions(const Position& pos, Bitboard pinned,
875 Bitboard blockSquares, MoveStack* mlist) {
877 // Calculate our parametrized parameters at compile time
878 const Rank TRANK_8 = (Us == WHITE ? RANK_8 : RANK_1);
879 const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
880 const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
884 // Find non-pinned pawns and push them one square
885 Bitboard b1 = move_pawns<Us, DELTA_N>(pos.pieces(PAWN, Us) & ~pinned);
887 // We don't have to AND with empty squares here,
888 // because the blocking squares will always be empty.
889 Bitboard b2 = b1 & blockSquares;
892 to = pop_1st_bit(&b2);
894 assert(pos.piece_on(to) == EMPTY);
896 if (square_rank(to) == TRANK_8)
898 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN);
899 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, ROOK);
900 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, BISHOP);
901 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, KNIGHT);
903 (*mlist++).move = make_move(to - TDELTA_N, to);
906 // Double pawn pushes
907 b2 = b1 & pos.empty_squares() & TRank3BB;
908 b2 = move_pawns<Us, DELTA_N>(b2) & blockSquares;
911 to = pop_1st_bit(&b2);
913 assert(pos.piece_on(to) == EMPTY);
914 assert(Us != WHITE || square_rank(to) == RANK_4);
915 assert(Us != BLACK || square_rank(to) == RANK_5);
917 (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to);
922 template<CastlingSide Side>
923 MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist) {
925 Color us = pos.side_to_move();
927 if ( (Side == KING_SIDE && pos.can_castle_kingside(us))
928 ||(Side == QUEEN_SIDE && pos.can_castle_queenside(us)))
930 Color them = opposite_color(us);
931 Square ksq = pos.king_square(us);
933 assert(pos.piece_on(ksq) == piece_of_color_and_type(us, KING));
935 Square rsq = (Side == KING_SIDE ? pos.initial_kr_square(us) : pos.initial_qr_square(us));
936 Square s1 = relative_square(us, Side == KING_SIDE ? SQ_G1 : SQ_C1);
937 Square s2 = relative_square(us, Side == KING_SIDE ? SQ_F1 : SQ_D1);
939 bool illegal = false;
941 assert(pos.piece_on(rsq) == piece_of_color_and_type(us, ROOK));
943 // It is a bit complicated to correctly handle Chess960
944 for (s = Min(ksq, s1); s <= Max(ksq, s1); s++)
945 if ( (s != ksq && s != rsq && pos.square_is_occupied(s))
946 ||(pos.attackers_to(s) & pos.pieces_of_color(them)))
949 for (s = Min(rsq, s2); s <= Max(rsq, s2); s++)
950 if (s != ksq && s != rsq && pos.square_is_occupied(s))
953 if ( Side == QUEEN_SIDE
954 && square_file(rsq) == FILE_B
955 && ( pos.piece_on(relative_square(us, SQ_A1)) == piece_of_color_and_type(them, ROOK)
956 || pos.piece_on(relative_square(us, SQ_A1)) == piece_of_color_and_type(them, QUEEN)))
960 (*mlist++).move = make_castle_move(ksq, rsq);
965 bool castling_is_check(const Position& pos, CastlingSide side) {
967 // After castling opponent king is attacked by the castled rook?
968 File rookFile = (side == QUEEN_SIDE ? FILE_D : FILE_F);
969 Color us = pos.side_to_move();
970 Square ksq = pos.king_square(us);
971 Bitboard occ = pos.occupied_squares();
973 clear_bit(&occ, ksq); // Remove our king from the board
974 Square rsq = make_square(rookFile, square_rank(ksq));
975 return bit_is_set(rook_attacks_bb(rsq, occ), pos.king_square(opposite_color(us)));