2 * moves.c - Move generation and checking
4 * Copyright 1991 by Digital Equipment Corporation, Maynard,
7 * Enhancements Copyright 1992-2001, 2002, 2003, 2004, 2005, 2006,
8 * 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
10 * Enhancements Copyright 2005 Alessandro Scotti
12 * The following terms apply to Digital Equipment Corporation's copyright
14 * ------------------------------------------------------------------------
17 * Permission to use, copy, modify, and distribute this software and its
18 * documentation for any purpose and without fee is hereby granted,
19 * provided that the above copyright notice appear in all copies and that
20 * both that copyright notice and this permission notice appear in
21 * supporting documentation, and that the name of Digital not be
22 * used in advertising or publicity pertaining to distribution of the
23 * software without specific, written prior permission.
25 * DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
26 * ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
27 * DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
28 * ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
29 * WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
30 * ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
32 * ------------------------------------------------------------------------
34 * The following terms apply to the enhanced version of XBoard
35 * distributed by the Free Software Foundation:
36 * ------------------------------------------------------------------------
38 * GNU XBoard is free software: you can redistribute it and/or modify
39 * it under the terms of the GNU General Public License as published by
40 * the Free Software Foundation, either version 3 of the License, or (at
41 * your option) any later version.
43 * GNU XBoard is distributed in the hope that it will be useful, but
44 * WITHOUT ANY WARRANTY; without even the implied warranty of
45 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
46 * General Public License for more details.
48 * You should have received a copy of the GNU General Public License
49 * along with this program. If not, see http://www.gnu.org/licenses/. *
51 *------------------------------------------------------------------------
52 ** See the file ChangeLog for a revision history. */
59 #else /* not HAVE_STRING_H */
61 #endif /* not HAVE_STRING_H */
67 int WhitePiece P((ChessSquare));
68 int BlackPiece P((ChessSquare));
69 int SameColor P((ChessSquare, ChessSquare));
70 int PosFlags(int index);
72 extern signed char initialRights[BOARD_FILES]; /* [HGM] all rights enabled, set in InitPosition */
78 return (int) piece >= (int) WhitePawn && (int) piece < (int) BlackPawn;
84 return (int) piece >= (int) BlackPawn && (int) piece < (int) EmptySquare;
87 int SameColor(piece1, piece2)
88 ChessSquare piece1, piece2;
90 return ((int) piece1 >= (int) WhitePawn && /* [HGM] can be > King ! */
91 (int) piece1 < (int) BlackPawn &&
92 (int) piece2 >= (int) WhitePawn &&
93 (int) piece2 < (int) BlackPawn)
94 || ((int) piece1 >= (int) BlackPawn &&
95 (int) piece1 < (int) EmptySquare &&
96 (int) piece2 >= (int) BlackPawn &&
97 (int) piece2 < (int) EmptySquare);
100 char pieceToChar[] = {
101 'P', 'N', 'B', 'R', 'Q', 'F', 'E', 'A', 'C', 'W', 'M',
102 'O', 'H', 'I', 'J', 'G', 'D', 'V', 'L', 'S', 'U', 'K',
103 'p', 'n', 'b', 'r', 'q', 'f', 'e', 'a', 'c', 'w', 'm',
104 'o', 'h', 'i', 'j', 'g', 'd', 'v', 'l', 's', 'u', 'k',
106 char pieceNickName[EmptySquare];
111 if((int)p < 0 || (int)p >= (int)EmptySquare) return('x'); /* [HGM] for safety */
112 return pieceToChar[(int) p];
115 int PieceToNumber(p) /* [HGM] holdings: count piece type, ignoring non-participating piece types */
119 ChessSquare start = (int)p >= (int)BlackPawn ? BlackPawn : WhitePawn;
121 while(start++ != p) if(pieceToChar[(int)start-1] != '.') i++;
125 ChessSquare CharToPiece(c)
129 for(i=0; i< (int) EmptySquare; i++)
130 if(pieceNickName[i] == c) return (ChessSquare) i;
131 for(i=0; i< (int) EmptySquare; i++)
132 if(pieceToChar[i] == c) return (ChessSquare) i;
136 void CopyBoard(to, from)
141 for (i = 0; i < BOARD_HEIGHT; i++)
142 for (j = 0; j < BOARD_WIDTH; j++)
143 to[i][j] = from[i][j];
144 for (j = 0; j < BOARD_FILES-1; j++) // [HGM] gamestate: copy castling rights and ep status
145 to[CASTLING][j] = from[CASTLING][j];
146 to[HOLDINGS_SET] = 0; // flag used in ICS play
149 int CompareBoards(board1, board2)
150 Board board1, board2;
154 for (i = 0; i < BOARD_HEIGHT; i++)
155 for (j = 0; j < BOARD_WIDTH; j++) {
156 if (board1[i][j] != board2[i][j])
163 /* Call callback once for each pseudo-legal move in the given
164 position, except castling moves. A move is pseudo-legal if it is
165 legal, or if it would be legal except that it leaves the king in
166 check. In the arguments, epfile is EP_NONE if the previous move
167 was not a double pawn push, or the file 0..7 if it was, or
168 EP_UNKNOWN if we don't know and want to allow all e.p. captures.
169 Promotion moves generated are to Queen only.
171 void GenPseudoLegal(board, flags, callback, closure)
174 MoveCallback callback;
178 int i, j, d, s, fs, rs, rt, ft, m;
179 int epfile = (signed char)board[EP_STATUS]; // [HGM] gamestate: extract ep status from board
180 int promoRank = gameInfo.variant == VariantMakruk ? 3 : 1;
182 for (rf = 0; rf < BOARD_HEIGHT; rf++)
183 for (ff = BOARD_LEFT; ff < BOARD_RGHT; ff++) {
186 if (flags & F_WHITE_ON_MOVE) {
187 if (!WhitePiece(board[rf][ff])) continue;
189 if (!BlackPiece(board[rf][ff])) continue;
191 m = 0; piece = board[rf][ff];
192 if(PieceToChar(piece) == '~')
193 piece = (ChessSquare) ( DEMOTED piece );
194 if(gameInfo.variant == VariantShogi)
195 piece = (ChessSquare) ( SHOGI piece );
198 /* case EmptySquare: [HGM] this is nonsense, and conflicts with Shogi cases */
200 /* can't happen ([HGM] except for faries...) */
204 if(gameInfo.variant == VariantXiangqi) {
205 /* [HGM] capture and move straight ahead in Xiangqi */
206 if (rf < BOARD_HEIGHT-1 &&
207 !SameColor(board[rf][ff], board[rf + 1][ff]) ) {
208 callback(board, flags, NormalMove,
209 rf, ff, rf + 1, ff, closure);
211 /* and move sideways when across the river */
212 for (s = -1; s <= 1; s += 2) {
213 if (rf >= BOARD_HEIGHT>>1 &&
214 ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
215 !WhitePiece(board[rf][ff+s]) ) {
216 callback(board, flags, NormalMove,
217 rf, ff, rf, ff+s, closure);
222 if (rf < BOARD_HEIGHT-1 && board[rf + 1][ff] == EmptySquare) {
223 callback(board, flags,
224 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
225 rf, ff, rf + 1, ff, closure);
227 if (rf == 1 && board[2][ff] == EmptySquare &&
228 gameInfo.variant != VariantShatranj && /* [HGM] */
229 gameInfo.variant != VariantCourier && /* [HGM] */
230 board[3][ff] == EmptySquare ) {
231 callback(board, flags, NormalMove,
232 rf, ff, 3, ff, closure);
234 for (s = -1; s <= 1; s += 2) {
235 if (rf < BOARD_HEIGHT-1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
236 ((flags & F_KRIEGSPIEL_CAPTURE) ||
237 BlackPiece(board[rf + 1][ff + s]))) {
238 callback(board, flags,
239 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
240 rf, ff, rf + 1, ff + s, closure);
242 if (rf == BOARD_HEIGHT-4) {
243 if (ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
244 (epfile == ff + s || epfile == EP_UNKNOWN) &&
245 board[BOARD_HEIGHT-4][ff + s] == BlackPawn &&
246 board[BOARD_HEIGHT-3][ff + s] == EmptySquare) {
247 callback(board, flags, WhiteCapturesEnPassant,
248 rf, ff, 5, ff + s, closure);
255 if(gameInfo.variant == VariantXiangqi) {
256 /* [HGM] capture straight ahead in Xiangqi */
257 if (rf > 0 && !SameColor(board[rf][ff], board[rf - 1][ff]) ) {
258 callback(board, flags, NormalMove,
259 rf, ff, rf - 1, ff, closure);
261 /* and move sideways when across the river */
262 for (s = -1; s <= 1; s += 2) {
263 if (rf < BOARD_HEIGHT>>1 &&
264 ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
265 !BlackPiece(board[rf][ff+s]) ) {
266 callback(board, flags, NormalMove,
267 rf, ff, rf, ff+s, closure);
272 if (rf > 0 && board[rf - 1][ff] == EmptySquare) {
273 callback(board, flags,
274 rf <= promoRank ? BlackPromotion : NormalMove,
275 rf, ff, rf - 1, ff, closure);
277 if (rf == BOARD_HEIGHT-2 && board[BOARD_HEIGHT-3][ff] == EmptySquare &&
278 gameInfo.variant != VariantShatranj && /* [HGM] */
279 gameInfo.variant != VariantCourier && /* [HGM] */
280 board[BOARD_HEIGHT-4][ff] == EmptySquare) {
281 callback(board, flags, NormalMove,
282 rf, ff, BOARD_HEIGHT-4, ff, closure);
284 for (s = -1; s <= 1; s += 2) {
285 if (rf > 0 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
286 ((flags & F_KRIEGSPIEL_CAPTURE) ||
287 WhitePiece(board[rf - 1][ff + s]))) {
288 callback(board, flags,
289 rf <= promoRank ? BlackPromotion : NormalMove,
290 rf, ff, rf - 1, ff + s, closure);
293 if (ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
294 (epfile == ff + s || epfile == EP_UNKNOWN) &&
295 board[3][ff + s] == WhitePawn &&
296 board[2][ff + s] == EmptySquare) {
297 callback(board, flags, BlackCapturesEnPassant,
298 rf, ff, 2, ff + s, closure);
309 for (i = -1; i <= 1; i += 2)
310 for (j = -1; j <= 1; j += 2)
311 for (s = 1; s <= 2; s++) {
314 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
315 && ( gameInfo.variant != VariantXiangqi || board[rf+i*(s-1)][ff+j*(2-s)] == EmptySquare)
316 && !SameColor(board[rf][ff], board[rt][ft]))
317 callback(board, flags, NormalMove,
318 rf, ff, rt, ft, closure);
322 case SHOGI WhiteKnight:
323 for (s = -1; s <= 1; s += 2) {
324 if (rf < BOARD_HEIGHT-2 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
325 !SameColor(board[rf][ff], board[rf + 2][ff + s])) {
326 callback(board, flags, NormalMove,
327 rf, ff, rf + 2, ff + s, closure);
332 case SHOGI BlackKnight:
333 for (s = -1; s <= 1; s += 2) {
334 if (rf > 1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
335 !SameColor(board[rf][ff], board[rf - 2][ff + s])) {
336 callback(board, flags, NormalMove,
337 rf, ff, rf - 2, ff + s, closure);
344 for (d = 0; d <= 1; d++)
345 for (s = -1; s <= 1; s += 2) {
348 rt = rf + (i * s) * d;
349 ft = ff + (i * s) * (1 - d);
350 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
351 if (m == 0 && board[rt][ft] == EmptySquare)
352 callback(board, flags, NormalMove,
353 rf, ff, rt, ft, closure);
354 if (m == 1 && board[rt][ft] != EmptySquare &&
355 !SameColor(board[rf][ff], board[rt][ft]) )
356 callback(board, flags, NormalMove,
357 rf, ff, rt, ft, closure);
358 if (board[rt][ft] != EmptySquare && m++) break;
363 /* Gold General (and all its promoted versions) . First do the */
364 /* diagonal forward steps, then proceed as normal Wazir */
365 case SHOGI WhiteWazir:
366 case SHOGI (PROMOTED WhitePawn):
367 case SHOGI (PROMOTED WhiteKnight):
368 case SHOGI (PROMOTED WhiteQueen):
369 case SHOGI (PROMOTED WhiteFerz):
370 for (s = -1; s <= 1; s += 2) {
371 if (rf < BOARD_HEIGHT-1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
372 !SameColor(board[rf][ff], board[rf + 1][ff + s])) {
373 callback(board, flags, NormalMove,
374 rf, ff, rf + 1, ff + s, closure);
379 case SHOGI BlackWazir:
380 case SHOGI (PROMOTED BlackPawn):
381 case SHOGI (PROMOTED BlackKnight):
382 case SHOGI (PROMOTED BlackQueen):
383 case SHOGI (PROMOTED BlackFerz):
384 for (s = -1; s <= 1; s += 2) {
385 if (rf > 0 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
386 !SameColor(board[rf][ff], board[rf - 1][ff + s])) {
387 callback(board, flags, NormalMove,
388 rf, ff, rf - 1, ff + s, closure);
395 for (d = 0; d <= 1; d++)
396 for (s = -1; s <= 1; s += 2) {
398 ft = ff + s * (1 - d);
399 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
400 && !SameColor(board[rf][ff], board[rt][ft]) &&
401 (gameInfo.variant != VariantXiangqi || InPalace(rt, ft) ) )
402 callback(board, flags, NormalMove,
403 rf, ff, rt, ft, closure);
409 /* [HGM] support Shatranj pieces */
410 for (rs = -1; rs <= 1; rs += 2)
411 for (fs = -1; fs <= 1; fs += 2) {
414 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
415 && ( gameInfo.variant != VariantXiangqi ||
416 board[rf+rs][ff+fs] == EmptySquare && (2*rf < BOARD_HEIGHT) == (2*rt < BOARD_HEIGHT) )
418 && !SameColor(board[rf][ff], board[rt][ft]))
419 callback(board, flags, NormalMove,
420 rf, ff, rt, ft, closure);
421 if(gameInfo.variant != VariantFairy && gameInfo.variant != VariantGreat) continue;
422 rt = rf + rs; // in unknown variant we assume Modern Elephant, which can also do one step
424 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
425 && !SameColor(board[rf][ff], board[rt][ft]))
426 callback(board, flags, NormalMove,
427 rf, ff, rt, ft, closure);
431 /* Shogi Dragon Horse has to continue with Wazir after Bishop */
432 case SHOGI WhiteCardinal:
433 case SHOGI BlackCardinal:
436 /* Capablanca Archbishop continues as Knight */
441 /* Shogi Bishops are ordinary Bishops */
442 case SHOGI WhiteBishop:
443 case SHOGI BlackBishop:
446 for (rs = -1; rs <= 1; rs += 2)
447 for (fs = -1; fs <= 1; fs += 2)
451 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
452 if (SameColor(board[rf][ff], board[rt][ft])) break;
453 callback(board, flags, NormalMove,
454 rf, ff, rt, ft, closure);
455 if (board[rt][ft] != EmptySquare) break;
457 if(m==1) goto mounted;
458 if(m==2) goto finishGold;
459 /* Bishop falls through */
462 /* Shogi Lance is unlike anything, and asymmetric at that */
463 case SHOGI WhiteQueen:
467 if (rt >= BOARD_HEIGHT) break;
468 if (SameColor(board[rf][ff], board[rt][ft])) break;
469 callback(board, flags, NormalMove,
470 rf, ff, rt, ft, closure);
471 if (board[rt][ft] != EmptySquare) break;
475 case SHOGI BlackQueen:
480 if (SameColor(board[rf][ff], board[rt][ft])) break;
481 callback(board, flags, NormalMove,
482 rf, ff, rt, ft, closure);
483 if (board[rt][ft] != EmptySquare) break;
487 /* Make Dragon-King Dababba & Rook-like outside Shogi, for better disambiguation in variant Fairy */
490 for (d = 0; d <= 1; d++) // Dababba moves that Rook cannot do
491 for (s = -2; s <= 2; s += 4) {
493 ft = ff + s * (1 - d);
494 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT || board[rf+rt>>1][ff+ft>>1] == EmptySquare) continue;
495 if (SameColor(board[rf][ff], board[rt][ft])) continue;
496 callback(board, flags, NormalMove, rf, ff, rt, ft, closure);
500 /* Shogi Dragon King has to continue as Ferz after Rook moves */
501 case SHOGI WhiteDragon:
502 case SHOGI BlackDragon:
505 /* Capablanca Chancellor sets flag to continue as Knight */
510 /* Shogi Rooks are ordinary Rooks */
511 case SHOGI WhiteRook:
512 case SHOGI BlackRook:
516 for (d = 0; d <= 1; d++)
517 for (s = -1; s <= 1; s += 2)
519 rt = rf + (i * s) * d;
520 ft = ff + (i * s) * (1 - d);
521 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
522 if (SameColor(board[rf][ff], board[rt][ft])) break;
523 callback(board, flags, NormalMove,
524 rf, ff, rt, ft, closure);
525 if (board[rt][ft] != EmptySquare) break;
527 if(m==1) goto mounted;
528 if(m==2) goto finishSilver;
533 for (rs = -1; rs <= 1; rs++)
534 for (fs = -1; fs <= 1; fs++) {
535 if (rs == 0 && fs == 0) continue;
539 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
540 if (SameColor(board[rf][ff], board[rt][ft])) break;
541 callback(board, flags, NormalMove,
542 rf, ff, rt, ft, closure);
543 if (board[rt][ft] != EmptySquare) break;
548 /* Shogi Pawn and Silver General: first the Pawn move, */
549 /* then the General continues like a Ferz */
551 if(gameInfo.variant != VariantMakruk) goto commoner;
552 case SHOGI WhitePawn:
553 case SHOGI WhiteFerz:
554 if (rf < BOARD_HEIGHT-1 &&
555 !SameColor(board[rf][ff], board[rf + 1][ff]) )
556 callback(board, flags, NormalMove,
557 rf, ff, rf + 1, ff, closure);
558 if(piece != SHOGI WhitePawn) goto finishSilver;
562 if(gameInfo.variant != VariantMakruk) goto commoner;
563 case SHOGI BlackPawn:
564 case SHOGI BlackFerz:
566 !SameColor(board[rf][ff], board[rf - 1][ff]) )
567 callback(board, flags, NormalMove,
568 rf, ff, rf - 1, ff, closure);
569 if(piece == SHOGI BlackPawn) break;
574 /* [HGM] support Shatranj pieces */
575 for (rs = -1; rs <= 1; rs += 2)
576 for (fs = -1; fs <= 1; fs += 2) {
579 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
580 if (!SameColor(board[rf][ff], board[rt][ft]) &&
581 (gameInfo.variant != VariantXiangqi || InPalace(rt, ft) ) )
582 callback(board, flags, NormalMove,
583 rf, ff, rt, ft, closure);
589 m++; // [HGM] superchess: use for Centaur
591 case SHOGI WhiteKing:
592 case SHOGI BlackKing:
596 for (i = -1; i <= 1; i++)
597 for (j = -1; j <= 1; j++) {
598 if (i == 0 && j == 0) continue;
601 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
602 if (SameColor(board[rf][ff], board[rt][ft])) continue;
603 callback(board, flags, NormalMove,
604 rf, ff, rt, ft, closure);
606 if(m==1) goto mounted;
609 case WhiteNightrider:
610 case BlackNightrider:
611 for (i = -1; i <= 1; i += 2)
612 for (j = -1; j <= 1; j += 2)
613 for (s = 1; s <= 2; s++) { int k;
617 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
618 if (SameColor(board[rf][ff], board[rt][ft])) break;
619 callback(board, flags, NormalMove,
620 rf, ff, rt, ft, closure);
621 if (board[rt][ft] != EmptySquare) break;
626 // Use Lance as Berolina / Spartan Pawn.
628 if (rf < BOARD_HEIGHT-1 && BlackPiece(board[rf + 1][ff]))
629 callback(board, flags,
630 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
631 rf, ff, rf + 1, ff, closure);
632 for (s = -1; s <= 1; s += 2) {
633 if (rf < BOARD_HEIGHT-1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT && board[rf + 1][ff + s] == EmptySquare)
634 callback(board, flags,
635 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
636 rf, ff, rf + 1, ff + s, closure);
637 if (rf == 1 && ff + 2*s >= BOARD_LEFT && ff + 2*s < BOARD_RGHT && board[3][ff + 2*s] == EmptySquare )
638 callback(board, flags, NormalMove, rf, ff, 3, ff + 2*s, closure);
643 if (rf > 0 && WhitePiece(board[rf - 1][ff]))
644 callback(board, flags,
645 rf <= promoRank ? BlackPromotion : NormalMove,
646 rf, ff, rf - 1, ff, closure);
647 for (s = -1; s <= 1; s += 2) {
648 if (rf > 0 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT && board[rf - 1][ff + s] == EmptySquare)
649 callback(board, flags,
650 rf <= promoRank ? BlackPromotion : NormalMove,
651 rf, ff, rf - 1, ff + s, closure);
652 if (rf == BOARD_HEIGHT-2 && ff + 2*s >= BOARD_LEFT && ff + 2*s < BOARD_RGHT && board[rf-2][ff + 2*s] == EmptySquare )
653 callback(board, flags, NormalMove, rf, ff, rf-2, ff + 2*s, closure);
657 case WhiteFalcon: // [HGM] wild: for wildcards, self-capture symbolizes move to anywhere
661 callback(board, flags, NormalMove, rf, ff, rf, ff, closure);
674 extern void GenLegalCallback P((Board board, int flags, ChessMove kind,
675 int rf, int ff, int rt, int ft,
678 void GenLegalCallback(board, flags, kind, rf, ff, rt, ft, closure)
685 register GenLegalClosure *cl = (GenLegalClosure *) closure;
687 if (!(flags & F_IGNORE_CHECK) &&
688 CheckTest(board, flags, rf, ff, rt, ft,
689 kind == WhiteCapturesEnPassant ||
690 kind == BlackCapturesEnPassant)) return;
691 if (flags & F_ATOMIC_CAPTURE) {
692 if (board[rt][ft] != EmptySquare ||
693 kind == WhiteCapturesEnPassant || kind == BlackCapturesEnPassant) {
695 ChessSquare king = (flags & F_WHITE_ON_MOVE) ? WhiteKing : BlackKing;
696 if (board[rf][ff] == king) return;
697 for (r = rt-1; r <= rt+1; r++) {
698 for (f = ft-1; f <= ft+1; f++) {
699 if (r >= 0 && r < BOARD_HEIGHT && f >= BOARD_LEFT && f < BOARD_RGHT &&
700 board[r][f] == king) return;
705 cl->cb(board, flags, kind, rf, ff, rt, ft, cl->cl);
712 int captures; // [HGM] losers
713 } LegalityTestClosure;
716 /* Like GenPseudoLegal, but (1) include castling moves, (2) unless
717 F_IGNORE_CHECK is set in the flags, omit moves that would leave the
718 king in check, and (3) if F_ATOMIC_CAPTURE is set in the flags, omit
719 moves that would destroy your own king. The CASTLE_OK flags are
720 true if castling is not yet ruled out by a move of the king or
721 rook. Return TRUE if the player on move is currently in check and
722 F_IGNORE_CHECK is not set. [HGM] add castlingRights parameter */
723 int GenLegal(board, flags, callback, closure)
726 MoveCallback callback;
730 int ff, ft, k, left, right;
731 int ignoreCheck = (flags & F_IGNORE_CHECK) != 0;
732 ChessSquare wKing = WhiteKing, bKing = BlackKing, *castlingRights = board[CASTLING];
736 GenPseudoLegal(board, flags, GenLegalCallback, (VOIDSTAR) &cl);
739 CheckTest(board, flags, -1, -1, -1, -1, FALSE)) return TRUE;
741 /* Generate castling moves */
742 if(gameInfo.variant == VariantKnightmate) { /* [HGM] Knightmate */
743 wKing = WhiteUnicorn; bKing = BlackUnicorn;
746 for (ff = BOARD_WIDTH>>1; ff >= (BOARD_WIDTH-1)>>1; ff-- /*ics wild 1*/) {
747 if ((flags & F_WHITE_ON_MOVE) &&
748 (flags & F_WHITE_KCASTLE_OK) &&
749 board[0][ff] == wKing &&
750 board[0][ff + 1] == EmptySquare &&
751 board[0][ff + 2] == EmptySquare &&
752 board[0][BOARD_RGHT-3] == EmptySquare &&
753 board[0][BOARD_RGHT-2] == EmptySquare &&
754 board[0][BOARD_RGHT-1] == WhiteRook &&
755 castlingRights[0] != NoRights && /* [HGM] check rights */
756 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
758 (!CheckTest(board, flags, 0, ff, 0, ff + 1, FALSE) &&
759 !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-3, FALSE) &&
760 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-2, FALSE)) &&
761 !CheckTest(board, flags, 0, ff, 0, ff + 2, FALSE)))) {
763 callback(board, flags,
764 ff==BOARD_WIDTH>>1 ? WhiteKingSideCastle : WhiteKingSideCastleWild,
765 0, ff, 0, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
767 if ((flags & F_WHITE_ON_MOVE) &&
768 (flags & F_WHITE_QCASTLE_OK) &&
769 board[0][ff] == wKing &&
770 board[0][ff - 1] == EmptySquare &&
771 board[0][ff - 2] == EmptySquare &&
772 board[0][BOARD_LEFT+2] == EmptySquare &&
773 board[0][BOARD_LEFT+1] == EmptySquare &&
774 board[0][BOARD_LEFT+0] == WhiteRook &&
775 castlingRights[1] != NoRights && /* [HGM] check rights */
776 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
778 (!CheckTest(board, flags, 0, ff, 0, ff - 1, FALSE) &&
779 !CheckTest(board, flags, 0, ff, 0, BOARD_LEFT+3, FALSE) &&
780 !CheckTest(board, flags, 0, ff, 0, ff - 2, FALSE)))) {
782 callback(board, flags,
783 ff==BOARD_WIDTH>>1 ? WhiteQueenSideCastle : WhiteQueenSideCastleWild,
784 0, ff, 0, ff - ((gameInfo.boardWidth+2)>>2), closure);
786 if (!(flags & F_WHITE_ON_MOVE) &&
787 (flags & F_BLACK_KCASTLE_OK) &&
788 board[BOARD_HEIGHT-1][ff] == bKing &&
789 board[BOARD_HEIGHT-1][ff + 1] == EmptySquare &&
790 board[BOARD_HEIGHT-1][ff + 2] == EmptySquare &&
791 board[BOARD_HEIGHT-1][BOARD_RGHT-3] == EmptySquare &&
792 board[BOARD_HEIGHT-1][BOARD_RGHT-2] == EmptySquare &&
793 board[BOARD_HEIGHT-1][BOARD_RGHT-1] == BlackRook &&
794 castlingRights[3] != NoRights && /* [HGM] check rights */
795 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
797 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 1, FALSE) &&
798 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-3, FALSE) &&
799 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-2, FALSE)) &&
800 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 2, FALSE)))) {
802 callback(board, flags,
803 ff==BOARD_WIDTH>>1 ? BlackKingSideCastle : BlackKingSideCastleWild,
804 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
806 if (!(flags & F_WHITE_ON_MOVE) &&
807 (flags & F_BLACK_QCASTLE_OK) &&
808 board[BOARD_HEIGHT-1][ff] == bKing &&
809 board[BOARD_HEIGHT-1][ff - 1] == EmptySquare &&
810 board[BOARD_HEIGHT-1][ff - 2] == EmptySquare &&
811 board[BOARD_HEIGHT-1][BOARD_LEFT+2] == EmptySquare &&
812 board[BOARD_HEIGHT-1][BOARD_LEFT+1] == EmptySquare &&
813 board[BOARD_HEIGHT-1][BOARD_LEFT+0] == BlackRook &&
814 castlingRights[4] != NoRights && /* [HGM] check rights */
815 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
817 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 1, FALSE) &&
818 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_LEFT+3, FALSE) &&
819 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 2, FALSE)))) {
821 callback(board, flags,
822 ff==BOARD_WIDTH>>1 ? BlackQueenSideCastle : BlackQueenSideCastleWild,
823 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - ((gameInfo.boardWidth+2)>>2), closure);
827 if(flags & F_FRC_TYPE_CASTLING) {
829 /* generate all potential FRC castling moves (KxR), ignoring flags */
830 /* [HGM] test if the Rooks we find have castling rights */
833 if ((flags & F_WHITE_ON_MOVE) != 0) {
834 ff = castlingRights[2]; /* King file if we have any rights */
835 if(ff != NoRights && board[0][ff] == WhiteKing) {
836 if (appData.debugMode) {
837 fprintf(debugFP, "FRC castling, %d %d %d %d %d %d\n",
838 castlingRights[0],castlingRights[1],ff,castlingRights[3],castlingRights[4],castlingRights[5]);
840 ft = castlingRights[0]; /* Rook file if we have H-side rights */
842 right = BOARD_RGHT-2;
843 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
844 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
845 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
846 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
847 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
848 if(ft != NoRights && board[0][ft] == WhiteRook)
849 callback(board, flags, WhiteHSideCastleFR, 0, ff, 0, ft, closure);
851 ft = castlingRights[1]; /* Rook file if we have A-side rights */
854 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
855 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
856 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
857 if(ff > BOARD_LEFT+2)
858 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
859 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
860 if(ft != NoRights && board[0][ft] == WhiteRook)
861 callback(board, flags, WhiteASideCastleFR, 0, ff, 0, ft, closure);
864 ff = castlingRights[5]; /* King file if we have any rights */
865 if(ff != NoRights && board[BOARD_HEIGHT-1][ff] == BlackKing) {
866 ft = castlingRights[3]; /* Rook file if we have H-side rights */
868 right = BOARD_RGHT-2;
869 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
870 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
871 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
872 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
873 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
874 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
875 callback(board, flags, BlackHSideCastleFR, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ft, closure);
877 ft = castlingRights[4]; /* Rook file if we have A-side rights */
880 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
881 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
882 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
883 if(ff > BOARD_LEFT+2)
884 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
885 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
886 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
887 callback(board, flags, BlackASideCastleFR, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ft, closure);
903 extern void CheckTestCallback P((Board board, int flags, ChessMove kind,
904 int rf, int ff, int rt, int ft,
908 void CheckTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
915 register CheckTestClosure *cl = (CheckTestClosure *) closure;
917 if (rt == cl->rking && ft == cl->fking) cl->check++;
921 /* If the player on move were to move from (rf, ff) to (rt, ft), would
922 he leave himself in check? Or if rf == -1, is the player on move
923 in check now? enPassant must be TRUE if the indicated move is an
924 e.p. capture. The possibility of castling out of a check along the
925 back rank is not accounted for (i.e., we still return nonzero), as
926 this is illegal anyway. Return value is the number of times the
928 int CheckTest(board, flags, rf, ff, rt, ft, enPassant)
931 int rf, ff, rt, ft, enPassant;
934 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
935 ChessSquare captured = EmptySquare;
936 /* Suppress warnings on uninitialized variables */
938 if(gameInfo.variant == VariantXiangqi)
939 king = flags & F_WHITE_ON_MOVE ? WhiteWazir : BlackWazir;
940 if(gameInfo.variant == VariantKnightmate)
941 king = flags & F_WHITE_ON_MOVE ? WhiteUnicorn : BlackUnicorn;
945 captured = board[rf][ft];
946 board[rf][ft] = EmptySquare;
948 captured = board[rt][ft];
950 board[rt][ft] = board[rf][ff];
951 board[rf][ff] = EmptySquare;
952 } else board[rt][ft] = ff; // [HGM] drop
954 /* For compatibility with ICS wild 9, we scan the board in the
955 order a1, a2, a3, ... b1, b2, ..., h8 to find the first king,
956 and we test only whether that one is in check. */
958 for (cl.fking = BOARD_LEFT+0; cl.fking < BOARD_RGHT; cl.fking++)
959 for (cl.rking = 0; cl.rking < BOARD_HEIGHT; cl.rking++) {
960 if (board[cl.rking][cl.fking] == king) {
961 if(gameInfo.variant == VariantXiangqi) {
962 /* [HGM] In Xiangqi opposing Kings means check as well */
964 dir = (king >= BlackPawn) ? -1 : 1;
965 for( i=cl.rking+dir; i>=0 && i<BOARD_HEIGHT &&
966 board[i][cl.fking] == EmptySquare; i+=dir );
967 if(i>=0 && i<BOARD_HEIGHT &&
968 board[i][cl.fking] == (dir>0 ? BlackWazir : WhiteWazir) )
972 GenPseudoLegal(board, flags ^ F_WHITE_ON_MOVE, CheckTestCallback, (VOIDSTAR) &cl);
973 goto undo_move; /* 2-level break */
980 board[rf][ff] = board[rt][ft];
982 board[rf][ft] = captured;
983 board[rt][ft] = EmptySquare;
985 board[rt][ft] = captured;
987 } else board[rt][ft] = EmptySquare; // [HGM] drop
989 return cl.fking < BOARD_RGHT ? cl.check : 1000; // [HGM] atomic: return 1000 if we have no king
992 ChessMove LegalDrop(board, flags, piece, rt, ft)
997 { // [HGM] put drop legality testing in separate routine for clarity
999 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
1000 if(board[rt][ft] != EmptySquare) return ImpossibleMove; // must drop to empty square
1001 n = PieceToNumber(piece);
1002 if(gameInfo.holdingsWidth == 0 || (flags & F_WHITE_ON_MOVE ? board[n][BOARD_WIDTH-1] : board[BOARD_HEIGHT-1-n][0]) != piece)
1003 return ImpossibleMove; // piece not available
1004 if(gameInfo.variant == VariantShogi) { // in Shogi lots of drops are forbidden!
1005 if((piece == WhitePawn || piece == WhiteQueen) && rt == BOARD_HEIGHT-1 ||
1006 (piece == BlackPawn || piece == BlackQueen) && rt == 0 ||
1007 piece == WhiteKnight && rt > BOARD_HEIGHT-3 ||
1008 piece == BlackKnight && rt < 2 ) return IllegalMove; // e.g. where dropped piece has no moves
1009 if(piece == WhitePawn || piece == BlackPawn) {
1011 for(r=1; r<BOARD_HEIGHT-1; r++)
1012 if(board[r][ft] == piece) return IllegalMove; // or there already is a Pawn in file
1013 // should still test if we mate with this Pawn
1016 if( (piece == WhitePawn || piece == BlackPawn) &&
1017 (rt == 0 || rt == BOARD_HEIGHT -1 ) )
1018 return IllegalMove; /* no pawn drops on 1st/8th */
1020 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
1021 if (!(flags & F_IGNORE_CHECK) &&
1022 CheckTest(board, flags, DROP_RANK, piece, rt, ft, FALSE) ) return IllegalMove;
1023 return flags & F_WHITE_ON_MOVE ? WhiteDrop : BlackDrop;
1026 extern void LegalityTestCallback P((Board board, int flags, ChessMove kind,
1027 int rf, int ff, int rt, int ft,
1030 void LegalityTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
1037 register LegalityTestClosure *cl = (LegalityTestClosure *) closure;
1039 // if (appData.debugMode) {
1040 // fprintf(debugFP, "Legality test: %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
1042 if(board[rt][ft] != EmptySquare || kind==WhiteCapturesEnPassant || kind==BlackCapturesEnPassant)
1043 cl->captures++; // [HGM] losers: count legal captures
1044 if (rf == cl->rf && ff == cl->ff && rt == cl->rt && ft == cl->ft)
1048 ChessMove LegalityTest(board, flags, rf, ff, rt, ft, promoChar)
1051 int rf, ff, rt, ft, promoChar;
1053 LegalityTestClosure cl; ChessSquare piece, *castlingRights = board[CASTLING];
1055 if(rf == DROP_RANK) return LegalDrop(board, flags, ff, rt, ft);
1056 piece = board[rf][ff];
1058 if (appData.debugMode) {
1060 for(i=0; i<6; i++) fprintf(debugFP, "%d ", castlingRights[i]);
1061 fprintf(debugFP, "Legality test? %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
1063 /* [HGM] Cobra and Falcon are wildcard pieces; consider all their moves legal */
1064 /* (perhaps we should disallow moves that obviously leave us in check?) */
1065 if(piece == WhiteFalcon || piece == BlackFalcon ||
1066 piece == WhiteCobra || piece == BlackCobra)
1067 return CheckTest(board, flags, rf, ff, rt, ft, FALSE) ? IllegalMove : NormalMove;
1073 cl.kind = IllegalMove;
1074 cl.captures = 0; // [HGM] losers: prepare to count legal captures.
1075 GenLegal(board, flags, LegalityTestCallback, (VOIDSTAR) &cl);
1076 if((flags & F_MANDATORY_CAPTURE) && cl.captures && board[rt][ft] == EmptySquare
1077 && cl.kind != WhiteCapturesEnPassant && cl.kind != BlackCapturesEnPassant)
1078 return(IllegalMove); // [HGM] losers: if there are legal captures, non-capts are illegal
1080 if(promoChar == 'x') promoChar = NULLCHAR; // [HGM] is this ever the case?
1081 if(gameInfo.variant == VariantShogi) {
1082 /* [HGM] Shogi promotions. '=' means defer */
1083 if(rf != DROP_RANK && cl.kind == NormalMove) {
1084 ChessSquare piece = board[rf][ff];
1086 if(promoChar == PieceToChar(BlackQueen)) promoChar = NULLCHAR; /* [HGM] Kludge */
1087 if(promoChar == 'd' && (piece == WhiteRook || piece == BlackRook) ||
1088 promoChar == 'h' && (piece == WhiteBishop || piece == BlackBishop) ||
1089 promoChar == 'g' && (piece <= WhiteFerz || piece <= BlackFerz && piece >= BlackPawn) )
1090 promoChar = '+'; // allowed ICS notations
1091 if(appData.debugMode)fprintf(debugFP,"SHOGI promoChar = %c\n", promoChar ? promoChar : '-');
1092 if(promoChar != NULLCHAR && promoChar != '+' && promoChar != '=')
1093 return CharToPiece(promoChar) == EmptySquare ? ImpossibleMove : IllegalMove;
1094 else if(flags & F_WHITE_ON_MOVE) {
1095 if( (int) piece < (int) WhiteWazir &&
1096 (rf >= BOARD_HEIGHT*2/3 || rt >= BOARD_HEIGHT*2/3) ) {
1097 if( (piece == WhitePawn || piece == WhiteQueen) && rt > BOARD_HEIGHT-2 ||
1098 piece == WhiteKnight && rt > BOARD_HEIGHT-3) /* promotion mandatory */
1099 cl.kind = promoChar == '=' ? IllegalMove : WhitePromotion;
1100 else /* promotion optional, default is defer */
1101 cl.kind = promoChar == '+' ? WhitePromotion : WhiteNonPromotion;
1102 } else cl.kind = promoChar == '+' ? IllegalMove : NormalMove;
1104 if( (int) piece < (int) BlackWazir && (rf < BOARD_HEIGHT/3 || rt < BOARD_HEIGHT/3) ) {
1105 if( (piece == BlackPawn || piece == BlackQueen) && rt < 1 ||
1106 piece == BlackKnight && rt < 2 ) /* promotion obligatory */
1107 cl.kind = promoChar == '=' ? IllegalMove : BlackPromotion;
1108 else /* promotion optional, default is defer */
1109 cl.kind = promoChar == '+' ? BlackPromotion : BlackNonPromotion;
1110 } else cl.kind = promoChar == '+' ? IllegalMove : NormalMove;
1114 if (promoChar != NULLCHAR) {
1115 if(promoChar == '=') cl.kind = IllegalMove; else // [HGM] shogi: no deferred promotion outside Shogi
1116 if (cl.kind == WhitePromotion || cl.kind == BlackPromotion) {
1117 if(CharToPiece(flags & F_WHITE_ON_MOVE ? ToUpper(promoChar) : ToLower(promoChar)) == EmptySquare)
1118 cl.kind = ImpossibleMove; // non-existing piece
1120 cl.kind = IllegalMove;
1130 extern void MateTestCallback P((Board board, int flags, ChessMove kind,
1131 int rf, int ff, int rt, int ft,
1134 void MateTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
1141 register MateTestClosure *cl = (MateTestClosure *) closure;
1146 /* Return MT_NONE, MT_CHECK, MT_CHECKMATE, or MT_STALEMATE */
1147 int MateTest(board, flags)
1152 int inCheck, r, f, myPieces=0, hisPieces=0, nrKing=0;
1153 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
1155 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) {
1156 // [HGM] losers: Count pieces and kings, to detect other unorthodox winning conditions
1157 nrKing += (board[r][f] == king); // stm has king
1158 if( board[r][f] != EmptySquare ) {
1159 if((int)board[r][f] <= (int)king && (int)board[r][f] >= (int)king - (int)WhiteKing + (int)WhitePawn)
1164 if(appData.debugMode) fprintf(debugFP, "MateTest: K=%d, my=%d, his=%d\n", nrKing, myPieces, hisPieces);
1165 switch(gameInfo.variant) { // [HGM] losers: extinction wins
1166 case VariantShatranj:
1167 if(hisPieces == 1) return myPieces > 1 ? MT_BARE : MT_DRAW;
1171 if(nrKing == 0) return MT_NOKING;
1174 if(myPieces == 1) return MT_BARE;
1177 inCheck = GenLegal(board, flags, MateTestCallback, (VOIDSTAR) &cl);
1178 // [HGM] 3check: yet to do!
1180 return inCheck ? MT_CHECK : MT_NONE;
1182 if(gameInfo.holdingsWidth && gameInfo.variant != VariantSuper || gameInfo.variant != VariantGreat) { // drop game
1183 int r, f, n, holdings = flags & F_WHITE_ON_MOVE ? BOARD_WIDTH-1 : 0;
1184 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) if(board[r][f] == EmptySquare) // all empty squares
1185 for(n=0; n<BOARD_HEIGHT; n++) // all pieces in hand
1186 if(board[n][holdings] != EmptySquare) {
1187 int moveType = LegalDrop(board, flags, board[n][holdings], r, f);
1188 if(moveType == WhiteDrop || moveType == BlackDrop) return MT_CHECK; // we can resolve check by legal drop
1191 if(gameInfo.variant == VariantSuicide) // [HGM] losers: always stalemate, since no check, but result varies
1192 return myPieces == hisPieces ? MT_STALEMATE :
1193 myPieces > hisPieces ? MT_STAINMATE : MT_STEALMATE;
1194 else if(gameInfo.variant == VariantLosers) return inCheck ? MT_TRICKMATE : MT_STEALMATE;
1195 else if(gameInfo.variant == VariantGiveaway) return MT_STEALMATE; // no check exists, stalemated = win
1197 return inCheck ? MT_CHECKMATE
1198 : (gameInfo.variant == VariantXiangqi || gameInfo.variant == VariantShatranj) ?
1199 MT_STAINMATE : MT_STALEMATE;
1204 extern void DisambiguateCallback P((Board board, int flags, ChessMove kind,
1205 int rf, int ff, int rt, int ft,
1208 void DisambiguateCallback(board, flags, kind, rf, ff, rt, ft, closure)
1215 register DisambiguateClosure *cl = (DisambiguateClosure *) closure;
1216 int wildCard = FALSE; ChessSquare piece = board[rf][ff];
1218 // [HGM] wild: for wild-card pieces rt and rf are dummies
1219 if(piece == WhiteFalcon || piece == BlackFalcon ||
1220 piece == WhiteCobra || piece == BlackCobra)
1223 if ((cl->pieceIn == EmptySquare || cl->pieceIn == board[rf][ff]
1224 || PieceToChar(board[rf][ff]) == '~'
1225 && cl->pieceIn == (ChessSquare)(DEMOTED board[rf][ff])
1227 (cl->rfIn == -1 || cl->rfIn == rf) &&
1228 (cl->ffIn == -1 || cl->ffIn == ff) &&
1229 (cl->rtIn == -1 || cl->rtIn == rt || wildCard) &&
1230 (cl->ftIn == -1 || cl->ftIn == ft || wildCard)) {
1233 if(cl->count == 1 || board[rt][ft] != EmptySquare) {
1234 // [HGM] oneclick: if multiple moves, be sure we remember capture
1235 cl->piece = board[rf][ff];
1238 cl->rt = wildCard ? cl->rtIn : rt;
1239 cl->ft = wildCard ? cl->ftIn : ft;
1242 cl->captures += (board[rt][ft] != EmptySquare); // [HGM] oneclick: count captures
1246 void Disambiguate(board, flags, closure)
1249 DisambiguateClosure *closure;
1251 int illegal = 0; char c = closure->promoCharIn;
1253 closure->count = closure->captures = 0;
1254 closure->rf = closure->ff = closure->rt = closure->ft = 0;
1255 closure->kind = ImpossibleMove;
1256 if (appData.debugMode) {
1257 fprintf(debugFP, "Disambiguate in: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1258 closure->pieceIn,closure->ffIn,closure->rfIn,closure->ftIn,closure->rtIn,
1259 closure->promoCharIn, closure->promoCharIn >= ' ' ? closure->promoCharIn : '-');
1261 GenLegal(board, flags, DisambiguateCallback, (VOIDSTAR) closure);
1262 if (closure->count == 0) {
1263 /* See if it's an illegal move due to check */
1265 GenLegal(board, flags|F_IGNORE_CHECK, DisambiguateCallback, (VOIDSTAR) closure);
1266 if (closure->count == 0) {
1267 /* No, it's not even that */
1268 if (appData.debugMode) { int i, j;
1269 for(i=BOARD_HEIGHT-1; i>=0; i--) {
1270 for(j=0; j<BOARD_WIDTH; j++)
1271 fprintf(debugFP, "%3d", (int) board[i][j]);
1272 fprintf(debugFP, "\n");
1279 if (c == 'x') c = NULLCHAR; // get rid of any 'x' (which should never happen?)
1280 if(gameInfo.variant == VariantShogi) {
1281 /* [HGM] Shogi promotions. On input, '=' means defer, '+' promote. Afterwards, c is set to '+' for promotions, NULL other */
1282 if(closure->rfIn != DROP_RANK && closure->kind == NormalMove) {
1283 ChessSquare piece = closure->piece;
1284 if (c == 'd' && (piece == WhiteRook || piece == BlackRook) ||
1285 c == 'h' && (piece == WhiteBishop || piece == BlackBishop) ||
1286 c == 'g' && (piece <= WhiteFerz || piece <= BlackFerz && piece >= BlackPawn) )
1287 c = '+'; // allowed ICS notations
1288 if(c != NULLCHAR && c != '+' && c != '=') closure->kind = IllegalMove; // otherwise specifying a piece is illegal
1289 else if(flags & F_WHITE_ON_MOVE) {
1290 if( (int) piece < (int) WhiteWazir &&
1291 (closure->rf >= BOARD_HEIGHT-(BOARD_HEIGHT/3) || closure->rt >= BOARD_HEIGHT-(BOARD_HEIGHT/3)) ) {
1292 if( (piece == WhitePawn || piece == WhiteQueen) && closure->rt > BOARD_HEIGHT-2 ||
1293 piece == WhiteKnight && closure->rt > BOARD_HEIGHT-3) /* promotion mandatory */
1294 closure->kind = c == '=' ? IllegalMove : WhitePromotion;
1295 else /* promotion optional, default is defer */
1296 closure->kind = c == '+' ? WhitePromotion : WhiteNonPromotion;
1297 } else closure->kind = c == '+' ? IllegalMove : NormalMove;
1299 if( (int) piece < (int) BlackWazir && (closure->rf < BOARD_HEIGHT/3 || closure->rt < BOARD_HEIGHT/3) ) {
1300 if( (piece == BlackPawn || piece == BlackQueen) && closure->rt < 1 ||
1301 piece == BlackKnight && closure->rt < 2 ) /* promotion obligatory */
1302 closure->kind = c == '=' ? IllegalMove : BlackPromotion;
1303 else /* promotion optional, default is defer */
1304 closure->kind = c == '+' ? BlackPromotion : BlackNonPromotion;
1305 } else closure->kind = c == '+' ? IllegalMove : NormalMove;
1308 if(closure->kind == WhitePromotion || closure->kind == BlackPromotion) c = '+'; else
1309 if(closure->kind == WhiteNonPromotion || closure->kind == BlackNonPromotion) c = '=';
1311 if (closure->kind == WhitePromotion || closure->kind == BlackPromotion) {
1312 if(c == NULLCHAR) { // missing promoChar on mandatory promotion; use default for variant
1313 if(gameInfo.variant == VariantShatranj || gameInfo.variant == VariantCourier || gameInfo.variant == VariantMakruk)
1314 c = PieceToChar(BlackFerz);
1315 else if(gameInfo.variant == VariantGreat)
1316 c = PieceToChar(BlackMan);
1318 c = PieceToChar(BlackQueen);
1319 } else if(c == '=') closure->kind = IllegalMove; // no deferral outside Shogi
1320 } else if (c != NULLCHAR) closure->kind = IllegalMove;
1322 closure->promoChar = ToLower(c); // this can be NULLCHAR! Note we keep original promoChar even if illegal.
1323 if(c != '+' && c != '=' && c != NULLCHAR && CharToPiece(flags & F_WHITE_ON_MOVE ? ToUpper(c) : ToLower(c)) == EmptySquare)
1324 closure->kind = ImpossibleMove; // but we cannot handle non-existing piece types!
1325 if (closure->count > 1) {
1326 closure->kind = AmbiguousMove;
1329 /* Note: If more than one illegal move matches, but no legal
1330 moves, we return IllegalMove, not AmbiguousMove. Caller
1331 can look at closure->count to detect this.
1333 closure->kind = IllegalMove;
1335 if (appData.debugMode) {
1336 fprintf(debugFP, "Disambiguate out: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1337 closure->piece,closure->ff,closure->rf,closure->ft,closure->rt,closure->promoChar,
1338 closure->promoChar >= ' ' ? closure->promoChar:'-');
1352 } CoordsToAlgebraicClosure;
1354 extern void CoordsToAlgebraicCallback P((Board board, int flags,
1355 ChessMove kind, int rf, int ff,
1356 int rt, int ft, VOIDSTAR closure));
1358 void CoordsToAlgebraicCallback(board, flags, kind, rf, ff, rt, ft, closure)
1365 register CoordsToAlgebraicClosure *cl =
1366 (CoordsToAlgebraicClosure *) closure;
1368 if ((rt == cl->rt && ft == cl->ft || rt == rf && ft == ff) && // [HGM] null move matches any toSquare
1369 (board[rf][ff] == cl->piece
1370 || PieceToChar(board[rf][ff]) == '~' &&
1371 (ChessSquare) (DEMOTED board[rf][ff]) == cl->piece)
1375 cl->kind = kind; /* this is the move we want */
1377 cl->file++; /* need file to rule out this move */
1381 cl->rank++; /* need rank to rule out this move */
1383 cl->either++; /* rank or file will rule out this move */
1389 /* Convert coordinates to normal algebraic notation.
1390 promoChar must be NULLCHAR or 'x' if not a promotion.
1392 ChessMove CoordsToAlgebraic(board, flags, rf, ff, rt, ft, promoChar, out)
1401 char *outp = out, c;
1402 CoordsToAlgebraicClosure cl;
1404 if (rf == DROP_RANK) {
1405 /* Bughouse piece drop */
1406 *outp++ = ToUpper(PieceToChar((ChessSquare) ff));
1411 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1413 return (flags & F_WHITE_ON_MOVE) ? WhiteDrop : BlackDrop;
1416 if (promoChar == 'x') promoChar = NULLCHAR;
1417 piece = board[rf][ff];
1418 if(PieceToChar(piece)=='~') piece = (ChessSquare)(DEMOTED piece);
1420 if (appData.debugMode)
1421 fprintf(debugFP, "CoordsToAlgebraic, piece=%d (%d,%d)-(%d,%d) %c\n", (int)piece,ff,rf,ft,rt,promoChar >= ' ' ? promoChar : '-');
1425 kind = LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1426 if (kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1427 /* Keep short notation if move is illegal only because it
1428 leaves the player in check, but still return IllegalMove */
1429 kind = LegalityTest(board, flags|F_IGNORE_CHECK, rf, ff, rt, ft, promoChar);
1430 if (kind == IllegalMove) break;
1435 if (ff == ft && board[rt][ft] == EmptySquare) { /* [HGM] Xiangqi has straight noncapts! */
1436 /* Non-capture; use style "e5" */
1439 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1441 /* Capture; use style "exd5" */
1442 if(gameInfo.variant != VariantXiangqi || board[rt][ft] != EmptySquare )
1443 *outp++ = 'x'; /* [HGM] Xiangqi has sideway noncaptures across river! */
1447 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1449 /* Use promotion suffix style "=Q" */
1451 if (appData.debugMode)
1452 fprintf(debugFP, "movetype=%d, promochar=%d=%c\n", (int)kind, promoChar, promoChar >= ' ' ? promoChar : '-');
1453 if (promoChar != NULLCHAR) {
1454 if(gameInfo.variant == VariantShogi) {
1455 /* [HGM] ... but not in Shogi! */
1456 *outp++ = promoChar == '=' ? '=' : '+';
1459 *outp++ = ToUpper(promoChar);
1468 /* Fabien moved code: FRC castling first (if KxR), wild castling second */
1469 /* Code added by Tord: FRC castling. */
1470 if((piece == WhiteKing && board[rt][ft] == WhiteRook) ||
1471 (piece == BlackKing && board[rt][ft] == BlackRook)) {
1473 safeStrCpy(out, "O-O", MOVE_LEN);
1475 safeStrCpy(out, "O-O-O", MOVE_LEN);
1476 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1478 /* End of code added by Tord */
1479 /* Test for castling or ICS wild castling */
1480 /* Use style "O-O" (oh-oh) for PGN compatibility */
1481 else if (rf == rt &&
1482 rf == ((piece == WhiteKing) ? 0 : BOARD_HEIGHT-1) &&
1483 (ft - ff > 1 || ff - ft > 1) && // No castling if legal King move (on narrow boards!)
1484 ((ff == BOARD_WIDTH>>1 && (ft == BOARD_LEFT+2 || ft == BOARD_RGHT-2)) ||
1485 (ff == (BOARD_WIDTH-1)>>1 && (ft == BOARD_LEFT+1 || ft == BOARD_RGHT-3)))) {
1486 if(ft==BOARD_LEFT+1 || ft==BOARD_RGHT-2)
1487 safeStrCpy(out, "O-O", MOVE_LEN);
1489 safeStrCpy(out, "O-O-O", MOVE_LEN);
1491 /* This notation is always unambiguous, unless there are
1492 kings on both the d and e files, with "wild castling"
1493 possible for the king on the d file and normal castling
1494 possible for the other. ICS rules for wild 9
1495 effectively make castling illegal for either king in
1496 this situation. So I am not going to worry about it;
1497 I'll just generate an ambiguous O-O in this case.
1499 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1502 /* else fall through */
1510 cl.kind = IllegalMove;
1511 cl.rank = cl.file = cl.either = 0;
1512 GenLegal(board, flags, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1514 if (cl.kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1515 /* Generate pretty moves for moving into check, but
1516 still return IllegalMove.
1518 GenLegal(board, flags|F_IGNORE_CHECK, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1519 if (cl.kind == IllegalMove) break;
1520 cl.kind = IllegalMove;
1523 /* Style is "Nf3" or "Nxf7" if this is unambiguous,
1524 else "Ngf3" or "Ngxf7",
1525 else "N1f3" or "N5xf7",
1526 else "Ng1f3" or "Ng5xf7".
1528 c = PieceToChar(piece) ;
1529 if( c == '~' || c == '+') {
1530 /* [HGM] print nonexistent piece as its demoted version */
1531 piece = (ChessSquare) (DEMOTED piece);
1533 if(c=='+') *outp++ = c;
1534 *outp++ = ToUpper(PieceToChar(piece));
1536 if (cl.file || (cl.either && !cl.rank)) {
1542 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1545 if(board[rt][ft] != EmptySquare)
1551 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1552 if (gameInfo.variant == VariantShogi) {
1553 /* [HGM] in Shogi non-pawns can promote */
1554 *outp++ = promoChar; // Don't bother to correct move type, return value is never used!
1560 /* Moving a nonexistent piece */
1564 /* Not a legal move, even ignoring check.
1565 If there was a piece on the from square,
1566 use style "Ng1g3" or "Ng1xe8";
1567 if there was a pawn or nothing (!),
1568 use style "g1g3" or "g1xe8". Use "x"
1569 if a piece was on the to square, even
1570 a piece of the same color.
1574 if (piece != EmptySquare && piece != WhitePawn && piece != BlackPawn) {
1576 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<=BOARD_RGHT; f++)
1577 c += (board[r][f] == piece); // count on-board pieces of given type
1578 *outp++ = ToUpper(PieceToChar(piece));
1580 if(c != 1) { // [HGM] but if there is only one piece of the mentioned type, no from-square, thank you!
1584 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1586 if (board[rt][ft] != EmptySquare) *outp++ = 'x';
1590 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1591 /* Use promotion suffix style "=Q" */
1592 if (promoChar != NULLCHAR && promoChar != 'x') {
1594 *outp++ = ToUpper(promoChar);
1601 // [HGM] XQ: the following code serves to detect perpetual chasing (Asian rules)
1610 // I guess the following variables logically belong in the closure too, but I was too lazy and used globals
1612 int preyStackPointer, chaseStackPointer;
1615 char rf, ff, rt, ft;
1625 // there are three new callbacks for use with GenLegal: for adding captures, deleting them, and finding a recapture
1627 extern void AtacksCallback P((Board board, int flags, ChessMove kind,
1628 int rf, int ff, int rt, int ft,
1631 void AttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1637 { // For adding captures that can lead to chase indictment to the chaseStack
1638 if(board[rt][ft] == EmptySquare) return; // non-capture
1639 if(board[rt][ft] == WhitePawn && rt < BOARD_HEIGHT/2) return; // Pawn before river can be chased
1640 if(board[rt][ft] == BlackPawn && rt >= BOARD_HEIGHT/2) return; // Pawn before river can be chased
1641 if(board[rf][ff] == WhitePawn || board[rf][ff] == BlackPawn) return; // Pawns are allowed to chase
1642 if(board[rf][ff] == WhiteWazir || board[rf][ff] == BlackWazir) return; // King is allowed to chase
1643 // move cannot be excluded from being a chase trivially (based on attacker and victim); save it on chaseStack
1644 chaseStack[chaseStackPointer].rf = rf;
1645 chaseStack[chaseStackPointer].ff = ff;
1646 chaseStack[chaseStackPointer].rt = rt;
1647 chaseStack[chaseStackPointer].ft = ft;
1648 chaseStackPointer++;
1651 extern void ExistingAtacksCallback P((Board board, int flags, ChessMove kind,
1652 int rf, int ff, int rt, int ft,
1655 void ExistingAttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1661 { // for removing pre-exsting captures from the chaseStack, to be left with newly created ones
1663 register ChaseClosure *cl = (ChaseClosure *) closure; //closure tells us the move played in the repeat loop
1665 if(board[rt][ft] == EmptySquare) return; // no capture
1666 if(rf == cl->rf && ff == cl->ff) { // attacks with same piece from new position are not considered new
1667 rf = cl->rt; ff = cl->ft; // doctor their fromSquare so they will be recognized in chaseStack
1669 // search move in chaseStack, and delete it if it occurred there (as we know now it is not a new capture)
1670 for(i=0; i<chaseStackPointer; i++) {
1671 if(chaseStack[i].rf == rf && chaseStack[i].ff == ff &&
1672 chaseStack[i].rt == rt && chaseStack[i].ft == ft ) {
1673 // move found on chaseStack, delete it by overwriting with move popped from top of chaseStack
1674 chaseStack[i] = chaseStack[--chaseStackPointer];
1680 extern void ProtectedCallback P((Board board, int flags, ChessMove kind,
1681 int rf, int ff, int rt, int ft,
1684 void ProtectedCallback(board, flags, kind, rf, ff, rt, ft, closure)
1690 { // for determining if a piece (given through the closure) is protected
1691 register ChaseClosure *cl = (ChaseClosure *) closure; // closure tells us where to recapture
1693 if(rt == cl->rt && ft == cl->ft) cl->recaptures++; // count legal recaptures to this square
1694 if(appData.debugMode && board[rt][ft] != EmptySquare)
1695 fprintf(debugFP, "try %c%c%c%c=%d\n", ff+AAA, rf+ONE,ft+AAA, rt+ONE, cl->recaptures);
1698 extern char moveList[MAX_MOVES][MOVE_LEN];
1700 int PerpetualChase(int first, int last)
1701 { // this routine detects if the side to move in the 'first' position is perpetually chasing (when not checking)
1704 ChessSquare captured;
1706 preyStackPointer = 0; // clear stack of chased pieces
1707 for(i=first; i<last; i+=2) { // for all positions with same side to move
1708 if(appData.debugMode) fprintf(debugFP, "judge position %i\n", i);
1709 chaseStackPointer = 0; // clear stack that is going to hold possible chases
1710 // determine all captures possible after the move, and put them on chaseStack
1711 GenLegal(boards[i+1], PosFlags(i), AttacksCallback, &cl);
1712 if(appData.debugMode) { int n;
1713 for(n=0; n<chaseStackPointer; n++)
1714 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1715 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1716 fprintf(debugFP, ": all capts\n");
1718 // determine all captures possible before the move, and delete them from chaseStack
1719 cl.rf = moveList[i][1]-ONE; // prepare closure to pass move that led from i to i+1
1720 cl.ff = moveList[i][0]-AAA+BOARD_LEFT;
1721 cl.rt = moveList[i][3]-ONE;
1722 cl.ft = moveList[i][2]-AAA+BOARD_LEFT;
1723 GenLegal(boards[i], PosFlags(i), ExistingAttacksCallback, &cl);
1724 if(appData.debugMode) { int n;
1725 for(n=0; n<chaseStackPointer; n++)
1726 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1727 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1728 fprintf(debugFP, ": new capts after %c%c%c%c\n", cl.ff+AAA, cl.rf+ONE, cl.ft+AAA, cl.rt+ONE);
1730 // chaseSack now contains all captures made possible by the move
1731 for(j=0; j<chaseStackPointer; j++) { // run through chaseStack to identify true chases
1732 int attacker = (int)boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1733 int victim = (int)boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1735 if(attacker >= (int) BlackPawn) attacker = BLACK_TO_WHITE attacker; // convert to white, as piecee type
1736 if(victim >= (int) BlackPawn) victim = BLACK_TO_WHITE victim;
1738 if((attacker == WhiteKnight || attacker == WhiteCannon) && victim == WhiteRook)
1739 continue; // C or H attack on R is always chase; leave on chaseStack
1741 if(attacker == victim) {
1742 if(LegalityTest(boards[i+1], PosFlags(i+1), chaseStack[j].rt,
1743 chaseStack[j].ft, chaseStack[j].rf, chaseStack[j].ff, NULLCHAR) == NormalMove) {
1744 // we can capture back with equal piece, so this is no chase but a sacrifice
1745 chaseStack[j] = chaseStack[--chaseStackPointer]; // delete the capture from the chaseStack
1746 j--; /* ! */ continue;
1751 // the attack is on a lower piece, or on a pinned or blocked equal one
1752 // test if the victim is protected by a true protector. First make the capture.
1753 captured = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1754 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1755 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = EmptySquare;
1756 // Then test if the opponent can recapture
1757 cl.recaptures = 0; // prepare closure to pass recapture square and count moves to it
1758 cl.rt = chaseStack[j].rt;
1759 cl.ft = chaseStack[j].ft;
1760 if(appData.debugMode) {
1761 fprintf(debugFP, "test if we can recapture %c%c\n", cl.ft+AAA, cl.rt+ONE);
1763 GenLegal(boards[i+1], PosFlags(i+1), ProtectedCallback, &cl); // try all moves
1764 // unmake the capture
1765 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1766 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = captured;
1767 // if a recapture was found, piece is protected, and we are not chasing it.
1768 if(cl.recaptures) { // attacked piece was defended by true protector, no chase
1769 chaseStack[j] = chaseStack[--chaseStackPointer]; // so delete from chaseStack
1773 // chaseStack now contains all moves that chased
1774 if(appData.debugMode) { int n;
1775 for(n=0; n<chaseStackPointer; n++)
1776 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1777 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1778 fprintf(debugFP, ": chases\n");
1780 if(i == first) { // copy all people chased by first move of repeat cycle to preyStack
1781 for(j=0; j<chaseStackPointer; j++) {
1782 preyStack[j].rank = chaseStack[j].rt;
1783 preyStack[j].file = chaseStack[j].ft;
1785 preyStackPointer = chaseStackPointer;
1788 for(j=0; j<chaseStackPointer; j++) {
1789 for(k=0; k<preyStackPointer; k++) {
1790 // search the victim of each chase move on the preyStack (first occurrence)
1791 if(chaseStack[j].ft == preyStack[k].file && chaseStack[j].rt == preyStack[k].rank ) {
1792 if(k < tail) break; // piece was already identified as still being chased
1793 preyStack[preyStackPointer] = preyStack[tail]; // move chased piece to bottom part of preyStack
1794 preyStack[tail] = preyStack[k]; // by swapping
1795 preyStack[k] = preyStack[preyStackPointer];
1801 preyStackPointer = tail; // keep bottom part of preyStack, popping pieces unchased on move i.
1802 if(appData.debugMode) { int n;
1803 for(n=0; n<preyStackPointer; n++)
1804 fprintf(debugFP, "%c%c ", preyStack[n].file+AAA, preyStack[n].rank+ONE);
1805 fprintf(debugFP, "always chased upto ply %d\n", i);
1807 // now adjust the location of the chased pieces according to opponent move
1808 for(j=0; j<preyStackPointer; j++) {
1809 if(preyStack[j].rank == moveList[i+1][1]-ONE &&
1810 preyStack[j].file == moveList[i+1][0]-AAA+BOARD_LEFT) {
1811 preyStack[j].rank = moveList[i+1][3]-ONE;
1812 preyStack[j].file = moveList[i+1][2]-AAA+BOARD_LEFT;
1817 return preyStackPointer; // if any piece was left on preyStack, it has been perpetually chased