2 * moves.c - Move generation and checking
4 * Copyright 1991 by Digital Equipment Corporation, Maynard,
7 * Enhancements Copyright 1992-2001, 2002, 2003, 2004, 2005, 2006,
8 * 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
10 * Enhancements Copyright 2005 Alessandro Scotti
12 * The following terms apply to Digital Equipment Corporation's copyright
14 * ------------------------------------------------------------------------
17 * Permission to use, copy, modify, and distribute this software and its
18 * documentation for any purpose and without fee is hereby granted,
19 * provided that the above copyright notice appear in all copies and that
20 * both that copyright notice and this permission notice appear in
21 * supporting documentation, and that the name of Digital not be
22 * used in advertising or publicity pertaining to distribution of the
23 * software without specific, written prior permission.
25 * DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
26 * ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
27 * DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
28 * ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
29 * WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
30 * ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
32 * ------------------------------------------------------------------------
34 * The following terms apply to the enhanced version of XBoard
35 * distributed by the Free Software Foundation:
36 * ------------------------------------------------------------------------
38 * GNU XBoard is free software: you can redistribute it and/or modify
39 * it under the terms of the GNU General Public License as published by
40 * the Free Software Foundation, either version 3 of the License, or (at
41 * your option) any later version.
43 * GNU XBoard is distributed in the hope that it will be useful, but
44 * WITHOUT ANY WARRANTY; without even the implied warranty of
45 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
46 * General Public License for more details.
48 * You should have received a copy of the GNU General Public License
49 * along with this program. If not, see http://www.gnu.org/licenses/. *
51 *------------------------------------------------------------------------
52 ** See the file ChangeLog for a revision history. */
59 #else /* not HAVE_STRING_H */
61 #endif /* not HAVE_STRING_H */
67 int WhitePiece P((ChessSquare));
68 int BlackPiece P((ChessSquare));
69 int SameColor P((ChessSquare, ChessSquare));
70 int PosFlags(int index);
72 extern signed char initialRights[BOARD_FILES]; /* [HGM] all rights enabled, set in InitPosition */
78 return (int) piece >= (int) WhitePawn && (int) piece < (int) BlackPawn;
84 return (int) piece >= (int) BlackPawn && (int) piece < (int) EmptySquare;
87 int SameColor(piece1, piece2)
88 ChessSquare piece1, piece2;
90 return ((int) piece1 >= (int) WhitePawn && /* [HGM] can be > King ! */
91 (int) piece1 < (int) BlackPawn &&
92 (int) piece2 >= (int) WhitePawn &&
93 (int) piece2 < (int) BlackPawn)
94 || ((int) piece1 >= (int) BlackPawn &&
95 (int) piece1 < (int) EmptySquare &&
96 (int) piece2 >= (int) BlackPawn &&
97 (int) piece2 < (int) EmptySquare);
100 char pieceToChar[] = {
101 'P', 'N', 'B', 'R', 'Q', 'F', 'E', 'A', 'C', 'W', 'M',
102 'O', 'H', 'I', 'J', 'G', 'D', 'V', 'L', 'S', 'U', 'K',
103 'p', 'n', 'b', 'r', 'q', 'f', 'e', 'a', 'c', 'w', 'm',
104 'o', 'h', 'i', 'j', 'g', 'd', 'v', 'l', 's', 'u', 'k',
106 char pieceNickName[EmptySquare];
111 if((int)p < 0 || (int)p >= (int)EmptySquare) return('x'); /* [HGM] for safety */
112 return pieceToChar[(int) p];
115 int PieceToNumber(p) /* [HGM] holdings: count piece type, ignoring non-participating piece types */
119 ChessSquare start = (int)p >= (int)BlackPawn ? BlackPawn : WhitePawn;
121 while(start++ != p) if(pieceToChar[(int)start-1] != '.') i++;
125 ChessSquare CharToPiece(c)
129 for(i=0; i< (int) EmptySquare; i++)
130 if(pieceNickName[i] == c) return (ChessSquare) i;
131 for(i=0; i< (int) EmptySquare; i++)
132 if(pieceToChar[i] == c) return (ChessSquare) i;
136 void CopyBoard(to, from)
141 for (i = 0; i < BOARD_HEIGHT; i++)
142 for (j = 0; j < BOARD_WIDTH; j++)
143 to[i][j] = from[i][j];
144 for (j = 0; j < BOARD_FILES-1; j++) // [HGM] gamestate: copy castling rights and ep status
145 to[CASTLING][j] = from[CASTLING][j];
146 to[HOLDINGS_SET] = 0; // flag used in ICS play
149 int CompareBoards(board1, board2)
150 Board board1, board2;
154 for (i = 0; i < BOARD_HEIGHT; i++)
155 for (j = 0; j < BOARD_WIDTH; j++) {
156 if (board1[i][j] != board2[i][j])
163 /* Call callback once for each pseudo-legal move in the given
164 position, except castling moves. A move is pseudo-legal if it is
165 legal, or if it would be legal except that it leaves the king in
166 check. In the arguments, epfile is EP_NONE if the previous move
167 was not a double pawn push, or the file 0..7 if it was, or
168 EP_UNKNOWN if we don't know and want to allow all e.p. captures.
169 Promotion moves generated are to Queen only.
171 void GenPseudoLegal(board, flags, callback, closure)
174 MoveCallback callback;
178 int i, j, d, s, fs, rs, rt, ft, m;
179 int epfile = (signed char)board[EP_STATUS]; // [HGM] gamestate: extract ep status from board
180 int promoRank = gameInfo.variant == VariantMakruk ? 3 : 1;
182 for (rf = 0; rf < BOARD_HEIGHT; rf++)
183 for (ff = BOARD_LEFT; ff < BOARD_RGHT; ff++) {
186 if (flags & F_WHITE_ON_MOVE) {
187 if (!WhitePiece(board[rf][ff])) continue;
189 if (!BlackPiece(board[rf][ff])) continue;
191 m = 0; piece = board[rf][ff];
192 if(PieceToChar(piece) == '~')
193 piece = (ChessSquare) ( DEMOTED piece );
194 if(gameInfo.variant == VariantShogi)
195 piece = (ChessSquare) ( SHOGI piece );
198 /* case EmptySquare: [HGM] this is nonsense, and conflicts with Shogi cases */
200 /* can't happen ([HGM] except for faries...) */
204 if(gameInfo.variant == VariantXiangqi) {
205 /* [HGM] capture and move straight ahead in Xiangqi */
206 if (rf < BOARD_HEIGHT-1 &&
207 !SameColor(board[rf][ff], board[rf + 1][ff]) ) {
208 callback(board, flags, NormalMove,
209 rf, ff, rf + 1, ff, closure);
211 /* and move sideways when across the river */
212 for (s = -1; s <= 1; s += 2) {
213 if (rf >= BOARD_HEIGHT>>1 &&
214 ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
215 !WhitePiece(board[rf][ff+s]) ) {
216 callback(board, flags, NormalMove,
217 rf, ff, rf, ff+s, closure);
222 if (rf < BOARD_HEIGHT-1 && board[rf + 1][ff] == EmptySquare) {
223 callback(board, flags,
224 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
225 rf, ff, rf + 1, ff, closure);
227 if (rf == 1 && board[2][ff] == EmptySquare &&
228 gameInfo.variant != VariantShatranj && /* [HGM] */
229 gameInfo.variant != VariantCourier && /* [HGM] */
230 board[3][ff] == EmptySquare ) {
231 callback(board, flags, NormalMove,
232 rf, ff, 3, ff, closure);
234 for (s = -1; s <= 1; s += 2) {
235 if (rf < BOARD_HEIGHT-1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
236 ((flags & F_KRIEGSPIEL_CAPTURE) ||
237 BlackPiece(board[rf + 1][ff + s]))) {
238 callback(board, flags,
239 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
240 rf, ff, rf + 1, ff + s, closure);
242 if (rf == BOARD_HEIGHT-4) {
243 if (ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
244 (epfile == ff + s || epfile == EP_UNKNOWN) &&
245 board[BOARD_HEIGHT-4][ff + s] == BlackPawn &&
246 board[BOARD_HEIGHT-3][ff + s] == EmptySquare) {
247 callback(board, flags, WhiteCapturesEnPassant,
248 rf, ff, 5, ff + s, closure);
255 if(gameInfo.variant == VariantXiangqi) {
256 /* [HGM] capture straight ahead in Xiangqi */
257 if (rf > 0 && !SameColor(board[rf][ff], board[rf - 1][ff]) ) {
258 callback(board, flags, NormalMove,
259 rf, ff, rf - 1, ff, closure);
261 /* and move sideways when across the river */
262 for (s = -1; s <= 1; s += 2) {
263 if (rf < BOARD_HEIGHT>>1 &&
264 ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
265 !BlackPiece(board[rf][ff+s]) ) {
266 callback(board, flags, NormalMove,
267 rf, ff, rf, ff+s, closure);
272 if (rf > 0 && board[rf - 1][ff] == EmptySquare) {
273 callback(board, flags,
274 rf <= promoRank ? BlackPromotion : NormalMove,
275 rf, ff, rf - 1, ff, closure);
277 if (rf == BOARD_HEIGHT-2 && board[BOARD_HEIGHT-3][ff] == EmptySquare &&
278 gameInfo.variant != VariantShatranj && /* [HGM] */
279 gameInfo.variant != VariantCourier && /* [HGM] */
280 board[BOARD_HEIGHT-4][ff] == EmptySquare) {
281 callback(board, flags, NormalMove,
282 rf, ff, BOARD_HEIGHT-4, ff, closure);
284 for (s = -1; s <= 1; s += 2) {
285 if (rf > 0 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
286 ((flags & F_KRIEGSPIEL_CAPTURE) ||
287 WhitePiece(board[rf - 1][ff + s]))) {
288 callback(board, flags,
289 rf <= promoRank ? BlackPromotion : NormalMove,
290 rf, ff, rf - 1, ff + s, closure);
293 if (ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
294 (epfile == ff + s || epfile == EP_UNKNOWN) &&
295 board[3][ff + s] == WhitePawn &&
296 board[2][ff + s] == EmptySquare) {
297 callback(board, flags, BlackCapturesEnPassant,
298 rf, ff, 2, ff + s, closure);
309 for (i = -1; i <= 1; i += 2)
310 for (j = -1; j <= 1; j += 2)
311 for (s = 1; s <= 2; s++) {
314 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
315 && ( gameInfo.variant != VariantXiangqi || board[rf+i*(s-1)][ff+j*(2-s)] == EmptySquare)
316 && !SameColor(board[rf][ff], board[rt][ft]))
317 callback(board, flags, NormalMove,
318 rf, ff, rt, ft, closure);
322 case SHOGI WhiteKnight:
323 for (s = -1; s <= 1; s += 2) {
324 if (rf < BOARD_HEIGHT-2 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
325 !SameColor(board[rf][ff], board[rf + 2][ff + s])) {
326 callback(board, flags, NormalMove,
327 rf, ff, rf + 2, ff + s, closure);
332 case SHOGI BlackKnight:
333 for (s = -1; s <= 1; s += 2) {
334 if (rf > 1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
335 !SameColor(board[rf][ff], board[rf - 2][ff + s])) {
336 callback(board, flags, NormalMove,
337 rf, ff, rf - 2, ff + s, closure);
344 for (d = 0; d <= 1; d++)
345 for (s = -1; s <= 1; s += 2) {
348 rt = rf + (i * s) * d;
349 ft = ff + (i * s) * (1 - d);
350 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
351 if (m == 0 && board[rt][ft] == EmptySquare)
352 callback(board, flags, NormalMove,
353 rf, ff, rt, ft, closure);
354 if (m == 1 && board[rt][ft] != EmptySquare &&
355 !SameColor(board[rf][ff], board[rt][ft]) )
356 callback(board, flags, NormalMove,
357 rf, ff, rt, ft, closure);
358 if (board[rt][ft] != EmptySquare && m++) break;
363 /* Gold General (and all its promoted versions) . First do the */
364 /* diagonal forward steps, then proceed as normal Wazir */
365 case SHOGI WhiteWazir:
366 case SHOGI (PROMOTED WhitePawn):
367 case SHOGI (PROMOTED WhiteKnight):
368 case SHOGI (PROMOTED WhiteQueen):
369 case SHOGI (PROMOTED WhiteFerz):
370 for (s = -1; s <= 1; s += 2) {
371 if (rf < BOARD_HEIGHT-1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
372 !SameColor(board[rf][ff], board[rf + 1][ff + s])) {
373 callback(board, flags, NormalMove,
374 rf, ff, rf + 1, ff + s, closure);
379 case SHOGI BlackWazir:
380 case SHOGI (PROMOTED BlackPawn):
381 case SHOGI (PROMOTED BlackKnight):
382 case SHOGI (PROMOTED BlackQueen):
383 case SHOGI (PROMOTED BlackFerz):
384 for (s = -1; s <= 1; s += 2) {
385 if (rf > 0 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
386 !SameColor(board[rf][ff], board[rf - 1][ff + s])) {
387 callback(board, flags, NormalMove,
388 rf, ff, rf - 1, ff + s, closure);
395 for (d = 0; d <= 1; d++)
396 for (s = -1; s <= 1; s += 2) {
398 ft = ff + s * (1 - d);
399 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
400 && !SameColor(board[rf][ff], board[rt][ft]) &&
401 (gameInfo.variant != VariantXiangqi || InPalace(rt, ft) ) )
402 callback(board, flags, NormalMove,
403 rf, ff, rt, ft, closure);
409 /* [HGM] support Shatranj pieces */
410 for (rs = -1; rs <= 1; rs += 2)
411 for (fs = -1; fs <= 1; fs += 2) {
414 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
415 && ( gameInfo.variant != VariantXiangqi ||
416 board[rf+rs][ff+fs] == EmptySquare && (2*rf < BOARD_HEIGHT) == (2*rt < BOARD_HEIGHT) )
418 && !SameColor(board[rf][ff], board[rt][ft]))
419 callback(board, flags, NormalMove,
420 rf, ff, rt, ft, closure);
421 if(gameInfo.variant != VariantFairy && gameInfo.variant != VariantGreat) continue;
422 rt = rf + rs; // in unknown variant we assume Modern Elephant, which can also do one step
424 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
425 && !SameColor(board[rf][ff], board[rt][ft]))
426 callback(board, flags, NormalMove,
427 rf, ff, rt, ft, closure);
431 /* Make Dragon-Horse also do Dababba moves outside Shogi, for better disambiguation in variant Fairy */
434 for (d = 0; d <= 1; d++) // Dababba moves that Rook cannot do
435 for (s = -2; s <= 2; s += 4) {
437 ft = ff + s * (1 - d);
438 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
439 if (SameColor(board[rf][ff], board[rt][ft])) continue;
440 callback(board, flags, NormalMove, rf, ff, rt, ft, closure);
443 /* Shogi Dragon Horse has to continue with Wazir after Bishop */
444 case SHOGI WhiteCardinal:
445 case SHOGI BlackCardinal:
448 /* Capablanca Archbishop continues as Knight */
453 /* Shogi Bishops are ordinary Bishops */
454 case SHOGI WhiteBishop:
455 case SHOGI BlackBishop:
458 for (rs = -1; rs <= 1; rs += 2)
459 for (fs = -1; fs <= 1; fs += 2)
463 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
464 if (SameColor(board[rf][ff], board[rt][ft])) break;
465 callback(board, flags, NormalMove,
466 rf, ff, rt, ft, closure);
467 if (board[rt][ft] != EmptySquare) break;
469 if(m==1) goto mounted;
470 if(m==2) goto finishGold;
471 /* Bishop falls through */
474 /* Shogi Lance is unlike anything, and asymmetric at that */
475 case SHOGI WhiteQueen:
479 if (rt >= BOARD_HEIGHT) break;
480 if (SameColor(board[rf][ff], board[rt][ft])) break;
481 callback(board, flags, NormalMove,
482 rf, ff, rt, ft, closure);
483 if (board[rt][ft] != EmptySquare) break;
487 case SHOGI BlackQueen:
492 if (SameColor(board[rf][ff], board[rt][ft])) break;
493 callback(board, flags, NormalMove,
494 rf, ff, rt, ft, closure);
495 if (board[rt][ft] != EmptySquare) break;
499 /* Make Dragon-King Dababba & Rook-like outside Shogi, for better disambiguation in variant Fairy */
502 for (d = 0; d <= 1; d++) // Dababba moves that Rook cannot do
503 for (s = -2; s <= 2; s += 4) {
505 ft = ff + s * (1 - d);
506 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT || board[rf+rt>>1][ff+ft>>1] == EmptySquare) continue;
507 if (SameColor(board[rf][ff], board[rt][ft])) continue;
508 callback(board, flags, NormalMove, rf, ff, rt, ft, closure);
512 /* Shogi Dragon King has to continue as Ferz after Rook moves */
513 case SHOGI WhiteDragon:
514 case SHOGI BlackDragon:
517 /* Capablanca Chancellor sets flag to continue as Knight */
522 /* Shogi Rooks are ordinary Rooks */
523 case SHOGI WhiteRook:
524 case SHOGI BlackRook:
528 for (d = 0; d <= 1; d++)
529 for (s = -1; s <= 1; s += 2)
531 rt = rf + (i * s) * d;
532 ft = ff + (i * s) * (1 - d);
533 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
534 if (SameColor(board[rf][ff], board[rt][ft])) break;
535 callback(board, flags, NormalMove,
536 rf, ff, rt, ft, closure);
537 if (board[rt][ft] != EmptySquare) break;
539 if(m==1) goto mounted;
540 if(m==2) goto finishSilver;
545 for (rs = -1; rs <= 1; rs++)
546 for (fs = -1; fs <= 1; fs++) {
547 if (rs == 0 && fs == 0) continue;
551 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
552 if (SameColor(board[rf][ff], board[rt][ft])) break;
553 callback(board, flags, NormalMove,
554 rf, ff, rt, ft, closure);
555 if (board[rt][ft] != EmptySquare) break;
560 /* Shogi Pawn and Silver General: first the Pawn move, */
561 /* then the General continues like a Ferz */
563 if(gameInfo.variant != VariantMakruk) goto commoner;
564 case SHOGI WhitePawn:
565 case SHOGI WhiteFerz:
566 if (rf < BOARD_HEIGHT-1 &&
567 !SameColor(board[rf][ff], board[rf + 1][ff]) )
568 callback(board, flags, NormalMove,
569 rf, ff, rf + 1, ff, closure);
570 if(piece != SHOGI WhitePawn) goto finishSilver;
574 if(gameInfo.variant != VariantMakruk) goto commoner;
575 case SHOGI BlackPawn:
576 case SHOGI BlackFerz:
578 !SameColor(board[rf][ff], board[rf - 1][ff]) )
579 callback(board, flags, NormalMove,
580 rf, ff, rf - 1, ff, closure);
581 if(piece == SHOGI BlackPawn) break;
586 /* [HGM] support Shatranj pieces */
587 for (rs = -1; rs <= 1; rs += 2)
588 for (fs = -1; fs <= 1; fs += 2) {
591 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
592 if (!SameColor(board[rf][ff], board[rt][ft]) &&
593 (gameInfo.variant != VariantXiangqi || InPalace(rt, ft) ) )
594 callback(board, flags, NormalMove,
595 rf, ff, rt, ft, closure);
601 m++; // [HGM] superchess: use for Centaur
603 case SHOGI WhiteKing:
604 case SHOGI BlackKing:
608 for (i = -1; i <= 1; i++)
609 for (j = -1; j <= 1; j++) {
610 if (i == 0 && j == 0) continue;
613 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
614 if (SameColor(board[rf][ff], board[rt][ft])) continue;
615 callback(board, flags, NormalMove,
616 rf, ff, rt, ft, closure);
618 if(m==1) goto mounted;
621 case WhiteNightrider:
622 case BlackNightrider:
623 for (i = -1; i <= 1; i += 2)
624 for (j = -1; j <= 1; j += 2)
625 for (s = 1; s <= 2; s++) { int k;
629 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
630 if (SameColor(board[rf][ff], board[rt][ft])) break;
631 callback(board, flags, NormalMove,
632 rf, ff, rt, ft, closure);
633 if (board[rt][ft] != EmptySquare) break;
639 /* First do Bishop,then continue like Chancellor */
640 for (rs = -1; rs <= 1; rs += 2)
641 for (fs = -1; fs <= 1; fs += 2)
645 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
646 if (SameColor(board[rf][ff], board[rt][ft])) break;
647 callback(board, flags, NormalMove,
648 rf, ff, rt, ft, closure);
649 if (board[rt][ft] != EmptySquare) break;
654 // Use Lance as Berolina / Spartan Pawn.
656 if(gameInfo.variant == VariantSuper) goto Amazon;
657 if (rf < BOARD_HEIGHT-1 && BlackPiece(board[rf + 1][ff]))
658 callback(board, flags,
659 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
660 rf, ff, rf + 1, ff, closure);
661 for (s = -1; s <= 1; s += 2) {
662 if (rf < BOARD_HEIGHT-1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT && board[rf + 1][ff + s] == EmptySquare)
663 callback(board, flags,
664 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
665 rf, ff, rf + 1, ff + s, closure);
666 if (rf == 1 && ff + 2*s >= BOARD_LEFT && ff + 2*s < BOARD_RGHT && board[3][ff + 2*s] == EmptySquare )
667 callback(board, flags, NormalMove, rf, ff, 3, ff + 2*s, closure);
672 if(gameInfo.variant == VariantSuper) goto Amazon;
673 if (rf > 0 && WhitePiece(board[rf - 1][ff]))
674 callback(board, flags,
675 rf <= promoRank ? BlackPromotion : NormalMove,
676 rf, ff, rf - 1, ff, closure);
677 for (s = -1; s <= 1; s += 2) {
678 if (rf > 0 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT && board[rf - 1][ff + s] == EmptySquare)
679 callback(board, flags,
680 rf <= promoRank ? BlackPromotion : NormalMove,
681 rf, ff, rf - 1, ff + s, closure);
682 if (rf == BOARD_HEIGHT-2 && ff + 2*s >= BOARD_LEFT && ff + 2*s < BOARD_RGHT && board[rf-2][ff + 2*s] == EmptySquare )
683 callback(board, flags, NormalMove, rf, ff, rf-2, ff + 2*s, closure);
687 case WhiteFalcon: // [HGM] wild: for wildcards, self-capture symbolizes move to anywhere
691 callback(board, flags, NormalMove, rf, ff, rf, ff, closure);
704 extern void GenLegalCallback P((Board board, int flags, ChessMove kind,
705 int rf, int ff, int rt, int ft,
708 void GenLegalCallback(board, flags, kind, rf, ff, rt, ft, closure)
715 register GenLegalClosure *cl = (GenLegalClosure *) closure;
717 if (!(flags & F_IGNORE_CHECK) &&
718 CheckTest(board, flags, rf, ff, rt, ft,
719 kind == WhiteCapturesEnPassant ||
720 kind == BlackCapturesEnPassant)) return;
721 if (flags & F_ATOMIC_CAPTURE) {
722 if (board[rt][ft] != EmptySquare ||
723 kind == WhiteCapturesEnPassant || kind == BlackCapturesEnPassant) {
725 ChessSquare king = (flags & F_WHITE_ON_MOVE) ? WhiteKing : BlackKing;
726 if (board[rf][ff] == king) return;
727 for (r = rt-1; r <= rt+1; r++) {
728 for (f = ft-1; f <= ft+1; f++) {
729 if (r >= 0 && r < BOARD_HEIGHT && f >= BOARD_LEFT && f < BOARD_RGHT &&
730 board[r][f] == king) return;
735 cl->cb(board, flags, kind, rf, ff, rt, ft, cl->cl);
742 int captures; // [HGM] losers
743 } LegalityTestClosure;
746 /* Like GenPseudoLegal, but (1) include castling moves, (2) unless
747 F_IGNORE_CHECK is set in the flags, omit moves that would leave the
748 king in check, and (3) if F_ATOMIC_CAPTURE is set in the flags, omit
749 moves that would destroy your own king. The CASTLE_OK flags are
750 true if castling is not yet ruled out by a move of the king or
751 rook. Return TRUE if the player on move is currently in check and
752 F_IGNORE_CHECK is not set. [HGM] add castlingRights parameter */
753 int GenLegal(board, flags, callback, closure)
756 MoveCallback callback;
760 int ff, ft, k, left, right, swap;
761 int ignoreCheck = (flags & F_IGNORE_CHECK) != 0;
762 ChessSquare wKing = WhiteKing, bKing = BlackKing, *castlingRights = board[CASTLING];
766 GenPseudoLegal(board, flags, GenLegalCallback, (VOIDSTAR) &cl);
769 CheckTest(board, flags, -1, -1, -1, -1, FALSE)) return TRUE;
771 /* Generate castling moves */
772 if(gameInfo.variant == VariantKnightmate) { /* [HGM] Knightmate */
773 wKing = WhiteUnicorn; bKing = BlackUnicorn;
776 for (ff = BOARD_WIDTH>>1; ff >= (BOARD_WIDTH-1)>>1; ff-- /*ics wild 1*/) {
777 if ((flags & F_WHITE_ON_MOVE) &&
778 (flags & F_WHITE_KCASTLE_OK) &&
779 board[0][ff] == wKing &&
780 board[0][ff + 1] == EmptySquare &&
781 board[0][ff + 2] == EmptySquare &&
782 board[0][BOARD_RGHT-3] == EmptySquare &&
783 board[0][BOARD_RGHT-2] == EmptySquare &&
784 board[0][BOARD_RGHT-1] == WhiteRook &&
785 castlingRights[0] != NoRights && /* [HGM] check rights */
786 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
788 (!CheckTest(board, flags, 0, ff, 0, ff + 1, FALSE) &&
789 !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-3, FALSE) &&
790 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-2, FALSE)) &&
791 !CheckTest(board, flags, 0, ff, 0, ff + 2, FALSE)))) {
793 callback(board, flags,
794 ff==BOARD_WIDTH>>1 ? WhiteKingSideCastle : WhiteKingSideCastleWild,
795 0, ff, 0, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
797 if ((flags & F_WHITE_ON_MOVE) &&
798 (flags & F_WHITE_QCASTLE_OK) &&
799 board[0][ff] == wKing &&
800 board[0][ff - 1] == EmptySquare &&
801 board[0][ff - 2] == EmptySquare &&
802 board[0][BOARD_LEFT+2] == EmptySquare &&
803 board[0][BOARD_LEFT+1] == EmptySquare &&
804 board[0][BOARD_LEFT+0] == WhiteRook &&
805 castlingRights[1] != NoRights && /* [HGM] check rights */
806 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
808 (!CheckTest(board, flags, 0, ff, 0, ff - 1, FALSE) &&
809 !CheckTest(board, flags, 0, ff, 0, BOARD_LEFT+3, FALSE) &&
810 !CheckTest(board, flags, 0, ff, 0, ff - 2, FALSE)))) {
812 callback(board, flags,
813 ff==BOARD_WIDTH>>1 ? WhiteQueenSideCastle : WhiteQueenSideCastleWild,
814 0, ff, 0, ff - ((gameInfo.boardWidth+2)>>2), closure);
816 if (!(flags & F_WHITE_ON_MOVE) &&
817 (flags & F_BLACK_KCASTLE_OK) &&
818 board[BOARD_HEIGHT-1][ff] == bKing &&
819 board[BOARD_HEIGHT-1][ff + 1] == EmptySquare &&
820 board[BOARD_HEIGHT-1][ff + 2] == EmptySquare &&
821 board[BOARD_HEIGHT-1][BOARD_RGHT-3] == EmptySquare &&
822 board[BOARD_HEIGHT-1][BOARD_RGHT-2] == EmptySquare &&
823 board[BOARD_HEIGHT-1][BOARD_RGHT-1] == BlackRook &&
824 castlingRights[3] != NoRights && /* [HGM] check rights */
825 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
827 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 1, FALSE) &&
828 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-3, FALSE) &&
829 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-2, FALSE)) &&
830 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 2, FALSE)))) {
832 callback(board, flags,
833 ff==BOARD_WIDTH>>1 ? BlackKingSideCastle : BlackKingSideCastleWild,
834 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
836 if (!(flags & F_WHITE_ON_MOVE) &&
837 (flags & F_BLACK_QCASTLE_OK) &&
838 board[BOARD_HEIGHT-1][ff] == bKing &&
839 board[BOARD_HEIGHT-1][ff - 1] == EmptySquare &&
840 board[BOARD_HEIGHT-1][ff - 2] == EmptySquare &&
841 board[BOARD_HEIGHT-1][BOARD_LEFT+2] == EmptySquare &&
842 board[BOARD_HEIGHT-1][BOARD_LEFT+1] == EmptySquare &&
843 board[BOARD_HEIGHT-1][BOARD_LEFT+0] == BlackRook &&
844 castlingRights[4] != NoRights && /* [HGM] check rights */
845 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
847 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 1, FALSE) &&
848 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_LEFT+3, FALSE) &&
849 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 2, FALSE)))) {
851 callback(board, flags,
852 ff==BOARD_WIDTH>>1 ? BlackQueenSideCastle : BlackQueenSideCastleWild,
853 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - ((gameInfo.boardWidth+2)>>2), closure);
857 if((swap = gameInfo.variant == VariantSChess) || flags & F_FRC_TYPE_CASTLING) {
859 /* generate all potential FRC castling moves (KxR), ignoring flags */
860 /* [HGM] test if the Rooks we find have castling rights */
861 /* In S-Chess we generate RxK for allowed castlings, for gating at Rook square */
864 if ((flags & F_WHITE_ON_MOVE) != 0) {
865 ff = castlingRights[2]; /* King file if we have any rights */
866 if(ff != NoRights && board[0][ff] == WhiteKing) {
867 if (appData.debugMode) {
868 fprintf(debugFP, "FRC castling, %d %d %d %d %d %d\n",
869 castlingRights[0],castlingRights[1],ff,castlingRights[3],castlingRights[4],castlingRights[5]);
871 ft = castlingRights[0]; /* Rook file if we have H-side rights */
873 right = BOARD_RGHT-2;
874 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
875 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
876 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
877 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
878 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
879 if(ft != NoRights && board[0][ft] == WhiteRook)
880 callback(board, flags, WhiteHSideCastleFR, 0, swap ? ft : ff, 0, swap ? ff : ft, closure);
882 ft = castlingRights[1]; /* Rook file if we have A-side rights */
885 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
886 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
887 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
888 if(ff > BOARD_LEFT+2)
889 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
890 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
891 if(ft != NoRights && board[0][ft] == WhiteRook)
892 callback(board, flags, WhiteASideCastleFR, 0, swap ? ft : ff, 0, swap ? ff : ft, closure);
895 ff = castlingRights[5]; /* King file if we have any rights */
896 if(ff != NoRights && board[BOARD_HEIGHT-1][ff] == BlackKing) {
897 ft = castlingRights[3]; /* Rook file if we have H-side rights */
899 right = BOARD_RGHT-2;
900 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
901 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
902 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
903 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
904 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
905 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
906 callback(board, flags, BlackHSideCastleFR, BOARD_HEIGHT-1, swap ? ft : ff, BOARD_HEIGHT-1, swap ? ff : ft, closure);
908 ft = castlingRights[4]; /* Rook file if we have A-side rights */
911 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
912 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
913 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
914 if(ff > BOARD_LEFT+2)
915 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
916 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
917 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
918 callback(board, flags, BlackASideCastleFR, BOARD_HEIGHT-1, swap ? ft : ff, BOARD_HEIGHT-1, swap ? ff : ft, closure);
934 extern void CheckTestCallback P((Board board, int flags, ChessMove kind,
935 int rf, int ff, int rt, int ft,
939 void CheckTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
946 register CheckTestClosure *cl = (CheckTestClosure *) closure;
948 if (rt == cl->rking && ft == cl->fking) cl->check++;
952 /* If the player on move were to move from (rf, ff) to (rt, ft), would
953 he leave himself in check? Or if rf == -1, is the player on move
954 in check now? enPassant must be TRUE if the indicated move is an
955 e.p. capture. The possibility of castling out of a check along the
956 back rank is not accounted for (i.e., we still return nonzero), as
957 this is illegal anyway. Return value is the number of times the
959 int CheckTest(board, flags, rf, ff, rt, ft, enPassant)
962 int rf, ff, rt, ft, enPassant;
965 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
966 ChessSquare captured = EmptySquare;
967 /* Suppress warnings on uninitialized variables */
969 if(gameInfo.variant == VariantXiangqi)
970 king = flags & F_WHITE_ON_MOVE ? WhiteWazir : BlackWazir;
971 if(gameInfo.variant == VariantKnightmate)
972 king = flags & F_WHITE_ON_MOVE ? WhiteUnicorn : BlackUnicorn;
976 captured = board[rf][ft];
977 board[rf][ft] = EmptySquare;
979 captured = board[rt][ft];
981 board[rt][ft] = board[rf][ff];
982 board[rf][ff] = EmptySquare;
983 } else board[rt][ft] = ff; // [HGM] drop
985 /* For compatibility with ICS wild 9, we scan the board in the
986 order a1, a2, a3, ... b1, b2, ..., h8 to find the first king,
987 and we test only whether that one is in check. */
989 for (cl.fking = BOARD_LEFT+0; cl.fking < BOARD_RGHT; cl.fking++)
990 for (cl.rking = 0; cl.rking < BOARD_HEIGHT; cl.rking++) {
991 if (board[cl.rking][cl.fking] == king) {
992 if(gameInfo.variant == VariantXiangqi) {
993 /* [HGM] In Xiangqi opposing Kings means check as well */
995 dir = (king >= BlackPawn) ? -1 : 1;
996 for( i=cl.rking+dir; i>=0 && i<BOARD_HEIGHT &&
997 board[i][cl.fking] == EmptySquare; i+=dir );
998 if(i>=0 && i<BOARD_HEIGHT &&
999 board[i][cl.fking] == (dir>0 ? BlackWazir : WhiteWazir) )
1003 GenPseudoLegal(board, flags ^ F_WHITE_ON_MOVE, CheckTestCallback, (VOIDSTAR) &cl);
1004 goto undo_move; /* 2-level break */
1011 board[rf][ff] = board[rt][ft];
1013 board[rf][ft] = captured;
1014 board[rt][ft] = EmptySquare;
1016 board[rt][ft] = captured;
1018 } else board[rt][ft] = EmptySquare; // [HGM] drop
1020 return cl.fking < BOARD_RGHT ? cl.check : 1000; // [HGM] atomic: return 1000 if we have no king
1023 ChessMove LegalDrop(board, flags, piece, rt, ft)
1028 { // [HGM] put drop legality testing in separate routine for clarity
1030 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
1031 if(board[rt][ft] != EmptySquare) return ImpossibleMove; // must drop to empty square
1032 n = PieceToNumber(piece);
1033 if(gameInfo.holdingsWidth == 0 || (flags & F_WHITE_ON_MOVE ? board[n][BOARD_WIDTH-1] : board[BOARD_HEIGHT-1-n][0]) != piece)
1034 return ImpossibleMove; // piece not available
1035 if(gameInfo.variant == VariantShogi) { // in Shogi lots of drops are forbidden!
1036 if((piece == WhitePawn || piece == WhiteQueen) && rt == BOARD_HEIGHT-1 ||
1037 (piece == BlackPawn || piece == BlackQueen) && rt == 0 ||
1038 piece == WhiteKnight && rt > BOARD_HEIGHT-3 ||
1039 piece == BlackKnight && rt < 2 ) return IllegalMove; // e.g. where dropped piece has no moves
1040 if(piece == WhitePawn || piece == BlackPawn) {
1042 for(r=1; r<BOARD_HEIGHT-1; r++)
1043 if(board[r][ft] == piece) return IllegalMove; // or there already is a Pawn in file
1044 // should still test if we mate with this Pawn
1047 if( (piece == WhitePawn || piece == BlackPawn) &&
1048 (rt == 0 || rt == BOARD_HEIGHT -1 ) )
1049 return IllegalMove; /* no pawn drops on 1st/8th */
1051 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
1052 if (!(flags & F_IGNORE_CHECK) &&
1053 CheckTest(board, flags, DROP_RANK, piece, rt, ft, FALSE) ) return IllegalMove;
1054 return flags & F_WHITE_ON_MOVE ? WhiteDrop : BlackDrop;
1057 extern void LegalityTestCallback P((Board board, int flags, ChessMove kind,
1058 int rf, int ff, int rt, int ft,
1061 void LegalityTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
1068 register LegalityTestClosure *cl = (LegalityTestClosure *) closure;
1070 // if (appData.debugMode) {
1071 // fprintf(debugFP, "Legality test: %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
1073 if(board[rt][ft] != EmptySquare || kind==WhiteCapturesEnPassant || kind==BlackCapturesEnPassant)
1074 cl->captures++; // [HGM] losers: count legal captures
1075 if (rf == cl->rf && ff == cl->ff && rt == cl->rt && ft == cl->ft)
1079 ChessMove LegalityTest(board, flags, rf, ff, rt, ft, promoChar)
1082 int rf, ff, rt, ft, promoChar;
1084 LegalityTestClosure cl; ChessSquare piece, *castlingRights = board[CASTLING];
1086 if(rf == DROP_RANK) return LegalDrop(board, flags, ff, rt, ft);
1087 piece = board[rf][ff];
1089 if (appData.debugMode) {
1091 for(i=0; i<6; i++) fprintf(debugFP, "%d ", castlingRights[i]);
1092 fprintf(debugFP, "Legality test? %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
1094 /* [HGM] Cobra and Falcon are wildcard pieces; consider all their moves legal */
1095 /* (perhaps we should disallow moves that obviously leave us in check?) */
1096 if(piece == WhiteFalcon || piece == BlackFalcon ||
1097 piece == WhiteCobra || piece == BlackCobra)
1098 return CheckTest(board, flags, rf, ff, rt, ft, FALSE) ? IllegalMove : NormalMove;
1104 cl.kind = IllegalMove;
1105 cl.captures = 0; // [HGM] losers: prepare to count legal captures.
1106 GenLegal(board, flags, LegalityTestCallback, (VOIDSTAR) &cl);
1107 if((flags & F_MANDATORY_CAPTURE) && cl.captures && board[rt][ft] == EmptySquare
1108 && cl.kind != WhiteCapturesEnPassant && cl.kind != BlackCapturesEnPassant)
1109 return(IllegalMove); // [HGM] losers: if there are legal captures, non-capts are illegal
1111 if(promoChar == 'x') promoChar = NULLCHAR; // [HGM] is this ever the case?
1112 if(gameInfo.variant == VariantSChess && promoChar && promoChar != '=' && board[rf][ff] != WhitePawn && board[rf][ff] != BlackPawn) {
1113 if(board[rf][ff] < BlackPawn) { // white
1114 if(rf != 0) return IllegalMove; // must be on back rank
1115 if(board[PieceToNumber(CharToPiece(ToUpper(promoChar)))][BOARD_WIDTH-2] == 0) return ImpossibleMove;// must be in stock
1117 if(rf != BOARD_HEIGHT-1) return IllegalMove;
1118 if(board[BOARD_HEIGHT-1-PieceToNumber(CharToPiece(ToLower(promoChar)))][1] == 0) return ImpossibleMove;
1121 if(gameInfo.variant == VariantShogi) {
1122 /* [HGM] Shogi promotions. '=' means defer */
1123 if(rf != DROP_RANK && cl.kind == NormalMove) {
1124 ChessSquare piece = board[rf][ff];
1126 if(promoChar == PieceToChar(BlackQueen)) promoChar = NULLCHAR; /* [HGM] Kludge */
1127 if(promoChar == 'd' && (piece == WhiteRook || piece == BlackRook) ||
1128 promoChar == 'h' && (piece == WhiteBishop || piece == BlackBishop) ||
1129 promoChar == 'g' && (piece <= WhiteFerz || piece <= BlackFerz && piece >= BlackPawn) )
1130 promoChar = '+'; // allowed ICS notations
1131 if(appData.debugMode)fprintf(debugFP,"SHOGI promoChar = %c\n", promoChar ? promoChar : '-');
1132 if(promoChar != NULLCHAR && promoChar != '+' && promoChar != '=')
1133 return CharToPiece(promoChar) == EmptySquare ? ImpossibleMove : IllegalMove;
1134 else if(flags & F_WHITE_ON_MOVE) {
1135 if( (int) piece < (int) WhiteWazir &&
1136 (rf >= BOARD_HEIGHT*2/3 || rt >= BOARD_HEIGHT*2/3) ) {
1137 if( (piece == WhitePawn || piece == WhiteQueen) && rt > BOARD_HEIGHT-2 ||
1138 piece == WhiteKnight && rt > BOARD_HEIGHT-3) /* promotion mandatory */
1139 cl.kind = promoChar == '=' ? IllegalMove : WhitePromotion;
1140 else /* promotion optional, default is defer */
1141 cl.kind = promoChar == '+' ? WhitePromotion : WhiteNonPromotion;
1142 } else cl.kind = promoChar == '+' ? IllegalMove : NormalMove;
1144 if( (int) piece < (int) BlackWazir && (rf < BOARD_HEIGHT/3 || rt < BOARD_HEIGHT/3) ) {
1145 if( (piece == BlackPawn || piece == BlackQueen) && rt < 1 ||
1146 piece == BlackKnight && rt < 2 ) /* promotion obligatory */
1147 cl.kind = promoChar == '=' ? IllegalMove : BlackPromotion;
1148 else /* promotion optional, default is defer */
1149 cl.kind = promoChar == '+' ? BlackPromotion : BlackNonPromotion;
1150 } else cl.kind = promoChar == '+' ? IllegalMove : NormalMove;
1154 if (promoChar != NULLCHAR) {
1155 if(promoChar == '=') cl.kind = IllegalMove; else // [HGM] shogi: no deferred promotion outside Shogi
1156 if (cl.kind == WhitePromotion || cl.kind == BlackPromotion) {
1157 if(CharToPiece(flags & F_WHITE_ON_MOVE ? ToUpper(promoChar) : ToLower(promoChar)) == EmptySquare)
1158 cl.kind = ImpossibleMove; // non-existing piece
1160 cl.kind = IllegalMove;
1170 extern void MateTestCallback P((Board board, int flags, ChessMove kind,
1171 int rf, int ff, int rt, int ft,
1174 void MateTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
1181 register MateTestClosure *cl = (MateTestClosure *) closure;
1186 /* Return MT_NONE, MT_CHECK, MT_CHECKMATE, or MT_STALEMATE */
1187 int MateTest(board, flags)
1192 int inCheck, r, f, myPieces=0, hisPieces=0, nrKing=0;
1193 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
1195 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) {
1196 // [HGM] losers: Count pieces and kings, to detect other unorthodox winning conditions
1197 nrKing += (board[r][f] == king); // stm has king
1198 if( board[r][f] != EmptySquare ) {
1199 if((int)board[r][f] <= (int)king && (int)board[r][f] >= (int)king - (int)WhiteKing + (int)WhitePawn)
1204 if(appData.debugMode) fprintf(debugFP, "MateTest: K=%d, my=%d, his=%d\n", nrKing, myPieces, hisPieces);
1205 switch(gameInfo.variant) { // [HGM] losers: extinction wins
1206 case VariantShatranj:
1207 if(hisPieces == 1) return myPieces > 1 ? MT_BARE : MT_DRAW;
1211 if(nrKing == 0) return MT_NOKING;
1214 if(myPieces == 1) return MT_BARE;
1217 inCheck = GenLegal(board, flags, MateTestCallback, (VOIDSTAR) &cl);
1218 // [HGM] 3check: yet to do!
1220 return inCheck ? MT_CHECK : MT_NONE;
1222 if(gameInfo.holdingsWidth && gameInfo.variant != VariantSuper || gameInfo.variant != VariantGreat) { // drop game
1223 int r, f, n, holdings = flags & F_WHITE_ON_MOVE ? BOARD_WIDTH-1 : 0;
1224 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) if(board[r][f] == EmptySquare) // all empty squares
1225 for(n=0; n<BOARD_HEIGHT; n++) // all pieces in hand
1226 if(board[n][holdings] != EmptySquare) {
1227 int moveType = LegalDrop(board, flags, board[n][holdings], r, f);
1228 if(moveType == WhiteDrop || moveType == BlackDrop) return MT_CHECK; // we can resolve check by legal drop
1231 if(gameInfo.variant == VariantSuicide) // [HGM] losers: always stalemate, since no check, but result varies
1232 return myPieces == hisPieces ? MT_STALEMATE :
1233 myPieces > hisPieces ? MT_STAINMATE : MT_STEALMATE;
1234 else if(gameInfo.variant == VariantLosers) return inCheck ? MT_TRICKMATE : MT_STEALMATE;
1235 else if(gameInfo.variant == VariantGiveaway) return MT_STEALMATE; // no check exists, stalemated = win
1237 return inCheck ? MT_CHECKMATE
1238 : (gameInfo.variant == VariantXiangqi || gameInfo.variant == VariantShatranj) ?
1239 MT_STAINMATE : MT_STALEMATE;
1244 extern void DisambiguateCallback P((Board board, int flags, ChessMove kind,
1245 int rf, int ff, int rt, int ft,
1248 void DisambiguateCallback(board, flags, kind, rf, ff, rt, ft, closure)
1255 register DisambiguateClosure *cl = (DisambiguateClosure *) closure;
1256 int wildCard = FALSE; ChessSquare piece = board[rf][ff];
1258 // [HGM] wild: for wild-card pieces rt and rf are dummies
1259 if(piece == WhiteFalcon || piece == BlackFalcon ||
1260 piece == WhiteCobra || piece == BlackCobra)
1263 if ((cl->pieceIn == EmptySquare || cl->pieceIn == board[rf][ff]
1264 || PieceToChar(board[rf][ff]) == '~'
1265 && cl->pieceIn == (ChessSquare)(DEMOTED board[rf][ff])
1267 (cl->rfIn == -1 || cl->rfIn == rf) &&
1268 (cl->ffIn == -1 || cl->ffIn == ff) &&
1269 (cl->rtIn == -1 || cl->rtIn == rt || wildCard) &&
1270 (cl->ftIn == -1 || cl->ftIn == ft || wildCard)) {
1273 if(cl->count == 1 || board[rt][ft] != EmptySquare) {
1274 // [HGM] oneclick: if multiple moves, be sure we remember capture
1275 cl->piece = board[rf][ff];
1278 cl->rt = wildCard ? cl->rtIn : rt;
1279 cl->ft = wildCard ? cl->ftIn : ft;
1282 cl->captures += (board[rt][ft] != EmptySquare); // [HGM] oneclick: count captures
1286 void Disambiguate(board, flags, closure)
1289 DisambiguateClosure *closure;
1291 int illegal = 0; char c = closure->promoCharIn;
1293 closure->count = closure->captures = 0;
1294 closure->rf = closure->ff = closure->rt = closure->ft = 0;
1295 closure->kind = ImpossibleMove;
1296 if (appData.debugMode) {
1297 fprintf(debugFP, "Disambiguate in: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1298 closure->pieceIn,closure->ffIn,closure->rfIn,closure->ftIn,closure->rtIn,
1299 closure->promoCharIn, closure->promoCharIn >= ' ' ? closure->promoCharIn : '-');
1301 GenLegal(board, flags, DisambiguateCallback, (VOIDSTAR) closure);
1302 if (closure->count == 0) {
1303 /* See if it's an illegal move due to check */
1305 GenLegal(board, flags|F_IGNORE_CHECK, DisambiguateCallback, (VOIDSTAR) closure);
1306 if (closure->count == 0) {
1307 /* No, it's not even that */
1308 if (appData.debugMode) { int i, j;
1309 for(i=BOARD_HEIGHT-1; i>=0; i--) {
1310 for(j=0; j<BOARD_WIDTH; j++)
1311 fprintf(debugFP, "%3d", (int) board[i][j]);
1312 fprintf(debugFP, "\n");
1319 if (c == 'x') c = NULLCHAR; // get rid of any 'x' (which should never happen?)
1320 if(gameInfo.variant == VariantSChess && c && c != '=' && closure->piece != WhitePawn && closure->piece != BlackPawn) {
1321 if(closure->piece < BlackPawn) { // white
1322 if(closure->rf != 0) closure->kind = IllegalMove; // must be on back rank
1323 if(board[PieceToNumber(CharToPiece(ToUpper(c)))][BOARD_WIDTH-2] == 0) closure->kind = ImpossibleMove;// must be in stock
1325 if(closure->rf != BOARD_HEIGHT-1) closure->kind = IllegalMove;
1326 if(board[BOARD_HEIGHT-1-PieceToNumber(CharToPiece(ToLower(c)))][1] == 0) closure->kind = ImpossibleMove;
1329 if(gameInfo.variant == VariantShogi) {
1330 /* [HGM] Shogi promotions. On input, '=' means defer, '+' promote. Afterwards, c is set to '+' for promotions, NULL other */
1331 if(closure->rfIn != DROP_RANK && closure->kind == NormalMove) {
1332 ChessSquare piece = closure->piece;
1333 if (c == 'd' && (piece == WhiteRook || piece == BlackRook) ||
1334 c == 'h' && (piece == WhiteBishop || piece == BlackBishop) ||
1335 c == 'g' && (piece <= WhiteFerz || piece <= BlackFerz && piece >= BlackPawn) )
1336 c = '+'; // allowed ICS notations
1337 if(c != NULLCHAR && c != '+' && c != '=') closure->kind = IllegalMove; // otherwise specifying a piece is illegal
1338 else if(flags & F_WHITE_ON_MOVE) {
1339 if( (int) piece < (int) WhiteWazir &&
1340 (closure->rf >= BOARD_HEIGHT-(BOARD_HEIGHT/3) || closure->rt >= BOARD_HEIGHT-(BOARD_HEIGHT/3)) ) {
1341 if( (piece == WhitePawn || piece == WhiteQueen) && closure->rt > BOARD_HEIGHT-2 ||
1342 piece == WhiteKnight && closure->rt > BOARD_HEIGHT-3) /* promotion mandatory */
1343 closure->kind = c == '=' ? IllegalMove : WhitePromotion;
1344 else /* promotion optional, default is defer */
1345 closure->kind = c == '+' ? WhitePromotion : WhiteNonPromotion;
1346 } else closure->kind = c == '+' ? IllegalMove : NormalMove;
1348 if( (int) piece < (int) BlackWazir && (closure->rf < BOARD_HEIGHT/3 || closure->rt < BOARD_HEIGHT/3) ) {
1349 if( (piece == BlackPawn || piece == BlackQueen) && closure->rt < 1 ||
1350 piece == BlackKnight && closure->rt < 2 ) /* promotion obligatory */
1351 closure->kind = c == '=' ? IllegalMove : BlackPromotion;
1352 else /* promotion optional, default is defer */
1353 closure->kind = c == '+' ? BlackPromotion : BlackNonPromotion;
1354 } else closure->kind = c == '+' ? IllegalMove : NormalMove;
1357 if(closure->kind == WhitePromotion || closure->kind == BlackPromotion) c = '+'; else
1358 if(closure->kind == WhiteNonPromotion || closure->kind == BlackNonPromotion) c = '=';
1360 if (closure->kind == WhitePromotion || closure->kind == BlackPromotion) {
1361 if(c == NULLCHAR) { // missing promoChar on mandatory promotion; use default for variant
1362 if(gameInfo.variant == VariantShatranj || gameInfo.variant == VariantCourier || gameInfo.variant == VariantMakruk)
1363 c = PieceToChar(BlackFerz);
1364 else if(gameInfo.variant == VariantGreat)
1365 c = PieceToChar(BlackMan);
1367 c = PieceToChar(BlackQueen);
1368 } else if(c == '=') closure->kind = IllegalMove; // no deferral outside Shogi
1369 } else if (c != NULLCHAR) closure->kind = IllegalMove;
1371 closure->promoChar = ToLower(c); // this can be NULLCHAR! Note we keep original promoChar even if illegal.
1372 if(c != '+' && c != '=' && c != NULLCHAR && CharToPiece(flags & F_WHITE_ON_MOVE ? ToUpper(c) : ToLower(c)) == EmptySquare)
1373 closure->kind = ImpossibleMove; // but we cannot handle non-existing piece types!
1374 if (closure->count > 1) {
1375 closure->kind = AmbiguousMove;
1378 /* Note: If more than one illegal move matches, but no legal
1379 moves, we return IllegalMove, not AmbiguousMove. Caller
1380 can look at closure->count to detect this.
1382 closure->kind = IllegalMove;
1384 if (appData.debugMode) {
1385 fprintf(debugFP, "Disambiguate out: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1386 closure->piece,closure->ff,closure->rf,closure->ft,closure->rt,closure->promoChar,
1387 closure->promoChar >= ' ' ? closure->promoChar:'-');
1401 } CoordsToAlgebraicClosure;
1403 extern void CoordsToAlgebraicCallback P((Board board, int flags,
1404 ChessMove kind, int rf, int ff,
1405 int rt, int ft, VOIDSTAR closure));
1407 void CoordsToAlgebraicCallback(board, flags, kind, rf, ff, rt, ft, closure)
1414 register CoordsToAlgebraicClosure *cl =
1415 (CoordsToAlgebraicClosure *) closure;
1417 if ((rt == cl->rt && ft == cl->ft || rt == rf && ft == ff) && // [HGM] null move matches any toSquare
1418 (board[rf][ff] == cl->piece
1419 || PieceToChar(board[rf][ff]) == '~' &&
1420 (ChessSquare) (DEMOTED board[rf][ff]) == cl->piece)
1424 cl->kind = kind; /* this is the move we want */
1426 cl->file++; /* need file to rule out this move */
1430 cl->rank++; /* need rank to rule out this move */
1432 cl->either++; /* rank or file will rule out this move */
1438 /* Convert coordinates to normal algebraic notation.
1439 promoChar must be NULLCHAR or 'x' if not a promotion.
1441 ChessMove CoordsToAlgebraic(board, flags, rf, ff, rt, ft, promoChar, out)
1450 char *outp = out, c;
1451 CoordsToAlgebraicClosure cl;
1453 if (rf == DROP_RANK) {
1454 /* Bughouse piece drop */
1455 *outp++ = ToUpper(PieceToChar((ChessSquare) ff));
1460 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1462 return (flags & F_WHITE_ON_MOVE) ? WhiteDrop : BlackDrop;
1465 if (promoChar == 'x') promoChar = NULLCHAR;
1466 piece = board[rf][ff];
1467 if(PieceToChar(piece)=='~') piece = (ChessSquare)(DEMOTED piece);
1469 if (appData.debugMode)
1470 fprintf(debugFP, "CoordsToAlgebraic, piece=%d (%d,%d)-(%d,%d) %c\n", (int)piece,ff,rf,ft,rt,promoChar >= ' ' ? promoChar : '-');
1474 kind = LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1475 if (kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1476 /* Keep short notation if move is illegal only because it
1477 leaves the player in check, but still return IllegalMove */
1478 kind = LegalityTest(board, flags|F_IGNORE_CHECK, rf, ff, rt, ft, promoChar);
1479 if (kind == IllegalMove) break;
1484 if (ff == ft && board[rt][ft] == EmptySquare) { /* [HGM] Xiangqi has straight noncapts! */
1485 /* Non-capture; use style "e5" */
1488 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1490 /* Capture; use style "exd5" */
1491 if(gameInfo.variant != VariantXiangqi || board[rt][ft] != EmptySquare )
1492 *outp++ = 'x'; /* [HGM] Xiangqi has sideway noncaptures across river! */
1496 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1498 /* Use promotion suffix style "=Q" */
1500 if (appData.debugMode)
1501 fprintf(debugFP, "movetype=%d, promochar=%d=%c\n", (int)kind, promoChar, promoChar >= ' ' ? promoChar : '-');
1502 if (promoChar != NULLCHAR) {
1503 if(gameInfo.variant == VariantShogi) {
1504 /* [HGM] ... but not in Shogi! */
1505 *outp++ = promoChar == '=' ? '=' : '+';
1508 *outp++ = ToUpper(promoChar);
1517 /* Fabien moved code: FRC castling first (if KxR), wild castling second */
1518 /* Code added by Tord: FRC castling. */
1519 if((piece == WhiteKing && board[rt][ft] == WhiteRook) ||
1520 (piece == BlackKing && board[rt][ft] == BlackRook)) {
1522 safeStrCpy(out, "O-O", MOVE_LEN);
1524 safeStrCpy(out, "O-O-O", MOVE_LEN);
1525 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1527 /* End of code added by Tord */
1528 /* Test for castling or ICS wild castling */
1529 /* Use style "O-O" (oh-oh) for PGN compatibility */
1530 else if (rf == rt &&
1531 rf == ((piece == WhiteKing) ? 0 : BOARD_HEIGHT-1) &&
1532 (ft - ff > 1 || ff - ft > 1) && // No castling if legal King move (on narrow boards!)
1533 ((ff == BOARD_WIDTH>>1 && (ft == BOARD_LEFT+2 || ft == BOARD_RGHT-2)) ||
1534 (ff == (BOARD_WIDTH-1)>>1 && (ft == BOARD_LEFT+1 || ft == BOARD_RGHT-3)))) {
1535 if(ft==BOARD_LEFT+1 || ft==BOARD_RGHT-2)
1536 snprintf(out, MOVE_LEN, "O-O%c%c", promoChar ? '/' : 0, ToUpper(promoChar));
1538 snprintf(out, MOVE_LEN, "O-O-O%c%c", promoChar ? '/' : 0, ToUpper(promoChar));
1540 /* This notation is always unambiguous, unless there are
1541 kings on both the d and e files, with "wild castling"
1542 possible for the king on the d file and normal castling
1543 possible for the other. ICS rules for wild 9
1544 effectively make castling illegal for either king in
1545 this situation. So I am not going to worry about it;
1546 I'll just generate an ambiguous O-O in this case.
1548 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1551 /* else fall through */
1559 cl.kind = IllegalMove;
1560 cl.rank = cl.file = cl.either = 0;
1561 GenLegal(board, flags, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1563 if (cl.kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1564 /* Generate pretty moves for moving into check, but
1565 still return IllegalMove.
1567 GenLegal(board, flags|F_IGNORE_CHECK, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1568 if (cl.kind == IllegalMove) break;
1569 cl.kind = IllegalMove;
1572 /* Style is "Nf3" or "Nxf7" if this is unambiguous,
1573 else "Ngf3" or "Ngxf7",
1574 else "N1f3" or "N5xf7",
1575 else "Ng1f3" or "Ng5xf7".
1577 c = PieceToChar(piece) ;
1578 if( c == '~' || c == '+') {
1579 /* [HGM] print nonexistent piece as its demoted version */
1580 piece = (ChessSquare) (DEMOTED piece);
1582 if(c=='+') *outp++ = c;
1583 *outp++ = ToUpper(PieceToChar(piece));
1585 if (cl.file || (cl.either && !cl.rank)) {
1591 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1594 if(board[rt][ft] != EmptySquare)
1600 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1601 if (gameInfo.variant == VariantShogi) {
1602 /* [HGM] in Shogi non-pawns can promote */
1603 *outp++ = promoChar; // Don't bother to correct move type, return value is never used!
1605 else if (gameInfo.variant == VariantSChess && promoChar) { // and in S-Chess we have gating
1607 *outp++ = ToUpper(promoChar);
1613 /* Moving a nonexistent piece */
1617 /* Not a legal move, even ignoring check.
1618 If there was a piece on the from square,
1619 use style "Ng1g3" or "Ng1xe8";
1620 if there was a pawn or nothing (!),
1621 use style "g1g3" or "g1xe8". Use "x"
1622 if a piece was on the to square, even
1623 a piece of the same color.
1627 if (piece != EmptySquare && piece != WhitePawn && piece != BlackPawn) {
1629 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<=BOARD_RGHT; f++)
1630 c += (board[r][f] == piece); // count on-board pieces of given type
1631 *outp++ = ToUpper(PieceToChar(piece));
1633 if(c != 1) { // [HGM] but if there is only one piece of the mentioned type, no from-square, thank you!
1637 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1639 if (board[rt][ft] != EmptySquare) *outp++ = 'x';
1643 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1644 /* Use promotion suffix style "=Q" */
1645 if (promoChar != NULLCHAR && promoChar != 'x') {
1647 *outp++ = ToUpper(promoChar);
1654 // [HGM] XQ: the following code serves to detect perpetual chasing (Asian rules)
1663 // I guess the following variables logically belong in the closure too, but I was too lazy and used globals
1665 int preyStackPointer, chaseStackPointer;
1668 char rf, ff, rt, ft;
1678 // there are three new callbacks for use with GenLegal: for adding captures, deleting them, and finding a recapture
1680 extern void AtacksCallback P((Board board, int flags, ChessMove kind,
1681 int rf, int ff, int rt, int ft,
1684 void AttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1690 { // For adding captures that can lead to chase indictment to the chaseStack
1691 if(board[rt][ft] == EmptySquare) return; // non-capture
1692 if(board[rt][ft] == WhitePawn && rt < BOARD_HEIGHT/2) return; // Pawn before river can be chased
1693 if(board[rt][ft] == BlackPawn && rt >= BOARD_HEIGHT/2) return; // Pawn before river can be chased
1694 if(board[rf][ff] == WhitePawn || board[rf][ff] == BlackPawn) return; // Pawns are allowed to chase
1695 if(board[rf][ff] == WhiteWazir || board[rf][ff] == BlackWazir) return; // King is allowed to chase
1696 // move cannot be excluded from being a chase trivially (based on attacker and victim); save it on chaseStack
1697 chaseStack[chaseStackPointer].rf = rf;
1698 chaseStack[chaseStackPointer].ff = ff;
1699 chaseStack[chaseStackPointer].rt = rt;
1700 chaseStack[chaseStackPointer].ft = ft;
1701 chaseStackPointer++;
1704 extern void ExistingAtacksCallback P((Board board, int flags, ChessMove kind,
1705 int rf, int ff, int rt, int ft,
1708 void ExistingAttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1714 { // for removing pre-exsting captures from the chaseStack, to be left with newly created ones
1716 register ChaseClosure *cl = (ChaseClosure *) closure; //closure tells us the move played in the repeat loop
1718 if(board[rt][ft] == EmptySquare) return; // no capture
1719 if(rf == cl->rf && ff == cl->ff) { // attacks with same piece from new position are not considered new
1720 rf = cl->rt; ff = cl->ft; // doctor their fromSquare so they will be recognized in chaseStack
1722 // search move in chaseStack, and delete it if it occurred there (as we know now it is not a new capture)
1723 for(i=0; i<chaseStackPointer; i++) {
1724 if(chaseStack[i].rf == rf && chaseStack[i].ff == ff &&
1725 chaseStack[i].rt == rt && chaseStack[i].ft == ft ) {
1726 // move found on chaseStack, delete it by overwriting with move popped from top of chaseStack
1727 chaseStack[i] = chaseStack[--chaseStackPointer];
1733 extern void ProtectedCallback P((Board board, int flags, ChessMove kind,
1734 int rf, int ff, int rt, int ft,
1737 void ProtectedCallback(board, flags, kind, rf, ff, rt, ft, closure)
1743 { // for determining if a piece (given through the closure) is protected
1744 register ChaseClosure *cl = (ChaseClosure *) closure; // closure tells us where to recapture
1746 if(rt == cl->rt && ft == cl->ft) cl->recaptures++; // count legal recaptures to this square
1747 if(appData.debugMode && board[rt][ft] != EmptySquare)
1748 fprintf(debugFP, "try %c%c%c%c=%d\n", ff+AAA, rf+ONE,ft+AAA, rt+ONE, cl->recaptures);
1751 extern char moveList[MAX_MOVES][MOVE_LEN];
1753 int PerpetualChase(int first, int last)
1754 { // this routine detects if the side to move in the 'first' position is perpetually chasing (when not checking)
1757 ChessSquare captured;
1759 preyStackPointer = 0; // clear stack of chased pieces
1760 for(i=first; i<last; i+=2) { // for all positions with same side to move
1761 if(appData.debugMode) fprintf(debugFP, "judge position %i\n", i);
1762 chaseStackPointer = 0; // clear stack that is going to hold possible chases
1763 // determine all captures possible after the move, and put them on chaseStack
1764 GenLegal(boards[i+1], PosFlags(i), AttacksCallback, &cl);
1765 if(appData.debugMode) { int n;
1766 for(n=0; n<chaseStackPointer; n++)
1767 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1768 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1769 fprintf(debugFP, ": all capts\n");
1771 // determine all captures possible before the move, and delete them from chaseStack
1772 cl.rf = moveList[i][1]-ONE; // prepare closure to pass move that led from i to i+1
1773 cl.ff = moveList[i][0]-AAA+BOARD_LEFT;
1774 cl.rt = moveList[i][3]-ONE;
1775 cl.ft = moveList[i][2]-AAA+BOARD_LEFT;
1776 GenLegal(boards[i], PosFlags(i), ExistingAttacksCallback, &cl);
1777 if(appData.debugMode) { int n;
1778 for(n=0; n<chaseStackPointer; n++)
1779 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1780 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1781 fprintf(debugFP, ": new capts after %c%c%c%c\n", cl.ff+AAA, cl.rf+ONE, cl.ft+AAA, cl.rt+ONE);
1783 // chaseSack now contains all captures made possible by the move
1784 for(j=0; j<chaseStackPointer; j++) { // run through chaseStack to identify true chases
1785 int attacker = (int)boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1786 int victim = (int)boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1788 if(attacker >= (int) BlackPawn) attacker = BLACK_TO_WHITE attacker; // convert to white, as piecee type
1789 if(victim >= (int) BlackPawn) victim = BLACK_TO_WHITE victim;
1791 if((attacker == WhiteKnight || attacker == WhiteCannon) && victim == WhiteRook)
1792 continue; // C or H attack on R is always chase; leave on chaseStack
1794 if(attacker == victim) {
1795 if(LegalityTest(boards[i+1], PosFlags(i+1), chaseStack[j].rt,
1796 chaseStack[j].ft, chaseStack[j].rf, chaseStack[j].ff, NULLCHAR) == NormalMove) {
1797 // we can capture back with equal piece, so this is no chase but a sacrifice
1798 chaseStack[j] = chaseStack[--chaseStackPointer]; // delete the capture from the chaseStack
1799 j--; /* ! */ continue;
1804 // the attack is on a lower piece, or on a pinned or blocked equal one
1805 // test if the victim is protected by a true protector. First make the capture.
1806 captured = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1807 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1808 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = EmptySquare;
1809 // Then test if the opponent can recapture
1810 cl.recaptures = 0; // prepare closure to pass recapture square and count moves to it
1811 cl.rt = chaseStack[j].rt;
1812 cl.ft = chaseStack[j].ft;
1813 if(appData.debugMode) {
1814 fprintf(debugFP, "test if we can recapture %c%c\n", cl.ft+AAA, cl.rt+ONE);
1816 GenLegal(boards[i+1], PosFlags(i+1), ProtectedCallback, &cl); // try all moves
1817 // unmake the capture
1818 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1819 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = captured;
1820 // if a recapture was found, piece is protected, and we are not chasing it.
1821 if(cl.recaptures) { // attacked piece was defended by true protector, no chase
1822 chaseStack[j] = chaseStack[--chaseStackPointer]; // so delete from chaseStack
1826 // chaseStack now contains all moves that chased
1827 if(appData.debugMode) { int n;
1828 for(n=0; n<chaseStackPointer; n++)
1829 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1830 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1831 fprintf(debugFP, ": chases\n");
1833 if(i == first) { // copy all people chased by first move of repeat cycle to preyStack
1834 for(j=0; j<chaseStackPointer; j++) {
1835 preyStack[j].rank = chaseStack[j].rt;
1836 preyStack[j].file = chaseStack[j].ft;
1838 preyStackPointer = chaseStackPointer;
1841 for(j=0; j<chaseStackPointer; j++) {
1842 for(k=0; k<preyStackPointer; k++) {
1843 // search the victim of each chase move on the preyStack (first occurrence)
1844 if(chaseStack[j].ft == preyStack[k].file && chaseStack[j].rt == preyStack[k].rank ) {
1845 if(k < tail) break; // piece was already identified as still being chased
1846 preyStack[preyStackPointer] = preyStack[tail]; // move chased piece to bottom part of preyStack
1847 preyStack[tail] = preyStack[k]; // by swapping
1848 preyStack[k] = preyStack[preyStackPointer];
1854 preyStackPointer = tail; // keep bottom part of preyStack, popping pieces unchased on move i.
1855 if(appData.debugMode) { int n;
1856 for(n=0; n<preyStackPointer; n++)
1857 fprintf(debugFP, "%c%c ", preyStack[n].file+AAA, preyStack[n].rank+ONE);
1858 fprintf(debugFP, "always chased upto ply %d\n", i);
1860 // now adjust the location of the chased pieces according to opponent move
1861 for(j=0; j<preyStackPointer; j++) {
1862 if(preyStack[j].rank == moveList[i+1][1]-ONE &&
1863 preyStack[j].file == moveList[i+1][0]-AAA+BOARD_LEFT) {
1864 preyStack[j].rank = moveList[i+1][3]-ONE;
1865 preyStack[j].file = moveList[i+1][2]-AAA+BOARD_LEFT;
1870 return preyStackPointer; // if any piece was left on preyStack, it has been perpetually chased