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;
638 // Use Lance as Berolina / Spartan Pawn.
640 if (rf < BOARD_HEIGHT-1 && BlackPiece(board[rf + 1][ff]))
641 callback(board, flags,
642 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
643 rf, ff, rf + 1, ff, closure);
644 for (s = -1; s <= 1; s += 2) {
645 if (rf < BOARD_HEIGHT-1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT && board[rf + 1][ff + s] == EmptySquare)
646 callback(board, flags,
647 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
648 rf, ff, rf + 1, ff + s, closure);
649 if (rf == 1 && ff + 2*s >= BOARD_LEFT && ff + 2*s < BOARD_RGHT && board[3][ff + 2*s] == EmptySquare )
650 callback(board, flags, NormalMove, rf, ff, 3, ff + 2*s, closure);
655 if (rf > 0 && WhitePiece(board[rf - 1][ff]))
656 callback(board, flags,
657 rf <= promoRank ? BlackPromotion : NormalMove,
658 rf, ff, rf - 1, ff, closure);
659 for (s = -1; s <= 1; s += 2) {
660 if (rf > 0 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT && board[rf - 1][ff + s] == EmptySquare)
661 callback(board, flags,
662 rf <= promoRank ? BlackPromotion : NormalMove,
663 rf, ff, rf - 1, ff + s, closure);
664 if (rf == BOARD_HEIGHT-2 && ff + 2*s >= BOARD_LEFT && ff + 2*s < BOARD_RGHT && board[rf-2][ff + 2*s] == EmptySquare )
665 callback(board, flags, NormalMove, rf, ff, rf-2, ff + 2*s, closure);
669 case WhiteFalcon: // [HGM] wild: for wildcards, self-capture symbolizes move to anywhere
673 callback(board, flags, NormalMove, rf, ff, rf, ff, closure);
686 extern void GenLegalCallback P((Board board, int flags, ChessMove kind,
687 int rf, int ff, int rt, int ft,
690 void GenLegalCallback(board, flags, kind, rf, ff, rt, ft, closure)
697 register GenLegalClosure *cl = (GenLegalClosure *) closure;
699 if (!(flags & F_IGNORE_CHECK) &&
700 CheckTest(board, flags, rf, ff, rt, ft,
701 kind == WhiteCapturesEnPassant ||
702 kind == BlackCapturesEnPassant)) return;
703 if (flags & F_ATOMIC_CAPTURE) {
704 if (board[rt][ft] != EmptySquare ||
705 kind == WhiteCapturesEnPassant || kind == BlackCapturesEnPassant) {
707 ChessSquare king = (flags & F_WHITE_ON_MOVE) ? WhiteKing : BlackKing;
708 if (board[rf][ff] == king) return;
709 for (r = rt-1; r <= rt+1; r++) {
710 for (f = ft-1; f <= ft+1; f++) {
711 if (r >= 0 && r < BOARD_HEIGHT && f >= BOARD_LEFT && f < BOARD_RGHT &&
712 board[r][f] == king) return;
717 cl->cb(board, flags, kind, rf, ff, rt, ft, cl->cl);
724 int captures; // [HGM] losers
725 } LegalityTestClosure;
728 /* Like GenPseudoLegal, but (1) include castling moves, (2) unless
729 F_IGNORE_CHECK is set in the flags, omit moves that would leave the
730 king in check, and (3) if F_ATOMIC_CAPTURE is set in the flags, omit
731 moves that would destroy your own king. The CASTLE_OK flags are
732 true if castling is not yet ruled out by a move of the king or
733 rook. Return TRUE if the player on move is currently in check and
734 F_IGNORE_CHECK is not set. [HGM] add castlingRights parameter */
735 int GenLegal(board, flags, callback, closure)
738 MoveCallback callback;
742 int ff, ft, k, left, right, swap;
743 int ignoreCheck = (flags & F_IGNORE_CHECK) != 0;
744 ChessSquare wKing = WhiteKing, bKing = BlackKing, *castlingRights = board[CASTLING];
748 GenPseudoLegal(board, flags, GenLegalCallback, (VOIDSTAR) &cl);
751 CheckTest(board, flags, -1, -1, -1, -1, FALSE)) return TRUE;
753 /* Generate castling moves */
754 if(gameInfo.variant == VariantKnightmate) { /* [HGM] Knightmate */
755 wKing = WhiteUnicorn; bKing = BlackUnicorn;
758 for (ff = BOARD_WIDTH>>1; ff >= (BOARD_WIDTH-1)>>1; ff-- /*ics wild 1*/) {
759 if ((flags & F_WHITE_ON_MOVE) &&
760 (flags & F_WHITE_KCASTLE_OK) &&
761 board[0][ff] == wKing &&
762 board[0][ff + 1] == EmptySquare &&
763 board[0][ff + 2] == EmptySquare &&
764 board[0][BOARD_RGHT-3] == EmptySquare &&
765 board[0][BOARD_RGHT-2] == EmptySquare &&
766 board[0][BOARD_RGHT-1] == WhiteRook &&
767 castlingRights[0] != NoRights && /* [HGM] check rights */
768 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
770 (!CheckTest(board, flags, 0, ff, 0, ff + 1, FALSE) &&
771 !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-3, FALSE) &&
772 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-2, FALSE)) &&
773 !CheckTest(board, flags, 0, ff, 0, ff + 2, FALSE)))) {
775 callback(board, flags,
776 ff==BOARD_WIDTH>>1 ? WhiteKingSideCastle : WhiteKingSideCastleWild,
777 0, ff, 0, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
779 if ((flags & F_WHITE_ON_MOVE) &&
780 (flags & F_WHITE_QCASTLE_OK) &&
781 board[0][ff] == wKing &&
782 board[0][ff - 1] == EmptySquare &&
783 board[0][ff - 2] == EmptySquare &&
784 board[0][BOARD_LEFT+2] == EmptySquare &&
785 board[0][BOARD_LEFT+1] == EmptySquare &&
786 board[0][BOARD_LEFT+0] == WhiteRook &&
787 castlingRights[1] != NoRights && /* [HGM] check rights */
788 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
790 (!CheckTest(board, flags, 0, ff, 0, ff - 1, FALSE) &&
791 !CheckTest(board, flags, 0, ff, 0, BOARD_LEFT+3, FALSE) &&
792 !CheckTest(board, flags, 0, ff, 0, ff - 2, FALSE)))) {
794 callback(board, flags,
795 ff==BOARD_WIDTH>>1 ? WhiteQueenSideCastle : WhiteQueenSideCastleWild,
796 0, ff, 0, ff - ((gameInfo.boardWidth+2)>>2), closure);
798 if (!(flags & F_WHITE_ON_MOVE) &&
799 (flags & F_BLACK_KCASTLE_OK) &&
800 board[BOARD_HEIGHT-1][ff] == bKing &&
801 board[BOARD_HEIGHT-1][ff + 1] == EmptySquare &&
802 board[BOARD_HEIGHT-1][ff + 2] == EmptySquare &&
803 board[BOARD_HEIGHT-1][BOARD_RGHT-3] == EmptySquare &&
804 board[BOARD_HEIGHT-1][BOARD_RGHT-2] == EmptySquare &&
805 board[BOARD_HEIGHT-1][BOARD_RGHT-1] == BlackRook &&
806 castlingRights[3] != NoRights && /* [HGM] check rights */
807 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
809 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 1, FALSE) &&
810 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-3, FALSE) &&
811 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-2, FALSE)) &&
812 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 2, FALSE)))) {
814 callback(board, flags,
815 ff==BOARD_WIDTH>>1 ? BlackKingSideCastle : BlackKingSideCastleWild,
816 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
818 if (!(flags & F_WHITE_ON_MOVE) &&
819 (flags & F_BLACK_QCASTLE_OK) &&
820 board[BOARD_HEIGHT-1][ff] == bKing &&
821 board[BOARD_HEIGHT-1][ff - 1] == EmptySquare &&
822 board[BOARD_HEIGHT-1][ff - 2] == EmptySquare &&
823 board[BOARD_HEIGHT-1][BOARD_LEFT+2] == EmptySquare &&
824 board[BOARD_HEIGHT-1][BOARD_LEFT+1] == EmptySquare &&
825 board[BOARD_HEIGHT-1][BOARD_LEFT+0] == BlackRook &&
826 castlingRights[4] != NoRights && /* [HGM] check rights */
827 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
829 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 1, FALSE) &&
830 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_LEFT+3, FALSE) &&
831 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 2, FALSE)))) {
833 callback(board, flags,
834 ff==BOARD_WIDTH>>1 ? BlackQueenSideCastle : BlackQueenSideCastleWild,
835 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - ((gameInfo.boardWidth+2)>>2), closure);
839 if((swap = gameInfo.variant == VariantSChess) || flags & F_FRC_TYPE_CASTLING) {
841 /* generate all potential FRC castling moves (KxR), ignoring flags */
842 /* [HGM] test if the Rooks we find have castling rights */
843 /* In S-Chess we generate RxK for allowed castlings, for gating at Rook square */
846 if ((flags & F_WHITE_ON_MOVE) != 0) {
847 ff = castlingRights[2]; /* King file if we have any rights */
848 if(ff != NoRights && board[0][ff] == WhiteKing) {
849 if (appData.debugMode) {
850 fprintf(debugFP, "FRC castling, %d %d %d %d %d %d\n",
851 castlingRights[0],castlingRights[1],ff,castlingRights[3],castlingRights[4],castlingRights[5]);
853 ft = castlingRights[0]; /* Rook file if we have H-side rights */
855 right = BOARD_RGHT-2;
856 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
857 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
858 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
859 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
860 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
861 if(ft != NoRights && board[0][ft] == WhiteRook)
862 callback(board, flags, WhiteHSideCastleFR, 0, swap ? ft : ff, 0, swap ? ff : ft, closure);
864 ft = castlingRights[1]; /* Rook file if we have A-side rights */
867 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
868 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
869 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
870 if(ff > BOARD_LEFT+2)
871 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
872 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
873 if(ft != NoRights && board[0][ft] == WhiteRook)
874 callback(board, flags, WhiteASideCastleFR, 0, swap ? ft : ff, 0, swap ? ff : ft, closure);
877 ff = castlingRights[5]; /* King file if we have any rights */
878 if(ff != NoRights && board[BOARD_HEIGHT-1][ff] == BlackKing) {
879 ft = castlingRights[3]; /* Rook file if we have H-side rights */
881 right = BOARD_RGHT-2;
882 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
883 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
884 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
885 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
886 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
887 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
888 callback(board, flags, BlackHSideCastleFR, BOARD_HEIGHT-1, swap ? ft : ff, BOARD_HEIGHT-1, swap ? ff : ft, closure);
890 ft = castlingRights[4]; /* Rook file if we have A-side rights */
893 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
894 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
895 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
896 if(ff > BOARD_LEFT+2)
897 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
898 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
899 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
900 callback(board, flags, BlackASideCastleFR, BOARD_HEIGHT-1, swap ? ft : ff, BOARD_HEIGHT-1, swap ? ff : ft, closure);
916 extern void CheckTestCallback P((Board board, int flags, ChessMove kind,
917 int rf, int ff, int rt, int ft,
921 void CheckTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
928 register CheckTestClosure *cl = (CheckTestClosure *) closure;
930 if (rt == cl->rking && ft == cl->fking) cl->check++;
934 /* If the player on move were to move from (rf, ff) to (rt, ft), would
935 he leave himself in check? Or if rf == -1, is the player on move
936 in check now? enPassant must be TRUE if the indicated move is an
937 e.p. capture. The possibility of castling out of a check along the
938 back rank is not accounted for (i.e., we still return nonzero), as
939 this is illegal anyway. Return value is the number of times the
941 int CheckTest(board, flags, rf, ff, rt, ft, enPassant)
944 int rf, ff, rt, ft, enPassant;
947 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
948 ChessSquare captured = EmptySquare;
949 /* Suppress warnings on uninitialized variables */
951 if(gameInfo.variant == VariantXiangqi)
952 king = flags & F_WHITE_ON_MOVE ? WhiteWazir : BlackWazir;
953 if(gameInfo.variant == VariantKnightmate)
954 king = flags & F_WHITE_ON_MOVE ? WhiteUnicorn : BlackUnicorn;
958 captured = board[rf][ft];
959 board[rf][ft] = EmptySquare;
961 captured = board[rt][ft];
963 board[rt][ft] = board[rf][ff];
964 board[rf][ff] = EmptySquare;
965 } else board[rt][ft] = ff; // [HGM] drop
967 /* For compatibility with ICS wild 9, we scan the board in the
968 order a1, a2, a3, ... b1, b2, ..., h8 to find the first king,
969 and we test only whether that one is in check. */
971 for (cl.fking = BOARD_LEFT+0; cl.fking < BOARD_RGHT; cl.fking++)
972 for (cl.rking = 0; cl.rking < BOARD_HEIGHT; cl.rking++) {
973 if (board[cl.rking][cl.fking] == king) {
974 if(gameInfo.variant == VariantXiangqi) {
975 /* [HGM] In Xiangqi opposing Kings means check as well */
977 dir = (king >= BlackPawn) ? -1 : 1;
978 for( i=cl.rking+dir; i>=0 && i<BOARD_HEIGHT &&
979 board[i][cl.fking] == EmptySquare; i+=dir );
980 if(i>=0 && i<BOARD_HEIGHT &&
981 board[i][cl.fking] == (dir>0 ? BlackWazir : WhiteWazir) )
985 GenPseudoLegal(board, flags ^ F_WHITE_ON_MOVE, CheckTestCallback, (VOIDSTAR) &cl);
986 goto undo_move; /* 2-level break */
993 board[rf][ff] = board[rt][ft];
995 board[rf][ft] = captured;
996 board[rt][ft] = EmptySquare;
998 board[rt][ft] = captured;
1000 } else board[rt][ft] = EmptySquare; // [HGM] drop
1002 return cl.fking < BOARD_RGHT ? cl.check : 1000; // [HGM] atomic: return 1000 if we have no king
1005 ChessMove LegalDrop(board, flags, piece, rt, ft)
1010 { // [HGM] put drop legality testing in separate routine for clarity
1012 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
1013 if(board[rt][ft] != EmptySquare) return ImpossibleMove; // must drop to empty square
1014 n = PieceToNumber(piece);
1015 if(gameInfo.holdingsWidth == 0 || (flags & F_WHITE_ON_MOVE ? board[n][BOARD_WIDTH-1] : board[BOARD_HEIGHT-1-n][0]) != piece)
1016 return ImpossibleMove; // piece not available
1017 if(gameInfo.variant == VariantShogi) { // in Shogi lots of drops are forbidden!
1018 if((piece == WhitePawn || piece == WhiteQueen) && rt == BOARD_HEIGHT-1 ||
1019 (piece == BlackPawn || piece == BlackQueen) && rt == 0 ||
1020 piece == WhiteKnight && rt > BOARD_HEIGHT-3 ||
1021 piece == BlackKnight && rt < 2 ) return IllegalMove; // e.g. where dropped piece has no moves
1022 if(piece == WhitePawn || piece == BlackPawn) {
1024 for(r=1; r<BOARD_HEIGHT-1; r++)
1025 if(board[r][ft] == piece) return IllegalMove; // or there already is a Pawn in file
1026 // should still test if we mate with this Pawn
1029 if( (piece == WhitePawn || piece == BlackPawn) &&
1030 (rt == 0 || rt == BOARD_HEIGHT -1 ) )
1031 return IllegalMove; /* no pawn drops on 1st/8th */
1033 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
1034 if (!(flags & F_IGNORE_CHECK) &&
1035 CheckTest(board, flags, DROP_RANK, piece, rt, ft, FALSE) ) return IllegalMove;
1036 return flags & F_WHITE_ON_MOVE ? WhiteDrop : BlackDrop;
1039 extern void LegalityTestCallback P((Board board, int flags, ChessMove kind,
1040 int rf, int ff, int rt, int ft,
1043 void LegalityTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
1050 register LegalityTestClosure *cl = (LegalityTestClosure *) closure;
1052 // if (appData.debugMode) {
1053 // fprintf(debugFP, "Legality test: %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
1055 if(board[rt][ft] != EmptySquare || kind==WhiteCapturesEnPassant || kind==BlackCapturesEnPassant)
1056 cl->captures++; // [HGM] losers: count legal captures
1057 if (rf == cl->rf && ff == cl->ff && rt == cl->rt && ft == cl->ft)
1061 ChessMove LegalityTest(board, flags, rf, ff, rt, ft, promoChar)
1064 int rf, ff, rt, ft, promoChar;
1066 LegalityTestClosure cl; ChessSquare piece, *castlingRights = board[CASTLING];
1068 if(rf == DROP_RANK) return LegalDrop(board, flags, ff, rt, ft);
1069 piece = board[rf][ff];
1071 if (appData.debugMode) {
1073 for(i=0; i<6; i++) fprintf(debugFP, "%d ", castlingRights[i]);
1074 fprintf(debugFP, "Legality test? %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
1076 /* [HGM] Cobra and Falcon are wildcard pieces; consider all their moves legal */
1077 /* (perhaps we should disallow moves that obviously leave us in check?) */
1078 if(piece == WhiteFalcon || piece == BlackFalcon ||
1079 piece == WhiteCobra || piece == BlackCobra)
1080 return CheckTest(board, flags, rf, ff, rt, ft, FALSE) ? IllegalMove : NormalMove;
1086 cl.kind = IllegalMove;
1087 cl.captures = 0; // [HGM] losers: prepare to count legal captures.
1088 GenLegal(board, flags, LegalityTestCallback, (VOIDSTAR) &cl);
1089 if((flags & F_MANDATORY_CAPTURE) && cl.captures && board[rt][ft] == EmptySquare
1090 && cl.kind != WhiteCapturesEnPassant && cl.kind != BlackCapturesEnPassant)
1091 return(IllegalMove); // [HGM] losers: if there are legal captures, non-capts are illegal
1093 if(promoChar == 'x') promoChar = NULLCHAR; // [HGM] is this ever the case?
1094 if(gameInfo.variant == VariantSChess && promoChar && promoChar != '=' && board[rf][ff] != WhitePawn && board[rf][ff] != BlackPawn) {
1095 if(board[rf][ff] < BlackPawn) { // white
1096 if(rf != 0) return IllegalMove; // must be on back rank
1097 if(board[PieceToNumber(CharToPiece(ToUpper(promoChar)))][BOARD_WIDTH-2] == 0) return ImpossibleMove;// must be in stock
1099 if(rf != BOARD_HEIGHT-1) return IllegalMove;
1100 if(board[BOARD_HEIGHT-1-PieceToNumber(CharToPiece(ToLower(promoChar)))][1] == 0) return ImpossibleMove;
1103 if(gameInfo.variant == VariantShogi) {
1104 /* [HGM] Shogi promotions. '=' means defer */
1105 if(rf != DROP_RANK && cl.kind == NormalMove) {
1106 ChessSquare piece = board[rf][ff];
1108 if(promoChar == PieceToChar(BlackQueen)) promoChar = NULLCHAR; /* [HGM] Kludge */
1109 if(promoChar == 'd' && (piece == WhiteRook || piece == BlackRook) ||
1110 promoChar == 'h' && (piece == WhiteBishop || piece == BlackBishop) ||
1111 promoChar == 'g' && (piece <= WhiteFerz || piece <= BlackFerz && piece >= BlackPawn) )
1112 promoChar = '+'; // allowed ICS notations
1113 if(appData.debugMode)fprintf(debugFP,"SHOGI promoChar = %c\n", promoChar ? promoChar : '-');
1114 if(promoChar != NULLCHAR && promoChar != '+' && promoChar != '=')
1115 return CharToPiece(promoChar) == EmptySquare ? ImpossibleMove : IllegalMove;
1116 else if(flags & F_WHITE_ON_MOVE) {
1117 if( (int) piece < (int) WhiteWazir &&
1118 (rf >= BOARD_HEIGHT*2/3 || rt >= BOARD_HEIGHT*2/3) ) {
1119 if( (piece == WhitePawn || piece == WhiteQueen) && rt > BOARD_HEIGHT-2 ||
1120 piece == WhiteKnight && rt > BOARD_HEIGHT-3) /* promotion mandatory */
1121 cl.kind = promoChar == '=' ? IllegalMove : WhitePromotion;
1122 else /* promotion optional, default is defer */
1123 cl.kind = promoChar == '+' ? WhitePromotion : WhiteNonPromotion;
1124 } else cl.kind = promoChar == '+' ? IllegalMove : NormalMove;
1126 if( (int) piece < (int) BlackWazir && (rf < BOARD_HEIGHT/3 || rt < BOARD_HEIGHT/3) ) {
1127 if( (piece == BlackPawn || piece == BlackQueen) && rt < 1 ||
1128 piece == BlackKnight && rt < 2 ) /* promotion obligatory */
1129 cl.kind = promoChar == '=' ? IllegalMove : BlackPromotion;
1130 else /* promotion optional, default is defer */
1131 cl.kind = promoChar == '+' ? BlackPromotion : BlackNonPromotion;
1132 } else cl.kind = promoChar == '+' ? IllegalMove : NormalMove;
1136 if (promoChar != NULLCHAR) {
1137 if(promoChar == '=') cl.kind = IllegalMove; else // [HGM] shogi: no deferred promotion outside Shogi
1138 if (cl.kind == WhitePromotion || cl.kind == BlackPromotion) {
1139 if(CharToPiece(flags & F_WHITE_ON_MOVE ? ToUpper(promoChar) : ToLower(promoChar)) == EmptySquare)
1140 cl.kind = ImpossibleMove; // non-existing piece
1142 cl.kind = IllegalMove;
1152 extern void MateTestCallback P((Board board, int flags, ChessMove kind,
1153 int rf, int ff, int rt, int ft,
1156 void MateTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
1163 register MateTestClosure *cl = (MateTestClosure *) closure;
1168 /* Return MT_NONE, MT_CHECK, MT_CHECKMATE, or MT_STALEMATE */
1169 int MateTest(board, flags)
1174 int inCheck, r, f, myPieces=0, hisPieces=0, nrKing=0;
1175 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
1177 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) {
1178 // [HGM] losers: Count pieces and kings, to detect other unorthodox winning conditions
1179 nrKing += (board[r][f] == king); // stm has king
1180 if( board[r][f] != EmptySquare ) {
1181 if((int)board[r][f] <= (int)king && (int)board[r][f] >= (int)king - (int)WhiteKing + (int)WhitePawn)
1186 if(appData.debugMode) fprintf(debugFP, "MateTest: K=%d, my=%d, his=%d\n", nrKing, myPieces, hisPieces);
1187 switch(gameInfo.variant) { // [HGM] losers: extinction wins
1188 case VariantShatranj:
1189 if(hisPieces == 1) return myPieces > 1 ? MT_BARE : MT_DRAW;
1193 if(nrKing == 0) return MT_NOKING;
1196 if(myPieces == 1) return MT_BARE;
1199 inCheck = GenLegal(board, flags, MateTestCallback, (VOIDSTAR) &cl);
1200 // [HGM] 3check: yet to do!
1202 return inCheck ? MT_CHECK : MT_NONE;
1204 if(gameInfo.holdingsWidth && gameInfo.variant != VariantSuper || gameInfo.variant != VariantGreat) { // drop game
1205 int r, f, n, holdings = flags & F_WHITE_ON_MOVE ? BOARD_WIDTH-1 : 0;
1206 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) if(board[r][f] == EmptySquare) // all empty squares
1207 for(n=0; n<BOARD_HEIGHT; n++) // all pieces in hand
1208 if(board[n][holdings] != EmptySquare) {
1209 int moveType = LegalDrop(board, flags, board[n][holdings], r, f);
1210 if(moveType == WhiteDrop || moveType == BlackDrop) return MT_CHECK; // we can resolve check by legal drop
1213 if(gameInfo.variant == VariantSuicide) // [HGM] losers: always stalemate, since no check, but result varies
1214 return myPieces == hisPieces ? MT_STALEMATE :
1215 myPieces > hisPieces ? MT_STAINMATE : MT_STEALMATE;
1216 else if(gameInfo.variant == VariantLosers) return inCheck ? MT_TRICKMATE : MT_STEALMATE;
1217 else if(gameInfo.variant == VariantGiveaway) return MT_STEALMATE; // no check exists, stalemated = win
1219 return inCheck ? MT_CHECKMATE
1220 : (gameInfo.variant == VariantXiangqi || gameInfo.variant == VariantShatranj) ?
1221 MT_STAINMATE : MT_STALEMATE;
1226 extern void DisambiguateCallback P((Board board, int flags, ChessMove kind,
1227 int rf, int ff, int rt, int ft,
1230 void DisambiguateCallback(board, flags, kind, rf, ff, rt, ft, closure)
1237 register DisambiguateClosure *cl = (DisambiguateClosure *) closure;
1238 int wildCard = FALSE; ChessSquare piece = board[rf][ff];
1240 // [HGM] wild: for wild-card pieces rt and rf are dummies
1241 if(piece == WhiteFalcon || piece == BlackFalcon ||
1242 piece == WhiteCobra || piece == BlackCobra)
1245 if ((cl->pieceIn == EmptySquare || cl->pieceIn == board[rf][ff]
1246 || PieceToChar(board[rf][ff]) == '~'
1247 && cl->pieceIn == (ChessSquare)(DEMOTED board[rf][ff])
1249 (cl->rfIn == -1 || cl->rfIn == rf) &&
1250 (cl->ffIn == -1 || cl->ffIn == ff) &&
1251 (cl->rtIn == -1 || cl->rtIn == rt || wildCard) &&
1252 (cl->ftIn == -1 || cl->ftIn == ft || wildCard)) {
1255 if(cl->count == 1 || board[rt][ft] != EmptySquare) {
1256 // [HGM] oneclick: if multiple moves, be sure we remember capture
1257 cl->piece = board[rf][ff];
1260 cl->rt = wildCard ? cl->rtIn : rt;
1261 cl->ft = wildCard ? cl->ftIn : ft;
1264 cl->captures += (board[rt][ft] != EmptySquare); // [HGM] oneclick: count captures
1268 void Disambiguate(board, flags, closure)
1271 DisambiguateClosure *closure;
1273 int illegal = 0; char c = closure->promoCharIn;
1275 closure->count = closure->captures = 0;
1276 closure->rf = closure->ff = closure->rt = closure->ft = 0;
1277 closure->kind = ImpossibleMove;
1278 if (appData.debugMode) {
1279 fprintf(debugFP, "Disambiguate in: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1280 closure->pieceIn,closure->ffIn,closure->rfIn,closure->ftIn,closure->rtIn,
1281 closure->promoCharIn, closure->promoCharIn >= ' ' ? closure->promoCharIn : '-');
1283 GenLegal(board, flags, DisambiguateCallback, (VOIDSTAR) closure);
1284 if (closure->count == 0) {
1285 /* See if it's an illegal move due to check */
1287 GenLegal(board, flags|F_IGNORE_CHECK, DisambiguateCallback, (VOIDSTAR) closure);
1288 if (closure->count == 0) {
1289 /* No, it's not even that */
1290 if (appData.debugMode) { int i, j;
1291 for(i=BOARD_HEIGHT-1; i>=0; i--) {
1292 for(j=0; j<BOARD_WIDTH; j++)
1293 fprintf(debugFP, "%3d", (int) board[i][j]);
1294 fprintf(debugFP, "\n");
1301 if (c == 'x') c = NULLCHAR; // get rid of any 'x' (which should never happen?)
1302 if(gameInfo.variant == VariantSChess && c && c != '=' && closure->piece != WhitePawn && closure->piece != BlackPawn) {
1303 if(closure->piece < BlackPawn) { // white
1304 if(closure->rf != 0) closure->kind = IllegalMove; // must be on back rank
1305 if(board[PieceToNumber(CharToPiece(ToUpper(c)))][BOARD_WIDTH-2] == 0) closure->kind = ImpossibleMove;// must be in stock
1307 if(closure->rf != BOARD_HEIGHT-1) closure->kind = IllegalMove;
1308 if(board[BOARD_HEIGHT-1-PieceToNumber(CharToPiece(ToLower(c)))][1] == 0) closure->kind = ImpossibleMove;
1311 if(gameInfo.variant == VariantShogi) {
1312 /* [HGM] Shogi promotions. On input, '=' means defer, '+' promote. Afterwards, c is set to '+' for promotions, NULL other */
1313 if(closure->rfIn != DROP_RANK && closure->kind == NormalMove) {
1314 ChessSquare piece = closure->piece;
1315 if (c == 'd' && (piece == WhiteRook || piece == BlackRook) ||
1316 c == 'h' && (piece == WhiteBishop || piece == BlackBishop) ||
1317 c == 'g' && (piece <= WhiteFerz || piece <= BlackFerz && piece >= BlackPawn) )
1318 c = '+'; // allowed ICS notations
1319 if(c != NULLCHAR && c != '+' && c != '=') closure->kind = IllegalMove; // otherwise specifying a piece is illegal
1320 else if(flags & F_WHITE_ON_MOVE) {
1321 if( (int) piece < (int) WhiteWazir &&
1322 (closure->rf >= BOARD_HEIGHT-(BOARD_HEIGHT/3) || closure->rt >= BOARD_HEIGHT-(BOARD_HEIGHT/3)) ) {
1323 if( (piece == WhitePawn || piece == WhiteQueen) && closure->rt > BOARD_HEIGHT-2 ||
1324 piece == WhiteKnight && closure->rt > BOARD_HEIGHT-3) /* promotion mandatory */
1325 closure->kind = c == '=' ? IllegalMove : WhitePromotion;
1326 else /* promotion optional, default is defer */
1327 closure->kind = c == '+' ? WhitePromotion : WhiteNonPromotion;
1328 } else closure->kind = c == '+' ? IllegalMove : NormalMove;
1330 if( (int) piece < (int) BlackWazir && (closure->rf < BOARD_HEIGHT/3 || closure->rt < BOARD_HEIGHT/3) ) {
1331 if( (piece == BlackPawn || piece == BlackQueen) && closure->rt < 1 ||
1332 piece == BlackKnight && closure->rt < 2 ) /* promotion obligatory */
1333 closure->kind = c == '=' ? IllegalMove : BlackPromotion;
1334 else /* promotion optional, default is defer */
1335 closure->kind = c == '+' ? BlackPromotion : BlackNonPromotion;
1336 } else closure->kind = c == '+' ? IllegalMove : NormalMove;
1339 if(closure->kind == WhitePromotion || closure->kind == BlackPromotion) c = '+'; else
1340 if(closure->kind == WhiteNonPromotion || closure->kind == BlackNonPromotion) c = '=';
1342 if (closure->kind == WhitePromotion || closure->kind == BlackPromotion) {
1343 if(c == NULLCHAR) { // missing promoChar on mandatory promotion; use default for variant
1344 if(gameInfo.variant == VariantShatranj || gameInfo.variant == VariantCourier || gameInfo.variant == VariantMakruk)
1345 c = PieceToChar(BlackFerz);
1346 else if(gameInfo.variant == VariantGreat)
1347 c = PieceToChar(BlackMan);
1349 c = PieceToChar(BlackQueen);
1350 } else if(c == '=') closure->kind = IllegalMove; // no deferral outside Shogi
1351 } else if (c != NULLCHAR) closure->kind = IllegalMove;
1353 closure->promoChar = ToLower(c); // this can be NULLCHAR! Note we keep original promoChar even if illegal.
1354 if(c != '+' && c != '=' && c != NULLCHAR && CharToPiece(flags & F_WHITE_ON_MOVE ? ToUpper(c) : ToLower(c)) == EmptySquare)
1355 closure->kind = ImpossibleMove; // but we cannot handle non-existing piece types!
1356 if (closure->count > 1) {
1357 closure->kind = AmbiguousMove;
1360 /* Note: If more than one illegal move matches, but no legal
1361 moves, we return IllegalMove, not AmbiguousMove. Caller
1362 can look at closure->count to detect this.
1364 closure->kind = IllegalMove;
1366 if (appData.debugMode) {
1367 fprintf(debugFP, "Disambiguate out: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1368 closure->piece,closure->ff,closure->rf,closure->ft,closure->rt,closure->promoChar,
1369 closure->promoChar >= ' ' ? closure->promoChar:'-');
1383 } CoordsToAlgebraicClosure;
1385 extern void CoordsToAlgebraicCallback P((Board board, int flags,
1386 ChessMove kind, int rf, int ff,
1387 int rt, int ft, VOIDSTAR closure));
1389 void CoordsToAlgebraicCallback(board, flags, kind, rf, ff, rt, ft, closure)
1396 register CoordsToAlgebraicClosure *cl =
1397 (CoordsToAlgebraicClosure *) closure;
1399 if ((rt == cl->rt && ft == cl->ft || rt == rf && ft == ff) && // [HGM] null move matches any toSquare
1400 (board[rf][ff] == cl->piece
1401 || PieceToChar(board[rf][ff]) == '~' &&
1402 (ChessSquare) (DEMOTED board[rf][ff]) == cl->piece)
1406 cl->kind = kind; /* this is the move we want */
1408 cl->file++; /* need file to rule out this move */
1412 cl->rank++; /* need rank to rule out this move */
1414 cl->either++; /* rank or file will rule out this move */
1420 /* Convert coordinates to normal algebraic notation.
1421 promoChar must be NULLCHAR or 'x' if not a promotion.
1423 ChessMove CoordsToAlgebraic(board, flags, rf, ff, rt, ft, promoChar, out)
1432 char *outp = out, c;
1433 CoordsToAlgebraicClosure cl;
1435 if (rf == DROP_RANK) {
1436 /* Bughouse piece drop */
1437 *outp++ = ToUpper(PieceToChar((ChessSquare) ff));
1442 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1444 return (flags & F_WHITE_ON_MOVE) ? WhiteDrop : BlackDrop;
1447 if (promoChar == 'x') promoChar = NULLCHAR;
1448 piece = board[rf][ff];
1449 if(PieceToChar(piece)=='~') piece = (ChessSquare)(DEMOTED piece);
1451 if (appData.debugMode)
1452 fprintf(debugFP, "CoordsToAlgebraic, piece=%d (%d,%d)-(%d,%d) %c\n", (int)piece,ff,rf,ft,rt,promoChar >= ' ' ? promoChar : '-');
1456 kind = LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1457 if (kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1458 /* Keep short notation if move is illegal only because it
1459 leaves the player in check, but still return IllegalMove */
1460 kind = LegalityTest(board, flags|F_IGNORE_CHECK, rf, ff, rt, ft, promoChar);
1461 if (kind == IllegalMove) break;
1466 if (ff == ft && board[rt][ft] == EmptySquare) { /* [HGM] Xiangqi has straight noncapts! */
1467 /* Non-capture; use style "e5" */
1470 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1472 /* Capture; use style "exd5" */
1473 if(gameInfo.variant != VariantXiangqi || board[rt][ft] != EmptySquare )
1474 *outp++ = 'x'; /* [HGM] Xiangqi has sideway noncaptures across river! */
1478 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1480 /* Use promotion suffix style "=Q" */
1482 if (appData.debugMode)
1483 fprintf(debugFP, "movetype=%d, promochar=%d=%c\n", (int)kind, promoChar, promoChar >= ' ' ? promoChar : '-');
1484 if (promoChar != NULLCHAR) {
1485 if(gameInfo.variant == VariantShogi) {
1486 /* [HGM] ... but not in Shogi! */
1487 *outp++ = promoChar == '=' ? '=' : '+';
1490 *outp++ = ToUpper(promoChar);
1499 /* Fabien moved code: FRC castling first (if KxR), wild castling second */
1500 /* Code added by Tord: FRC castling. */
1501 if((piece == WhiteKing && board[rt][ft] == WhiteRook) ||
1502 (piece == BlackKing && board[rt][ft] == BlackRook)) {
1504 safeStrCpy(out, "O-O", MOVE_LEN);
1506 safeStrCpy(out, "O-O-O", MOVE_LEN);
1507 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1509 /* End of code added by Tord */
1510 /* Test for castling or ICS wild castling */
1511 /* Use style "O-O" (oh-oh) for PGN compatibility */
1512 else if (rf == rt &&
1513 rf == ((piece == WhiteKing) ? 0 : BOARD_HEIGHT-1) &&
1514 (ft - ff > 1 || ff - ft > 1) && // No castling if legal King move (on narrow boards!)
1515 ((ff == BOARD_WIDTH>>1 && (ft == BOARD_LEFT+2 || ft == BOARD_RGHT-2)) ||
1516 (ff == (BOARD_WIDTH-1)>>1 && (ft == BOARD_LEFT+1 || ft == BOARD_RGHT-3)))) {
1517 if(ft==BOARD_LEFT+1 || ft==BOARD_RGHT-2)
1518 snprintf(out, MOVE_LEN, "O-O%c%c", promoChar ? '/' : 0, ToUpper(promoChar));
1520 snprintf(out, MOVE_LEN, "O-O-O%c%c", promoChar ? '/' : 0, ToUpper(promoChar));
1522 /* This notation is always unambiguous, unless there are
1523 kings on both the d and e files, with "wild castling"
1524 possible for the king on the d file and normal castling
1525 possible for the other. ICS rules for wild 9
1526 effectively make castling illegal for either king in
1527 this situation. So I am not going to worry about it;
1528 I'll just generate an ambiguous O-O in this case.
1530 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1533 /* else fall through */
1541 cl.kind = IllegalMove;
1542 cl.rank = cl.file = cl.either = 0;
1543 GenLegal(board, flags, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1545 if (cl.kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1546 /* Generate pretty moves for moving into check, but
1547 still return IllegalMove.
1549 GenLegal(board, flags|F_IGNORE_CHECK, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1550 if (cl.kind == IllegalMove) break;
1551 cl.kind = IllegalMove;
1554 /* Style is "Nf3" or "Nxf7" if this is unambiguous,
1555 else "Ngf3" or "Ngxf7",
1556 else "N1f3" or "N5xf7",
1557 else "Ng1f3" or "Ng5xf7".
1559 c = PieceToChar(piece) ;
1560 if( c == '~' || c == '+') {
1561 /* [HGM] print nonexistent piece as its demoted version */
1562 piece = (ChessSquare) (DEMOTED piece);
1564 if(c=='+') *outp++ = c;
1565 *outp++ = ToUpper(PieceToChar(piece));
1567 if (cl.file || (cl.either && !cl.rank)) {
1573 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1576 if(board[rt][ft] != EmptySquare)
1582 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1583 if (gameInfo.variant == VariantShogi) {
1584 /* [HGM] in Shogi non-pawns can promote */
1585 *outp++ = promoChar; // Don't bother to correct move type, return value is never used!
1587 else if (gameInfo.variant == VariantSChess && promoChar) { // and in S-Chess we have gating
1589 *outp++ = ToUpper(promoChar);
1595 /* Moving a nonexistent piece */
1599 /* Not a legal move, even ignoring check.
1600 If there was a piece on the from square,
1601 use style "Ng1g3" or "Ng1xe8";
1602 if there was a pawn or nothing (!),
1603 use style "g1g3" or "g1xe8". Use "x"
1604 if a piece was on the to square, even
1605 a piece of the same color.
1609 if (piece != EmptySquare && piece != WhitePawn && piece != BlackPawn) {
1611 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<=BOARD_RGHT; f++)
1612 c += (board[r][f] == piece); // count on-board pieces of given type
1613 *outp++ = ToUpper(PieceToChar(piece));
1615 if(c != 1) { // [HGM] but if there is only one piece of the mentioned type, no from-square, thank you!
1619 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1621 if (board[rt][ft] != EmptySquare) *outp++ = 'x';
1625 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1626 /* Use promotion suffix style "=Q" */
1627 if (promoChar != NULLCHAR && promoChar != 'x') {
1629 *outp++ = ToUpper(promoChar);
1636 // [HGM] XQ: the following code serves to detect perpetual chasing (Asian rules)
1645 // I guess the following variables logically belong in the closure too, but I was too lazy and used globals
1647 int preyStackPointer, chaseStackPointer;
1650 char rf, ff, rt, ft;
1660 // there are three new callbacks for use with GenLegal: for adding captures, deleting them, and finding a recapture
1662 extern void AtacksCallback P((Board board, int flags, ChessMove kind,
1663 int rf, int ff, int rt, int ft,
1666 void AttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1672 { // For adding captures that can lead to chase indictment to the chaseStack
1673 if(board[rt][ft] == EmptySquare) return; // non-capture
1674 if(board[rt][ft] == WhitePawn && rt < BOARD_HEIGHT/2) return; // Pawn before river can be chased
1675 if(board[rt][ft] == BlackPawn && rt >= BOARD_HEIGHT/2) return; // Pawn before river can be chased
1676 if(board[rf][ff] == WhitePawn || board[rf][ff] == BlackPawn) return; // Pawns are allowed to chase
1677 if(board[rf][ff] == WhiteWazir || board[rf][ff] == BlackWazir) return; // King is allowed to chase
1678 // move cannot be excluded from being a chase trivially (based on attacker and victim); save it on chaseStack
1679 chaseStack[chaseStackPointer].rf = rf;
1680 chaseStack[chaseStackPointer].ff = ff;
1681 chaseStack[chaseStackPointer].rt = rt;
1682 chaseStack[chaseStackPointer].ft = ft;
1683 chaseStackPointer++;
1686 extern void ExistingAtacksCallback P((Board board, int flags, ChessMove kind,
1687 int rf, int ff, int rt, int ft,
1690 void ExistingAttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1696 { // for removing pre-exsting captures from the chaseStack, to be left with newly created ones
1698 register ChaseClosure *cl = (ChaseClosure *) closure; //closure tells us the move played in the repeat loop
1700 if(board[rt][ft] == EmptySquare) return; // no capture
1701 if(rf == cl->rf && ff == cl->ff) { // attacks with same piece from new position are not considered new
1702 rf = cl->rt; ff = cl->ft; // doctor their fromSquare so they will be recognized in chaseStack
1704 // search move in chaseStack, and delete it if it occurred there (as we know now it is not a new capture)
1705 for(i=0; i<chaseStackPointer; i++) {
1706 if(chaseStack[i].rf == rf && chaseStack[i].ff == ff &&
1707 chaseStack[i].rt == rt && chaseStack[i].ft == ft ) {
1708 // move found on chaseStack, delete it by overwriting with move popped from top of chaseStack
1709 chaseStack[i] = chaseStack[--chaseStackPointer];
1715 extern void ProtectedCallback P((Board board, int flags, ChessMove kind,
1716 int rf, int ff, int rt, int ft,
1719 void ProtectedCallback(board, flags, kind, rf, ff, rt, ft, closure)
1725 { // for determining if a piece (given through the closure) is protected
1726 register ChaseClosure *cl = (ChaseClosure *) closure; // closure tells us where to recapture
1728 if(rt == cl->rt && ft == cl->ft) cl->recaptures++; // count legal recaptures to this square
1729 if(appData.debugMode && board[rt][ft] != EmptySquare)
1730 fprintf(debugFP, "try %c%c%c%c=%d\n", ff+AAA, rf+ONE,ft+AAA, rt+ONE, cl->recaptures);
1733 extern char moveList[MAX_MOVES][MOVE_LEN];
1735 int PerpetualChase(int first, int last)
1736 { // this routine detects if the side to move in the 'first' position is perpetually chasing (when not checking)
1739 ChessSquare captured;
1741 preyStackPointer = 0; // clear stack of chased pieces
1742 for(i=first; i<last; i+=2) { // for all positions with same side to move
1743 if(appData.debugMode) fprintf(debugFP, "judge position %i\n", i);
1744 chaseStackPointer = 0; // clear stack that is going to hold possible chases
1745 // determine all captures possible after the move, and put them on chaseStack
1746 GenLegal(boards[i+1], PosFlags(i), AttacksCallback, &cl);
1747 if(appData.debugMode) { int n;
1748 for(n=0; n<chaseStackPointer; n++)
1749 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1750 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1751 fprintf(debugFP, ": all capts\n");
1753 // determine all captures possible before the move, and delete them from chaseStack
1754 cl.rf = moveList[i][1]-ONE; // prepare closure to pass move that led from i to i+1
1755 cl.ff = moveList[i][0]-AAA+BOARD_LEFT;
1756 cl.rt = moveList[i][3]-ONE;
1757 cl.ft = moveList[i][2]-AAA+BOARD_LEFT;
1758 GenLegal(boards[i], PosFlags(i), ExistingAttacksCallback, &cl);
1759 if(appData.debugMode) { int n;
1760 for(n=0; n<chaseStackPointer; n++)
1761 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1762 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1763 fprintf(debugFP, ": new capts after %c%c%c%c\n", cl.ff+AAA, cl.rf+ONE, cl.ft+AAA, cl.rt+ONE);
1765 // chaseSack now contains all captures made possible by the move
1766 for(j=0; j<chaseStackPointer; j++) { // run through chaseStack to identify true chases
1767 int attacker = (int)boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1768 int victim = (int)boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1770 if(attacker >= (int) BlackPawn) attacker = BLACK_TO_WHITE attacker; // convert to white, as piecee type
1771 if(victim >= (int) BlackPawn) victim = BLACK_TO_WHITE victim;
1773 if((attacker == WhiteKnight || attacker == WhiteCannon) && victim == WhiteRook)
1774 continue; // C or H attack on R is always chase; leave on chaseStack
1776 if(attacker == victim) {
1777 if(LegalityTest(boards[i+1], PosFlags(i+1), chaseStack[j].rt,
1778 chaseStack[j].ft, chaseStack[j].rf, chaseStack[j].ff, NULLCHAR) == NormalMove) {
1779 // we can capture back with equal piece, so this is no chase but a sacrifice
1780 chaseStack[j] = chaseStack[--chaseStackPointer]; // delete the capture from the chaseStack
1781 j--; /* ! */ continue;
1786 // the attack is on a lower piece, or on a pinned or blocked equal one
1787 // test if the victim is protected by a true protector. First make the capture.
1788 captured = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1789 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1790 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = EmptySquare;
1791 // Then test if the opponent can recapture
1792 cl.recaptures = 0; // prepare closure to pass recapture square and count moves to it
1793 cl.rt = chaseStack[j].rt;
1794 cl.ft = chaseStack[j].ft;
1795 if(appData.debugMode) {
1796 fprintf(debugFP, "test if we can recapture %c%c\n", cl.ft+AAA, cl.rt+ONE);
1798 GenLegal(boards[i+1], PosFlags(i+1), ProtectedCallback, &cl); // try all moves
1799 // unmake the capture
1800 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1801 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = captured;
1802 // if a recapture was found, piece is protected, and we are not chasing it.
1803 if(cl.recaptures) { // attacked piece was defended by true protector, no chase
1804 chaseStack[j] = chaseStack[--chaseStackPointer]; // so delete from chaseStack
1808 // chaseStack now contains all moves that chased
1809 if(appData.debugMode) { int n;
1810 for(n=0; n<chaseStackPointer; n++)
1811 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1812 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1813 fprintf(debugFP, ": chases\n");
1815 if(i == first) { // copy all people chased by first move of repeat cycle to preyStack
1816 for(j=0; j<chaseStackPointer; j++) {
1817 preyStack[j].rank = chaseStack[j].rt;
1818 preyStack[j].file = chaseStack[j].ft;
1820 preyStackPointer = chaseStackPointer;
1823 for(j=0; j<chaseStackPointer; j++) {
1824 for(k=0; k<preyStackPointer; k++) {
1825 // search the victim of each chase move on the preyStack (first occurrence)
1826 if(chaseStack[j].ft == preyStack[k].file && chaseStack[j].rt == preyStack[k].rank ) {
1827 if(k < tail) break; // piece was already identified as still being chased
1828 preyStack[preyStackPointer] = preyStack[tail]; // move chased piece to bottom part of preyStack
1829 preyStack[tail] = preyStack[k]; // by swapping
1830 preyStack[k] = preyStack[preyStackPointer];
1836 preyStackPointer = tail; // keep bottom part of preyStack, popping pieces unchased on move i.
1837 if(appData.debugMode) { int n;
1838 for(n=0; n<preyStackPointer; n++)
1839 fprintf(debugFP, "%c%c ", preyStack[n].file+AAA, preyStack[n].rank+ONE);
1840 fprintf(debugFP, "always chased upto ply %d\n", i);
1842 // now adjust the location of the chased pieces according to opponent move
1843 for(j=0; j<preyStackPointer; j++) {
1844 if(preyStack[j].rank == moveList[i+1][1]-ONE &&
1845 preyStack[j].file == moveList[i+1][0]-AAA+BOARD_LEFT) {
1846 preyStack[j].rank = moveList[i+1][3]-ONE;
1847 preyStack[j].file = moveList[i+1][2]-AAA+BOARD_LEFT;
1852 return preyStackPointer; // if any piece was left on preyStack, it has been perpetually chased