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);
424 /* Shogi Dragon Horse has to continue with Wazir after Bishop */
425 case SHOGI WhiteCardinal:
426 case SHOGI BlackCardinal:
429 /* Capablanca Archbishop continues as Knight */
434 /* Shogi Bishops are ordinary Bishops */
435 case SHOGI WhiteBishop:
436 case SHOGI BlackBishop:
439 for (rs = -1; rs <= 1; rs += 2)
440 for (fs = -1; fs <= 1; fs += 2)
444 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
445 if (SameColor(board[rf][ff], board[rt][ft])) break;
446 callback(board, flags, NormalMove,
447 rf, ff, rt, ft, closure);
448 if (board[rt][ft] != EmptySquare) break;
450 if(m==1) goto mounted;
451 if(m==2) goto finishGold;
452 /* Bishop falls through */
455 /* Shogi Lance is unlike anything, and asymmetric at that */
456 case SHOGI WhiteQueen:
460 if (rt >= BOARD_HEIGHT) break;
461 if (SameColor(board[rf][ff], board[rt][ft])) break;
462 callback(board, flags, NormalMove,
463 rf, ff, rt, ft, closure);
464 if (board[rt][ft] != EmptySquare) break;
468 case SHOGI BlackQueen:
473 if (SameColor(board[rf][ff], board[rt][ft])) break;
474 callback(board, flags, NormalMove,
475 rf, ff, rt, ft, closure);
476 if (board[rt][ft] != EmptySquare) break;
480 /* Shogi Dragon King has to continue as Ferz after Rook moves */
481 case SHOGI WhiteDragon:
482 case SHOGI BlackDragon:
485 /* Capablanca Chancellor sets flag to continue as Knight */
490 /* Shogi Rooks are ordinary Rooks */
491 case SHOGI WhiteRook:
492 case SHOGI BlackRook:
495 for (d = 0; d <= 1; d++)
496 for (s = -1; s <= 1; s += 2)
498 rt = rf + (i * s) * d;
499 ft = ff + (i * s) * (1 - d);
500 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
501 if (SameColor(board[rf][ff], board[rt][ft])) break;
502 callback(board, flags, NormalMove,
503 rf, ff, rt, ft, closure);
504 if (board[rt][ft] != EmptySquare) break;
506 if(m==1) goto mounted;
507 if(m==2) goto finishSilver;
512 for (rs = -1; rs <= 1; rs++)
513 for (fs = -1; fs <= 1; fs++) {
514 if (rs == 0 && fs == 0) continue;
518 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
519 if (SameColor(board[rf][ff], board[rt][ft])) break;
520 callback(board, flags, NormalMove,
521 rf, ff, rt, ft, closure);
522 if (board[rt][ft] != EmptySquare) break;
527 /* Shogi Pawn and Silver General: first the Pawn move, */
528 /* then the General continues like a Ferz */
530 if(gameInfo.variant != VariantMakruk) goto commoner;
531 case SHOGI WhitePawn:
532 case SHOGI WhiteFerz:
533 if (rf < BOARD_HEIGHT-1 &&
534 !SameColor(board[rf][ff], board[rf + 1][ff]) )
535 callback(board, flags, NormalMove,
536 rf, ff, rf + 1, ff, closure);
537 if(piece != SHOGI WhitePawn) goto finishSilver;
541 if(gameInfo.variant != VariantMakruk) goto commoner;
542 case SHOGI BlackPawn:
543 case SHOGI BlackFerz:
545 !SameColor(board[rf][ff], board[rf - 1][ff]) )
546 callback(board, flags, NormalMove,
547 rf, ff, rf - 1, ff, closure);
548 if(piece == SHOGI BlackPawn) break;
553 /* [HGM] support Shatranj pieces */
554 for (rs = -1; rs <= 1; rs += 2)
555 for (fs = -1; fs <= 1; fs += 2) {
558 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
559 if (!SameColor(board[rf][ff], board[rt][ft]) &&
560 (gameInfo.variant != VariantXiangqi || InPalace(rt, ft) ) )
561 callback(board, flags, NormalMove,
562 rf, ff, rt, ft, closure);
568 m++; // [HGM] superchess: use for Centaur
570 case SHOGI WhiteKing:
571 case SHOGI BlackKing:
575 for (i = -1; i <= 1; i++)
576 for (j = -1; j <= 1; j++) {
577 if (i == 0 && j == 0) continue;
580 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
581 if (SameColor(board[rf][ff], board[rt][ft])) continue;
582 callback(board, flags, NormalMove,
583 rf, ff, rt, ft, closure);
585 if(m==1) goto mounted;
588 case WhiteNightrider:
589 case BlackNightrider:
590 for (i = -1; i <= 1; i += 2)
591 for (j = -1; j <= 1; j += 2)
592 for (s = 1; s <= 2; s++) { int k;
596 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
597 if (SameColor(board[rf][ff], board[rt][ft])) break;
598 callback(board, flags, NormalMove,
599 rf, ff, rt, ft, closure);
600 if (board[rt][ft] != EmptySquare) break;
604 case WhiteFalcon: // [HGM] wild: for wildcards, self-capture symbolizes move to anywhere
610 callback(board, flags, NormalMove, rf, ff, rf, ff, closure);
623 extern void GenLegalCallback P((Board board, int flags, ChessMove kind,
624 int rf, int ff, int rt, int ft,
627 void GenLegalCallback(board, flags, kind, rf, ff, rt, ft, closure)
634 register GenLegalClosure *cl = (GenLegalClosure *) closure;
636 if (!(flags & F_IGNORE_CHECK) &&
637 CheckTest(board, flags, rf, ff, rt, ft,
638 kind == WhiteCapturesEnPassant ||
639 kind == BlackCapturesEnPassant)) return;
640 if (flags & F_ATOMIC_CAPTURE) {
641 if (board[rt][ft] != EmptySquare ||
642 kind == WhiteCapturesEnPassant || kind == BlackCapturesEnPassant) {
644 ChessSquare king = (flags & F_WHITE_ON_MOVE) ? WhiteKing : BlackKing;
645 if (board[rf][ff] == king) return;
646 for (r = rt-1; r <= rt+1; r++) {
647 for (f = ft-1; f <= ft+1; f++) {
648 if (r >= 0 && r < BOARD_HEIGHT && f >= BOARD_LEFT && f < BOARD_RGHT &&
649 board[r][f] == king) return;
654 cl->cb(board, flags, kind, rf, ff, rt, ft, cl->cl);
661 int captures; // [HGM] losers
662 } LegalityTestClosure;
665 /* Like GenPseudoLegal, but (1) include castling moves, (2) unless
666 F_IGNORE_CHECK is set in the flags, omit moves that would leave the
667 king in check, and (3) if F_ATOMIC_CAPTURE is set in the flags, omit
668 moves that would destroy your own king. The CASTLE_OK flags are
669 true if castling is not yet ruled out by a move of the king or
670 rook. Return TRUE if the player on move is currently in check and
671 F_IGNORE_CHECK is not set. [HGM] add castlingRights parameter */
672 int GenLegal(board, flags, callback, closure)
675 MoveCallback callback;
679 int ff, ft, k, left, right;
680 int ignoreCheck = (flags & F_IGNORE_CHECK) != 0;
681 ChessSquare wKing = WhiteKing, bKing = BlackKing, *castlingRights = board[CASTLING];
685 GenPseudoLegal(board, flags, GenLegalCallback, (VOIDSTAR) &cl);
688 CheckTest(board, flags, -1, -1, -1, -1, FALSE)) return TRUE;
690 /* Generate castling moves */
691 if(gameInfo.variant == VariantKnightmate) { /* [HGM] Knightmate */
692 wKing = WhiteUnicorn; bKing = BlackUnicorn;
695 for (ff = BOARD_WIDTH>>1; ff >= (BOARD_WIDTH-1)>>1; ff-- /*ics wild 1*/) {
696 if ((flags & F_WHITE_ON_MOVE) &&
697 (flags & F_WHITE_KCASTLE_OK) &&
698 board[0][ff] == wKing &&
699 board[0][ff + 1] == EmptySquare &&
700 board[0][ff + 2] == EmptySquare &&
701 board[0][BOARD_RGHT-3] == EmptySquare &&
702 board[0][BOARD_RGHT-2] == EmptySquare &&
703 board[0][BOARD_RGHT-1] == WhiteRook &&
704 castlingRights[0] != NoRights && /* [HGM] check rights */
705 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
707 (!CheckTest(board, flags, 0, ff, 0, ff + 1, FALSE) &&
708 !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-3, FALSE) &&
709 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-2, FALSE)) &&
710 !CheckTest(board, flags, 0, ff, 0, ff + 2, FALSE)))) {
712 callback(board, flags,
713 ff==BOARD_WIDTH>>1 ? WhiteKingSideCastle : WhiteKingSideCastleWild,
714 0, ff, 0, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
716 if ((flags & F_WHITE_ON_MOVE) &&
717 (flags & F_WHITE_QCASTLE_OK) &&
718 board[0][ff] == wKing &&
719 board[0][ff - 1] == EmptySquare &&
720 board[0][ff - 2] == EmptySquare &&
721 board[0][BOARD_LEFT+2] == EmptySquare &&
722 board[0][BOARD_LEFT+1] == EmptySquare &&
723 board[0][BOARD_LEFT+0] == WhiteRook &&
724 castlingRights[1] != NoRights && /* [HGM] check rights */
725 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
727 (!CheckTest(board, flags, 0, ff, 0, ff - 1, FALSE) &&
728 !CheckTest(board, flags, 0, ff, 0, BOARD_LEFT+3, FALSE) &&
729 !CheckTest(board, flags, 0, ff, 0, ff - 2, FALSE)))) {
731 callback(board, flags,
732 ff==BOARD_WIDTH>>1 ? WhiteQueenSideCastle : WhiteQueenSideCastleWild,
733 0, ff, 0, ff - ((gameInfo.boardWidth+2)>>2), closure);
735 if (!(flags & F_WHITE_ON_MOVE) &&
736 (flags & F_BLACK_KCASTLE_OK) &&
737 board[BOARD_HEIGHT-1][ff] == bKing &&
738 board[BOARD_HEIGHT-1][ff + 1] == EmptySquare &&
739 board[BOARD_HEIGHT-1][ff + 2] == EmptySquare &&
740 board[BOARD_HEIGHT-1][BOARD_RGHT-3] == EmptySquare &&
741 board[BOARD_HEIGHT-1][BOARD_RGHT-2] == EmptySquare &&
742 board[BOARD_HEIGHT-1][BOARD_RGHT-1] == BlackRook &&
743 castlingRights[3] != NoRights && /* [HGM] check rights */
744 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
746 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 1, FALSE) &&
747 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-3, FALSE) &&
748 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-2, FALSE)) &&
749 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 2, FALSE)))) {
751 callback(board, flags,
752 ff==BOARD_WIDTH>>1 ? BlackKingSideCastle : BlackKingSideCastleWild,
753 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
755 if (!(flags & F_WHITE_ON_MOVE) &&
756 (flags & F_BLACK_QCASTLE_OK) &&
757 board[BOARD_HEIGHT-1][ff] == bKing &&
758 board[BOARD_HEIGHT-1][ff - 1] == EmptySquare &&
759 board[BOARD_HEIGHT-1][ff - 2] == EmptySquare &&
760 board[BOARD_HEIGHT-1][BOARD_LEFT+2] == EmptySquare &&
761 board[BOARD_HEIGHT-1][BOARD_LEFT+1] == EmptySquare &&
762 board[BOARD_HEIGHT-1][BOARD_LEFT+0] == BlackRook &&
763 castlingRights[4] != NoRights && /* [HGM] check rights */
764 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
766 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 1, FALSE) &&
767 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_LEFT+3, FALSE) &&
768 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 2, FALSE)))) {
770 callback(board, flags,
771 ff==BOARD_WIDTH>>1 ? BlackQueenSideCastle : BlackQueenSideCastleWild,
772 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - ((gameInfo.boardWidth+2)>>2), closure);
776 if(flags & F_FRC_TYPE_CASTLING) {
778 /* generate all potential FRC castling moves (KxR), ignoring flags */
779 /* [HGM] test if the Rooks we find have castling rights */
782 if ((flags & F_WHITE_ON_MOVE) != 0) {
783 ff = castlingRights[2]; /* King file if we have any rights */
784 if(ff != NoRights && board[0][ff] == WhiteKing) {
785 if (appData.debugMode) {
786 fprintf(debugFP, "FRC castling, %d %d %d %d %d %d\n",
787 castlingRights[0],castlingRights[1],ff,castlingRights[3],castlingRights[4],castlingRights[5]);
789 ft = castlingRights[0]; /* Rook file if we have H-side rights */
791 right = BOARD_RGHT-2;
792 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
793 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
794 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
795 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
796 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
797 if(ft != NoRights && board[0][ft] == WhiteRook)
798 callback(board, flags, WhiteHSideCastleFR, 0, ff, 0, ft, closure);
800 ft = castlingRights[1]; /* Rook file if we have A-side rights */
803 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
804 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
805 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
806 if(ff > BOARD_LEFT+2)
807 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
808 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
809 if(ft != NoRights && board[0][ft] == WhiteRook)
810 callback(board, flags, WhiteASideCastleFR, 0, ff, 0, ft, closure);
813 ff = castlingRights[5]; /* King file if we have any rights */
814 if(ff != NoRights && board[BOARD_HEIGHT-1][ff] == BlackKing) {
815 ft = castlingRights[3]; /* Rook file if we have H-side rights */
817 right = BOARD_RGHT-2;
818 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
819 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
820 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
821 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
822 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
823 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
824 callback(board, flags, BlackHSideCastleFR, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ft, closure);
826 ft = castlingRights[4]; /* Rook file if we have A-side rights */
829 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
830 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
831 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
832 if(ff > BOARD_LEFT+2)
833 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
834 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
835 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
836 callback(board, flags, BlackASideCastleFR, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ft, closure);
852 extern void CheckTestCallback P((Board board, int flags, ChessMove kind,
853 int rf, int ff, int rt, int ft,
857 void CheckTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
864 register CheckTestClosure *cl = (CheckTestClosure *) closure;
866 if (rt == cl->rking && ft == cl->fking) cl->check++;
870 /* If the player on move were to move from (rf, ff) to (rt, ft), would
871 he leave himself in check? Or if rf == -1, is the player on move
872 in check now? enPassant must be TRUE if the indicated move is an
873 e.p. capture. The possibility of castling out of a check along the
874 back rank is not accounted for (i.e., we still return nonzero), as
875 this is illegal anyway. Return value is the number of times the
877 int CheckTest(board, flags, rf, ff, rt, ft, enPassant)
880 int rf, ff, rt, ft, enPassant;
883 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
884 ChessSquare captured = EmptySquare;
885 /* Suppress warnings on uninitialized variables */
887 if(gameInfo.variant == VariantXiangqi)
888 king = flags & F_WHITE_ON_MOVE ? WhiteWazir : BlackWazir;
889 if(gameInfo.variant == VariantKnightmate)
890 king = flags & F_WHITE_ON_MOVE ? WhiteUnicorn : BlackUnicorn;
894 captured = board[rf][ft];
895 board[rf][ft] = EmptySquare;
897 captured = board[rt][ft];
899 board[rt][ft] = board[rf][ff];
900 board[rf][ff] = EmptySquare;
901 } else board[rt][ft] = ff; // [HGM] drop
903 /* For compatibility with ICS wild 9, we scan the board in the
904 order a1, a2, a3, ... b1, b2, ..., h8 to find the first king,
905 and we test only whether that one is in check. */
907 for (cl.fking = BOARD_LEFT+0; cl.fking < BOARD_RGHT; cl.fking++)
908 for (cl.rking = 0; cl.rking < BOARD_HEIGHT; cl.rking++) {
909 if (board[cl.rking][cl.fking] == king) {
910 if(gameInfo.variant == VariantXiangqi) {
911 /* [HGM] In Xiangqi opposing Kings means check as well */
913 dir = (king >= BlackPawn) ? -1 : 1;
914 for( i=cl.rking+dir; i>=0 && i<BOARD_HEIGHT &&
915 board[i][cl.fking] == EmptySquare; i+=dir );
916 if(i>=0 && i<BOARD_HEIGHT &&
917 board[i][cl.fking] == (dir>0 ? BlackWazir : WhiteWazir) )
921 GenPseudoLegal(board, flags ^ F_WHITE_ON_MOVE, CheckTestCallback, (VOIDSTAR) &cl);
922 goto undo_move; /* 2-level break */
929 board[rf][ff] = board[rt][ft];
931 board[rf][ft] = captured;
932 board[rt][ft] = EmptySquare;
934 board[rt][ft] = captured;
936 } else board[rt][ft] = EmptySquare; // [HGM] drop
938 return cl.fking < BOARD_RGHT ? cl.check : 1000; // [HGM] atomic: return 1000 if we have no king
941 ChessMove LegalDrop(board, flags, piece, rt, ft)
946 { // [HGM] put drop legality testing in separate routine for clarity
948 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
949 if(board[rt][ft] != EmptySquare) return ImpossibleMove; // must drop to empty square
950 n = PieceToNumber(piece);
951 if(gameInfo.holdingsWidth == 0 || (flags & F_WHITE_ON_MOVE ? board[n][BOARD_WIDTH-1] : board[BOARD_HEIGHT-1-n][0]) != piece)
952 return ImpossibleMove; // piece not available
953 if(gameInfo.variant == VariantShogi) { // in Shogi lots of drops are forbidden!
954 if((piece == WhitePawn || piece == WhiteQueen) && rt == BOARD_HEIGHT-1 ||
955 (piece == BlackPawn || piece == BlackQueen) && rt == 0 ||
956 piece == WhiteKnight && rt > BOARD_HEIGHT-3 ||
957 piece == BlackKnight && rt < 2 ) return IllegalMove; // e.g. where dropped piece has no moves
958 if(piece == WhitePawn || piece == BlackPawn) {
960 for(r=1; r<BOARD_HEIGHT-1; r++)
961 if(board[r][ft] == piece) return IllegalMove; // or there already is a Pawn in file
962 // should still test if we mate with this Pawn
965 if( (piece == WhitePawn || piece == BlackPawn) &&
966 (rt == 0 || rt == BOARD_HEIGHT -1 ) )
967 return IllegalMove; /* no pawn drops on 1st/8th */
969 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
970 if (!(flags & F_IGNORE_CHECK) &&
971 CheckTest(board, flags, DROP_RANK, piece, rt, ft, FALSE) ) return IllegalMove;
972 return flags & F_WHITE_ON_MOVE ? WhiteDrop : BlackDrop;
975 extern void LegalityTestCallback P((Board board, int flags, ChessMove kind,
976 int rf, int ff, int rt, int ft,
979 void LegalityTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
986 register LegalityTestClosure *cl = (LegalityTestClosure *) closure;
988 // if (appData.debugMode) {
989 // fprintf(debugFP, "Legality test: %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
991 if(board[rt][ft] != EmptySquare || kind==WhiteCapturesEnPassant || kind==BlackCapturesEnPassant)
992 cl->captures++; // [HGM] losers: count legal captures
993 if (rf == cl->rf && ff == cl->ff && rt == cl->rt && ft == cl->ft)
997 ChessMove LegalityTest(board, flags, rf, ff, rt, ft, promoChar)
1000 int rf, ff, rt, ft, promoChar;
1002 LegalityTestClosure cl; ChessSquare piece, *castlingRights = board[CASTLING];
1004 if(rf == DROP_RANK) return LegalDrop(board, flags, ff, rt, ft);
1005 piece = board[rf][ff];
1007 if (appData.debugMode) {
1009 for(i=0; i<6; i++) fprintf(debugFP, "%d ", castlingRights[i]);
1010 fprintf(debugFP, "Legality test? %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
1012 /* [HGM] Lance, Cobra and Falcon are wildcard pieces; consider all their moves legal */
1013 /* (perhaps we should disallow moves that obviously leave us in check?) */
1014 if(piece == WhiteFalcon || piece == BlackFalcon ||
1015 piece == WhiteCobra || piece == BlackCobra ||
1016 piece == WhiteLance || piece == BlackLance)
1017 return CheckTest(board, flags, rf, ff, rt, ft, FALSE) ? IllegalMove : NormalMove;
1023 cl.kind = IllegalMove;
1024 cl.captures = 0; // [HGM] losers: prepare to count legal captures.
1025 GenLegal(board, flags, LegalityTestCallback, (VOIDSTAR) &cl);
1026 if((flags & F_MANDATORY_CAPTURE) && cl.captures && board[rt][ft] == EmptySquare
1027 && cl.kind != WhiteCapturesEnPassant && cl.kind != BlackCapturesEnPassant)
1028 return(IllegalMove); // [HGM] losers: if there are legal captures, non-capts are illegal
1030 if(promoChar == 'x') promoChar = NULLCHAR; // [HGM] is this ever the case?
1031 if(gameInfo.variant == VariantShogi) {
1032 /* [HGM] Shogi promotions. '=' means defer */
1033 if(rf != DROP_RANK && cl.kind == NormalMove) {
1034 ChessSquare piece = board[rf][ff];
1036 if(promoChar == PieceToChar(BlackQueen)) promoChar = NULLCHAR; /* [HGM] Kludge */
1037 if(promoChar == 'd' && (piece == WhiteRook || piece == BlackRook) ||
1038 promoChar == 'h' && (piece == WhiteBishop || piece == BlackBishop) ||
1039 promoChar == 'g' && (piece <= WhiteFerz || piece <= BlackFerz && piece >= BlackPawn) )
1040 promoChar = '+'; // allowed ICS notations
1041 if(appData.debugMode)fprintf(debugFP,"SHOGI promoChar = %c\n", promoChar ? promoChar : '-');
1042 if(promoChar != NULLCHAR && promoChar != '+' && promoChar != '=')
1043 cl.kind = IllegalMove;
1044 else if(flags & F_WHITE_ON_MOVE) {
1045 if( (int) piece < (int) WhiteWazir &&
1046 (rf >= BOARD_HEIGHT*2/3 || rt >= BOARD_HEIGHT*2/3) ) {
1047 if( (piece == WhitePawn || piece == WhiteQueen) && rt > BOARD_HEIGHT-2 ||
1048 piece == WhiteKnight && rt > BOARD_HEIGHT-3) /* promotion mandatory */
1049 cl.kind = promoChar == '=' ? IllegalMove : WhitePromotion;
1050 else /* promotion optional, default is promote */
1051 cl.kind = promoChar == '=' ? WhiteNonPromotion : WhitePromotion;
1052 } else cl.kind = (promoChar == NULLCHAR || promoChar == '=') ? NormalMove : IllegalMove;
1054 if( (int) piece < (int) BlackWazir && (rf < BOARD_HEIGHT/3 || rt < BOARD_HEIGHT/3) ) {
1055 if( (piece == BlackPawn || piece == BlackQueen) && rt < 1 ||
1056 piece == BlackKnight && rt < 2 ) /* promotion obligatory */
1057 cl.kind = promoChar == '=' ? IllegalMove : BlackPromotion;
1058 else /* promotion optional, default is promote */
1059 cl.kind = promoChar == '=' ? BlackNonPromotion : BlackPromotion;
1061 } else cl.kind = (promoChar == NULLCHAR || promoChar == '=') ? NormalMove : IllegalMove;
1065 if (promoChar != NULLCHAR) {
1066 if(promoChar == '=') cl.kind = IllegalMove; else // [HGM] shogi: no deferred promotion outside Shogi
1067 if (cl.kind == WhitePromotion || cl.kind == BlackPromotion) {
1068 if(CharToPiece(promoChar) == EmptySquare) cl.kind = ImpossibleMove; // non-existing piece
1070 cl.kind = IllegalMove;
1080 extern void MateTestCallback P((Board board, int flags, ChessMove kind,
1081 int rf, int ff, int rt, int ft,
1084 void MateTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
1091 register MateTestClosure *cl = (MateTestClosure *) closure;
1096 /* Return MT_NONE, MT_CHECK, MT_CHECKMATE, or MT_STALEMATE */
1097 int MateTest(board, flags)
1102 int inCheck, r, f, myPieces=0, hisPieces=0, nrKing=0;
1103 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
1105 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) {
1106 // [HGM] losers: Count pieces and kings, to detect other unorthodox winning conditions
1107 nrKing += (board[r][f] == king); // stm has king
1108 if( board[r][f] != EmptySquare ) {
1109 if((int)board[r][f] <= (int)king && (int)board[r][f] >= (int)king - (int)WhiteKing + (int)WhitePawn)
1114 if(appData.debugMode) fprintf(debugFP, "MateTest: K=%d, my=%d, his=%d\n", nrKing, myPieces, hisPieces);
1115 switch(gameInfo.variant) { // [HGM] losers: extinction wins
1116 case VariantShatranj:
1117 if(hisPieces == 1) return myPieces > 1 ? MT_BARE : MT_DRAW;
1121 if(nrKing == 0) return MT_NOKING;
1124 if(myPieces == 1) return MT_BARE;
1127 inCheck = GenLegal(board, flags, MateTestCallback, (VOIDSTAR) &cl);
1128 // [HGM] 3check: yet to do!
1130 return inCheck ? MT_CHECK : MT_NONE;
1132 if(gameInfo.holdingsWidth && gameInfo.variant != VariantSuper || gameInfo.variant != VariantGreat) { // drop game
1133 int r, f, n, holdings = flags & F_WHITE_ON_MOVE ? BOARD_WIDTH-1 : 0;
1134 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) if(board[r][f] == EmptySquare) // all empty squares
1135 for(n=0; n<BOARD_HEIGHT; n++) // all pieces in hand
1136 if(board[n][holdings] != EmptySquare) {
1137 int moveType = LegalDrop(board, flags, board[n][holdings], r, f);
1138 if(moveType == WhiteDrop || moveType == BlackDrop) return MT_CHECK; // we can resolve check by legal drop
1141 if(gameInfo.variant == VariantSuicide) // [HGM] losers: always stalemate, since no check, but result varies
1142 return myPieces == hisPieces ? MT_STALEMATE :
1143 myPieces > hisPieces ? MT_STAINMATE : MT_STEALMATE;
1144 else if(gameInfo.variant == VariantLosers) return inCheck ? MT_TRICKMATE : MT_STEALMATE;
1145 else if(gameInfo.variant == VariantGiveaway) return MT_STEALMATE; // no check exists, stalemated = win
1147 return inCheck ? MT_CHECKMATE
1148 : (gameInfo.variant == VariantXiangqi || gameInfo.variant == VariantShatranj) ?
1149 MT_STAINMATE : MT_STALEMATE;
1154 extern void DisambiguateCallback P((Board board, int flags, ChessMove kind,
1155 int rf, int ff, int rt, int ft,
1158 void DisambiguateCallback(board, flags, kind, rf, ff, rt, ft, closure)
1165 register DisambiguateClosure *cl = (DisambiguateClosure *) closure;
1166 int wildCard = FALSE; ChessSquare piece = board[rf][ff];
1168 // [HGM] wild: for wild-card pieces rt and rf are dummies
1169 if(piece == WhiteFalcon || piece == BlackFalcon ||
1170 piece == WhiteCobra || piece == BlackCobra ||
1171 piece == WhiteLance || piece == BlackLance)
1174 if ((cl->pieceIn == EmptySquare || cl->pieceIn == board[rf][ff]
1175 || PieceToChar(board[rf][ff]) == '~'
1176 && cl->pieceIn == (ChessSquare)(DEMOTED board[rf][ff])
1178 (cl->rfIn == -1 || cl->rfIn == rf) &&
1179 (cl->ffIn == -1 || cl->ffIn == ff) &&
1180 (cl->rtIn == -1 || cl->rtIn == rt || wildCard) &&
1181 (cl->ftIn == -1 || cl->ftIn == ft || wildCard)) {
1184 if(cl->count == 1 || board[rt][ft] != EmptySquare) {
1185 // [HGM] oneclick: if multiple moves, be sure we remember capture
1186 cl->piece = board[rf][ff];
1189 cl->rt = wildCard ? cl->rtIn : rt;
1190 cl->ft = wildCard ? cl->ftIn : ft;
1193 cl->captures += (board[cl->rt][cl->ft] != EmptySquare); // [HGM] oneclick: count captures
1197 void Disambiguate(board, flags, closure)
1200 DisambiguateClosure *closure;
1202 int illegal = 0; char c = closure->promoCharIn;
1204 closure->count = closure->captures = 0;
1205 closure->rf = closure->ff = closure->rt = closure->ft = 0;
1206 closure->kind = ImpossibleMove;
1207 if (appData.debugMode) {
1208 fprintf(debugFP, "Disambiguate in: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1209 closure->pieceIn,closure->ffIn,closure->rfIn,closure->ftIn,closure->rtIn,
1210 closure->promoCharIn, closure->promoCharIn >= ' ' ? closure->promoCharIn : '-');
1212 GenLegal(board, flags, DisambiguateCallback, (VOIDSTAR) closure);
1213 if (closure->count == 0) {
1214 /* See if it's an illegal move due to check */
1216 GenLegal(board, flags|F_IGNORE_CHECK, DisambiguateCallback, (VOIDSTAR) closure);
1217 if (closure->count == 0) {
1218 /* No, it's not even that */
1219 if (appData.debugMode) { int i, j;
1220 for(i=BOARD_HEIGHT-1; i>=0; i--) {
1221 for(j=0; j<BOARD_WIDTH; j++)
1222 fprintf(debugFP, "%3d", (int) board[i][j]);
1223 fprintf(debugFP, "\n");
1230 if (c == 'x') c = NULLCHAR; // get rid of any 'x' (which should never happen?)
1231 if(gameInfo.variant == VariantShogi) {
1232 /* [HGM] Shogi promotions. On input, '=' means defer, NULL promote. Afterwards, c is set to '+' for promotions, NULL other */
1233 if(closure->rfIn != DROP_RANK && closure->kind == NormalMove) {
1234 ChessSquare piece = closure->piece;
1235 if (c == 'd' && (piece == WhiteRook || piece == BlackRook) ||
1236 c == 'h' && (piece == WhiteBishop || piece == BlackBishop) ||
1237 c == 'g' && (piece <= WhiteFerz || piece <= BlackFerz && piece >= BlackPawn) )
1238 c = '+'; // allowed ICS notations
1239 if(c != NULLCHAR && c != '+' && c != '=')
1240 closure->kind = IllegalMove; // the only allowed cases are '+', '='.
1241 else if(flags & F_WHITE_ON_MOVE) {
1242 if( (int) piece < (int) WhiteWazir &&
1243 (closure->rf >= BOARD_HEIGHT-(BOARD_HEIGHT/3) || closure->rt >= BOARD_HEIGHT-(BOARD_HEIGHT/3)) ) {
1244 if( (piece == WhitePawn || piece == WhiteQueen) && closure->rt > BOARD_HEIGHT-2 ||
1245 piece == WhiteKnight && closure->rt > BOARD_HEIGHT-3) /* promotion mandatory */
1246 closure->kind = c == '=' ? IllegalMove : WhitePromotion;
1247 else /* promotion optional, default is promote */
1248 closure->kind = c == '=' ? WhiteNonPromotion : WhitePromotion;
1249 } else closure->kind = (c == NULLCHAR || c == '=') ? NormalMove : IllegalMove;
1251 if( (int) piece < (int) BlackWazir && (closure->rf < BOARD_HEIGHT/3 || closure->rt < BOARD_HEIGHT/3) ) {
1252 if( (piece == BlackPawn || piece == BlackQueen) && closure->rt < 1 ||
1253 piece == BlackKnight && closure->rt < 2 ) /* promotion obligatory */
1254 closure->kind = c == '=' ? IllegalMove : BlackPromotion;
1255 else /* promotion optional, default is promote */
1256 closure->kind = c == '=' ? BlackNonPromotion : BlackPromotion;
1257 } else closure->kind = (c == NULLCHAR || c == '=') ? NormalMove : IllegalMove;
1260 c = (closure->kind == WhitePromotion || closure->kind == BlackPromotion) ? '+' : NULLCHAR;
1262 if (closure->kind == WhitePromotion || closure->kind == BlackPromotion) {
1263 if(c == NULLCHAR) c = 'q'; // even in Shatranj, Courier, Makruk, as Apply move corrects this to Ferz (how messy!)
1264 } else if (c != NULLCHAR) closure->kind = IllegalMove;
1266 closure->promoChar = ToLower(c); // this can be NULLCHAR! Note we keep original promoChar even if illegal.
1267 if(c != '+' && c != NULLCHAR && CharToPiece(c) == EmptySquare) closure->kind = ImpossibleMove; // but we cannot handle non-existing piece types!
1268 if (closure->count > 1) {
1269 closure->kind = AmbiguousMove;
1272 /* Note: If more than one illegal move matches, but no legal
1273 moves, we return IllegalMove, not AmbiguousMove. Caller
1274 can look at closure->count to detect this.
1276 closure->kind = IllegalMove;
1278 if (appData.debugMode) {
1279 fprintf(debugFP, "Disambiguate out: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1280 closure->piece,closure->ff,closure->rf,closure->ft,closure->rt,closure->promoChar,
1281 closure->promoChar >= ' ' ? closure->promoChar:'-');
1295 } CoordsToAlgebraicClosure;
1297 extern void CoordsToAlgebraicCallback P((Board board, int flags,
1298 ChessMove kind, int rf, int ff,
1299 int rt, int ft, VOIDSTAR closure));
1301 void CoordsToAlgebraicCallback(board, flags, kind, rf, ff, rt, ft, closure)
1308 register CoordsToAlgebraicClosure *cl =
1309 (CoordsToAlgebraicClosure *) closure;
1311 if (rt == cl->rt && ft == cl->ft &&
1312 (board[rf][ff] == cl->piece
1313 || PieceToChar(board[rf][ff]) == '~' &&
1314 (ChessSquare) (DEMOTED board[rf][ff]) == cl->piece)
1318 cl->kind = kind; /* this is the move we want */
1320 cl->file++; /* need file to rule out this move */
1324 cl->rank++; /* need rank to rule out this move */
1326 cl->either++; /* rank or file will rule out this move */
1332 /* Convert coordinates to normal algebraic notation.
1333 promoChar must be NULLCHAR or 'x' if not a promotion.
1335 ChessMove CoordsToAlgebraic(board, flags, rf, ff, rt, ft, promoChar, out)
1344 char *outp = out, c;
1345 CoordsToAlgebraicClosure cl;
1347 if (rf == DROP_RANK) {
1348 /* Bughouse piece drop */
1349 *outp++ = ToUpper(PieceToChar((ChessSquare) ff));
1354 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1356 return (flags & F_WHITE_ON_MOVE) ? WhiteDrop : BlackDrop;
1359 if (promoChar == 'x') promoChar = NULLCHAR;
1360 piece = board[rf][ff];
1361 if(PieceToChar(piece)=='~') piece = (ChessSquare)(DEMOTED piece);
1363 if (appData.debugMode)
1364 fprintf(debugFP, "CoordsToAlgebraic, piece=%d (%d,%d)-(%d,%d) %c\n", (int)piece,ff,rf,ft,rt,promoChar >= ' ' ? promoChar : '-');
1368 kind = LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1369 if (kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1370 /* Keep short notation if move is illegal only because it
1371 leaves the player in check, but still return IllegalMove */
1372 kind = LegalityTest(board, flags|F_IGNORE_CHECK, rf, ff, rt, ft, promoChar);
1373 if (kind == IllegalMove) break;
1378 if (ff == ft && board[rt][ft] == EmptySquare) { /* [HGM] Xiangqi has straight noncapts! */
1379 /* Non-capture; use style "e5" */
1382 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1384 /* Capture; use style "exd5" */
1385 if(gameInfo.variant != VariantXiangqi || board[rt][ft] != EmptySquare )
1386 *outp++ = 'x'; /* [HGM] Xiangqi has sideway noncaptures across river! */
1390 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1392 /* Use promotion suffix style "=Q" */
1394 if (appData.debugMode)
1395 fprintf(debugFP, "movetype=%d, promochar=%d=%c\n", (int)kind, promoChar, promoChar >= ' ' ? promoChar : '-');
1396 if (promoChar != NULLCHAR) {
1397 if(gameInfo.variant == VariantShogi) {
1398 /* [HGM] ... but not in Shogi! */
1399 *outp++ = promoChar == '=' ? '=' : '+';
1402 *outp++ = ToUpper(promoChar);
1411 /* Fabien moved code: FRC castling first (if KxR), wild castling second */
1412 /* Code added by Tord: FRC castling. */
1413 if((piece == WhiteKing && board[rt][ft] == WhiteRook) ||
1414 (piece == BlackKing && board[rt][ft] == BlackRook)) {
1416 safeStrCpy(out, "O-O", MOVE_LEN);
1418 safeStrCpy(out, "O-O-O", MOVE_LEN);
1419 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1421 /* End of code added by Tord */
1422 /* Test for castling or ICS wild castling */
1423 /* Use style "O-O" (oh-oh) for PGN compatibility */
1424 else if (rf == rt &&
1425 rf == ((piece == WhiteKing) ? 0 : BOARD_HEIGHT-1) &&
1426 (ft - ff > 1 || ff - ft > 1) && // No castling if legal King move (on narrow boards!)
1427 ((ff == BOARD_WIDTH>>1 && (ft == BOARD_LEFT+2 || ft == BOARD_RGHT-2)) ||
1428 (ff == (BOARD_WIDTH-1)>>1 && (ft == BOARD_LEFT+1 || ft == BOARD_RGHT-3)))) {
1429 if(ft==BOARD_LEFT+1 || ft==BOARD_RGHT-2)
1430 safeStrCpy(out, "O-O", MOVE_LEN);
1432 safeStrCpy(out, "O-O-O", MOVE_LEN);
1434 /* This notation is always unambiguous, unless there are
1435 kings on both the d and e files, with "wild castling"
1436 possible for the king on the d file and normal castling
1437 possible for the other. ICS rules for wild 9
1438 effectively make castling illegal for either king in
1439 this situation. So I am not going to worry about it;
1440 I'll just generate an ambiguous O-O in this case.
1442 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1445 /* else fall through */
1453 cl.kind = IllegalMove;
1454 cl.rank = cl.file = cl.either = 0;
1455 GenLegal(board, flags, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1457 if (cl.kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1458 /* Generate pretty moves for moving into check, but
1459 still return IllegalMove.
1461 GenLegal(board, flags|F_IGNORE_CHECK, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1462 if (cl.kind == IllegalMove) break;
1463 cl.kind = IllegalMove;
1466 /* Style is "Nf3" or "Nxf7" if this is unambiguous,
1467 else "Ngf3" or "Ngxf7",
1468 else "N1f3" or "N5xf7",
1469 else "Ng1f3" or "Ng5xf7".
1471 c = PieceToChar(piece) ;
1472 if( c == '~' || c == '+') {
1473 /* [HGM] print nonexistent piece as its demoted version */
1474 piece = (ChessSquare) (DEMOTED piece);
1476 if(c=='+') *outp++ = c;
1477 *outp++ = ToUpper(PieceToChar(piece));
1479 if (cl.file || (cl.either && !cl.rank)) {
1485 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1488 if(board[rt][ft] != EmptySquare)
1494 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1496 if (gameInfo.variant == VariantShogi) {
1497 /* [HGM] in Shogi non-pawns can promote */
1498 if(flags & F_WHITE_ON_MOVE) {
1499 if( (int) cl.piece < (int) WhiteWazir &&
1500 (rf >= BOARD_HEIGHT-(BOARD_HEIGHT/3) || rt >= BOARD_HEIGHT-(BOARD_HEIGHT/3)) ) {
1501 if( (piece == WhitePawn || piece == WhiteQueen) && rt > BOARD_HEIGHT-2 ||
1502 piece == WhiteKnight && rt > BOARD_HEIGHT-3) /* promotion mandatory */
1503 cl.kind = promoChar == '=' ? IllegalMove : WhitePromotion;
1504 else cl.kind = WhitePromotion; /* promotion optional */
1505 } else cl.kind = (promoChar == NULLCHAR || promoChar == 'x' || promoChar == '=') ?
1506 NormalMove : IllegalMove;
1508 if( (int) cl.piece < (int) BlackWazir && (rf < BOARD_HEIGHT/3 || rt < BOARD_HEIGHT/3) ) {
1509 if( (piece == BlackPawn || piece == BlackQueen) && rt < 1 ||
1510 piece == BlackKnight && rt < 2 ) /* promotion obligatory */
1511 cl.kind = promoChar == '=' ? IllegalMove : BlackPromotion;
1512 else cl.kind = BlackPromotion; /* promotion optional */
1513 } else cl.kind = (promoChar == NULLCHAR || promoChar == 'x' || promoChar == '=') ?
1514 NormalMove : IllegalMove;
1516 if(cl.kind == WhitePromotion || cl.kind == BlackPromotion) {
1517 /* for optional promotions append '+' or '=' */
1518 if(promoChar == '=') {
1520 cl.kind = NormalMove;
1521 } else *outp++ = '+';
1523 } else if(cl.kind == IllegalMove) {
1524 /* Illegal move specifies any given promotion */
1525 if(promoChar != NULLCHAR && promoChar != 'x') {
1527 *outp++ = ToUpper(promoChar);
1534 /* [HGM] Always long notation for fairies we don't know */
1539 case WhiteGrasshopper:
1540 case BlackGrasshopper:
1542 /* Moving a nonexistent piece */
1546 /* Not a legal move, even ignoring check.
1547 If there was a piece on the from square,
1548 use style "Ng1g3" or "Ng1xe8";
1549 if there was a pawn or nothing (!),
1550 use style "g1g3" or "g1xe8". Use "x"
1551 if a piece was on the to square, even
1552 a piece of the same color.
1555 if (piece != EmptySquare && piece != WhitePawn && piece != BlackPawn) {
1556 *outp++ = ToUpper(PieceToChar(piece));
1561 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1562 if (board[rt][ft] != EmptySquare) *outp++ = 'x';
1566 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1567 /* Use promotion suffix style "=Q" */
1568 if (promoChar != NULLCHAR && promoChar != 'x') {
1570 *outp++ = ToUpper(promoChar);
1577 // [HGM] XQ: the following code serves to detect perpetual chasing (Asian rules)
1586 // I guess the following variables logically belong in the closure too, but I was too lazy and used globals
1588 int preyStackPointer, chaseStackPointer;
1591 char rf, ff, rt, ft;
1601 // there are three new callbacks for use with GenLegal: for adding captures, deleting them, and finding a recapture
1603 extern void AtacksCallback P((Board board, int flags, ChessMove kind,
1604 int rf, int ff, int rt, int ft,
1607 void AttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1613 { // For adding captures that can lead to chase indictment to the chaseStack
1614 if(board[rt][ft] == EmptySquare) return; // non-capture
1615 if(board[rt][ft] == WhitePawn && rt < BOARD_HEIGHT/2) return; // Pawn before river can be chased
1616 if(board[rt][ft] == BlackPawn && rt >= BOARD_HEIGHT/2) return; // Pawn before river can be chased
1617 if(board[rf][ff] == WhitePawn || board[rf][ff] == BlackPawn) return; // Pawns are allowed to chase
1618 if(board[rf][ff] == WhiteWazir || board[rf][ff] == BlackWazir) return; // King is allowed to chase
1619 // move cannot be excluded from being a chase trivially (based on attacker and victim); save it on chaseStack
1620 chaseStack[chaseStackPointer].rf = rf;
1621 chaseStack[chaseStackPointer].ff = ff;
1622 chaseStack[chaseStackPointer].rt = rt;
1623 chaseStack[chaseStackPointer].ft = ft;
1624 chaseStackPointer++;
1627 extern void ExistingAtacksCallback P((Board board, int flags, ChessMove kind,
1628 int rf, int ff, int rt, int ft,
1631 void ExistingAttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1637 { // for removing pre-exsting captures from the chaseStack, to be left with newly created ones
1639 register ChaseClosure *cl = (ChaseClosure *) closure; //closure tells us the move played in the repeat loop
1641 if(board[rt][ft] == EmptySquare) return; // no capture
1642 if(rf == cl->rf && ff == cl->ff) { // attacks with same piece from new position are not considered new
1643 rf = cl->rt; ff = cl->ft; // doctor their fromSquare so they will be recognized in chaseStack
1645 // search move in chaseStack, and delete it if it occurred there (as we know now it is not a new capture)
1646 for(i=0; i<chaseStackPointer; i++) {
1647 if(chaseStack[i].rf == rf && chaseStack[i].ff == ff &&
1648 chaseStack[i].rt == rt && chaseStack[i].ft == ft ) {
1649 // move found on chaseStack, delete it by overwriting with move popped from top of chaseStack
1650 chaseStack[i] = chaseStack[--chaseStackPointer];
1656 extern void ProtectedCallback P((Board board, int flags, ChessMove kind,
1657 int rf, int ff, int rt, int ft,
1660 void ProtectedCallback(board, flags, kind, rf, ff, rt, ft, closure)
1666 { // for determining if a piece (given through the closure) is protected
1667 register ChaseClosure *cl = (ChaseClosure *) closure; // closure tells us where to recapture
1669 if(rt == cl->rt && ft == cl->ft) cl->recaptures++; // count legal recaptures to this square
1670 if(appData.debugMode && board[rt][ft] != EmptySquare)
1671 fprintf(debugFP, "try %c%c%c%c=%d\n", ff+AAA, rf+ONE,ft+AAA, rt+ONE, cl->recaptures);
1674 extern char moveList[MAX_MOVES][MOVE_LEN];
1676 int PerpetualChase(int first, int last)
1677 { // this routine detects if the side to move in the 'first' position is perpetually chasing (when not checking)
1680 ChessSquare captured;
1682 preyStackPointer = 0; // clear stack of chased pieces
1683 for(i=first; i<last; i+=2) { // for all positions with same side to move
1684 if(appData.debugMode) fprintf(debugFP, "judge position %i\n", i);
1685 chaseStackPointer = 0; // clear stack that is going to hold possible chases
1686 // determine all captures possible after the move, and put them on chaseStack
1687 GenLegal(boards[i+1], PosFlags(i), AttacksCallback, &cl);
1688 if(appData.debugMode) { int n;
1689 for(n=0; n<chaseStackPointer; n++)
1690 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1691 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1692 fprintf(debugFP, ": all capts\n");
1694 // determine all captures possible before the move, and delete them from chaseStack
1695 cl.rf = moveList[i][1]-ONE; // prepare closure to pass move that led from i to i+1
1696 cl.ff = moveList[i][0]-AAA+BOARD_LEFT;
1697 cl.rt = moveList[i][3]-ONE;
1698 cl.ft = moveList[i][2]-AAA+BOARD_LEFT;
1699 GenLegal(boards[i], PosFlags(i), ExistingAttacksCallback, &cl);
1700 if(appData.debugMode) { int n;
1701 for(n=0; n<chaseStackPointer; n++)
1702 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1703 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1704 fprintf(debugFP, ": new capts after %c%c%c%c\n", cl.ff+AAA, cl.rf+ONE, cl.ft+AAA, cl.rt+ONE);
1706 // chaseSack now contains all captures made possible by the move
1707 for(j=0; j<chaseStackPointer; j++) { // run through chaseStack to identify true chases
1708 int attacker = (int)boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1709 int victim = (int)boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1711 if(attacker >= (int) BlackPawn) attacker = BLACK_TO_WHITE attacker; // convert to white, as piecee type
1712 if(victim >= (int) BlackPawn) victim = BLACK_TO_WHITE victim;
1714 if((attacker == WhiteKnight || attacker == WhiteCannon) && victim == WhiteRook)
1715 continue; // C or H attack on R is always chase; leave on chaseStack
1717 if(attacker == victim) {
1718 if(LegalityTest(boards[i+1], PosFlags(i+1), chaseStack[j].rt,
1719 chaseStack[j].ft, chaseStack[j].rf, chaseStack[j].ff, NULLCHAR) == NormalMove) {
1720 // we can capture back with equal piece, so this is no chase but a sacrifice
1721 chaseStack[j] = chaseStack[--chaseStackPointer]; // delete the capture from the chaseStack
1722 j--; /* ! */ continue;
1727 // the attack is on a lower piece, or on a pinned or blocked equal one
1728 // test if the victim is protected by a true protector. First make the capture.
1729 captured = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1730 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1731 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = EmptySquare;
1732 // Then test if the opponent can recapture
1733 cl.recaptures = 0; // prepare closure to pass recapture square and count moves to it
1734 cl.rt = chaseStack[j].rt;
1735 cl.ft = chaseStack[j].ft;
1736 if(appData.debugMode) {
1737 fprintf(debugFP, "test if we can recapture %c%c\n", cl.ft+AAA, cl.rt+ONE);
1739 GenLegal(boards[i+1], PosFlags(i+1), ProtectedCallback, &cl); // try all moves
1740 // unmake the capture
1741 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1742 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = captured;
1743 // if a recapture was found, piece is protected, and we are not chasing it.
1744 if(cl.recaptures) { // attacked piece was defended by true protector, no chase
1745 chaseStack[j] = chaseStack[--chaseStackPointer]; // so delete from chaseStack
1749 // chaseStack now contains all moves that chased
1750 if(appData.debugMode) { int n;
1751 for(n=0; n<chaseStackPointer; n++)
1752 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1753 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1754 fprintf(debugFP, ": chases\n");
1756 if(i == first) { // copy all people chased by first move of repeat cycle to preyStack
1757 for(j=0; j<chaseStackPointer; j++) {
1758 preyStack[j].rank = chaseStack[j].rt;
1759 preyStack[j].file = chaseStack[j].ft;
1761 preyStackPointer = chaseStackPointer;
1764 for(j=0; j<chaseStackPointer; j++) {
1765 for(k=0; k<preyStackPointer; k++) {
1766 // search the victim of each chase move on the preyStack (first occurrence)
1767 if(chaseStack[j].ft == preyStack[k].file && chaseStack[j].rt == preyStack[k].rank ) {
1768 if(k < tail) break; // piece was already identified as still being chased
1769 preyStack[preyStackPointer] = preyStack[tail]; // move chased piece to bottom part of preyStack
1770 preyStack[tail] = preyStack[k]; // by swapping
1771 preyStack[k] = preyStack[preyStackPointer];
1777 preyStackPointer = tail; // keep bottom part of preyStack, popping pieces unchased on move i.
1778 if(appData.debugMode) { int n;
1779 for(n=0; n<preyStackPointer; n++)
1780 fprintf(debugFP, "%c%c ", preyStack[n].file+AAA, preyStack[n].rank+ONE);
1781 fprintf(debugFP, "always chased upto ply %d\n", i);
1783 // now adjust the location of the chased pieces according to opponent move
1784 for(j=0; j<preyStackPointer; j++) {
1785 if(preyStack[j].rank == moveList[i+1][1]-ONE &&
1786 preyStack[j].file == moveList[i+1][0]-AAA+BOARD_LEFT) {
1787 preyStack[j].rank = moveList[i+1][3]-ONE;
1788 preyStack[j].file = moveList[i+1][2]-AAA+BOARD_LEFT;
1793 return preyStackPointer; // if any piece was left on preyStack, it has been perpetually chased