2 Glaurung, a UCI chess playing engine.
3 Copyright (C) 2004-2008 Tord Romstad
5 Glaurung is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation, either version 3 of the License, or
8 (at your option) any later version.
10 Glaurung is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
30 //// Local definitions
35 int generate_white_pawn_captures(const Position &pos, MoveStack *mlist);
36 int generate_black_pawn_captures(const Position &pos, MoveStack *mlist);
37 int generate_white_pawn_noncaptures(const Position &pos, MoveStack *mlist);
38 int generate_black_pawn_noncaptures(const Position &pos, MoveStack *mlist);
39 int generate_knight_moves(const Position &pos, MoveStack *mlist,
40 Color side, Bitboard target);
41 int generate_bishop_moves(const Position &pos, MoveStack *mlist,
42 Color side, Bitboard target);
43 int generate_rook_moves(const Position &pos, MoveStack *mlist,
44 Color side, Bitboard target);
45 int generate_queen_moves(const Position &pos, MoveStack *mlist,
46 Color side, Bitboard target);
47 int generate_king_moves(const Position &pos, MoveStack *mlist,
48 Square from, Bitboard target);
49 int generate_castle_moves(const Position &pos, MoveStack *mlist, Color us);
59 /// generate_captures generates() all pseudo-legal captures and queen
60 /// promotions. The return value is the number of moves generated.
62 int generate_captures(const Position &pos, MoveStack *mlist) {
63 Color us = pos.side_to_move();
64 Bitboard target = pos.pieces_of_color(opposite_color(us));
68 assert(!pos.is_check());
71 n += generate_white_pawn_captures(pos, mlist);
73 n += generate_black_pawn_captures(pos, mlist);
74 n += generate_knight_moves(pos, mlist+n, us, target);
75 n += generate_bishop_moves(pos, mlist+n, us, target);
76 n += generate_rook_moves(pos, mlist+n, us, target);
77 n += generate_queen_moves(pos, mlist+n, us, target);
78 n += generate_king_moves(pos, mlist+n, pos.king_square(us), target);
84 /// generate_noncaptures() generates all pseudo-legal non-captures and
85 /// underpromotions. The return value is the number of moves generated.
87 int generate_noncaptures(const Position &pos, MoveStack *mlist) {
88 Color us = pos.side_to_move();
89 Bitboard target = pos.empty_squares();
93 assert(!pos.is_check());
96 n += generate_white_pawn_noncaptures(pos, mlist);
98 n += generate_black_pawn_noncaptures(pos, mlist);
99 n += generate_knight_moves(pos, mlist+n, us, target);
100 n += generate_bishop_moves(pos, mlist+n, us, target);
101 n += generate_rook_moves(pos, mlist+n, us, target);
102 n += generate_queen_moves(pos, mlist+n, us, target);
103 n += generate_king_moves(pos, mlist+n, pos.king_square(us), target);
104 n += generate_castle_moves(pos, mlist+n, us);
110 /// generate_checks() generates all pseudo-legal non-capturing, non-promoting
111 /// checks, except castling moves (will add this later). It returns the
112 /// number of generated moves.
114 int generate_checks(const Position &pos, MoveStack *mlist, Bitboard dc) {
116 Square ksq, from, to;
117 Bitboard empty, checkSqs, b1, b2, b3;
121 assert(!pos.is_check());
123 us = pos.side_to_move();
124 them = opposite_color(us);
126 ksq = pos.king_square(them);
127 assert(pos.piece_on(ksq) == king_of_color(them));
129 dc = pos.discovered_check_candidates(us);
130 empty = pos.empty_squares();
132 // Pawn moves. This is somewhat messy, and we use separate code for white
133 // and black, because we can't shift by negative numbers in C/C++. :-(
136 // Pawn moves which give discovered check. This is possible only if the
137 // pawn is not on the same file as the enemy king, because we don't
138 // generate captures.
140 // Find all friendly pawns not on the enemy king's file:
141 b1 = pos.pawns(us) & ~file_bb(ksq);
143 // Discovered checks, single pawn pushes:
144 b2 = b3 = ((b1 & dc) << 8) & ~Rank8BB & empty;
146 to = pop_1st_bit(&b3);
147 mlist[n++].move = make_move(to - DELTA_N, to);
150 // Discovered checks, double pawn pushes:
151 b3 = ((b2 & Rank3BB) << 8) & empty;
153 to = pop_1st_bit(&b3);
154 mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to);
157 // Direct checks. These are possible only for pawns on neighboring files
158 // of the enemy king:
160 b1 &= (~dc & neighboring_files_bb(ksq));
162 // Direct checks, single pawn pushes:
163 b2 = (b1 << 8) & empty;
164 b3 = b2 & pos.black_pawn_attacks(ksq);
166 to = pop_1st_bit(&b3);
167 mlist[n++].move = make_move(to - DELTA_N, to);
170 // Direct checks, double pawn pushes:
171 b3 = ((b2 & Rank3BB) << 8) & empty & pos.black_pawn_attacks(ksq);
173 to = pop_1st_bit(&b3);
174 mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to);
177 else { // (us == BLACK)
179 // Pawn moves which give discovered check. This is possible only if the
180 // pawn is not on the same file as the enemy king, because we don't
181 // generate captures.
183 // Find all friendly pawns not on the enemy king's file:
184 b1 = pos.pawns(us) & ~file_bb(ksq);
186 // Discovered checks, single pawn pushes:
187 b2 = b3 = ((b1 & dc) >> 8) & ~Rank1BB & empty;
189 to = pop_1st_bit(&b3);
190 mlist[n++].move = make_move(to - DELTA_S, to);
193 // Discovered checks, double pawn pushes:
194 b3 = ((b2 & Rank6BB) >> 8) & empty;
196 to = pop_1st_bit(&b3);
197 mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to);
200 // Direct checks. These are possible only for pawns on neighboring files
201 // of the enemy king:
203 b1 &= (~dc & neighboring_files_bb(ksq));
205 // Direct checks, single pawn pushes:
206 b2 = (b1 >> 8) & empty;
207 b3 = b2 & pos.white_pawn_attacks(ksq);
209 to = pop_1st_bit(&b3);
210 mlist[n++].move = make_move(to - DELTA_S, to);
213 // Direct checks, double pawn pushes:
214 b3 = ((b2 & Rank6BB) >> 8) & empty & pos.black_pawn_attacks(ksq);
216 to = pop_1st_bit(&b3);
217 mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to);
222 b1 = pos.knights(us);
224 // Discovered knight checks:
227 from = pop_1st_bit(&b2);
228 b3 = pos.knight_attacks(from) & empty;
230 to = pop_1st_bit(&b3);
231 mlist[n++].move = make_move(from, to);
235 // Direct knight checks:
237 checkSqs = pos.knight_attacks(ksq) & empty;
239 from = pop_1st_bit(&b2);
240 b3 = pos.knight_attacks(from) & checkSqs;
242 to = pop_1st_bit(&b3);
243 mlist[n++].move = make_move(from, to);
249 b1 = pos.bishops(us);
251 // Discovered bishop checks:
254 from = pop_1st_bit(&b2);
255 b3 = pos.bishop_attacks(from) & empty;
257 to = pop_1st_bit(&b3);
258 mlist[n++].move = make_move(from, to);
262 // Direct bishop checks:
264 checkSqs = pos.bishop_attacks(ksq) & empty;
266 from = pop_1st_bit(&b2);
267 b3 = pos.bishop_attacks(from) & checkSqs;
269 to = pop_1st_bit(&b3);
270 mlist[n++].move = make_move(from, to);
278 // Discovered rook checks:
281 from = pop_1st_bit(&b2);
282 b3 = pos.rook_attacks(from) & empty;
284 to = pop_1st_bit(&b3);
285 mlist[n++].move = make_move(from, to);
289 // Direct rook checks:
291 checkSqs = pos.rook_attacks(ksq) & empty;
293 from = pop_1st_bit(&b2);
294 b3 = pos.rook_attacks(from) & checkSqs;
296 to = pop_1st_bit(&b3);
297 mlist[n++].move = make_move(from, to);
305 // Discovered queen checks are impossible!
307 // Direct queen checks:
308 checkSqs = pos.queen_attacks(ksq) & empty;
310 from = pop_1st_bit(&b1);
311 b2 = pos.queen_attacks(from) & checkSqs;
313 to = pop_1st_bit(&b2);
314 mlist[n++].move = make_move(from, to);
320 from = pos.king_square(us);
321 if(bit_is_set(dc, from)) {
322 b1 = pos.king_attacks(from) & empty & ~QueenPseudoAttacks[ksq];
324 to = pop_1st_bit(&b1);
325 mlist[n++].move = make_move(from, to);
329 // TODO: Castling moves!
335 /// generate_evasions() generates all check evasions when the side to move is
336 /// in check. Unlike the other move generation functions, this one generates
337 /// only legal moves. It returns the number of generated moves. This
338 /// function is very ugly, and needs cleaning up some time later. FIXME
340 int generate_evasions(const Position &pos, MoveStack *mlist) {
342 Bitboard checkers = pos.checkers();
343 Bitboard pinned, b1, b2;
344 Square ksq, from, to;
348 assert(pos.is_check());
350 us = pos.side_to_move();
351 them = opposite_color(us);
353 ksq = pos.king_square(us);
354 assert(pos.piece_on(ksq) == king_of_color(us));
356 // Generate evasions for king:
357 b1 = pos.king_attacks(ksq) & ~pos.pieces_of_color(us);
358 b2 = pos.occupied_squares();
361 to = pop_1st_bit(&b1);
363 // Make sure to is not attacked by the other side. This is a bit ugly,
364 // because we can't use Position::square_is_attacked. Instead we use
365 // the low-level bishop_attacks_bb and rook_attacks_bb with the bitboard
366 // b2 (the occupied squares with the king removed) in order to test whether
367 // the king will remain in check on the destination square.
368 if(((pos.pawn_attacks(us, to) & pos.pawns(them)) == EmptyBoardBB) &&
369 ((pos.knight_attacks(to) & pos.knights(them)) == EmptyBoardBB) &&
370 ((pos.king_attacks(to) & pos.kings(them)) == EmptyBoardBB) &&
371 ((bishop_attacks_bb(to, b2) & pos.bishops_and_queens(them))
373 ((rook_attacks_bb(to, b2) & pos.rooks_and_queens(them)) == EmptyBoardBB))
374 mlist[n++].move = make_move(ksq, to);
378 // Generate evasions for other pieces only if not double check. We use a
379 // simple bit twiddling hack here rather than calling count_1s in order to
380 // save some time (we know that pos.checkers() has at most two nonzero bits).
381 if(!(checkers & (checkers - 1))) {
382 Square checksq = first_1(checkers);
383 assert(pos.color_of_piece_on(checksq) == them);
385 // Find pinned pieces:
386 pinned = pos.pinned_pieces(us);
388 // Generate captures of the checking piece:
391 b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & ~pinned;
393 from = pop_1st_bit(&b1);
394 if(relative_rank(us, checksq) == RANK_8) {
395 mlist[n++].move = make_promotion_move(from, checksq, QUEEN);
396 mlist[n++].move = make_promotion_move(from, checksq, ROOK);
397 mlist[n++].move = make_promotion_move(from, checksq, BISHOP);
398 mlist[n++].move = make_promotion_move(from, checksq, KNIGHT);
401 mlist[n++].move = make_move(from, checksq);
405 b1 = pos.knight_attacks(checksq) & pos.knights(us) & ~pinned;
407 from = pop_1st_bit(&b1);
408 mlist[n++].move = make_move(from, checksq);
411 // Bishop and queen captures:
412 b1 = pos.bishop_attacks(checksq) & pos.bishops_and_queens(us)
415 from = pop_1st_bit(&b1);
416 mlist[n++].move = make_move(from, checksq);
419 // Rook and queen captures:
420 b1 = pos.rook_attacks(checksq) & pos.rooks_and_queens(us)
423 from = pop_1st_bit(&b1);
424 mlist[n++].move = make_move(from, checksq);
427 // Blocking check evasions are possible only if the checking piece is
429 if(checkers & pos.sliders()) {
430 Bitboard blockSquares = squares_between(checksq, ksq);
431 assert((pos.occupied_squares() & blockSquares) == EmptyBoardBB);
433 // Pawn moves. Because a blocking evasion can never be a capture, we
434 // only generate pawn pushes. As so often, the code for pawns is a bit
435 // ugly, and uses separate clauses for white and black pawns. :-(
437 // Find non-pinned pawns:
438 b1 = pos.pawns(WHITE) & ~pinned;
440 // Single pawn pushes. We don't have to AND with empty squares here,
441 // because the blocking squares will always be empty.
442 b2 = (b1 << 8) & blockSquares;
444 to = pop_1st_bit(&b2);
445 assert(pos.piece_on(to) == EMPTY);
446 if(square_rank(to) == RANK_8) {
447 mlist[n++].move = make_promotion_move(to - DELTA_N, to, QUEEN);
448 mlist[n++].move = make_promotion_move(to - DELTA_N, to, ROOK);
449 mlist[n++].move = make_promotion_move(to - DELTA_N, to, BISHOP);
450 mlist[n++].move = make_promotion_move(to - DELTA_N, to, KNIGHT);
453 mlist[n++].move = make_move(to - DELTA_N, to);
455 // Double pawn pushes.
456 b2 = (((b1 << 8) & pos.empty_squares() & Rank3BB) << 8) & blockSquares;
458 to = pop_1st_bit(&b2);
459 assert(pos.piece_on(to) == EMPTY);
460 assert(square_rank(to) == RANK_4);
461 mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to);
464 else { // (us == BLACK)
465 // Find non-pinned pawns:
466 b1 = pos.pawns(BLACK) & ~pinned;
468 // Single pawn pushes. We don't have to AND with empty squares here,
469 // because the blocking squares will always be empty.
470 b2 = (b1 >> 8) & blockSquares;
472 to = pop_1st_bit(&b2);
473 assert(pos.piece_on(to) == EMPTY);
474 if(square_rank(to) == RANK_1) {
475 mlist[n++].move = make_promotion_move(to - DELTA_S, to, QUEEN);
476 mlist[n++].move = make_promotion_move(to - DELTA_S, to, ROOK);
477 mlist[n++].move = make_promotion_move(to - DELTA_S, to, BISHOP);
478 mlist[n++].move = make_promotion_move(to - DELTA_S, to, KNIGHT);
481 mlist[n++].move = make_move(to - DELTA_S, to);
483 // Double pawn pushes.
484 b2 = (((b1 >> 8) & pos.empty_squares() & Rank6BB) >> 8) & blockSquares;
486 to = pop_1st_bit(&b2);
487 assert(pos.piece_on(to) == EMPTY);
488 assert(square_rank(to) == RANK_5);
489 mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to);
494 b1 = pos.knights(us) & ~pinned;
496 from = pop_1st_bit(&b1);
497 b2 = pos.knight_attacks(from) & blockSquares;
499 to = pop_1st_bit(&b2);
500 mlist[n++].move = make_move(from, to);
505 b1 = pos.bishops(us) & ~pinned;
507 from = pop_1st_bit(&b1);
508 b2 = pos.bishop_attacks(from) & blockSquares;
510 to = pop_1st_bit(&b2);
511 mlist[n++].move = make_move(from, to);
516 b1 = pos.rooks(us) & ~pinned;
518 from = pop_1st_bit(&b1);
519 b2 = pos.rook_attacks(from) & blockSquares;
521 to = pop_1st_bit(&b2);
522 mlist[n++].move = make_move(from, to);
527 b1 = pos.queens(us) & ~pinned;
529 from = pop_1st_bit(&b1);
530 b2 = pos.queen_attacks(from) & blockSquares;
532 to = pop_1st_bit(&b2);
533 mlist[n++].move = make_move(from, to);
538 // Finally, the ugly special case of en passant captures. An en passant
539 // capture can only be a check evasion if the check is not a discovered
540 // check. If pos.ep_square() is set, the last move made must have been
541 // a double pawn push. If, furthermore, the checking piece is a pawn,
542 // an en passant check evasion may be possible.
543 if(pos.ep_square() != SQ_NONE && (checkers & pos.pawns(them))) {
544 to = pos.ep_square();
545 b1 = pos.pawn_attacks(them, to) & pos.pawns(us);
546 assert(b1 != EmptyBoardBB);
549 from = pop_1st_bit(&b1);
551 // Before generating the move, we have to make sure it is legal.
552 // This is somewhat tricky, because the two disappearing pawns may
553 // cause new "discovered checks". We test this by removing the
554 // two relevant bits from the occupied squares bitboard, and using
555 // the low-level bitboard functions for bishop and rook attacks.
556 b2 = pos.occupied_squares();
557 clear_bit(&b2, from);
558 clear_bit(&b2, checksq);
559 if(((bishop_attacks_bb(ksq, b2) & pos.bishops_and_queens(them))
561 ((rook_attacks_bb(ksq, b2) & pos.rooks_and_queens(them))
563 mlist[n++].move = make_ep_move(from, to);
572 /// generate_legal_moves() computes a complete list of legal moves in the
573 /// current position. This function is not very fast, and should be used
574 /// only in situations where performance is unimportant. It wouldn't be
575 /// very hard to write an efficient legal move generator, but for the moment
576 /// we don't need it.
578 int generate_legal_moves(const Position &pos, MoveStack *mlist) {
582 return generate_evasions(pos, mlist);
585 Bitboard pinned = pos.pinned_pieces(pos.side_to_move());
587 // Generate pseudo-legal moves:
588 n = generate_captures(pos, mlist);
589 n += generate_noncaptures(pos, mlist + n);
591 // Remove illegal moves from the list:
592 for(i = 0; i < n; i++) {
593 if(!pos.move_is_legal(mlist[i].move, pinned))
594 mlist[i--].move = mlist[--n].move;
602 /// generate_move_if_legal() takes a position and a (not necessarily
603 /// pseudo-legal) move and a pinned pieces bitboard as input, and tests
604 /// whether the move is legal. If the move is legal, the move itself is
605 /// returned. If not, the function returns MOVE_NONE. This function must
606 /// only be used when the side to move is not in check.
608 Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) {
614 assert(!pos.is_check());
615 assert(move_is_ok(m));
617 us = pos.side_to_move();
618 them = opposite_color(us);
620 pc = pos.piece_on(from);
622 // If the from square is not occupied by a piece belonging to the side to
623 // move, the move is obviously not legal.
624 if(color_of_piece(pc) != us )
632 // The piece must be a pawn:
633 if(type_of_piece(pc) != PAWN)
636 // The destination square must be the en passant square:
637 if(to != pos.ep_square())
640 assert(pos.square_is_empty(to));
641 assert(pos.piece_on(to - pawn_push(us)) == pawn_of_color(them));
643 // The move is pseudo-legal. If it is legal, return it.
644 if(pos.move_is_legal(m))
651 else if(move_is_short_castle(m)) {
653 // The piece must be a king:
654 if(type_of_piece(pc) != KING)
657 // The side to move must still have the right to castle kingside:
658 if(!pos.can_castle_kingside(us))
661 assert(from == pos.king_square(us));
662 assert(to == pos.initial_kr_square(us));
663 assert(pos.piece_on(to) == rook_of_color(us));
665 Square g1 = relative_square(us, SQ_G1);
666 Square f1 = relative_square(us, SQ_F1);
668 bool illegal = false;
670 for(s = Min(from, g1); s <= Max(from, g1); s++)
671 if((s != from && s != to && !pos.square_is_empty(s)) ||
672 pos.square_is_attacked(s, them))
674 for(s = Min(to, f1); s <= Max(to, f1); s++)
675 if(s != from && s != to && !pos.square_is_empty(s))
683 else if(move_is_long_castle(m)) {
685 // The piece must be a king:
686 if(type_of_piece(pc) != KING)
689 // The side to move must still have the right to castle kingside:
690 if(!pos.can_castle_queenside(us))
693 assert(from == pos.king_square(us));
694 assert(to == pos.initial_qr_square(us));
695 assert(pos.piece_on(to) == rook_of_color(us));
697 Square c1 = relative_square(us, SQ_C1);
698 Square d1 = relative_square(us, SQ_D1);
700 bool illegal = false;
702 for(s = Min(from, c1); s <= Max(from, c1); s++)
703 if((s != from && s != to && !pos.square_is_empty(s)) ||
704 pos.square_is_attacked(s, them))
706 for(s = Min(to, d1); s <= Max(to, d1); s++)
707 if(s != from && s != to && !pos.square_is_empty(s))
709 if(square_file(to) == FILE_B &&
710 (pos.piece_on(to + DELTA_W) == rook_of_color(them) ||
711 pos.piece_on(to + DELTA_W) == queen_of_color(them)))
723 // The destination square cannot be occupied by a friendly piece:
724 if(pos.color_of_piece_on(to) == us)
727 // Proceed according to the type of the moving piece.
728 switch(type_of_piece(pc)) {
731 // Pawn moves, as usual, are somewhat messy.
733 // If the destination square is on the 8th rank, the move must be a
735 if(square_rank(to) == RANK_8 && !move_promotion(m))
738 // Proceed according to the square delta between the source and
739 // destionation squares.
742 case DELTA_NW: case DELTA_NE:
743 // Capture. The destination square must be occupied by an enemy piece
744 // (en passant captures was handled earlier).
745 if(pos.color_of_piece_on(to) != them)
750 // Pawn push. The destination square must be empty.
751 if(!pos.square_is_empty(to))
756 // Double pawn push. The destination square must be on the fourth
757 // rank, and both the destination square and the square between the
758 // source and destination squares must be empty.
759 if(square_rank(to) != RANK_4 || !pos.square_is_empty(to) ||
760 !pos.square_is_empty(from + DELTA_N))
768 else { // (us == BLACK)
769 // If the destination square is on the 1st rank, the move must be a
771 if(square_rank(to) == RANK_1 && !move_promotion(m))
774 // Proceed according to the square delta between the source and
775 // destionation squares.
778 case DELTA_SW: case DELTA_SE:
779 // Capture. The destination square must be occupied by an enemy piece
780 // (en passant captures was handled earlier).
781 if(pos.color_of_piece_on(to) != them)
786 // Pawn push. The destination square must be empty.
787 if(!pos.square_is_empty(to))
792 // Double pawn push. The destination square must be on the fifth
793 // rank, and both the destination square and the square between the
794 // source and destination squares must be empty.
795 if(square_rank(to) != RANK_5 || !pos.square_is_empty(to) ||
796 !pos.square_is_empty(from + DELTA_S))
804 // The move is pseudo-legal. Return it if it is legal.
805 if(pos.move_is_legal(m))
812 if(pos.knight_attacks_square(from, to) && pos.move_is_legal(m) &&
820 if(pos.bishop_attacks_square(from, to) && pos.move_is_legal(m) &&
828 if(pos.rook_attacks_square(from, to) && pos.move_is_legal(m) &&
836 if(pos.queen_attacks_square(from, to) && pos.move_is_legal(m) &&
844 if(pos.king_attacks_square(from, to) && pos.move_is_legal(m) &&
863 int generate_white_pawn_captures(const Position &pos, MoveStack *mlist) {
864 Bitboard pawns = pos.pawns(WHITE);
865 Bitboard enemyPieces = pos.pieces_of_color(BLACK);
870 // Captures in the a1-h8 direction:
871 b1 = (pawns << 9) & ~FileABB & enemyPieces;
876 sq = pop_1st_bit(&b2);
877 mlist[n++].move = make_promotion_move(sq - DELTA_NE, sq, QUEEN);
883 sq = pop_1st_bit(&b2);
884 mlist[n++].move = make_move(sq - DELTA_NE, sq);
887 // Captures in the h1-a8 direction:
888 b1 = (pawns << 7) & ~FileHBB & enemyPieces;
893 sq = pop_1st_bit(&b2);
894 mlist[n++].move = make_promotion_move(sq - DELTA_NW, sq, QUEEN);
900 sq = pop_1st_bit(&b2);
901 mlist[n++].move = make_move(sq - DELTA_NW, sq);
904 // Non-capturing promotions:
905 b1 = (pawns << 8) & pos.empty_squares() & Rank8BB;
907 sq = pop_1st_bit(&b1);
908 mlist[n++].move = make_promotion_move(sq - DELTA_N, sq, QUEEN);
911 // En passant captures:
912 if(pos.ep_square() != SQ_NONE) {
913 assert(square_rank(pos.ep_square()) == RANK_6);
914 b1 = pawns & pos.black_pawn_attacks(pos.ep_square());
915 assert(b1 != EmptyBoardBB);
917 sq = pop_1st_bit(&b1);
918 mlist[n++].move = make_ep_move(sq, pos.ep_square());
926 int generate_black_pawn_captures(const Position &pos, MoveStack *mlist) {
927 Bitboard pawns = pos.pawns(BLACK);
928 Bitboard enemyPieces = pos.pieces_of_color(WHITE);
933 // Captures in the a8-h1 direction:
934 b1 = (pawns >> 7) & ~FileABB & enemyPieces;
939 sq = pop_1st_bit(&b2);
940 mlist[n++].move = make_promotion_move(sq - DELTA_SE, sq, QUEEN);
946 sq = pop_1st_bit(&b2);
947 mlist[n++].move = make_move(sq - DELTA_SE, sq);
950 // Captures in the h8-a1 direction:
951 b1 = (pawns >> 9) & ~FileHBB & enemyPieces;
956 sq = pop_1st_bit(&b2);
957 mlist[n++].move = make_promotion_move(sq - DELTA_SW, sq, QUEEN);
963 sq = pop_1st_bit(&b2);
964 mlist[n++].move = make_move(sq - DELTA_SW, sq);
967 // Non-capturing promotions:
968 b1 = (pawns >> 8) & pos.empty_squares() & Rank1BB;
970 sq = pop_1st_bit(&b1);
971 mlist[n++].move = make_promotion_move(sq - DELTA_S, sq, QUEEN);
974 // En passant captures:
975 if(pos.ep_square() != SQ_NONE) {
976 assert(square_rank(pos.ep_square()) == RANK_3);
977 b1 = pawns & pos.white_pawn_attacks(pos.ep_square());
978 assert(b1 != EmptyBoardBB);
980 sq = pop_1st_bit(&b1);
981 mlist[n++].move = make_ep_move(sq, pos.ep_square());
989 int generate_white_pawn_noncaptures(const Position &pos, MoveStack *mlist) {
990 Bitboard pawns = pos.pawns(WHITE);
991 Bitboard enemyPieces = pos.pieces_of_color(BLACK);
992 Bitboard emptySquares = pos.empty_squares();
997 // Underpromotion captures in the a1-h8 direction:
998 b1 = (pawns << 9) & ~FileABB & enemyPieces & Rank8BB;
1000 sq = pop_1st_bit(&b1);
1001 mlist[n++].move = make_promotion_move(sq - DELTA_NE, sq, ROOK);
1002 mlist[n++].move = make_promotion_move(sq - DELTA_NE, sq, BISHOP);
1003 mlist[n++].move = make_promotion_move(sq - DELTA_NE, sq, KNIGHT);
1006 // Underpromotion captures in the h1-a8 direction:
1007 b1 = (pawns << 7) & ~FileHBB & enemyPieces & Rank8BB;
1009 sq = pop_1st_bit(&b1);
1010 mlist[n++].move = make_promotion_move(sq - DELTA_NW, sq, ROOK);
1011 mlist[n++].move = make_promotion_move(sq - DELTA_NW, sq, BISHOP);
1012 mlist[n++].move = make_promotion_move(sq - DELTA_NW, sq, KNIGHT);
1015 // Single pawn pushes:
1016 b1 = (pawns << 8) & emptySquares;
1019 sq = pop_1st_bit(&b2);
1020 mlist[n++].move = make_promotion_move(sq - DELTA_N, sq, ROOK);
1021 mlist[n++].move = make_promotion_move(sq - DELTA_N, sq, BISHOP);
1022 mlist[n++].move = make_promotion_move(sq - DELTA_N, sq, KNIGHT);
1026 sq = pop_1st_bit(&b2);
1027 mlist[n++].move = make_move(sq - DELTA_N, sq);
1030 // Double pawn pushes:
1031 b2 = ((b1 & Rank3BB) << 8) & emptySquares;
1033 sq = pop_1st_bit(&b2);
1034 mlist[n++].move = make_move(sq - DELTA_N - DELTA_N, sq);
1041 int generate_black_pawn_noncaptures(const Position &pos, MoveStack *mlist) {
1042 Bitboard pawns = pos.pawns(BLACK);
1043 Bitboard enemyPieces = pos.pieces_of_color(WHITE);
1044 Bitboard emptySquares = pos.empty_squares();
1049 // Underpromotion captures in the a8-h1 direction:
1050 b1 = (pawns >> 7) & ~FileABB & enemyPieces & Rank1BB;
1052 sq = pop_1st_bit(&b1);
1053 mlist[n++].move = make_promotion_move(sq - DELTA_SE, sq, ROOK);
1054 mlist[n++].move = make_promotion_move(sq - DELTA_SE, sq, BISHOP);
1055 mlist[n++].move = make_promotion_move(sq - DELTA_SE, sq, KNIGHT);
1058 // Underpromotion captures in the h8-a1 direction:
1059 b1 = (pawns >> 9) & ~FileHBB & enemyPieces & Rank1BB;
1061 sq = pop_1st_bit(&b1);
1062 mlist[n++].move = make_promotion_move(sq - DELTA_SW, sq, ROOK);
1063 mlist[n++].move = make_promotion_move(sq - DELTA_SW, sq, BISHOP);
1064 mlist[n++].move = make_promotion_move(sq - DELTA_SW, sq, KNIGHT);
1067 // Single pawn pushes:
1068 b1 = (pawns >> 8) & emptySquares;
1071 sq = pop_1st_bit(&b2);
1072 mlist[n++].move = make_promotion_move(sq - DELTA_S, sq, ROOK);
1073 mlist[n++].move = make_promotion_move(sq - DELTA_S, sq, BISHOP);
1074 mlist[n++].move = make_promotion_move(sq - DELTA_S, sq, KNIGHT);
1078 sq = pop_1st_bit(&b2);
1079 mlist[n++].move = make_move(sq - DELTA_S, sq);
1082 // Double pawn pushes:
1083 b2 = ((b1 & Rank6BB) >> 8) & emptySquares;
1085 sq = pop_1st_bit(&b2);
1086 mlist[n++].move = make_move(sq - DELTA_S - DELTA_S, sq);
1093 int generate_knight_moves(const Position &pos, MoveStack *mlist,
1094 Color side, Bitboard target) {
1099 for(i = 0; i < pos.knight_count(side); i++) {
1100 from = pos.knight_list(side, i);
1101 b = pos.knight_attacks(from) & target;
1103 to = pop_1st_bit(&b);
1104 mlist[n++].move = make_move(from, to);
1111 int generate_bishop_moves(const Position &pos, MoveStack *mlist,
1112 Color side, Bitboard target) {
1117 for(i = 0; i < pos.bishop_count(side); i++) {
1118 from = pos.bishop_list(side, i);
1119 b = pos.bishop_attacks(from) & target;
1121 to = pop_1st_bit(&b);
1122 mlist[n++].move = make_move(from, to);
1129 int generate_rook_moves(const Position &pos, MoveStack *mlist,
1130 Color side, Bitboard target) {
1135 for(i = 0; i < pos.rook_count(side); i++) {
1136 from = pos.rook_list(side, i);
1137 b = pos.rook_attacks(from) & target;
1139 to = pop_1st_bit(&b);
1140 mlist[n++].move = make_move(from, to);
1147 int generate_queen_moves(const Position &pos, MoveStack *mlist,
1148 Color side, Bitboard target) {
1153 for(i = 0; i < pos.queen_count(side); i++) {
1154 from = pos.queen_list(side, i);
1155 b = pos.queen_attacks(from) & target;
1157 to = pop_1st_bit(&b);
1158 mlist[n++].move = make_move(from, to);
1165 int generate_king_moves(const Position &pos, MoveStack *mlist,
1166 Square from, Bitboard target) {
1171 b = pos.king_attacks(from) & target;
1173 to = pop_1st_bit(&b);
1174 mlist[n++].move = make_move(from, to);
1180 int generate_castle_moves(const Position &pos, MoveStack *mlist, Color us) {
1183 if(pos.can_castle(us)) {
1184 Color them = opposite_color(us);
1185 Square ksq = pos.king_square(us);
1186 assert(pos.piece_on(ksq) == king_of_color(us));
1188 if(pos.can_castle_kingside(us)) {
1189 Square rsq = pos.initial_kr_square(us);
1190 Square g1 = relative_square(us, SQ_G1);
1191 Square f1 = relative_square(us, SQ_F1);
1193 bool illegal = false;
1195 assert(pos.piece_on(rsq) == rook_of_color(us));
1197 for(s = Min(ksq, g1); s <= Max(ksq, g1); s++)
1198 if((s != ksq && s != rsq && pos.square_is_occupied(s))
1199 || pos.square_is_attacked(s, them))
1201 for(s = Min(rsq, f1); s <= Max(rsq, f1); s++)
1202 if(s != ksq && s != rsq && pos.square_is_occupied(s))
1206 mlist[n++].move = make_castle_move(ksq, rsq);
1209 if(pos.can_castle_queenside(us)) {
1210 Square rsq = pos.initial_qr_square(us);
1211 Square c1 = relative_square(us, SQ_C1);
1212 Square d1 = relative_square(us, SQ_D1);
1214 bool illegal = false;
1216 assert(pos.piece_on(rsq) == rook_of_color(us));
1218 for(s = Min(ksq, c1); s <= Max(ksq, c1); s++)
1219 if((s != ksq && s != rsq && pos.square_is_occupied(s))
1220 || pos.square_is_attacked(s, them))
1222 for(s = Min(rsq, d1); s <= Max(rsq, d1); s++)
1223 if(s != ksq && s != rsq && pos.square_is_occupied(s))
1225 if(square_file(rsq) == FILE_B &&
1226 (pos.piece_on(relative_square(us, SQ_A1)) == rook_of_color(them) ||
1227 pos.piece_on(relative_square(us, SQ_A1)) == queen_of_color(them)))
1231 mlist[n++].move = make_castle_move(ksq, rsq);