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-(BOARD_HEIGHT/3) || rt >= BOARD_HEIGHT-(BOARD_HEIGHT/3)) ) {
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 < BOARD_HEIGHT/3 || rt < BOARD_HEIGHT/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.holdingsWidth && gameInfo.variant != VariantSuper || gameInfo.variant != VariantGreat) { // drop game
1223 int r, f, n, holdings = flags & F_WHITE_ON_MOVE ? BOARD_WIDTH-1 : 0;
1224 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) if(board[r][f] == EmptySquare) // all empty squares
1225 for(n=0; n<BOARD_HEIGHT; n++) // all pieces in hand
1226 if(board[n][holdings] != EmptySquare) {
1227 int moveType = LegalDrop(board, flags, board[n][holdings], r, f);
1228 if(moveType == WhiteDrop || moveType == BlackDrop) return MT_CHECK; // we can resolve check by legal drop
1231 if(gameInfo.variant == VariantSuicide) // [HGM] losers: always stalemate, since no check, but result varies
1232 return myPieces == hisPieces ? MT_STALEMATE :
1233 myPieces > hisPieces ? MT_STAINMATE : MT_STEALMATE;
1234 else if(gameInfo.variant == VariantLosers) return inCheck ? MT_TRICKMATE : MT_STEALMATE;
1235 else if(gameInfo.variant == VariantGiveaway) return MT_STEALMATE; // no check exists, stalemated = win
1237 return inCheck ? MT_CHECKMATE
1238 : (gameInfo.variant == VariantXiangqi || gameInfo.variant == VariantShatranj) ?
1239 MT_STAINMATE : MT_STALEMATE;
1244 extern void DisambiguateCallback P((Board board, int flags, ChessMove kind,
1245 int rf, int ff, int rt, int ft,
1248 void DisambiguateCallback(board, flags, kind, rf, ff, rt, ft, closure)
1255 register DisambiguateClosure *cl = (DisambiguateClosure *) closure;
1256 int wildCard = FALSE; ChessSquare piece = board[rf][ff];
1258 // [HGM] wild: for wild-card pieces rt and rf are dummies
1259 if(piece == WhiteFalcon || piece == BlackFalcon ||
1260 piece == WhiteCobra || piece == BlackCobra ||
1261 piece == WhiteLance || piece == BlackLance)
1264 if ((cl->pieceIn == EmptySquare || cl->pieceIn == board[rf][ff]
1265 || PieceToChar(board[rf][ff]) == '~'
1266 && cl->pieceIn == (ChessSquare)(DEMOTED board[rf][ff])
1268 (cl->rfIn == -1 || cl->rfIn == rf) &&
1269 (cl->ffIn == -1 || cl->ffIn == ff) &&
1270 (cl->rtIn == -1 || cl->rtIn == rt || wildCard) &&
1271 (cl->ftIn == -1 || cl->ftIn == ft || wildCard)) {
1274 if(cl->count == 1 || board[rt][ft] != EmptySquare) {
1275 // [HGM] oneclick: if multiple moves, be sure we remember capture
1276 cl->piece = board[rf][ff];
1279 cl->rt = wildCard ? cl->rtIn : rt;
1280 cl->ft = wildCard ? cl->ftIn : ft;
1283 cl->captures += (board[cl->rt][cl->ft] != EmptySquare); // [HGM] oneclick: count captures
1287 void Disambiguate(board, flags, closure)
1290 DisambiguateClosure *closure;
1292 int illegal = 0; char c = closure->promoCharIn;
1294 closure->count = closure->captures = 0;
1295 closure->rf = closure->ff = closure->rt = closure->ft = 0;
1296 closure->kind = ImpossibleMove;
1297 if (appData.debugMode) {
1298 fprintf(debugFP, "Disambiguate in: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1299 closure->pieceIn,closure->ffIn,closure->rfIn,closure->ftIn,closure->rtIn,
1300 closure->promoCharIn, closure->promoCharIn >= ' ' ? closure->promoCharIn : '-');
1302 GenLegal(board, flags, DisambiguateCallback, (VOIDSTAR) closure);
1303 if (closure->count == 0) {
1304 /* See if it's an illegal move due to check */
1306 GenLegal(board, flags|F_IGNORE_CHECK, DisambiguateCallback, (VOIDSTAR) closure);
1307 if (closure->count == 0) {
1308 /* No, it's not even that */
1309 if (appData.debugMode) { int i, j;
1310 for(i=BOARD_HEIGHT-1; i>=0; i--) {
1311 for(j=0; j<BOARD_WIDTH; j++)
1312 fprintf(debugFP, "%3d", (int) board[i][j]);
1313 fprintf(debugFP, "\n");
1320 if(gameInfo.variant == VariantShogi) {
1321 /* [HGM] Shogi promotions. '=' means defer */
1322 if(closure->rfIn != DROP_RANK && closure->kind == NormalMove) {
1323 ChessSquare piece = closure->piece;
1324 if(c != NULLCHAR && c != 'x' && c != '+' && c != '=' &&
1325 ToUpper(PieceToChar(PROMOTED piece)) != ToUpper(c) )
1326 closure->kind = IllegalMove;
1327 else if(flags & F_WHITE_ON_MOVE) {
1328 if( (int) piece < (int) WhiteWazir &&
1329 (closure->rf >= BOARD_HEIGHT-(BOARD_HEIGHT/3) || closure->rt >= BOARD_HEIGHT-(BOARD_HEIGHT/3)) ) {
1330 if( (piece == WhitePawn || piece == WhiteQueen) && closure->rt > BOARD_HEIGHT-2 ||
1331 piece == WhiteKnight && closure->rt > BOARD_HEIGHT-3) /* promotion mandatory */
1332 closure->kind = c == '=' ? IllegalMove : WhitePromotionKnight;
1333 else /* promotion optional, default is promote */
1334 closure->kind = c == '=' ? NormalMove : WhitePromotionQueen;
1335 if(c != '=') closure->promoCharIn = 'q';
1336 } else closure->kind = (c == NULLCHAR || c == 'x' || c == '=') ?
1337 NormalMove : IllegalMove;
1339 if( (int) piece < (int) BlackWazir && (closure->rf < BOARD_HEIGHT/3 || closure->rt < BOARD_HEIGHT/3) ) {
1340 if( (piece == BlackPawn || piece == BlackQueen) && closure->rt < 1 ||
1341 piece == BlackKnight && closure->rt < 2 ) /* promotion obligatory */
1342 closure->kind = c == '=' ? IllegalMove : BlackPromotionKnight;
1343 else /* promotion optional, default is promote */
1344 closure->kind = c == '=' ? NormalMove : BlackPromotionQueen;
1345 if(c != '=') closure->promoCharIn = 'q';
1346 } else closure->kind = (c == NULLCHAR || c == 'x' || c == '=') ?
1347 NormalMove : IllegalMove;
1351 if (closure->promoCharIn != NULLCHAR && closure->promoCharIn != 'x') {
1352 if (closure->kind == WhitePromotionQueen
1353 || closure->kind == BlackPromotionQueen) {
1355 PromoCharToMoveType((flags & F_WHITE_ON_MOVE) != 0,
1356 closure->promoCharIn);
1358 closure->kind = IllegalMove;
1361 /* [HGM] returns 'q' for optional promotion, 'n' for mandatory */
1362 if(closure->promoCharIn != '=')
1363 closure->promoChar = ToLower(closure->promoCharIn);
1364 else closure->promoChar = '=';
1365 if (closure->promoChar == 'x') closure->promoChar = NULLCHAR;
1366 if (closure->count > 1) {
1367 closure->kind = AmbiguousMove;
1370 /* Note: If more than one illegal move matches, but no legal
1371 moves, we return IllegalMove, not AmbiguousMove. Caller
1372 can look at closure->count to detect this.
1374 closure->kind = IllegalMove;
1376 if(closure->kind == IllegalMove)
1377 /* [HGM] might be a variant we don't understand, pass on promotion info */
1378 closure->promoChar = ToLower(closure->promoCharIn);
1379 if (appData.debugMode) {
1380 fprintf(debugFP, "Disambiguate out: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1381 closure->piece,closure->ff,closure->rf,closure->ft,closure->rt,closure->promoChar,
1382 closure->promoChar >= ' ' ? closure->promoChar:'-');
1396 } CoordsToAlgebraicClosure;
1398 extern void CoordsToAlgebraicCallback P((Board board, int flags,
1399 ChessMove kind, int rf, int ff,
1400 int rt, int ft, VOIDSTAR closure));
1402 void CoordsToAlgebraicCallback(board, flags, kind, rf, ff, rt, ft, closure)
1409 register CoordsToAlgebraicClosure *cl =
1410 (CoordsToAlgebraicClosure *) closure;
1412 if (rt == cl->rt && ft == cl->ft &&
1413 (board[rf][ff] == cl->piece
1414 || PieceToChar(board[rf][ff]) == '~' &&
1415 (ChessSquare) (DEMOTED board[rf][ff]) == cl->piece)
1419 cl->kind = kind; /* this is the move we want */
1421 cl->file++; /* need file to rule out this move */
1425 cl->rank++; /* need rank to rule out this move */
1427 cl->either++; /* rank or file will rule out this move */
1433 /* Convert coordinates to normal algebraic notation.
1434 promoChar must be NULLCHAR or 'x' if not a promotion.
1436 ChessMove CoordsToAlgebraic(board, flags, rf, ff, rt, ft, promoChar, out)
1445 char *outp = out, c;
1446 CoordsToAlgebraicClosure cl;
1448 if (rf == DROP_RANK) {
1449 /* Bughouse piece drop */
1450 *outp++ = ToUpper(PieceToChar((ChessSquare) ff));
1455 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1457 return (flags & F_WHITE_ON_MOVE) ? WhiteDrop : BlackDrop;
1460 if (promoChar == 'x') promoChar = NULLCHAR;
1461 piece = board[rf][ff];
1462 if(PieceToChar(piece)=='~') piece = (ChessSquare)(DEMOTED piece);
1464 if (appData.debugMode)
1465 fprintf(debugFP, "CoordsToAlgebraic, piece=%d (%d,%d)-(%d,%d) %c\n", (int)piece,ff,rf,ft,rt,promoChar >= ' ' ? promoChar : '-');
1469 kind = LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1470 if (kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1471 /* Keep short notation if move is illegal only because it
1472 leaves the player in check, but still return IllegalMove */
1473 kind = LegalityTest(board, flags|F_IGNORE_CHECK, rf, ff, rt, ft, promoChar);
1474 if (kind == IllegalMove) break;
1479 if (ff == ft && board[rt][ft] == EmptySquare) { /* [HGM] Xiangqi has straight noncapts! */
1480 /* Non-capture; use style "e5" */
1483 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1485 /* Capture; use style "exd5" */
1486 if(gameInfo.variant != VariantXiangqi || board[rt][ft] != EmptySquare )
1487 *outp++ = 'x'; /* [HGM] Xiangqi has sideway noncaptures across river! */
1491 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1493 /* Use promotion suffix style "=Q" */
1495 if (appData.debugMode)
1496 fprintf(debugFP, "movetype=%d, promochar=%d=%c\n", (int)kind, promoChar, promoChar >= ' ' ? promoChar : '-');
1497 if (promoChar != NULLCHAR) {
1498 if(gameInfo.variant == VariantShogi) {
1499 /* [HGM] ... but not in Shogi! */
1500 *outp++ = promoChar == '=' ? '=' : '+';
1503 *outp++ = ToUpper(promoChar);
1512 /* Fabien moved code: FRC castling first (if KxR), wild castling second */
1513 /* Code added by Tord: FRC castling. */
1514 if((piece == WhiteKing && board[rt][ft] == WhiteRook) ||
1515 (piece == BlackKing && board[rt][ft] == BlackRook)) {
1516 if(ft > ff) strcpy(out, "O-O"); else strcpy(out, "O-O-O");
1517 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1519 /* End of code added by Tord */
1520 /* Test for castling or ICS wild castling */
1521 /* Use style "O-O" (oh-oh) for PGN compatibility */
1522 else if (rf == rt &&
1523 rf == ((piece == WhiteKing) ? 0 : BOARD_HEIGHT-1) &&
1524 (ft - ff > 1 || ff - ft > 1) && // No castling if legal King move (on narrow boards!)
1525 ((ff == BOARD_WIDTH>>1 && (ft == BOARD_LEFT+2 || ft == BOARD_RGHT-2)) ||
1526 (ff == (BOARD_WIDTH-1)>>1 && (ft == BOARD_LEFT+1 || ft == BOARD_RGHT-3)))) {
1527 if(ft==BOARD_LEFT+1 || ft==BOARD_RGHT-2)
1530 strcpy(out, "O-O-O");
1532 /* This notation is always unambiguous, unless there are
1533 kings on both the d and e files, with "wild castling"
1534 possible for the king on the d file and normal castling
1535 possible for the other. ICS rules for wild 9
1536 effectively make castling illegal for either king in
1537 this situation. So I am not going to worry about it;
1538 I'll just generate an ambiguous O-O in this case.
1540 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1543 /* else fall through */
1551 cl.kind = IllegalMove;
1552 cl.rank = cl.file = cl.either = 0;
1553 GenLegal(board, flags, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1555 if (cl.kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1556 /* Generate pretty moves for moving into check, but
1557 still return IllegalMove.
1559 GenLegal(board, flags|F_IGNORE_CHECK, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1560 if (cl.kind == IllegalMove) break;
1561 cl.kind = IllegalMove;
1564 /* Style is "Nf3" or "Nxf7" if this is unambiguous,
1565 else "Ngf3" or "Ngxf7",
1566 else "N1f3" or "N5xf7",
1567 else "Ng1f3" or "Ng5xf7".
1569 c = PieceToChar(piece) ;
1570 if( c == '~' || c == '+') {
1571 /* [HGM] print nonexistent piece as its demoted version */
1572 piece = (ChessSquare) (DEMOTED piece);
1574 if(c=='+') *outp++ = c;
1575 *outp++ = ToUpper(PieceToChar(piece));
1577 if (cl.file || (cl.either && !cl.rank)) {
1583 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1586 if(board[rt][ft] != EmptySquare)
1592 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1594 if (gameInfo.variant == VariantShogi) {
1595 /* [HGM] in Shogi non-pawns can promote */
1596 if(flags & F_WHITE_ON_MOVE) {
1597 if( (int) cl.piece < (int) WhiteWazir &&
1598 (rf >= BOARD_HEIGHT-(BOARD_HEIGHT/3) || rt >= BOARD_HEIGHT-(BOARD_HEIGHT/3)) ) {
1599 if( (piece == WhitePawn || piece == WhiteQueen) && rt > BOARD_HEIGHT-2 ||
1600 piece == WhiteKnight && rt > BOARD_HEIGHT-3) /* promotion mandatory */
1601 cl.kind = promoChar == '=' ? IllegalMove : WhitePromotionKnight;
1602 else cl.kind = WhitePromotionQueen; /* promotion optional */
1604 } else cl.kind = (promoChar == NULLCHAR || promoChar == 'x' || promoChar == '=') ?
1605 NormalMove : IllegalMove;
1607 if( (int) cl.piece < (int) BlackWazir && (rf < BOARD_HEIGHT/3 || rt < BOARD_HEIGHT/3) ) {
1608 if( (piece == BlackPawn || piece == BlackQueen) && rt < 1 ||
1609 piece == BlackKnight && rt < 2 ) /* promotion obligatory */
1610 cl.kind = promoChar == '=' ? IllegalMove : BlackPromotionKnight;
1611 else cl.kind = BlackPromotionQueen; /* promotion optional */
1612 } else cl.kind = (promoChar == NULLCHAR || promoChar == 'x' || promoChar == '=') ?
1613 NormalMove : IllegalMove;
1615 if(cl.kind == WhitePromotionQueen || cl.kind == BlackPromotionQueen) {
1616 /* for optional promotions append '+' or '=' */
1617 if(promoChar == '=') {
1619 cl.kind = NormalMove;
1620 } else *outp++ = '+';
1622 } else if(cl.kind == IllegalMove) {
1623 /* Illegal move specifies any given promotion */
1624 if(promoChar != NULLCHAR && promoChar != 'x') {
1626 *outp++ = ToUpper(promoChar);
1633 /* [HGM] Always long notation for fairies we don't know */
1638 case WhiteGrasshopper:
1639 case BlackGrasshopper:
1641 /* Moving a nonexistent piece */
1645 /* Not a legal move, even ignoring check.
1646 If there was a piece on the from square,
1647 use style "Ng1g3" or "Ng1xe8";
1648 if there was a pawn or nothing (!),
1649 use style "g1g3" or "g1xe8". Use "x"
1650 if a piece was on the to square, even
1651 a piece of the same color.
1654 if (piece != EmptySquare && piece != WhitePawn && piece != BlackPawn) {
1655 *outp++ = ToUpper(PieceToChar(piece));
1660 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1661 if (board[rt][ft] != EmptySquare) *outp++ = 'x';
1665 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1666 /* Use promotion suffix style "=Q" */
1667 if (promoChar != NULLCHAR && promoChar != 'x') {
1669 *outp++ = ToUpper(promoChar);
1676 // [HGM] XQ: the following code serves to detect perpetual chasing (Asian rules)
1685 // I guess the following variables logically belong in the closure too, but I was too lazy and used globals
1687 int preyStackPointer, chaseStackPointer;
1690 char rf, ff, rt, ft;
1700 // there are three new callbacks for use with GenLegal: for adding captures, deleting them, and finding a recapture
1702 extern void AtacksCallback P((Board board, int flags, ChessMove kind,
1703 int rf, int ff, int rt, int ft,
1706 void AttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1712 { // For adding captures that can lead to chase indictment to the chaseStack
1713 if(board[rt][ft] == EmptySquare) return; // non-capture
1714 if(board[rt][ft] == WhitePawn && rt < BOARD_HEIGHT/2) return; // Pawn before river can be chased
1715 if(board[rt][ft] == BlackPawn && rt >= BOARD_HEIGHT/2) return; // Pawn before river can be chased
1716 if(board[rf][ff] == WhitePawn || board[rf][ff] == BlackPawn) return; // Pawns are allowed to chase
1717 if(board[rf][ff] == WhiteWazir || board[rf][ff] == BlackWazir) return; // King is allowed to chase
1718 // move cannot be excluded from being a chase trivially (based on attacker and victim); save it on chaseStack
1719 chaseStack[chaseStackPointer].rf = rf;
1720 chaseStack[chaseStackPointer].ff = ff;
1721 chaseStack[chaseStackPointer].rt = rt;
1722 chaseStack[chaseStackPointer].ft = ft;
1723 chaseStackPointer++;
1726 extern void ExistingAtacksCallback P((Board board, int flags, ChessMove kind,
1727 int rf, int ff, int rt, int ft,
1730 void ExistingAttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1736 { // for removing pre-exsting captures from the chaseStack, to be left with newly created ones
1738 register ChaseClosure *cl = (ChaseClosure *) closure; //closure tells us the move played in the repeat loop
1740 if(board[rt][ft] == EmptySquare) return; // no capture
1741 if(rf == cl->rf && ff == cl->ff) { // attacks with same piece from new position are not considered new
1742 rf = cl->rt; ff = cl->ft; // doctor their fromSquare so they will be recognized in chaseStack
1744 // search move in chaseStack, and delete it if it occurred there (as we know now it is not a new capture)
1745 for(i=0; i<chaseStackPointer; i++) {
1746 if(chaseStack[i].rf == rf && chaseStack[i].ff == ff &&
1747 chaseStack[i].rt == rt && chaseStack[i].ft == ft ) {
1748 // move found on chaseStack, delete it by overwriting with move popped from top of chaseStack
1749 chaseStack[i] = chaseStack[--chaseStackPointer];
1755 extern void ProtectedCallback P((Board board, int flags, ChessMove kind,
1756 int rf, int ff, int rt, int ft,
1759 void ProtectedCallback(board, flags, kind, rf, ff, rt, ft, closure)
1765 { // for determining if a piece (given through the closure) is protected
1766 register ChaseClosure *cl = (ChaseClosure *) closure; // closure tells us where to recapture
1768 if(rt == cl->rt && ft == cl->ft) cl->recaptures++; // count legal recaptures to this square
1769 if(appData.debugMode && board[rt][ft] != EmptySquare)
1770 fprintf(debugFP, "try %c%c%c%c=%d\n", ff+AAA, rf+ONE,ft+AAA, rt+ONE, cl->recaptures);
1773 extern char moveList[MAX_MOVES][MOVE_LEN];
1775 int PerpetualChase(int first, int last)
1776 { // this routine detects if the side to move in the 'first' position is perpetually chasing (when not checking)
1779 ChessSquare captured;
1781 preyStackPointer = 0; // clear stack of chased pieces
1782 for(i=first; i<last; i+=2) { // for all positions with same side to move
1783 if(appData.debugMode) fprintf(debugFP, "judge position %i\n", i);
1784 chaseStackPointer = 0; // clear stack that is going to hold possible chases
1785 // determine all captures possible after the move, and put them on chaseStack
1786 GenLegal(boards[i+1], PosFlags(i), AttacksCallback, &cl);
1787 if(appData.debugMode) { int n;
1788 for(n=0; n<chaseStackPointer; n++)
1789 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1790 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1791 fprintf(debugFP, ": all capts\n");
1793 // determine all captures possible before the move, and delete them from chaseStack
1794 cl.rf = moveList[i][1]-ONE; // prepare closure to pass move that led from i to i+1
1795 cl.ff = moveList[i][0]-AAA+BOARD_LEFT;
1796 cl.rt = moveList[i][3]-ONE;
1797 cl.ft = moveList[i][2]-AAA+BOARD_LEFT;
1798 GenLegal(boards[i], PosFlags(i), ExistingAttacksCallback, &cl);
1799 if(appData.debugMode) { int n;
1800 for(n=0; n<chaseStackPointer; n++)
1801 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1802 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1803 fprintf(debugFP, ": new capts after %c%c%c%c\n", cl.ff+AAA, cl.rf+ONE, cl.ft+AAA, cl.rt+ONE);
1805 // chaseSack now contains all captures made possible by the move
1806 for(j=0; j<chaseStackPointer; j++) { // run through chaseStack to identify true chases
1807 int attacker = (int)boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1808 int victim = (int)boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1810 if(attacker >= (int) BlackPawn) attacker = BLACK_TO_WHITE attacker; // convert to white, as piecee type
1811 if(victim >= (int) BlackPawn) victim = BLACK_TO_WHITE victim;
1813 if((attacker == WhiteKnight || attacker == WhiteCannon) && victim == WhiteRook)
1814 continue; // C or H attack on R is always chase; leave on chaseStack
1816 if(attacker == victim) {
1817 if(LegalityTest(boards[i+1], PosFlags(i+1), chaseStack[j].rt,
1818 chaseStack[j].ft, chaseStack[j].rf, chaseStack[j].ff, NULLCHAR) == NormalMove) {
1819 // we can capture back with equal piece, so this is no chase but a sacrifice
1820 chaseStack[j] = chaseStack[--chaseStackPointer]; // delete the capture from the chaseStack
1821 j--; /* ! */ continue;
1826 // the attack is on a lower piece, or on a pinned or blocked equal one
1827 // test if the victim is protected by a true protector. First make the capture.
1828 captured = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1829 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1830 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = EmptySquare;
1831 // Then test if the opponent can recapture
1832 cl.recaptures = 0; // prepare closure to pass recapture square and count moves to it
1833 cl.rt = chaseStack[j].rt;
1834 cl.ft = chaseStack[j].ft;
1835 if(appData.debugMode) {
1836 fprintf(debugFP, "test if we can recapture %c%c\n", cl.ft+AAA, cl.rt+ONE);
1838 GenLegal(boards[i+1], PosFlags(i+1), ProtectedCallback, &cl); // try all moves
1839 // unmake the capture
1840 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1841 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = captured;
1842 // if a recapture was found, piece is protected, and we are not chasing it.
1843 if(cl.recaptures) { // attacked piece was defended by true protector, no chase
1844 chaseStack[j] = chaseStack[--chaseStackPointer]; // so delete from chaseStack
1848 // chaseStack now contains all moves that chased
1849 if(appData.debugMode) { int n;
1850 for(n=0; n<chaseStackPointer; n++)
1851 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1852 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1853 fprintf(debugFP, ": chases\n");
1855 if(i == first) { // copy all people chased by first move of repeat cycle to preyStack
1856 for(j=0; j<chaseStackPointer; j++) {
1857 preyStack[j].rank = chaseStack[j].rt;
1858 preyStack[j].file = chaseStack[j].ft;
1860 preyStackPointer = chaseStackPointer;
1863 for(j=0; j<chaseStackPointer; j++) {
1864 for(k=0; k<preyStackPointer; k++) {
1865 // search the victim of each chase move on the preyStack (first occurrence)
1866 if(chaseStack[j].ft == preyStack[k].file && chaseStack[j].rt == preyStack[k].rank ) {
1867 if(k < tail) break; // piece was already identified as still being chased
1868 preyStack[preyStackPointer] = preyStack[tail]; // move chased piece to bottom part of preyStack
1869 preyStack[tail] = preyStack[k]; // by swapping
1870 preyStack[k] = preyStack[preyStackPointer];
1876 preyStackPointer = tail; // keep bottom part of preyStack, popping pieces unchased on move i.
1877 if(appData.debugMode) { int n;
1878 for(n=0; n<preyStackPointer; n++)
1879 fprintf(debugFP, "%c%c ", preyStack[n].file+AAA, preyStack[n].rank+ONE);
1880 fprintf(debugFP, "always chased upto ply %d\n", i);
1882 // now adjust the location of the chased pieces according to opponent move
1883 for(j=0; j<preyStackPointer; j++) {
1884 if(preyStack[j].rank == moveList[i+1][1]-ONE &&
1885 preyStack[j].file == moveList[i+1][0]-AAA+BOARD_LEFT) {
1886 preyStack[j].rank = moveList[i+1][3]-ONE;
1887 preyStack[j].file = moveList[i+1][2]-AAA+BOARD_LEFT;
1892 return preyStackPointer; // if any piece was left on preyStack, it has been perpetually chased