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 ChessSquare PromoPiece(moveType)
106 case WhitePromotionQueen:
108 case BlackPromotionQueen:
110 case WhitePromotionRook:
112 case BlackPromotionRook:
114 case WhitePromotionBishop:
116 case BlackPromotionBishop:
118 case WhitePromotionKnight:
120 case BlackPromotionKnight:
122 case WhitePromotionKing:
124 case BlackPromotionKing:
126 case WhitePromotionChancellor:
127 return WhiteMarshall;
128 case BlackPromotionChancellor:
129 return BlackMarshall;
130 case WhitePromotionArchbishop:
132 case BlackPromotionArchbishop:
134 case WhitePromotionCentaur:
136 case BlackPromotionCentaur:
141 char pieceToChar[] = {
142 'P', 'N', 'B', 'R', 'Q', 'F', 'E', 'A', 'C', 'W', 'M',
143 'O', 'H', 'I', 'J', 'G', 'D', 'V', 'L', 'S', 'U', 'K',
144 'p', 'n', 'b', 'r', 'q', 'f', 'e', 'a', 'c', 'w', 'm',
145 'o', 'h', 'i', 'j', 'g', 'd', 'v', 'l', 's', 'u', 'k',
147 char pieceNickName[EmptySquare];
152 if((int)p < 0 || (int)p >= (int)EmptySquare) return('x'); /* [HGM] for safety */
153 return pieceToChar[(int) p];
156 int PieceToNumber(p) /* [HGM] holdings: count piece type, ignoring non-participating piece types */
160 ChessSquare start = (int)p >= (int)BlackPawn ? BlackPawn : WhitePawn;
162 while(start++ != p) if(pieceToChar[(int)start-1] != '.') i++;
166 ChessSquare CharToPiece(c)
170 for(i=0; i< (int) EmptySquare; i++)
171 if(pieceNickName[i] == c) return (ChessSquare) i;
172 for(i=0; i< (int) EmptySquare; i++)
173 if(pieceToChar[i] == c) return (ChessSquare) i;
177 ChessMove PromoCharToMoveType(whiteOnMove, promoChar)
180 { /* [HGM] made dependent on CharToPiece to alow alternate piece letters */
181 ChessSquare piece = CharToPiece(whiteOnMove ? ToUpper(promoChar) : ToLower(promoChar) );
183 if(promoChar == '=') return whiteOnMove ? WhiteNonPromotion : BlackNonPromotion;
184 if(promoChar == NULLCHAR) return NormalMove;
188 return WhitePromotionQueen;
190 return WhitePromotionRook;
192 return WhitePromotionBishop;
194 return WhitePromotionKnight;
196 return WhitePromotionKing;
198 return WhitePromotionArchbishop;
200 return WhitePromotionChancellor;
202 return WhitePromotionCentaur;
204 return BlackPromotionQueen;
206 return BlackPromotionRook;
208 return BlackPromotionBishop;
210 return BlackPromotionKnight;
212 return BlackPromotionKing;
214 return BlackPromotionArchbishop;
216 return BlackPromotionChancellor;
218 return BlackPromotionCentaur;
220 // not all promotion implemented yet! Take Queen for those we don't know.
221 return (whiteOnMove ? WhitePromotionQueen : BlackPromotionQueen);
225 void CopyBoard(to, from)
230 for (i = 0; i < BOARD_HEIGHT; i++)
231 for (j = 0; j < BOARD_WIDTH; j++)
232 to[i][j] = from[i][j];
233 for (j = 0; j < BOARD_FILES-1; j++) // [HGM] gamestate: copy castling rights and ep status
234 to[CASTLING][j] = from[CASTLING][j];
235 to[HOLDINGS_SET] = 0; // flag used in ICS play
238 int CompareBoards(board1, board2)
239 Board board1, board2;
243 for (i = 0; i < BOARD_HEIGHT; i++)
244 for (j = 0; j < BOARD_WIDTH; j++) {
245 if (board1[i][j] != board2[i][j])
252 /* Call callback once for each pseudo-legal move in the given
253 position, except castling moves. A move is pseudo-legal if it is
254 legal, or if it would be legal except that it leaves the king in
255 check. In the arguments, epfile is EP_NONE if the previous move
256 was not a double pawn push, or the file 0..7 if it was, or
257 EP_UNKNOWN if we don't know and want to allow all e.p. captures.
258 Promotion moves generated are to Queen only.
260 void GenPseudoLegal(board, flags, callback, closure)
263 MoveCallback callback;
267 int i, j, d, s, fs, rs, rt, ft, m;
268 int epfile = (signed char)board[EP_STATUS]; // [HGM] gamestate: extract ep status from board
269 int promoRank = gameInfo.variant == VariantMakruk ? 3 : 1;
271 for (rf = 0; rf < BOARD_HEIGHT; rf++)
272 for (ff = BOARD_LEFT; ff < BOARD_RGHT; ff++) {
275 if (flags & F_WHITE_ON_MOVE) {
276 if (!WhitePiece(board[rf][ff])) continue;
278 if (!BlackPiece(board[rf][ff])) continue;
280 m = 0; piece = board[rf][ff];
281 if(PieceToChar(piece) == '~')
282 piece = (ChessSquare) ( DEMOTED piece );
283 if(gameInfo.variant == VariantShogi)
284 piece = (ChessSquare) ( SHOGI piece );
287 /* case EmptySquare: [HGM] this is nonsense, and conflicts with Shogi cases */
289 /* can't happen ([HGM] except for faries...) */
293 if(gameInfo.variant == VariantXiangqi) {
294 /* [HGM] capture and move straight ahead in Xiangqi */
295 if (rf < BOARD_HEIGHT-1 &&
296 !SameColor(board[rf][ff], board[rf + 1][ff]) ) {
297 callback(board, flags, NormalMove,
298 rf, ff, rf + 1, ff, closure);
300 /* and move sideways when across the river */
301 for (s = -1; s <= 1; s += 2) {
302 if (rf >= BOARD_HEIGHT>>1 &&
303 ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
304 !WhitePiece(board[rf][ff+s]) ) {
305 callback(board, flags, NormalMove,
306 rf, ff, rf, ff+s, closure);
311 if (rf < BOARD_HEIGHT-1 && board[rf + 1][ff] == EmptySquare) {
312 callback(board, flags,
313 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotionQueen : NormalMove,
314 rf, ff, rf + 1, ff, closure);
316 if (rf == 1 && board[2][ff] == EmptySquare &&
317 gameInfo.variant != VariantShatranj && /* [HGM] */
318 gameInfo.variant != VariantCourier && /* [HGM] */
319 board[3][ff] == EmptySquare ) {
320 callback(board, flags, NormalMove,
321 rf, ff, 3, ff, closure);
323 for (s = -1; s <= 1; s += 2) {
324 if (rf < BOARD_HEIGHT-1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
325 ((flags & F_KRIEGSPIEL_CAPTURE) ||
326 BlackPiece(board[rf + 1][ff + s]))) {
327 callback(board, flags,
328 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotionQueen : NormalMove,
329 rf, ff, rf + 1, ff + s, closure);
331 if (rf == BOARD_HEIGHT-4) {
332 if (ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
333 (epfile == ff + s || epfile == EP_UNKNOWN) &&
334 board[BOARD_HEIGHT-4][ff + s] == BlackPawn &&
335 board[BOARD_HEIGHT-3][ff + s] == EmptySquare) {
336 callback(board, flags, WhiteCapturesEnPassant,
337 rf, ff, 5, ff + s, closure);
344 if(gameInfo.variant == VariantXiangqi) {
345 /* [HGM] capture straight ahead in Xiangqi */
346 if (rf > 0 && !SameColor(board[rf][ff], board[rf - 1][ff]) ) {
347 callback(board, flags, NormalMove,
348 rf, ff, rf - 1, ff, closure);
350 /* and move sideways when across the river */
351 for (s = -1; s <= 1; s += 2) {
352 if (rf < BOARD_HEIGHT>>1 &&
353 ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
354 !BlackPiece(board[rf][ff+s]) ) {
355 callback(board, flags, NormalMove,
356 rf, ff, rf, ff+s, closure);
361 if (rf > 0 && board[rf - 1][ff] == EmptySquare) {
362 callback(board, flags,
363 rf <= promoRank ? BlackPromotionQueen : NormalMove,
364 rf, ff, rf - 1, ff, closure);
366 if (rf == BOARD_HEIGHT-2 && board[BOARD_HEIGHT-3][ff] == EmptySquare &&
367 gameInfo.variant != VariantShatranj && /* [HGM] */
368 gameInfo.variant != VariantCourier && /* [HGM] */
369 board[BOARD_HEIGHT-4][ff] == EmptySquare) {
370 callback(board, flags, NormalMove,
371 rf, ff, BOARD_HEIGHT-4, ff, closure);
373 for (s = -1; s <= 1; s += 2) {
374 if (rf > 0 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
375 ((flags & F_KRIEGSPIEL_CAPTURE) ||
376 WhitePiece(board[rf - 1][ff + s]))) {
377 callback(board, flags,
378 rf <= promoRank ? BlackPromotionQueen : NormalMove,
379 rf, ff, rf - 1, ff + s, closure);
382 if (ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
383 (epfile == ff + s || epfile == EP_UNKNOWN) &&
384 board[3][ff + s] == WhitePawn &&
385 board[2][ff + s] == EmptySquare) {
386 callback(board, flags, BlackCapturesEnPassant,
387 rf, ff, 2, ff + s, closure);
398 for (i = -1; i <= 1; i += 2)
399 for (j = -1; j <= 1; j += 2)
400 for (s = 1; s <= 2; s++) {
403 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
404 && ( gameInfo.variant != VariantXiangqi || board[rf+i*(s-1)][ff+j*(2-s)] == EmptySquare)
405 && !SameColor(board[rf][ff], board[rt][ft]))
406 callback(board, flags, NormalMove,
407 rf, ff, rt, ft, closure);
411 case SHOGI WhiteKnight:
412 for (s = -1; s <= 1; s += 2) {
413 if (rf < BOARD_HEIGHT-2 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
414 !SameColor(board[rf][ff], board[rf + 2][ff + s])) {
415 callback(board, flags, NormalMove,
416 rf, ff, rf + 2, ff + s, closure);
421 case SHOGI BlackKnight:
422 for (s = -1; s <= 1; s += 2) {
423 if (rf > 1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
424 !SameColor(board[rf][ff], board[rf - 2][ff + s])) {
425 callback(board, flags, NormalMove,
426 rf, ff, rf - 2, ff + s, closure);
433 for (d = 0; d <= 1; d++)
434 for (s = -1; s <= 1; s += 2) {
437 rt = rf + (i * s) * d;
438 ft = ff + (i * s) * (1 - d);
439 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
440 if (m == 0 && board[rt][ft] == EmptySquare)
441 callback(board, flags, NormalMove,
442 rf, ff, rt, ft, closure);
443 if (m == 1 && board[rt][ft] != EmptySquare &&
444 !SameColor(board[rf][ff], board[rt][ft]) )
445 callback(board, flags, NormalMove,
446 rf, ff, rt, ft, closure);
447 if (board[rt][ft] != EmptySquare && m++) break;
452 /* Gold General (and all its promoted versions) . First do the */
453 /* diagonal forward steps, then proceed as normal Wazir */
454 case SHOGI WhiteWazir:
455 case SHOGI (PROMOTED WhitePawn):
456 case SHOGI (PROMOTED WhiteKnight):
457 case SHOGI (PROMOTED WhiteQueen):
458 case SHOGI (PROMOTED WhiteFerz):
459 for (s = -1; s <= 1; s += 2) {
460 if (rf < BOARD_HEIGHT-1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
461 !SameColor(board[rf][ff], board[rf + 1][ff + s])) {
462 callback(board, flags, NormalMove,
463 rf, ff, rf + 1, ff + s, closure);
468 case SHOGI BlackWazir:
469 case SHOGI (PROMOTED BlackPawn):
470 case SHOGI (PROMOTED BlackKnight):
471 case SHOGI (PROMOTED BlackQueen):
472 case SHOGI (PROMOTED BlackFerz):
473 for (s = -1; s <= 1; s += 2) {
474 if (rf > 0 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
475 !SameColor(board[rf][ff], board[rf - 1][ff + s])) {
476 callback(board, flags, NormalMove,
477 rf, ff, rf - 1, ff + s, closure);
484 for (d = 0; d <= 1; d++)
485 for (s = -1; s <= 1; s += 2) {
487 ft = ff + s * (1 - d);
488 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
489 && !SameColor(board[rf][ff], board[rt][ft]) &&
490 (gameInfo.variant != VariantXiangqi || InPalace(rt, ft) ) )
491 callback(board, flags, NormalMove,
492 rf, ff, rt, ft, closure);
498 /* [HGM] support Shatranj pieces */
499 for (rs = -1; rs <= 1; rs += 2)
500 for (fs = -1; fs <= 1; fs += 2) {
503 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
504 && ( gameInfo.variant != VariantXiangqi ||
505 board[rf+rs][ff+fs] == EmptySquare && (2*rf < BOARD_HEIGHT) == (2*rt < BOARD_HEIGHT) )
507 && !SameColor(board[rf][ff], board[rt][ft]))
508 callback(board, flags, NormalMove,
509 rf, ff, rt, ft, closure);
513 /* Shogi Dragon Horse has to continue with Wazir after Bishop */
514 case SHOGI WhiteCardinal:
515 case SHOGI BlackCardinal:
518 /* Capablanca Archbishop continues as Knight */
523 /* Shogi Bishops are ordinary Bishops */
524 case SHOGI WhiteBishop:
525 case SHOGI BlackBishop:
528 for (rs = -1; rs <= 1; rs += 2)
529 for (fs = -1; fs <= 1; fs += 2)
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 finishGold;
541 /* Bishop falls through */
544 /* Shogi Lance is unlike anything, and asymmetric at that */
545 case SHOGI WhiteQueen:
549 if (rt >= BOARD_HEIGHT) break;
550 if (SameColor(board[rf][ff], board[rt][ft])) break;
551 callback(board, flags, NormalMove,
552 rf, ff, rt, ft, closure);
553 if (board[rt][ft] != EmptySquare) break;
557 case SHOGI BlackQueen:
562 if (SameColor(board[rf][ff], board[rt][ft])) break;
563 callback(board, flags, NormalMove,
564 rf, ff, rt, ft, closure);
565 if (board[rt][ft] != EmptySquare) break;
569 /* Shogi Dragon King has to continue as Ferz after Rook moves */
570 case SHOGI WhiteDragon:
571 case SHOGI BlackDragon:
574 /* Capablanca Chancellor sets flag to continue as Knight */
579 /* Shogi Rooks are ordinary Rooks */
580 case SHOGI WhiteRook:
581 case SHOGI BlackRook:
584 for (d = 0; d <= 1; d++)
585 for (s = -1; s <= 1; s += 2)
587 rt = rf + (i * s) * d;
588 ft = ff + (i * s) * (1 - d);
589 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
590 if (SameColor(board[rf][ff], board[rt][ft])) break;
591 callback(board, flags, NormalMove,
592 rf, ff, rt, ft, closure);
593 if (board[rt][ft] != EmptySquare) break;
595 if(m==1) goto mounted;
596 if(m==2) goto finishSilver;
601 for (rs = -1; rs <= 1; rs++)
602 for (fs = -1; fs <= 1; fs++) {
603 if (rs == 0 && fs == 0) continue;
607 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
608 if (SameColor(board[rf][ff], board[rt][ft])) break;
609 callback(board, flags, NormalMove,
610 rf, ff, rt, ft, closure);
611 if (board[rt][ft] != EmptySquare) break;
616 /* Shogi Pawn and Silver General: first the Pawn move, */
617 /* then the General continues like a Ferz */
619 if(gameInfo.variant != VariantMakruk) goto commoner;
620 case SHOGI WhitePawn:
621 case SHOGI WhiteFerz:
622 if (rf < BOARD_HEIGHT-1 &&
623 !SameColor(board[rf][ff], board[rf + 1][ff]) )
624 callback(board, flags, NormalMove,
625 rf, ff, rf + 1, ff, closure);
626 if(piece != SHOGI WhitePawn) goto finishSilver;
630 if(gameInfo.variant != VariantMakruk) goto commoner;
631 case SHOGI BlackPawn:
632 case SHOGI BlackFerz:
634 !SameColor(board[rf][ff], board[rf - 1][ff]) )
635 callback(board, flags, NormalMove,
636 rf, ff, rf - 1, ff, closure);
637 if(piece == SHOGI BlackPawn) break;
642 /* [HGM] support Shatranj pieces */
643 for (rs = -1; rs <= 1; rs += 2)
644 for (fs = -1; fs <= 1; fs += 2) {
647 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
648 if (!SameColor(board[rf][ff], board[rt][ft]) &&
649 (gameInfo.variant != VariantXiangqi || InPalace(rt, ft) ) )
650 callback(board, flags, NormalMove,
651 rf, ff, rt, ft, closure);
657 m++; // [HGM] superchess: use for Centaur
659 case SHOGI WhiteKing:
660 case SHOGI BlackKing:
664 for (i = -1; i <= 1; i++)
665 for (j = -1; j <= 1; j++) {
666 if (i == 0 && j == 0) continue;
669 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
670 if (SameColor(board[rf][ff], board[rt][ft])) continue;
671 callback(board, flags, NormalMove,
672 rf, ff, rt, ft, closure);
674 if(m==1) goto mounted;
677 case WhiteNightrider:
678 case BlackNightrider:
679 for (i = -1; i <= 1; i += 2)
680 for (j = -1; j <= 1; j += 2)
681 for (s = 1; s <= 2; s++) { int k;
685 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
686 if (SameColor(board[rf][ff], board[rt][ft])) break;
687 callback(board, flags, NormalMove,
688 rf, ff, rt, ft, closure);
689 if (board[rt][ft] != EmptySquare) break;
693 case WhiteFalcon: // [HGM] wild: for wildcards, self-capture symbolizes move to anywhere
699 callback(board, flags, NormalMove, rf, ff, rf, ff, closure);
712 extern void GenLegalCallback P((Board board, int flags, ChessMove kind,
713 int rf, int ff, int rt, int ft,
716 void GenLegalCallback(board, flags, kind, rf, ff, rt, ft, closure)
723 register GenLegalClosure *cl = (GenLegalClosure *) closure;
725 if (!(flags & F_IGNORE_CHECK) &&
726 CheckTest(board, flags, rf, ff, rt, ft,
727 kind == WhiteCapturesEnPassant ||
728 kind == BlackCapturesEnPassant)) return;
729 if (flags & F_ATOMIC_CAPTURE) {
730 if (board[rt][ft] != EmptySquare ||
731 kind == WhiteCapturesEnPassant || kind == BlackCapturesEnPassant) {
733 ChessSquare king = (flags & F_WHITE_ON_MOVE) ? WhiteKing : BlackKing;
734 if (board[rf][ff] == king) return;
735 for (r = rt-1; r <= rt+1; r++) {
736 for (f = ft-1; f <= ft+1; f++) {
737 if (r >= 0 && r < BOARD_HEIGHT && f >= BOARD_LEFT && f < BOARD_RGHT &&
738 board[r][f] == king) return;
743 cl->cb(board, flags, kind, rf, ff, rt, ft, cl->cl);
750 int captures; // [HGM] losers
751 } LegalityTestClosure;
754 /* Like GenPseudoLegal, but (1) include castling moves, (2) unless
755 F_IGNORE_CHECK is set in the flags, omit moves that would leave the
756 king in check, and (3) if F_ATOMIC_CAPTURE is set in the flags, omit
757 moves that would destroy your own king. The CASTLE_OK flags are
758 true if castling is not yet ruled out by a move of the king or
759 rook. Return TRUE if the player on move is currently in check and
760 F_IGNORE_CHECK is not set. [HGM] add castlingRights parameter */
761 int GenLegal(board, flags, callback, closure)
764 MoveCallback callback;
768 int ff, ft, k, left, right;
769 int ignoreCheck = (flags & F_IGNORE_CHECK) != 0;
770 ChessSquare wKing = WhiteKing, bKing = BlackKing, *castlingRights = board[CASTLING];
774 GenPseudoLegal(board, flags, GenLegalCallback, (VOIDSTAR) &cl);
777 CheckTest(board, flags, -1, -1, -1, -1, FALSE)) return TRUE;
779 /* Generate castling moves */
780 if(gameInfo.variant == VariantKnightmate) { /* [HGM] Knightmate */
781 wKing = WhiteUnicorn; bKing = BlackUnicorn;
784 for (ff = BOARD_WIDTH>>1; ff >= (BOARD_WIDTH-1)>>1; ff-- /*ics wild 1*/) {
785 if ((flags & F_WHITE_ON_MOVE) &&
786 (flags & F_WHITE_KCASTLE_OK) &&
787 board[0][ff] == wKing &&
788 board[0][ff + 1] == EmptySquare &&
789 board[0][ff + 2] == EmptySquare &&
790 board[0][BOARD_RGHT-3] == EmptySquare &&
791 board[0][BOARD_RGHT-2] == EmptySquare &&
792 board[0][BOARD_RGHT-1] == WhiteRook &&
793 castlingRights[0] != NoRights && /* [HGM] check rights */
794 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
796 (!CheckTest(board, flags, 0, ff, 0, ff + 1, FALSE) &&
797 !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-3, FALSE) &&
798 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-2, FALSE)) &&
799 !CheckTest(board, flags, 0, ff, 0, ff + 2, FALSE)))) {
801 callback(board, flags,
802 ff==BOARD_WIDTH>>1 ? WhiteKingSideCastle : WhiteKingSideCastleWild,
803 0, ff, 0, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
805 if ((flags & F_WHITE_ON_MOVE) &&
806 (flags & F_WHITE_QCASTLE_OK) &&
807 board[0][ff] == wKing &&
808 board[0][ff - 1] == EmptySquare &&
809 board[0][ff - 2] == EmptySquare &&
810 board[0][BOARD_LEFT+2] == EmptySquare &&
811 board[0][BOARD_LEFT+1] == EmptySquare &&
812 board[0][BOARD_LEFT+0] == WhiteRook &&
813 castlingRights[1] != NoRights && /* [HGM] check rights */
814 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
816 (!CheckTest(board, flags, 0, ff, 0, ff - 1, FALSE) &&
817 !CheckTest(board, flags, 0, ff, 0, BOARD_LEFT+3, FALSE) &&
818 !CheckTest(board, flags, 0, ff, 0, ff - 2, FALSE)))) {
820 callback(board, flags,
821 ff==BOARD_WIDTH>>1 ? WhiteQueenSideCastle : WhiteQueenSideCastleWild,
822 0, ff, 0, ff - ((gameInfo.boardWidth+2)>>2), closure);
824 if (!(flags & F_WHITE_ON_MOVE) &&
825 (flags & F_BLACK_KCASTLE_OK) &&
826 board[BOARD_HEIGHT-1][ff] == bKing &&
827 board[BOARD_HEIGHT-1][ff + 1] == EmptySquare &&
828 board[BOARD_HEIGHT-1][ff + 2] == EmptySquare &&
829 board[BOARD_HEIGHT-1][BOARD_RGHT-3] == EmptySquare &&
830 board[BOARD_HEIGHT-1][BOARD_RGHT-2] == EmptySquare &&
831 board[BOARD_HEIGHT-1][BOARD_RGHT-1] == BlackRook &&
832 castlingRights[3] != NoRights && /* [HGM] check rights */
833 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
835 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 1, FALSE) &&
836 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-3, FALSE) &&
837 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-2, FALSE)) &&
838 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 2, FALSE)))) {
840 callback(board, flags,
841 ff==BOARD_WIDTH>>1 ? BlackKingSideCastle : BlackKingSideCastleWild,
842 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
844 if (!(flags & F_WHITE_ON_MOVE) &&
845 (flags & F_BLACK_QCASTLE_OK) &&
846 board[BOARD_HEIGHT-1][ff] == bKing &&
847 board[BOARD_HEIGHT-1][ff - 1] == EmptySquare &&
848 board[BOARD_HEIGHT-1][ff - 2] == EmptySquare &&
849 board[BOARD_HEIGHT-1][BOARD_LEFT+2] == EmptySquare &&
850 board[BOARD_HEIGHT-1][BOARD_LEFT+1] == EmptySquare &&
851 board[BOARD_HEIGHT-1][BOARD_LEFT+0] == BlackRook &&
852 castlingRights[4] != NoRights && /* [HGM] check rights */
853 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
855 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 1, FALSE) &&
856 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_LEFT+3, FALSE) &&
857 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 2, FALSE)))) {
859 callback(board, flags,
860 ff==BOARD_WIDTH>>1 ? BlackQueenSideCastle : BlackQueenSideCastleWild,
861 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - ((gameInfo.boardWidth+2)>>2), closure);
865 if(flags & F_FRC_TYPE_CASTLING) {
867 /* generate all potential FRC castling moves (KxR), ignoring flags */
868 /* [HGM] test if the Rooks we find have castling rights */
871 if ((flags & F_WHITE_ON_MOVE) != 0) {
872 ff = castlingRights[2]; /* King file if we have any rights */
873 if(ff != NoRights && board[0][ff] == WhiteKing) {
874 if (appData.debugMode) {
875 fprintf(debugFP, "FRC castling, %d %d %d %d %d %d\n",
876 castlingRights[0],castlingRights[1],ff,castlingRights[3],castlingRights[4],castlingRights[5]);
878 ft = castlingRights[0]; /* Rook file if we have H-side rights */
880 right = BOARD_RGHT-2;
881 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
882 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
883 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
884 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
885 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
886 if(ft != NoRights && board[0][ft] == WhiteRook)
887 callback(board, flags, WhiteHSideCastleFR, 0, ff, 0, ft, closure);
889 ft = castlingRights[1]; /* Rook file if we have A-side rights */
892 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
893 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
894 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
895 if(ff > BOARD_LEFT+2)
896 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
897 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
898 if(ft != NoRights && board[0][ft] == WhiteRook)
899 callback(board, flags, WhiteASideCastleFR, 0, ff, 0, ft, closure);
902 ff = castlingRights[5]; /* King file if we have any rights */
903 if(ff != NoRights && board[BOARD_HEIGHT-1][ff] == BlackKing) {
904 ft = castlingRights[3]; /* Rook file if we have H-side rights */
906 right = BOARD_RGHT-2;
907 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
908 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
909 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
910 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
911 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
912 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
913 callback(board, flags, BlackHSideCastleFR, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ft, closure);
915 ft = castlingRights[4]; /* Rook file if we have A-side rights */
918 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
919 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
920 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
921 if(ff > BOARD_LEFT+2)
922 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
923 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
924 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
925 callback(board, flags, BlackASideCastleFR, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ft, closure);
941 extern void CheckTestCallback P((Board board, int flags, ChessMove kind,
942 int rf, int ff, int rt, int ft,
946 void CheckTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
953 register CheckTestClosure *cl = (CheckTestClosure *) closure;
955 if (rt == cl->rking && ft == cl->fking) cl->check++;
959 /* If the player on move were to move from (rf, ff) to (rt, ft), would
960 he leave himself in check? Or if rf == -1, is the player on move
961 in check now? enPassant must be TRUE if the indicated move is an
962 e.p. capture. The possibility of castling out of a check along the
963 back rank is not accounted for (i.e., we still return nonzero), as
964 this is illegal anyway. Return value is the number of times the
966 int CheckTest(board, flags, rf, ff, rt, ft, enPassant)
969 int rf, ff, rt, ft, enPassant;
972 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
973 ChessSquare captured = EmptySquare;
974 /* Suppress warnings on uninitialized variables */
976 if(gameInfo.variant == VariantXiangqi)
977 king = flags & F_WHITE_ON_MOVE ? WhiteWazir : BlackWazir;
978 if(gameInfo.variant == VariantKnightmate)
979 king = flags & F_WHITE_ON_MOVE ? WhiteUnicorn : BlackUnicorn;
983 captured = board[rf][ft];
984 board[rf][ft] = EmptySquare;
986 captured = board[rt][ft];
988 board[rt][ft] = board[rf][ff];
989 board[rf][ff] = EmptySquare;
990 } else board[rt][ft] = ff; // [HGM] drop
992 /* For compatibility with ICS wild 9, we scan the board in the
993 order a1, a2, a3, ... b1, b2, ..., h8 to find the first king,
994 and we test only whether that one is in check. */
996 for (cl.fking = BOARD_LEFT+0; cl.fking < BOARD_RGHT; cl.fking++)
997 for (cl.rking = 0; cl.rking < BOARD_HEIGHT; cl.rking++) {
998 if (board[cl.rking][cl.fking] == king) {
999 if(gameInfo.variant == VariantXiangqi) {
1000 /* [HGM] In Xiangqi opposing Kings means check as well */
1002 dir = (king >= BlackPawn) ? -1 : 1;
1003 for( i=cl.rking+dir; i>=0 && i<BOARD_HEIGHT &&
1004 board[i][cl.fking] == EmptySquare; i+=dir );
1005 if(i>=0 && i<BOARD_HEIGHT &&
1006 board[i][cl.fking] == (dir>0 ? BlackWazir : WhiteWazir) )
1010 GenPseudoLegal(board, flags ^ F_WHITE_ON_MOVE, CheckTestCallback, (VOIDSTAR) &cl);
1011 goto undo_move; /* 2-level break */
1018 board[rf][ff] = board[rt][ft];
1020 board[rf][ft] = captured;
1021 board[rt][ft] = EmptySquare;
1023 board[rt][ft] = captured;
1025 } else board[rt][ft] = EmptySquare; // [HGM] drop
1027 return cl.fking < BOARD_RGHT ? cl.check : 1000; // [HGM] atomic: return 1000 if we have no king
1030 ChessMove LegalDrop(board, flags, piece, rt, ft)
1035 { // [HGM] put drop legality testing in separate routine for clarity
1037 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
1038 if(board[rt][ft] != EmptySquare) return ImpossibleMove; // must drop to empty square
1039 n = PieceToNumber(piece);
1040 if(gameInfo.holdingsWidth == 0 || (flags & F_WHITE_ON_MOVE ? board[n][BOARD_WIDTH-1] : board[BOARD_HEIGHT-1-n][0]) != piece)
1041 return ImpossibleMove; // piece not available
1042 if(gameInfo.variant == VariantShogi) { // in Shogi lots of drops are forbidden!
1043 if((piece == WhitePawn || piece == WhiteQueen) && rt == BOARD_HEIGHT-1 ||
1044 (piece == BlackPawn || piece == BlackQueen) && rt == 0 ||
1045 piece == WhiteKnight && rt > BOARD_HEIGHT-3 ||
1046 piece == BlackKnight && rt < 2 ) return IllegalMove; // e.g. where dropped piece has no moves
1047 if(piece == WhitePawn || piece == BlackPawn) {
1049 for(r=1; r<BOARD_HEIGHT-1; r++)
1050 if(board[r][ft] == piece) return IllegalMove; // or there already is a Pawn in file
1051 // should still test if we mate with this Pawn
1054 if( (piece == WhitePawn || piece == BlackPawn) &&
1055 (rt == 0 || rt == BOARD_HEIGHT -1 ) )
1056 return IllegalMove; /* no pawn drops on 1st/8th */
1058 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
1059 if (!(flags & F_IGNORE_CHECK) &&
1060 CheckTest(board, flags, DROP_RANK, piece, rt, ft, FALSE) ) return IllegalMove;
1061 return flags & F_WHITE_ON_MOVE ? WhiteDrop : BlackDrop;
1064 extern void LegalityTestCallback P((Board board, int flags, ChessMove kind,
1065 int rf, int ff, int rt, int ft,
1068 void LegalityTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
1075 register LegalityTestClosure *cl = (LegalityTestClosure *) closure;
1077 // if (appData.debugMode) {
1078 // fprintf(debugFP, "Legality test: %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
1080 if(board[rt][ft] != EmptySquare || kind==WhiteCapturesEnPassant || kind==BlackCapturesEnPassant)
1081 cl->captures++; // [HGM] losers: count legal captures
1082 if (rf == cl->rf && ff == cl->ff && rt == cl->rt && ft == cl->ft)
1086 ChessMove LegalityTest(board, flags, rf, ff, rt, ft, promoChar)
1089 int rf, ff, rt, ft, promoChar;
1091 LegalityTestClosure cl; ChessSquare piece, *castlingRights = board[CASTLING];
1093 if(rf == DROP_RANK) return LegalDrop(board, flags, ff, rt, ft);
1094 piece = board[rf][ff];
1096 if (appData.debugMode) {
1098 for(i=0; i<6; i++) fprintf(debugFP, "%d ", castlingRights[i]);
1099 fprintf(debugFP, "Legality test? %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
1101 /* [HGM] Lance, Cobra and Falcon are wildcard pieces; consider all their moves legal */
1102 /* (perhaps we should disallow moves that obviously leave us in check?) */
1103 if(piece == WhiteFalcon || piece == BlackFalcon ||
1104 piece == WhiteCobra || piece == BlackCobra ||
1105 piece == WhiteLance || piece == BlackLance)
1106 return CheckTest(board, flags, rf, ff, rt, ft, FALSE) ? IllegalMove : NormalMove;
1112 cl.kind = IllegalMove;
1113 cl.captures = 0; // [HGM] losers: prepare to count legal captures.
1114 GenLegal(board, flags, LegalityTestCallback, (VOIDSTAR) &cl);
1115 if((flags & F_MANDATORY_CAPTURE) && cl.captures && board[rt][ft] == EmptySquare
1116 && cl.kind != WhiteCapturesEnPassant && cl.kind != BlackCapturesEnPassant)
1117 return(IllegalMove); // [HGM] losers: if there are legal captures, non-capts are illegal
1119 if(gameInfo.variant == VariantShogi) {
1120 /* [HGM] Shogi promotions. '=' means defer */
1121 if(rf != DROP_RANK && cl.kind == NormalMove) {
1122 ChessSquare piece = board[rf][ff];
1124 if(promoChar == PieceToChar(BlackQueen)) promoChar = NULLCHAR; /* [HGM] Kludge */
1125 if(promoChar != NULLCHAR && promoChar != 'x' &&
1126 promoChar != '+' && promoChar != '=' &&
1127 ToUpper(PieceToChar(PROMOTED piece)) != ToUpper(promoChar) )
1128 cl.kind = IllegalMove;
1129 else if(flags & F_WHITE_ON_MOVE) {
1130 if( (int) piece < (int) WhiteWazir &&
1131 (rf > BOARD_HEIGHT-4 || rt > BOARD_HEIGHT-4) ) {
1132 if( (piece == WhitePawn || piece == WhiteQueen) && rt > BOARD_HEIGHT-2 ||
1133 piece == WhiteKnight && rt > BOARD_HEIGHT-3) /* promotion mandatory */
1134 cl.kind = promoChar == '=' ? IllegalMove : WhitePromotionKnight;
1135 else /* promotion optional, default is promote */
1136 cl.kind = promoChar == '=' ? WhiteNonPromotion : WhitePromotionQueen;
1138 } else cl.kind = (promoChar == NULLCHAR || promoChar == 'x' || promoChar == '=') ?
1139 NormalMove : IllegalMove;
1141 if( (int) piece < (int) BlackWazir && (rf < 3 || rt < 3) ) {
1142 if( (piece == BlackPawn || piece == BlackQueen) && rt < 1 ||
1143 piece == BlackKnight && rt < 2 ) /* promotion obligatory */
1144 cl.kind = promoChar == '=' ? IllegalMove : BlackPromotionKnight;
1145 else /* promotion optional, default is promote */
1146 cl.kind = promoChar == '=' ? BlackNonPromotion : BlackPromotionQueen;
1148 } else cl.kind = (promoChar == NULLCHAR || promoChar == 'x' || promoChar == '=') ?
1149 NormalMove : IllegalMove;
1153 if (promoChar != NULLCHAR && promoChar != 'x') {
1154 if(promoChar == '=') cl.kind = IllegalMove; else // [HGM] shogi: no deferred promotion outside Shogi
1155 if (cl.kind == WhitePromotionQueen || cl.kind == BlackPromotionQueen) {
1157 PromoCharToMoveType((flags & F_WHITE_ON_MOVE) != 0, promoChar);
1159 cl.kind = IllegalMove;
1162 /* [HGM] For promotions, 'ToQueen' = optional, 'ToKnight' = mandatory */
1170 extern void MateTestCallback P((Board board, int flags, ChessMove kind,
1171 int rf, int ff, int rt, int ft,
1174 void MateTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
1181 register MateTestClosure *cl = (MateTestClosure *) closure;
1186 /* Return MT_NONE, MT_CHECK, MT_CHECKMATE, or MT_STALEMATE */
1187 int MateTest(board, flags)
1192 int inCheck, r, f, myPieces=0, hisPieces=0, nrKing=0;
1193 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
1195 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) {
1196 // [HGM] losers: Count pieces and kings, to detect other unorthodox winning conditions
1197 nrKing += (board[r][f] == king); // stm has king
1198 if( board[r][f] != EmptySquare ) {
1199 if((int)board[r][f] <= (int)king && (int)board[r][f] >= (int)king - (int)WhiteKing + (int)WhitePawn)
1204 if(appData.debugMode) fprintf(debugFP, "MateTest: K=%d, my=%d, his=%d\n", nrKing, myPieces, hisPieces);
1205 switch(gameInfo.variant) { // [HGM] losers: extinction wins
1206 case VariantShatranj:
1207 if(hisPieces == 1) return myPieces > 1 ? MT_BARE : MT_DRAW;
1211 if(nrKing == 0) return MT_NOKING;
1214 if(myPieces == 1) return MT_BARE;
1217 inCheck = GenLegal(board, flags, MateTestCallback, (VOIDSTAR) &cl);
1218 // [HGM] 3check: yet to do!
1220 return inCheck ? MT_CHECK : MT_NONE;
1222 if(gameInfo.variant == VariantSuicide) // [HGM] losers: always stalemate, since no check, but result varies
1223 return myPieces == hisPieces ? MT_STALEMATE :
1224 myPieces > hisPieces ? MT_STAINMATE : MT_STEALMATE;
1225 else if(gameInfo.variant == VariantLosers) return inCheck ? MT_TRICKMATE : MT_STEALMATE;
1226 else if(gameInfo.variant == VariantGiveaway) return MT_STEALMATE; // no check exists, stalemated = win
1228 return inCheck ? MT_CHECKMATE
1229 : (gameInfo.variant == VariantXiangqi || gameInfo.variant == VariantShatranj) ?
1230 MT_STAINMATE : MT_STALEMATE;
1235 extern void DisambiguateCallback P((Board board, int flags, ChessMove kind,
1236 int rf, int ff, int rt, int ft,
1239 void DisambiguateCallback(board, flags, kind, rf, ff, rt, ft, closure)
1246 register DisambiguateClosure *cl = (DisambiguateClosure *) closure;
1247 int wildCard = FALSE; ChessSquare piece = board[rf][ff];
1249 // [HGM] wild: for wild-card pieces rt and rf are dummies
1250 if(piece == WhiteFalcon || piece == BlackFalcon ||
1251 piece == WhiteCobra || piece == BlackCobra ||
1252 piece == WhiteLance || piece == BlackLance)
1255 if ((cl->pieceIn == EmptySquare || cl->pieceIn == board[rf][ff]
1256 || PieceToChar(board[rf][ff]) == '~'
1257 && cl->pieceIn == (ChessSquare)(DEMOTED board[rf][ff])
1259 (cl->rfIn == -1 || cl->rfIn == rf) &&
1260 (cl->ffIn == -1 || cl->ffIn == ff) &&
1261 (cl->rtIn == -1 || cl->rtIn == rt || wildCard) &&
1262 (cl->ftIn == -1 || cl->ftIn == ft || wildCard)) {
1265 if(cl->count == 1 || board[rt][ft] != EmptySquare) {
1266 // [HGM] oneclick: if multiple moves, be sure we remember capture
1267 cl->piece = board[rf][ff];
1270 cl->rt = wildCard ? cl->rtIn : rt;
1271 cl->ft = wildCard ? cl->ftIn : ft;
1274 cl->captures += (board[cl->rt][cl->ft] != EmptySquare); // [HGM] oneclick: count captures
1278 void Disambiguate(board, flags, closure)
1281 DisambiguateClosure *closure;
1283 int illegal = 0; char c = closure->promoCharIn;
1285 closure->count = closure->captures = 0;
1286 closure->rf = closure->ff = closure->rt = closure->ft = 0;
1287 closure->kind = ImpossibleMove;
1288 if (appData.debugMode) {
1289 fprintf(debugFP, "Disambiguate in: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1290 closure->pieceIn,closure->ffIn,closure->rfIn,closure->ftIn,closure->rtIn,
1291 closure->promoCharIn, closure->promoCharIn >= ' ' ? closure->promoCharIn : '-');
1293 GenLegal(board, flags, DisambiguateCallback, (VOIDSTAR) closure);
1294 if (closure->count == 0) {
1295 /* See if it's an illegal move due to check */
1297 GenLegal(board, flags|F_IGNORE_CHECK, DisambiguateCallback, (VOIDSTAR) closure);
1298 if (closure->count == 0) {
1299 /* No, it's not even that */
1300 if (appData.debugMode) { int i, j;
1301 for(i=BOARD_HEIGHT-1; i>=0; i--) {
1302 for(j=0; j<BOARD_WIDTH; j++)
1303 fprintf(debugFP, "%3d", (int) board[i][j]);
1304 fprintf(debugFP, "\n");
1311 if(gameInfo.variant == VariantShogi) {
1312 /* [HGM] Shogi promotions. '=' means defer */
1313 if(closure->rfIn != DROP_RANK && closure->kind == NormalMove) {
1314 ChessSquare piece = closure->piece;
1315 if(c != NULLCHAR && c != 'x' && c != '+' && c != '=' &&
1316 ToUpper(PieceToChar(PROMOTED piece)) != ToUpper(c) )
1317 closure->kind = IllegalMove;
1318 else if(flags & F_WHITE_ON_MOVE) {
1319 if( (int) piece < (int) WhiteWazir &&
1320 (closure->rf > BOARD_HEIGHT-4 || closure->rt > BOARD_HEIGHT-4) ) {
1321 if( (piece == WhitePawn || piece == WhiteQueen) && closure->rt > BOARD_HEIGHT-2 ||
1322 piece == WhiteKnight && closure->rt > BOARD_HEIGHT-3) /* promotion mandatory */
1323 closure->kind = c == '=' ? IllegalMove : WhitePromotionKnight;
1324 else /* promotion optional, default is promote */
1325 closure->kind = c == '=' ? NormalMove : WhitePromotionQueen;
1326 if(c != '=') closure->promoCharIn = 'q';
1327 } else closure->kind = (c == NULLCHAR || c == 'x' || c == '=') ?
1328 NormalMove : IllegalMove;
1330 if( (int) piece < (int) BlackWazir && (closure->rf < 3 || closure->rt < 3) ) {
1331 if( (piece == BlackPawn || piece == BlackQueen) && closure->rt < 1 ||
1332 piece == BlackKnight && closure->rt < 2 ) /* promotion obligatory */
1333 closure->kind = c == '=' ? IllegalMove : BlackPromotionKnight;
1334 else /* promotion optional, default is promote */
1335 closure->kind = c == '=' ? NormalMove : BlackPromotionQueen;
1336 if(c != '=') closure->promoCharIn = 'q';
1337 } else closure->kind = (c == NULLCHAR || c == 'x' || c == '=') ?
1338 NormalMove : IllegalMove;
1342 if (closure->promoCharIn != NULLCHAR && closure->promoCharIn != 'x') {
1343 if (closure->kind == WhitePromotionQueen
1344 || closure->kind == BlackPromotionQueen) {
1346 PromoCharToMoveType((flags & F_WHITE_ON_MOVE) != 0,
1347 closure->promoCharIn);
1349 closure->kind = IllegalMove;
1352 /* [HGM] returns 'q' for optional promotion, 'n' for mandatory */
1353 if(closure->promoCharIn != '=')
1354 closure->promoChar = ToLower(closure->promoCharIn);
1355 else closure->promoChar = '=';
1356 if (closure->promoChar == 'x') closure->promoChar = NULLCHAR;
1357 if (closure->count > 1) {
1358 closure->kind = AmbiguousMove;
1361 /* Note: If more than one illegal move matches, but no legal
1362 moves, we return IllegalMove, not AmbiguousMove. Caller
1363 can look at closure->count to detect this.
1365 closure->kind = IllegalMove;
1367 if(closure->kind == IllegalMove)
1368 /* [HGM] might be a variant we don't understand, pass on promotion info */
1369 closure->promoChar = ToLower(closure->promoCharIn);
1370 if (appData.debugMode) {
1371 fprintf(debugFP, "Disambiguate out: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1372 closure->piece,closure->ff,closure->rf,closure->ft,closure->rt,closure->promoChar,
1373 closure->promoChar >= ' ' ? closure->promoChar:'-');
1387 } CoordsToAlgebraicClosure;
1389 extern void CoordsToAlgebraicCallback P((Board board, int flags,
1390 ChessMove kind, int rf, int ff,
1391 int rt, int ft, VOIDSTAR closure));
1393 void CoordsToAlgebraicCallback(board, flags, kind, rf, ff, rt, ft, closure)
1400 register CoordsToAlgebraicClosure *cl =
1401 (CoordsToAlgebraicClosure *) closure;
1403 if (rt == cl->rt && ft == cl->ft &&
1404 (board[rf][ff] == cl->piece
1405 || PieceToChar(board[rf][ff]) == '~' &&
1406 (ChessSquare) (DEMOTED board[rf][ff]) == cl->piece)
1410 cl->kind = kind; /* this is the move we want */
1412 cl->file++; /* need file to rule out this move */
1416 cl->rank++; /* need rank to rule out this move */
1418 cl->either++; /* rank or file will rule out this move */
1424 /* Convert coordinates to normal algebraic notation.
1425 promoChar must be NULLCHAR or 'x' if not a promotion.
1427 ChessMove CoordsToAlgebraic(board, flags, rf, ff, rt, ft, promoChar, out)
1436 char *outp = out, c;
1437 CoordsToAlgebraicClosure cl;
1439 if (rf == DROP_RANK) {
1440 /* Bughouse piece drop */
1441 *outp++ = ToUpper(PieceToChar((ChessSquare) ff));
1446 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1448 return (flags & F_WHITE_ON_MOVE) ? WhiteDrop : BlackDrop;
1451 if (promoChar == 'x') promoChar = NULLCHAR;
1452 piece = board[rf][ff];
1453 if(PieceToChar(piece)=='~') piece = (ChessSquare)(DEMOTED piece);
1455 if (appData.debugMode)
1456 fprintf(debugFP, "CoordsToAlgebraic, piece=%d (%d,%d)-(%d,%d) %c\n", (int)piece,ff,rf,ft,rt,promoChar >= ' ' ? promoChar : '-');
1460 kind = LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1461 if (kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1462 /* Keep short notation if move is illegal only because it
1463 leaves the player in check, but still return IllegalMove */
1464 kind = LegalityTest(board, flags|F_IGNORE_CHECK, rf, ff, rt, ft, promoChar);
1465 if (kind == IllegalMove) break;
1470 if (ff == ft && board[rt][ft] == EmptySquare) { /* [HGM] Xiangqi has straight noncapts! */
1471 /* Non-capture; use style "e5" */
1474 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1476 /* Capture; use style "exd5" */
1477 if(gameInfo.variant != VariantXiangqi || board[rt][ft] != EmptySquare )
1478 *outp++ = 'x'; /* [HGM] Xiangqi has sideway noncaptures across river! */
1482 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1484 /* Use promotion suffix style "=Q" */
1486 if (appData.debugMode)
1487 fprintf(debugFP, "movetype=%d, promochar=%d=%c\n", (int)kind, promoChar, promoChar >= ' ' ? promoChar : '-');
1488 if (promoChar != NULLCHAR) {
1489 if(gameInfo.variant == VariantShogi) {
1490 /* [HGM] ... but not in Shogi! */
1491 *outp++ = promoChar == '=' ? '=' : '+';
1494 *outp++ = ToUpper(promoChar);
1503 /* Fabien moved code: FRC castling first (if KxR), wild castling second */
1504 /* Code added by Tord: FRC castling. */
1505 if((piece == WhiteKing && board[rt][ft] == WhiteRook) ||
1506 (piece == BlackKing && board[rt][ft] == BlackRook)) {
1507 if(ft > ff) strcpy(out, "O-O"); else strcpy(out, "O-O-O");
1508 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1510 /* End of code added by Tord */
1511 /* Test for castling or ICS wild castling */
1512 /* Use style "O-O" (oh-oh) for PGN compatibility */
1513 else if (rf == rt &&
1514 rf == ((piece == WhiteKing) ? 0 : BOARD_HEIGHT-1) &&
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)
1520 strcpy(out, "O-O-O");
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'; }
1584 if (gameInfo.variant == VariantShogi) {
1585 /* [HGM] in Shogi non-pawns can promote */
1586 if(flags & F_WHITE_ON_MOVE) {
1587 if( (int) cl.piece < (int) WhiteWazir &&
1588 (rf > BOARD_HEIGHT-4 || rt > BOARD_HEIGHT-4) ) {
1589 if( (piece == WhitePawn || piece == WhiteQueen) && rt > BOARD_HEIGHT-2 ||
1590 piece == WhiteKnight && rt > BOARD_HEIGHT-3) /* promotion mandatory */
1591 cl.kind = promoChar == '=' ? IllegalMove : WhitePromotionKnight;
1592 else cl.kind = WhitePromotionQueen; /* promotion optional */
1594 } else cl.kind = (promoChar == NULLCHAR || promoChar == 'x' || promoChar == '=') ?
1595 NormalMove : IllegalMove;
1597 if( (int) cl.piece < (int) BlackWazir && (rf < 3 || rt < 3) ) {
1598 if( (piece == BlackPawn || piece == BlackQueen) && rt < 1 ||
1599 piece == BlackKnight && rt < 2 ) /* promotion obligatory */
1600 cl.kind = promoChar == '=' ? IllegalMove : BlackPromotionKnight;
1601 else cl.kind = BlackPromotionQueen; /* promotion optional */
1602 } else cl.kind = (promoChar == NULLCHAR || promoChar == 'x' || promoChar == '=') ?
1603 NormalMove : IllegalMove;
1605 if(cl.kind == WhitePromotionQueen || cl.kind == BlackPromotionQueen) {
1606 /* for optional promotions append '+' or '=' */
1607 if(promoChar == '=') {
1609 cl.kind = NormalMove;
1610 } else *outp++ = '+';
1612 } else if(cl.kind == IllegalMove) {
1613 /* Illegal move specifies any given promotion */
1614 if(promoChar != NULLCHAR && promoChar != 'x') {
1616 *outp++ = ToUpper(promoChar);
1623 /* [HGM] Always long notation for fairies we don't know */
1628 case WhiteGrasshopper:
1629 case BlackGrasshopper:
1631 /* Moving a nonexistent piece */
1635 /* Not a legal move, even ignoring check.
1636 If there was a piece on the from square,
1637 use style "Ng1g3" or "Ng1xe8";
1638 if there was a pawn or nothing (!),
1639 use style "g1g3" or "g1xe8". Use "x"
1640 if a piece was on the to square, even
1641 a piece of the same color.
1644 if (piece != EmptySquare && piece != WhitePawn && piece != BlackPawn) {
1645 *outp++ = ToUpper(PieceToChar(piece));
1650 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1651 if (board[rt][ft] != EmptySquare) *outp++ = 'x';
1655 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1656 /* Use promotion suffix style "=Q" */
1657 if (promoChar != NULLCHAR && promoChar != 'x') {
1659 *outp++ = ToUpper(promoChar);
1666 // [HGM] XQ: the following code serves to detect perpetual chasing (Asian rules)
1675 // I guess the following variables logically belong in the closure too, but I was too lazy and used globals
1677 int preyStackPointer, chaseStackPointer;
1680 char rf, ff, rt, ft;
1690 // there are three new callbacks for use with GenLegal: for adding captures, deleting them, and finding a recapture
1692 extern void AtacksCallback P((Board board, int flags, ChessMove kind,
1693 int rf, int ff, int rt, int ft,
1696 void AttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1702 { // For adding captures that can lead to chase indictment to the chaseStack
1703 if(board[rt][ft] == EmptySquare) return; // non-capture
1704 if(board[rt][ft] == WhitePawn && rt < BOARD_HEIGHT/2) return; // Pawn before river can be chased
1705 if(board[rt][ft] == BlackPawn && rt >= BOARD_HEIGHT/2) return; // Pawn before river can be chased
1706 if(board[rf][ff] == WhitePawn || board[rf][ff] == BlackPawn) return; // Pawns are allowed to chase
1707 if(board[rf][ff] == WhiteWazir || board[rf][ff] == BlackWazir) return; // King is allowed to chase
1708 // move cannot be excluded from being a chase trivially (based on attacker and victim); save it on chaseStack
1709 chaseStack[chaseStackPointer].rf = rf;
1710 chaseStack[chaseStackPointer].ff = ff;
1711 chaseStack[chaseStackPointer].rt = rt;
1712 chaseStack[chaseStackPointer].ft = ft;
1713 chaseStackPointer++;
1716 extern void ExistingAtacksCallback P((Board board, int flags, ChessMove kind,
1717 int rf, int ff, int rt, int ft,
1720 void ExistingAttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1726 { // for removing pre-exsting captures from the chaseStack, to be left with newly created ones
1728 register ChaseClosure *cl = (ChaseClosure *) closure; //closure tells us the move played in the repeat loop
1730 if(board[rt][ft] == EmptySquare) return; // no capture
1731 if(rf == cl->rf && ff == cl->ff) { // attacks with same piece from new position are not considered new
1732 rf = cl->rt; ff = cl->ft; // doctor their fromSquare so they will be recognized in chaseStack
1734 // search move in chaseStack, and delete it if it occurred there (as we know now it is not a new capture)
1735 for(i=0; i<chaseStackPointer; i++) {
1736 if(chaseStack[i].rf == rf && chaseStack[i].ff == ff &&
1737 chaseStack[i].rt == rt && chaseStack[i].ft == ft ) {
1738 // move found on chaseStack, delete it by overwriting with move popped from top of chaseStack
1739 chaseStack[i] = chaseStack[--chaseStackPointer];
1745 extern void ProtectedCallback P((Board board, int flags, ChessMove kind,
1746 int rf, int ff, int rt, int ft,
1749 void ProtectedCallback(board, flags, kind, rf, ff, rt, ft, closure)
1755 { // for determining if a piece (given through the closure) is protected
1756 register ChaseClosure *cl = (ChaseClosure *) closure; // closure tells us where to recapture
1758 if(rt == cl->rt && ft == cl->ft) cl->recaptures++; // count legal recaptures to this square
1759 if(appData.debugMode && board[rt][ft] != EmptySquare)
1760 fprintf(debugFP, "try %c%c%c%c=%d\n", ff+AAA, rf+ONE,ft+AAA, rt+ONE, cl->recaptures);
1763 extern char moveList[MAX_MOVES][MOVE_LEN];
1765 int PerpetualChase(int first, int last)
1766 { // this routine detects if the side to move in the 'first' position is perpetually chasing (when not checking)
1769 ChessSquare captured;
1771 preyStackPointer = 0; // clear stack of chased pieces
1772 for(i=first; i<last; i+=2) { // for all positions with same side to move
1773 if(appData.debugMode) fprintf(debugFP, "judge position %i\n", i);
1774 chaseStackPointer = 0; // clear stack that is going to hold possible chases
1775 // determine all captures possible after the move, and put them on chaseStack
1776 GenLegal(boards[i+1], PosFlags(i), AttacksCallback, &cl);
1777 if(appData.debugMode) { int n;
1778 for(n=0; n<chaseStackPointer; n++)
1779 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1780 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1781 fprintf(debugFP, ": all capts\n");
1783 // determine all captures possible before the move, and delete them from chaseStack
1784 cl.rf = moveList[i][1]-ONE; // prepare closure to pass move that led from i to i+1
1785 cl.ff = moveList[i][0]-AAA+BOARD_LEFT;
1786 cl.rt = moveList[i][3]-ONE;
1787 cl.ft = moveList[i][2]-AAA+BOARD_LEFT;
1788 GenLegal(boards[i], PosFlags(i), ExistingAttacksCallback, &cl);
1789 if(appData.debugMode) { int n;
1790 for(n=0; n<chaseStackPointer; n++)
1791 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1792 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1793 fprintf(debugFP, ": new capts after %c%c%c%c\n", cl.ff+AAA, cl.rf+ONE, cl.ft+AAA, cl.rt+ONE);
1795 // chaseSack now contains all captures made possible by the move
1796 for(j=0; j<chaseStackPointer; j++) { // run through chaseStack to identify true chases
1797 int attacker = (int)boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1798 int victim = (int)boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1800 if(attacker >= (int) BlackPawn) attacker = BLACK_TO_WHITE attacker; // convert to white, as piecee type
1801 if(victim >= (int) BlackPawn) victim = BLACK_TO_WHITE victim;
1803 if((attacker == WhiteKnight || attacker == WhiteCannon) && victim == WhiteRook)
1804 continue; // C or H attack on R is always chase; leave on chaseStack
1806 if(attacker == victim) {
1807 if(LegalityTest(boards[i+1], PosFlags(i+1), chaseStack[j].rt,
1808 chaseStack[j].ft, chaseStack[j].rf, chaseStack[j].ff, NULLCHAR) == NormalMove) {
1809 // we can capture back with equal piece, so this is no chase but a sacrifice
1810 chaseStack[j] = chaseStack[--chaseStackPointer]; // delete the capture from the chaseStack
1811 j--; /* ! */ continue;
1816 // the attack is on a lower piece, or on a pinned or blocked equal one
1817 // test if the victim is protected by a true protector. First make the capture.
1818 captured = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1819 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1820 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = EmptySquare;
1821 // Then test if the opponent can recapture
1822 cl.recaptures = 0; // prepare closure to pass recapture square and count moves to it
1823 cl.rt = chaseStack[j].rt;
1824 cl.ft = chaseStack[j].ft;
1825 if(appData.debugMode) {
1826 fprintf(debugFP, "test if we can recapture %c%c\n", cl.ft+AAA, cl.rt+ONE);
1828 GenLegal(boards[i+1], PosFlags(i+1), ProtectedCallback, &cl); // try all moves
1829 // unmake the capture
1830 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1831 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = captured;
1832 // if a recapture was found, piece is protected, and we are not chasing it.
1833 if(cl.recaptures) { // attacked piece was defended by true protector, no chase
1834 chaseStack[j] = chaseStack[--chaseStackPointer]; // so delete from chaseStack
1838 // chaseStack now contains all moves that chased
1839 if(appData.debugMode) { int n;
1840 for(n=0; n<chaseStackPointer; n++)
1841 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1842 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1843 fprintf(debugFP, ": chases\n");
1845 if(i == first) { // copy all people chased by first move of repeat cycle to preyStack
1846 for(j=0; j<chaseStackPointer; j++) {
1847 preyStack[j].rank = chaseStack[j].rt;
1848 preyStack[j].file = chaseStack[j].ft;
1850 preyStackPointer = chaseStackPointer;
1853 for(j=0; j<chaseStackPointer; j++) {
1854 for(k=0; k<preyStackPointer; k++) {
1855 // search the victim of each chase move on the preyStack (first occurrence)
1856 if(chaseStack[j].ft == preyStack[k].file && chaseStack[j].rt == preyStack[k].rank ) {
1857 if(k < tail) break; // piece was already identified as still being chased
1858 preyStack[preyStackPointer] = preyStack[tail]; // move chased piece to bottom part of preyStack
1859 preyStack[tail] = preyStack[k]; // by swapping
1860 preyStack[k] = preyStack[preyStackPointer];
1866 preyStackPointer = tail; // keep bottom part of preyStack, popping pieces unchased on move i.
1867 if(appData.debugMode) { int n;
1868 for(n=0; n<preyStackPointer; n++)
1869 fprintf(debugFP, "%c%c ", preyStack[n].file+AAA, preyStack[n].rank+ONE);
1870 fprintf(debugFP, "always chased upto ply %d\n", i);
1872 // now adjust the location of the chased pieces according to opponent move
1873 for(j=0; j<preyStackPointer; j++) {
1874 if(preyStack[j].rank == moveList[i+1][1]-ONE &&
1875 preyStack[j].file == moveList[i+1][0]-AAA+BOARD_LEFT) {
1876 preyStack[j].rank = moveList[i+1][3]-ONE;
1877 preyStack[j].file = moveList[i+1][2]-AAA+BOARD_LEFT;
1882 return preyStackPointer; // if any piece was left on preyStack, it has been perpetually chased