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, 2011 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++) {
185 int rookRange = 1000;
187 if (flags & F_WHITE_ON_MOVE) {
188 if (!WhitePiece(board[rf][ff])) continue;
190 if (!BlackPiece(board[rf][ff])) continue;
192 m = 0; piece = board[rf][ff];
193 if(PieceToChar(piece) == '~')
194 piece = (ChessSquare) ( DEMOTED piece );
195 if(gameInfo.variant == VariantShogi)
196 piece = (ChessSquare) ( SHOGI piece );
199 /* case EmptySquare: [HGM] this is nonsense, and conflicts with Shogi cases */
201 /* can't happen ([HGM] except for faries...) */
205 if(gameInfo.variant == VariantXiangqi) {
206 /* [HGM] capture and move straight ahead in Xiangqi */
207 if (rf < BOARD_HEIGHT-1 &&
208 !SameColor(board[rf][ff], board[rf + 1][ff]) ) {
209 callback(board, flags, NormalMove,
210 rf, ff, rf + 1, ff, closure);
212 /* and move sideways when across the river */
213 for (s = -1; s <= 1; s += 2) {
214 if (rf >= BOARD_HEIGHT>>1 &&
215 ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
216 !WhitePiece(board[rf][ff+s]) ) {
217 callback(board, flags, NormalMove,
218 rf, ff, rf, ff+s, closure);
223 if (rf < BOARD_HEIGHT-1 && board[rf + 1][ff] == EmptySquare) {
224 callback(board, flags,
225 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
226 rf, ff, rf + 1, ff, closure);
228 if (rf == 1 && board[2][ff] == EmptySquare &&
229 gameInfo.variant != VariantShatranj && /* [HGM] */
230 gameInfo.variant != VariantCourier && /* [HGM] */
231 board[3][ff] == EmptySquare ) {
232 callback(board, flags, NormalMove,
233 rf, ff, 3, ff, closure);
235 for (s = -1; s <= 1; s += 2) {
236 if (rf < BOARD_HEIGHT-1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
237 ((flags & F_KRIEGSPIEL_CAPTURE) ||
238 BlackPiece(board[rf + 1][ff + s]))) {
239 callback(board, flags,
240 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
241 rf, ff, rf + 1, ff + s, closure);
243 if (rf == BOARD_HEIGHT-4) {
244 if (ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
245 (epfile == ff + s || epfile == EP_UNKNOWN) &&
246 board[BOARD_HEIGHT-4][ff + s] == BlackPawn &&
247 board[BOARD_HEIGHT-3][ff + s] == EmptySquare) {
248 callback(board, flags, WhiteCapturesEnPassant,
249 rf, ff, 5, ff + s, closure);
256 if(gameInfo.variant == VariantXiangqi) {
257 /* [HGM] capture straight ahead in Xiangqi */
258 if (rf > 0 && !SameColor(board[rf][ff], board[rf - 1][ff]) ) {
259 callback(board, flags, NormalMove,
260 rf, ff, rf - 1, ff, closure);
262 /* and move sideways when across the river */
263 for (s = -1; s <= 1; s += 2) {
264 if (rf < BOARD_HEIGHT>>1 &&
265 ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
266 !BlackPiece(board[rf][ff+s]) ) {
267 callback(board, flags, NormalMove,
268 rf, ff, rf, ff+s, closure);
273 if (rf > 0 && board[rf - 1][ff] == EmptySquare) {
274 callback(board, flags,
275 rf <= promoRank ? BlackPromotion : NormalMove,
276 rf, ff, rf - 1, ff, closure);
278 if (rf == BOARD_HEIGHT-2 && board[BOARD_HEIGHT-3][ff] == EmptySquare &&
279 gameInfo.variant != VariantShatranj && /* [HGM] */
280 gameInfo.variant != VariantCourier && /* [HGM] */
281 board[BOARD_HEIGHT-4][ff] == EmptySquare) {
282 callback(board, flags, NormalMove,
283 rf, ff, BOARD_HEIGHT-4, ff, closure);
285 for (s = -1; s <= 1; s += 2) {
286 if (rf > 0 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
287 ((flags & F_KRIEGSPIEL_CAPTURE) ||
288 WhitePiece(board[rf - 1][ff + s]))) {
289 callback(board, flags,
290 rf <= promoRank ? BlackPromotion : NormalMove,
291 rf, ff, rf - 1, ff + s, closure);
294 if (ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
295 (epfile == ff + s || epfile == EP_UNKNOWN) &&
296 board[3][ff + s] == WhitePawn &&
297 board[2][ff + s] == EmptySquare) {
298 callback(board, flags, BlackCapturesEnPassant,
299 rf, ff, 2, ff + s, closure);
310 for (i = -1; i <= 1; i += 2)
311 for (j = -1; j <= 1; j += 2)
312 for (s = 1; s <= 2; s++) {
315 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
316 && ( gameInfo.variant != VariantXiangqi || board[rf+i*(s-1)][ff+j*(2-s)] == EmptySquare)
317 && !SameColor(board[rf][ff], board[rt][ft]))
318 callback(board, flags, NormalMove,
319 rf, ff, rt, ft, closure);
323 case SHOGI WhiteKnight:
324 for (s = -1; s <= 1; s += 2) {
325 if (rf < BOARD_HEIGHT-2 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
326 !SameColor(board[rf][ff], board[rf + 2][ff + s])) {
327 callback(board, flags, NormalMove,
328 rf, ff, rf + 2, ff + s, closure);
333 case SHOGI BlackKnight:
334 for (s = -1; s <= 1; s += 2) {
335 if (rf > 1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
336 !SameColor(board[rf][ff], board[rf - 2][ff + s])) {
337 callback(board, flags, NormalMove,
338 rf, ff, rf - 2, ff + s, closure);
345 for (d = 0; d <= 1; d++)
346 for (s = -1; s <= 1; s += 2) {
349 rt = rf + (i * s) * d;
350 ft = ff + (i * s) * (1 - d);
351 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
352 if (m == 0 && board[rt][ft] == EmptySquare)
353 callback(board, flags, NormalMove,
354 rf, ff, rt, ft, closure);
355 if (m == 1 && board[rt][ft] != EmptySquare &&
356 !SameColor(board[rf][ff], board[rt][ft]) )
357 callback(board, flags, NormalMove,
358 rf, ff, rt, ft, closure);
359 if (board[rt][ft] != EmptySquare && m++) break;
364 /* Gold General (and all its promoted versions) . First do the */
365 /* diagonal forward steps, then proceed as normal Wazir */
366 case SHOGI WhiteWazir:
367 case SHOGI (PROMOTED WhitePawn):
368 case SHOGI (PROMOTED WhiteKnight):
369 case SHOGI (PROMOTED WhiteQueen):
370 case SHOGI (PROMOTED WhiteFerz):
371 for (s = -1; s <= 1; s += 2) {
372 if (rf < BOARD_HEIGHT-1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
373 !SameColor(board[rf][ff], board[rf + 1][ff + s])) {
374 callback(board, flags, NormalMove,
375 rf, ff, rf + 1, ff + s, closure);
380 case SHOGI BlackWazir:
381 case SHOGI (PROMOTED BlackPawn):
382 case SHOGI (PROMOTED BlackKnight):
383 case SHOGI (PROMOTED BlackQueen):
384 case SHOGI (PROMOTED BlackFerz):
385 for (s = -1; s <= 1; s += 2) {
386 if (rf > 0 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
387 !SameColor(board[rf][ff], board[rf - 1][ff + s])) {
388 callback(board, flags, NormalMove,
389 rf, ff, rf - 1, ff + s, closure);
396 for (d = 0; d <= 1; d++)
397 for (s = -1; s <= 1; s += 2) {
399 ft = ff + s * (1 - d);
400 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
401 && !SameColor(board[rf][ff], board[rt][ft]) &&
402 (gameInfo.variant != VariantXiangqi || InPalace(rt, ft) ) )
403 callback(board, flags, NormalMove,
404 rf, ff, rt, ft, closure);
410 /* [HGM] support Shatranj pieces */
411 for (rs = -1; rs <= 1; rs += 2)
412 for (fs = -1; fs <= 1; fs += 2) {
415 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
416 && ( gameInfo.variant != VariantXiangqi ||
417 board[rf+rs][ff+fs] == EmptySquare && (2*rf < BOARD_HEIGHT) == (2*rt < BOARD_HEIGHT) )
419 && !SameColor(board[rf][ff], board[rt][ft]))
420 callback(board, flags, NormalMove,
421 rf, ff, rt, ft, closure);
422 if(gameInfo.variant == VariantShatranj || gameInfo.variant == VariantCourier
423 || gameInfo.variant == VariantXiangqi) continue; // classical Alfil
424 rt = rf + rs; // in unknown variant we assume Modern Elephant, which can also do one step
426 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
427 && !SameColor(board[rf][ff], board[rt][ft]))
428 callback(board, flags, NormalMove,
429 rf, ff, rt, ft, closure);
431 if(gameInfo.variant == VariantSpartan)
432 for(fs = -1; fs <= 1; fs += 2) {
434 if (!(ft < BOARD_LEFT || ft >= BOARD_RGHT) && board[rf][ft] == EmptySquare)
435 callback(board, flags, NormalMove, rf, ff, rf, ft, closure);
439 /* Make Dragon-Horse also do Dababba moves outside Shogi, for better disambiguation in variant Fairy */
442 for (d = 0; d <= 1; d++) // Dababba moves that Rook cannot do
443 for (s = -2; s <= 2; s += 4) {
445 ft = ff + s * (1 - d);
446 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
447 if (SameColor(board[rf][ff], board[rt][ft])) continue;
448 callback(board, flags, NormalMove, rf, ff, rt, ft, closure);
451 /* Shogi Dragon Horse has to continue with Wazir after Bishop */
452 case SHOGI WhiteCardinal:
453 case SHOGI BlackCardinal:
456 /* Capablanca Archbishop continues as Knight */
461 /* Shogi Bishops are ordinary Bishops */
462 case SHOGI WhiteBishop:
463 case SHOGI BlackBishop:
466 for (rs = -1; rs <= 1; rs += 2)
467 for (fs = -1; fs <= 1; fs += 2)
471 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
472 if (SameColor(board[rf][ff], board[rt][ft])) break;
473 callback(board, flags, NormalMove,
474 rf, ff, rt, ft, closure);
475 if (board[rt][ft] != EmptySquare) break;
477 if(m==1) goto mounted;
478 if(m==2) goto finishGold;
479 /* Bishop falls through */
482 /* Shogi Lance is unlike anything, and asymmetric at that */
483 case SHOGI WhiteQueen:
487 if (rt >= BOARD_HEIGHT) break;
488 if (SameColor(board[rf][ff], board[rt][ft])) break;
489 callback(board, flags, NormalMove,
490 rf, ff, rt, ft, closure);
491 if (board[rt][ft] != EmptySquare) break;
495 case SHOGI BlackQueen:
500 if (SameColor(board[rf][ff], board[rt][ft])) break;
501 callback(board, flags, NormalMove,
502 rf, ff, rt, ft, closure);
503 if (board[rt][ft] != EmptySquare) break;
507 /* Make Dragon-King Dababba & Rook-like outside Shogi, for better disambiguation in variant Fairy */
510 for (d = 0; d <= 1; d++) // Dababba moves that Rook cannot do
511 for (s = -2; s <= 2; s += 4) {
513 ft = ff + s * (1 - d);
514 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT || board[rf+rt>>1][ff+ft>>1] == EmptySquare) continue;
515 if (SameColor(board[rf][ff], board[rt][ft])) continue;
516 callback(board, flags, NormalMove, rf, ff, rt, ft, closure);
518 if(gameInfo.variant == VariantSpartan) rookRange = 2; // in Spartan Chess restrict range to modern Dababba
521 /* Shogi Dragon King has to continue as Ferz after Rook moves */
522 case SHOGI WhiteDragon:
523 case SHOGI BlackDragon:
526 /* Capablanca Chancellor sets flag to continue as Knight */
530 m += (gameInfo.variant == VariantSpartan); // in Spartan Chess Chancellor is used for Dragon King.
532 /* Shogi Rooks are ordinary Rooks */
533 case SHOGI WhiteRook:
534 case SHOGI BlackRook:
538 for (d = 0; d <= 1; d++)
539 for (s = -1; s <= 1; s += 2)
541 rt = rf + (i * s) * d;
542 ft = ff + (i * s) * (1 - d);
543 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
544 if (SameColor(board[rf][ff], board[rt][ft])) break;
545 callback(board, flags, NormalMove,
546 rf, ff, rt, ft, closure);
547 if (board[rt][ft] != EmptySquare || i == rookRange) break;
549 if(m==1) goto mounted;
550 if(m==2) goto finishSilver;
555 for (rs = -1; rs <= 1; rs++)
556 for (fs = -1; fs <= 1; fs++) {
557 if (rs == 0 && fs == 0) continue;
561 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
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;
570 /* Shogi Pawn and Silver General: first the Pawn move, */
571 /* then the General continues like a Ferz */
573 if(gameInfo.variant != VariantMakruk) goto commoner;
574 case SHOGI WhitePawn:
575 case SHOGI WhiteFerz:
576 if (rf < BOARD_HEIGHT-1 &&
577 !SameColor(board[rf][ff], board[rf + 1][ff]) )
578 callback(board, flags, NormalMove,
579 rf, ff, rf + 1, ff, closure);
580 if(piece != SHOGI WhitePawn) goto finishSilver;
584 if(gameInfo.variant != VariantMakruk) goto commoner;
585 case SHOGI BlackPawn:
586 case SHOGI BlackFerz:
588 !SameColor(board[rf][ff], board[rf - 1][ff]) )
589 callback(board, flags, NormalMove,
590 rf, ff, rf - 1, ff, closure);
591 if(piece == SHOGI BlackPawn) break;
596 /* [HGM] support Shatranj pieces */
597 for (rs = -1; rs <= 1; rs += 2)
598 for (fs = -1; fs <= 1; fs += 2) {
601 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
602 if (!SameColor(board[rf][ff], board[rt][ft]) &&
603 (gameInfo.variant != VariantXiangqi || InPalace(rt, ft) ) )
604 callback(board, flags, NormalMove,
605 rf, ff, rt, ft, closure);
611 m++; // [HGM] superchess: use for Centaur
613 case SHOGI WhiteKing:
614 case SHOGI BlackKing:
618 for (i = -1; i <= 1; i++)
619 for (j = -1; j <= 1; j++) {
620 if (i == 0 && j == 0) continue;
623 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
624 if (SameColor(board[rf][ff], board[rt][ft])) continue;
625 callback(board, flags, NormalMove,
626 rf, ff, rt, ft, closure);
628 if(m==1) goto mounted;
631 case WhiteNightrider:
632 case BlackNightrider:
633 for (i = -1; i <= 1; i += 2)
634 for (j = -1; j <= 1; j += 2)
635 for (s = 1; s <= 2; s++) { int k;
639 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
640 if (SameColor(board[rf][ff], board[rt][ft])) break;
641 callback(board, flags, NormalMove,
642 rf, ff, rt, ft, closure);
643 if (board[rt][ft] != EmptySquare) break;
649 /* First do Bishop,then continue like Chancellor */
650 for (rs = -1; rs <= 1; rs += 2)
651 for (fs = -1; fs <= 1; fs += 2)
655 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
656 if (SameColor(board[rf][ff], board[rt][ft])) break;
657 callback(board, flags, NormalMove,
658 rf, ff, rt, ft, closure);
659 if (board[rt][ft] != EmptySquare) break;
664 // Use Lance as Berolina / Spartan Pawn.
666 if(gameInfo.variant == VariantSuper) goto Amazon;
667 if (rf < BOARD_HEIGHT-1 && BlackPiece(board[rf + 1][ff]))
668 callback(board, flags,
669 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
670 rf, ff, rf + 1, ff, closure);
671 for (s = -1; s <= 1; s += 2) {
672 if (rf < BOARD_HEIGHT-1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT && board[rf + 1][ff + s] == EmptySquare)
673 callback(board, flags,
674 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
675 rf, ff, rf + 1, ff + s, closure);
676 if (rf == 1 && ff + 2*s >= BOARD_LEFT && ff + 2*s < BOARD_RGHT && board[3][ff + 2*s] == EmptySquare )
677 callback(board, flags, NormalMove, rf, ff, 3, ff + 2*s, closure);
682 if(gameInfo.variant == VariantSuper) goto Amazon;
683 if (rf > 0 && WhitePiece(board[rf - 1][ff]))
684 callback(board, flags,
685 rf <= promoRank ? BlackPromotion : NormalMove,
686 rf, ff, rf - 1, ff, closure);
687 for (s = -1; s <= 1; s += 2) {
688 if (rf > 0 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT && board[rf - 1][ff + s] == EmptySquare)
689 callback(board, flags,
690 rf <= promoRank ? BlackPromotion : NormalMove,
691 rf, ff, rf - 1, ff + s, closure);
692 if (rf == BOARD_HEIGHT-2 && ff + 2*s >= BOARD_LEFT && ff + 2*s < BOARD_RGHT && board[rf-2][ff + 2*s] == EmptySquare )
693 callback(board, flags, NormalMove, rf, ff, rf-2, ff + 2*s, closure);
697 case WhiteFalcon: // [HGM] wild: for wildcards, self-capture symbolizes move to anywhere
701 callback(board, flags, NormalMove, rf, ff, rf, ff, closure);
714 extern void GenLegalCallback P((Board board, int flags, ChessMove kind,
715 int rf, int ff, int rt, int ft,
718 void GenLegalCallback(board, flags, kind, rf, ff, rt, ft, closure)
725 register GenLegalClosure *cl = (GenLegalClosure *) closure;
727 if (!(flags & F_IGNORE_CHECK) ) {
728 int check, promo = (gameInfo.variant == VariantSpartan && kind == BlackPromotion);
729 if(promo) board[rf][ff] = BlackKing; // [HGM] spartan: promote to King before check-test
730 check = CheckTest(board, flags, rf, ff, rt, ft,
731 kind == WhiteCapturesEnPassant ||
732 kind == BlackCapturesEnPassant);
733 if(promo) board[rf][ff] = BlackLance;
736 if (flags & F_ATOMIC_CAPTURE) {
737 if (board[rt][ft] != EmptySquare ||
738 kind == WhiteCapturesEnPassant || kind == BlackCapturesEnPassant) {
740 ChessSquare king = (flags & F_WHITE_ON_MOVE) ? WhiteKing : BlackKing;
741 if (board[rf][ff] == king) return;
742 for (r = rt-1; r <= rt+1; r++) {
743 for (f = ft-1; f <= ft+1; f++) {
744 if (r >= 0 && r < BOARD_HEIGHT && f >= BOARD_LEFT && f < BOARD_RGHT &&
745 board[r][f] == king) return;
750 cl->cb(board, flags, kind, rf, ff, rt, ft, cl->cl);
757 int captures; // [HGM] losers
758 } LegalityTestClosure;
761 /* Like GenPseudoLegal, but (1) include castling moves, (2) unless
762 F_IGNORE_CHECK is set in the flags, omit moves that would leave the
763 king in check, and (3) if F_ATOMIC_CAPTURE is set in the flags, omit
764 moves that would destroy your own king. The CASTLE_OK flags are
765 true if castling is not yet ruled out by a move of the king or
766 rook. Return TRUE if the player on move is currently in check and
767 F_IGNORE_CHECK is not set. [HGM] add castlingRights parameter */
768 int GenLegal(board, flags, callback, closure)
771 MoveCallback callback;
775 int ff, ft, k, left, right, swap;
776 int ignoreCheck = (flags & F_IGNORE_CHECK) != 0;
777 ChessSquare wKing = WhiteKing, bKing = BlackKing, *castlingRights = board[CASTLING];
781 GenPseudoLegal(board, flags, GenLegalCallback, (VOIDSTAR) &cl);
784 CheckTest(board, flags, -1, -1, -1, -1, FALSE)) return TRUE;
786 /* Generate castling moves */
787 if(gameInfo.variant == VariantKnightmate) { /* [HGM] Knightmate */
788 wKing = WhiteUnicorn; bKing = BlackUnicorn;
791 for (ff = BOARD_WIDTH>>1; ff >= (BOARD_WIDTH-1)>>1; ff-- /*ics wild 1*/) {
792 if ((flags & F_WHITE_ON_MOVE) &&
793 (flags & F_WHITE_KCASTLE_OK) &&
794 board[0][ff] == wKing &&
795 board[0][ff + 1] == EmptySquare &&
796 board[0][ff + 2] == EmptySquare &&
797 board[0][BOARD_RGHT-3] == EmptySquare &&
798 board[0][BOARD_RGHT-2] == EmptySquare &&
799 board[0][BOARD_RGHT-1] == WhiteRook &&
800 castlingRights[0] != NoRights && /* [HGM] check rights */
801 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
803 (!CheckTest(board, flags, 0, ff, 0, ff + 1, FALSE) &&
804 !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-3, FALSE) &&
805 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-2, FALSE)) &&
806 !CheckTest(board, flags, 0, ff, 0, ff + 2, FALSE)))) {
808 callback(board, flags,
809 ff==BOARD_WIDTH>>1 ? WhiteKingSideCastle : WhiteKingSideCastleWild,
810 0, ff, 0, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
812 if ((flags & F_WHITE_ON_MOVE) &&
813 (flags & F_WHITE_QCASTLE_OK) &&
814 board[0][ff] == wKing &&
815 board[0][ff - 1] == EmptySquare &&
816 board[0][ff - 2] == EmptySquare &&
817 board[0][BOARD_LEFT+2] == EmptySquare &&
818 board[0][BOARD_LEFT+1] == EmptySquare &&
819 board[0][BOARD_LEFT+0] == WhiteRook &&
820 castlingRights[1] != NoRights && /* [HGM] check rights */
821 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
823 (!CheckTest(board, flags, 0, ff, 0, ff - 1, FALSE) &&
824 !CheckTest(board, flags, 0, ff, 0, BOARD_LEFT+3, FALSE) &&
825 !CheckTest(board, flags, 0, ff, 0, ff - 2, FALSE)))) {
827 callback(board, flags,
828 ff==BOARD_WIDTH>>1 ? WhiteQueenSideCastle : WhiteQueenSideCastleWild,
829 0, ff, 0, ff - ((gameInfo.boardWidth+2)>>2), closure);
831 if (!(flags & F_WHITE_ON_MOVE) &&
832 (flags & F_BLACK_KCASTLE_OK) &&
833 board[BOARD_HEIGHT-1][ff] == bKing &&
834 board[BOARD_HEIGHT-1][ff + 1] == EmptySquare &&
835 board[BOARD_HEIGHT-1][ff + 2] == EmptySquare &&
836 board[BOARD_HEIGHT-1][BOARD_RGHT-3] == EmptySquare &&
837 board[BOARD_HEIGHT-1][BOARD_RGHT-2] == EmptySquare &&
838 board[BOARD_HEIGHT-1][BOARD_RGHT-1] == BlackRook &&
839 castlingRights[3] != NoRights && /* [HGM] check rights */
840 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
842 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 1, FALSE) &&
843 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-3, FALSE) &&
844 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-2, FALSE)) &&
845 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 2, FALSE)))) {
847 callback(board, flags,
848 ff==BOARD_WIDTH>>1 ? BlackKingSideCastle : BlackKingSideCastleWild,
849 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
851 if (!(flags & F_WHITE_ON_MOVE) &&
852 (flags & F_BLACK_QCASTLE_OK) &&
853 board[BOARD_HEIGHT-1][ff] == bKing &&
854 board[BOARD_HEIGHT-1][ff - 1] == EmptySquare &&
855 board[BOARD_HEIGHT-1][ff - 2] == EmptySquare &&
856 board[BOARD_HEIGHT-1][BOARD_LEFT+2] == EmptySquare &&
857 board[BOARD_HEIGHT-1][BOARD_LEFT+1] == EmptySquare &&
858 board[BOARD_HEIGHT-1][BOARD_LEFT+0] == BlackRook &&
859 castlingRights[4] != NoRights && /* [HGM] check rights */
860 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
862 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 1, FALSE) &&
863 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_LEFT+3, FALSE) &&
864 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 2, FALSE)))) {
866 callback(board, flags,
867 ff==BOARD_WIDTH>>1 ? BlackQueenSideCastle : BlackQueenSideCastleWild,
868 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - ((gameInfo.boardWidth+2)>>2), closure);
872 if((swap = gameInfo.variant == VariantSChess) || flags & F_FRC_TYPE_CASTLING) {
874 /* generate all potential FRC castling moves (KxR), ignoring flags */
875 /* [HGM] test if the Rooks we find have castling rights */
876 /* In S-Chess we generate RxK for allowed castlings, for gating at Rook square */
879 if ((flags & F_WHITE_ON_MOVE) != 0) {
880 ff = castlingRights[2]; /* King file if we have any rights */
881 if(ff != NoRights && board[0][ff] == WhiteKing) {
882 if (appData.debugMode) {
883 fprintf(debugFP, "FRC castling, %d %d %d %d %d %d\n",
884 castlingRights[0],castlingRights[1],ff,castlingRights[3],castlingRights[4],castlingRights[5]);
886 ft = castlingRights[0]; /* Rook file if we have H-side rights */
888 right = BOARD_RGHT-2;
889 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
890 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
891 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
892 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
893 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
894 if(ft != NoRights && board[0][ft] == WhiteRook)
895 callback(board, flags, WhiteHSideCastleFR, 0, swap ? ft : ff, 0, swap ? ff : ft, closure);
897 ft = castlingRights[1]; /* Rook file if we have A-side rights */
900 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
901 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
902 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
903 if(ff > BOARD_LEFT+2)
904 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
905 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
906 if(ft != NoRights && board[0][ft] == WhiteRook)
907 callback(board, flags, WhiteASideCastleFR, 0, swap ? ft : ff, 0, swap ? ff : ft, closure);
910 ff = castlingRights[5]; /* King file if we have any rights */
911 if(ff != NoRights && board[BOARD_HEIGHT-1][ff] == BlackKing) {
912 ft = castlingRights[3]; /* Rook file if we have H-side rights */
914 right = BOARD_RGHT-2;
915 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
916 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
917 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
918 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
919 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
920 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
921 callback(board, flags, BlackHSideCastleFR, BOARD_HEIGHT-1, swap ? ft : ff, BOARD_HEIGHT-1, swap ? ff : ft, closure);
923 ft = castlingRights[4]; /* Rook file if we have A-side rights */
926 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
927 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
928 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
929 if(ff > BOARD_LEFT+2)
930 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
931 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
932 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
933 callback(board, flags, BlackASideCastleFR, BOARD_HEIGHT-1, swap ? ft : ff, BOARD_HEIGHT-1, swap ? ff : ft, closure);
949 extern void CheckTestCallback P((Board board, int flags, ChessMove kind,
950 int rf, int ff, int rt, int ft,
954 void CheckTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
961 register CheckTestClosure *cl = (CheckTestClosure *) closure;
963 if (rt == cl->rking && ft == cl->fking) cl->check++;
967 /* If the player on move were to move from (rf, ff) to (rt, ft), would
968 he leave himself in check? Or if rf == -1, is the player on move
969 in check now? enPassant must be TRUE if the indicated move is an
970 e.p. capture. The possibility of castling out of a check along the
971 back rank is not accounted for (i.e., we still return nonzero), as
972 this is illegal anyway. Return value is the number of times the
974 int CheckTest(board, flags, rf, ff, rt, ft, enPassant)
977 int rf, ff, rt, ft, enPassant;
980 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
981 ChessSquare captured = EmptySquare;
982 /* Suppress warnings on uninitialized variables */
984 if(gameInfo.variant == VariantXiangqi)
985 king = flags & F_WHITE_ON_MOVE ? WhiteWazir : BlackWazir;
986 if(gameInfo.variant == VariantKnightmate)
987 king = flags & F_WHITE_ON_MOVE ? WhiteUnicorn : BlackUnicorn;
991 captured = board[rf][ft];
992 board[rf][ft] = EmptySquare;
994 captured = board[rt][ft];
996 board[rt][ft] = board[rf][ff];
997 board[rf][ff] = EmptySquare;
998 } else board[rt][ft] = ff; // [HGM] drop
1000 /* For compatibility with ICS wild 9, we scan the board in the
1001 order a1, a2, a3, ... b1, b2, ..., h8 to find the first king,
1002 and we test only whether that one is in check. */
1003 for (cl.fking = BOARD_LEFT+0; cl.fking < BOARD_RGHT; cl.fking++)
1004 for (cl.rking = 0; cl.rking < BOARD_HEIGHT; cl.rking++) {
1005 if (board[cl.rking][cl.fking] == king) {
1007 if(gameInfo.variant == VariantXiangqi) {
1008 /* [HGM] In Xiangqi opposing Kings means check as well */
1010 dir = (king >= BlackPawn) ? -1 : 1;
1011 for( i=cl.rking+dir; i>=0 && i<BOARD_HEIGHT &&
1012 board[i][cl.fking] == EmptySquare; i+=dir );
1013 if(i>=0 && i<BOARD_HEIGHT &&
1014 board[i][cl.fking] == (dir>0 ? BlackWazir : WhiteWazir) )
1017 GenPseudoLegal(board, flags ^ F_WHITE_ON_MOVE, CheckTestCallback, (VOIDSTAR) &cl);
1018 if(gameInfo.variant != VariantSpartan || cl.check == 0) // in Spartan Chess go on to test if other King is checked too
1019 goto undo_move; /* 2-level break */
1026 board[rf][ff] = board[rt][ft];
1028 board[rf][ft] = captured;
1029 board[rt][ft] = EmptySquare;
1031 board[rt][ft] = captured;
1033 } else board[rt][ft] = EmptySquare; // [HGM] drop
1035 return cl.fking < BOARD_RGHT ? cl.check : 1000; // [HGM] atomic: return 1000 if we have no king
1038 ChessMove LegalDrop(board, flags, piece, rt, ft)
1043 { // [HGM] put drop legality testing in separate routine for clarity
1045 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
1046 if(board[rt][ft] != EmptySquare) return ImpossibleMove; // must drop to empty square
1047 n = PieceToNumber(piece);
1048 if(gameInfo.holdingsWidth == 0 || (flags & F_WHITE_ON_MOVE ? board[n][BOARD_WIDTH-1] : board[BOARD_HEIGHT-1-n][0]) != piece)
1049 return ImpossibleMove; // piece not available
1050 if(gameInfo.variant == VariantShogi) { // in Shogi lots of drops are forbidden!
1051 if((piece == WhitePawn || piece == WhiteQueen) && rt == BOARD_HEIGHT-1 ||
1052 (piece == BlackPawn || piece == BlackQueen) && rt == 0 ||
1053 piece == WhiteKnight && rt > BOARD_HEIGHT-3 ||
1054 piece == BlackKnight && rt < 2 ) return IllegalMove; // e.g. where dropped piece has no moves
1055 if(piece == WhitePawn || piece == BlackPawn) {
1057 for(r=1; r<BOARD_HEIGHT-1; r++)
1058 if(board[r][ft] == piece) return IllegalMove; // or there already is a Pawn in file
1059 // should still test if we mate with this Pawn
1061 } else if(gameInfo.variant == VariantSChess) { // only back-rank drops
1062 if (rt != (piece < BlackPawn ? 0 : BOARD_HEIGHT-1)) return IllegalMove;
1064 if( (piece == WhitePawn || piece == BlackPawn) &&
1065 (rt == 0 || rt == BOARD_HEIGHT -1 ) )
1066 return IllegalMove; /* no pawn drops on 1st/8th */
1068 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
1069 if (!(flags & F_IGNORE_CHECK) &&
1070 CheckTest(board, flags, DROP_RANK, piece, rt, ft, FALSE) ) return IllegalMove;
1071 return flags & F_WHITE_ON_MOVE ? WhiteDrop : BlackDrop;
1074 extern void LegalityTestCallback P((Board board, int flags, ChessMove kind,
1075 int rf, int ff, int rt, int ft,
1078 void LegalityTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
1085 register LegalityTestClosure *cl = (LegalityTestClosure *) closure;
1087 // if (appData.debugMode) {
1088 // fprintf(debugFP, "Legality test: %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
1090 if(board[rt][ft] != EmptySquare || kind==WhiteCapturesEnPassant || kind==BlackCapturesEnPassant)
1091 cl->captures++; // [HGM] losers: count legal captures
1092 if (rf == cl->rf && ff == cl->ff && rt == cl->rt && ft == cl->ft)
1096 ChessMove LegalityTest(board, flags, rf, ff, rt, ft, promoChar)
1099 int rf, ff, rt, ft, promoChar;
1101 LegalityTestClosure cl; ChessSquare piece, *castlingRights = board[CASTLING];
1103 if(rf == DROP_RANK) return LegalDrop(board, flags, ff, rt, ft);
1104 piece = board[rf][ff];
1106 if (appData.debugMode) {
1108 for(i=0; i<6; i++) fprintf(debugFP, "%d ", castlingRights[i]);
1109 fprintf(debugFP, "Legality test? %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
1111 /* [HGM] Cobra and Falcon are wildcard pieces; consider all their moves legal */
1112 /* (perhaps we should disallow moves that obviously leave us in check?) */
1113 if(piece == WhiteFalcon || piece == BlackFalcon ||
1114 piece == WhiteCobra || piece == BlackCobra)
1115 return CheckTest(board, flags, rf, ff, rt, ft, FALSE) ? IllegalMove : NormalMove;
1121 cl.kind = IllegalMove;
1122 cl.captures = 0; // [HGM] losers: prepare to count legal captures.
1123 GenLegal(board, flags, LegalityTestCallback, (VOIDSTAR) &cl);
1124 if((flags & F_MANDATORY_CAPTURE) && cl.captures && board[rt][ft] == EmptySquare
1125 && cl.kind != WhiteCapturesEnPassant && cl.kind != BlackCapturesEnPassant)
1126 return(IllegalMove); // [HGM] losers: if there are legal captures, non-capts are illegal
1128 if(promoChar == 'x') promoChar = NULLCHAR; // [HGM] is this ever the case?
1129 if(gameInfo.variant == VariantSChess && promoChar && promoChar != '=' && board[rf][ff] != WhitePawn && board[rf][ff] != BlackPawn) {
1130 if(board[rf][ff] < BlackPawn) { // white
1131 if(rf != 0) return IllegalMove; // must be on back rank
1132 if(board[PieceToNumber(CharToPiece(ToUpper(promoChar)))][BOARD_WIDTH-2] == 0) return ImpossibleMove;// must be in stock
1134 if(rf != BOARD_HEIGHT-1) return IllegalMove;
1135 if(board[BOARD_HEIGHT-1-PieceToNumber(CharToPiece(ToLower(promoChar)))][1] == 0) return ImpossibleMove;
1138 if(gameInfo.variant == VariantShogi) {
1139 /* [HGM] Shogi promotions. '=' means defer */
1140 if(rf != DROP_RANK && cl.kind == NormalMove) {
1141 ChessSquare piece = board[rf][ff];
1143 if(promoChar == PieceToChar(BlackQueen)) promoChar = NULLCHAR; /* [HGM] Kludge */
1144 if(promoChar == 'd' && (piece == WhiteRook || piece == BlackRook) ||
1145 promoChar == 'h' && (piece == WhiteBishop || piece == BlackBishop) ||
1146 promoChar == 'g' && (piece <= WhiteFerz || piece <= BlackFerz && piece >= BlackPawn) )
1147 promoChar = '+'; // allowed ICS notations
1148 if(appData.debugMode)fprintf(debugFP,"SHOGI promoChar = %c\n", promoChar ? promoChar : '-');
1149 if(promoChar != NULLCHAR && promoChar != '+' && promoChar != '=')
1150 return CharToPiece(promoChar) == EmptySquare ? ImpossibleMove : IllegalMove;
1151 else if(flags & F_WHITE_ON_MOVE) {
1152 if( (int) piece < (int) WhiteWazir &&
1153 (rf >= BOARD_HEIGHT*2/3 || rt >= BOARD_HEIGHT*2/3) ) {
1154 if( (piece == WhitePawn || piece == WhiteQueen) && rt > BOARD_HEIGHT-2 ||
1155 piece == WhiteKnight && rt > BOARD_HEIGHT-3) /* promotion mandatory */
1156 cl.kind = promoChar == '=' ? IllegalMove : WhitePromotion;
1157 else /* promotion optional, default is defer */
1158 cl.kind = promoChar == '+' ? WhitePromotion : WhiteNonPromotion;
1159 } else cl.kind = promoChar == '+' ? IllegalMove : NormalMove;
1161 if( (int) piece < (int) BlackWazir && (rf < BOARD_HEIGHT/3 || rt < BOARD_HEIGHT/3) ) {
1162 if( (piece == BlackPawn || piece == BlackQueen) && rt < 1 ||
1163 piece == BlackKnight && rt < 2 ) /* promotion obligatory */
1164 cl.kind = promoChar == '=' ? IllegalMove : BlackPromotion;
1165 else /* promotion optional, default is defer */
1166 cl.kind = promoChar == '+' ? BlackPromotion : BlackNonPromotion;
1167 } else cl.kind = promoChar == '+' ? IllegalMove : NormalMove;
1171 if (promoChar != NULLCHAR) {
1172 if(promoChar == '=') cl.kind = IllegalMove; else // [HGM] shogi: no deferred promotion outside Shogi
1173 if (cl.kind == WhitePromotion || cl.kind == BlackPromotion) {
1174 ChessSquare piece = CharToPiece(flags & F_WHITE_ON_MOVE ? ToUpper(promoChar) : ToLower(promoChar));
1175 if(piece == EmptySquare)
1176 cl.kind = ImpossibleMove; // non-existing piece
1177 if(gameInfo.variant == VariantSpartan && cl.kind == BlackPromotion ) {
1178 if(promoChar != PieceToChar(BlackKing)) {
1179 if(CheckTest(board, flags, rf, ff, rt, ft, FALSE)) cl.kind = IllegalMove; // [HGM] spartan: only promotion to King was possible
1180 if(piece == BlackLance) cl.kind = ImpossibleMove;
1181 } else { // promotion to King allowed only if we do not haave two yet
1182 int r, f, kings = 0;
1183 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) kings += (board[r][f] == BlackKing);
1184 if(kings == 2) cl.kind = IllegalMove;
1186 } else if(piece == WhitePawn || piece == BlackPawn) cl.kind = ImpossibleMove; // cannot stay Pawn in any variant
1187 else if((piece == WhiteUnicorn || piece == BlackUnicorn) && gameInfo.variant == VariantKnightmate)
1188 cl.kind = IllegalMove; // promotion to Royal Knight not allowed
1189 else if((piece == WhiteKing || piece == BlackKing) && gameInfo.variant != VariantSuicide && gameInfo.variant != VariantGiveaway)
1190 cl.kind = IllegalMove; // promotion to King usually not allowed
1192 cl.kind = IllegalMove;
1202 extern void MateTestCallback P((Board board, int flags, ChessMove kind,
1203 int rf, int ff, int rt, int ft,
1206 void MateTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
1213 register MateTestClosure *cl = (MateTestClosure *) closure;
1218 /* Return MT_NONE, MT_CHECK, MT_CHECKMATE, or MT_STALEMATE */
1219 int MateTest(board, flags)
1224 int inCheck, r, f, myPieces=0, hisPieces=0, nrKing=0;
1225 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
1227 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) {
1228 // [HGM] losers: Count pieces and kings, to detect other unorthodox winning conditions
1229 nrKing += (board[r][f] == king); // stm has king
1230 if( board[r][f] != EmptySquare ) {
1231 if((int)board[r][f] <= (int)king && (int)board[r][f] >= (int)king - (int)WhiteKing + (int)WhitePawn)
1236 if(appData.debugMode) fprintf(debugFP, "MateTest: K=%d, my=%d, his=%d\n", nrKing, myPieces, hisPieces);
1237 switch(gameInfo.variant) { // [HGM] losers: extinction wins
1238 case VariantShatranj:
1239 if(hisPieces == 1) return myPieces > 1 ? MT_BARE : MT_DRAW;
1243 if(nrKing == 0) return MT_NOKING;
1246 if(myPieces == 1) return MT_BARE;
1249 inCheck = GenLegal(board, flags, MateTestCallback, (VOIDSTAR) &cl);
1250 // [HGM] 3check: yet to do!
1252 return inCheck ? MT_CHECK : MT_NONE;
1254 if(gameInfo.holdingsWidth && gameInfo.variant != VariantSuper && gameInfo.variant != VariantGreat) { // drop game
1255 int r, f, n, holdings = flags & F_WHITE_ON_MOVE ? BOARD_WIDTH-1 : 0;
1256 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) if(board[r][f] == EmptySquare) // all empty squares
1257 for(n=0; n<BOARD_HEIGHT; n++) // all pieces in hand
1258 if(board[n][holdings] != EmptySquare) {
1259 int moveType = LegalDrop(board, flags, board[n][holdings], r, f);
1260 if(moveType == WhiteDrop || moveType == BlackDrop) return (inCheck ? MT_CHECK : MT_NONE); // we have legal drop
1263 if(gameInfo.variant == VariantSuicide) // [HGM] losers: always stalemate, since no check, but result varies
1264 return myPieces == hisPieces ? MT_STALEMATE :
1265 myPieces > hisPieces ? MT_STAINMATE : MT_STEALMATE;
1266 else if(gameInfo.variant == VariantLosers) return inCheck ? MT_TRICKMATE : MT_STEALMATE;
1267 else if(gameInfo.variant == VariantGiveaway) return MT_STEALMATE; // no check exists, stalemated = win
1269 return inCheck ? MT_CHECKMATE
1270 : (gameInfo.variant == VariantXiangqi || gameInfo.variant == VariantShatranj) ?
1271 MT_STAINMATE : MT_STALEMATE;
1276 extern void DisambiguateCallback P((Board board, int flags, ChessMove kind,
1277 int rf, int ff, int rt, int ft,
1280 void DisambiguateCallback(board, flags, kind, rf, ff, rt, ft, closure)
1287 register DisambiguateClosure *cl = (DisambiguateClosure *) closure;
1288 int wildCard = FALSE; ChessSquare piece = board[rf][ff];
1290 // [HGM] wild: for wild-card pieces rt and rf are dummies
1291 if(piece == WhiteFalcon || piece == BlackFalcon ||
1292 piece == WhiteCobra || piece == BlackCobra)
1295 if ((cl->pieceIn == EmptySquare || cl->pieceIn == board[rf][ff]
1296 || PieceToChar(board[rf][ff]) == '~'
1297 && cl->pieceIn == (ChessSquare)(DEMOTED board[rf][ff])
1299 (cl->rfIn == -1 || cl->rfIn == rf) &&
1300 (cl->ffIn == -1 || cl->ffIn == ff) &&
1301 (cl->rtIn == -1 || cl->rtIn == rt || wildCard) &&
1302 (cl->ftIn == -1 || cl->ftIn == ft || wildCard)) {
1305 if(cl->count == 1 || board[rt][ft] != EmptySquare) {
1306 // [HGM] oneclick: if multiple moves, be sure we remember capture
1307 cl->piece = board[rf][ff];
1310 cl->rt = wildCard ? cl->rtIn : rt;
1311 cl->ft = wildCard ? cl->ftIn : ft;
1314 cl->captures += (board[rt][ft] != EmptySquare); // [HGM] oneclick: count captures
1318 void Disambiguate(board, flags, closure)
1321 DisambiguateClosure *closure;
1323 int illegal = 0; char c = closure->promoCharIn;
1325 closure->count = closure->captures = 0;
1326 closure->rf = closure->ff = closure->rt = closure->ft = 0;
1327 closure->kind = ImpossibleMove;
1328 if (appData.debugMode) {
1329 fprintf(debugFP, "Disambiguate in: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1330 closure->pieceIn,closure->ffIn,closure->rfIn,closure->ftIn,closure->rtIn,
1331 closure->promoCharIn, closure->promoCharIn >= ' ' ? closure->promoCharIn : '-');
1333 GenLegal(board, flags, DisambiguateCallback, (VOIDSTAR) closure);
1334 if (closure->count == 0) {
1335 /* See if it's an illegal move due to check */
1337 GenLegal(board, flags|F_IGNORE_CHECK, DisambiguateCallback, (VOIDSTAR) closure);
1338 if (closure->count == 0) {
1339 /* No, it's not even that */
1340 if (appData.debugMode) { int i, j;
1341 for(i=BOARD_HEIGHT-1; i>=0; i--) {
1342 for(j=0; j<BOARD_WIDTH; j++)
1343 fprintf(debugFP, "%3d", (int) board[i][j]);
1344 fprintf(debugFP, "\n");
1351 if (c == 'x') c = NULLCHAR; // get rid of any 'x' (which should never happen?)
1352 if(gameInfo.variant == VariantSChess && c && c != '=' && closure->piece != WhitePawn && closure->piece != BlackPawn) {
1353 if(closure->piece < BlackPawn) { // white
1354 if(closure->rf != 0) closure->kind = IllegalMove; // must be on back rank
1355 if(board[PieceToNumber(CharToPiece(ToUpper(c)))][BOARD_WIDTH-2] == 0) closure->kind = ImpossibleMove;// must be in stock
1357 if(closure->rf != BOARD_HEIGHT-1) closure->kind = IllegalMove;
1358 if(board[BOARD_HEIGHT-1-PieceToNumber(CharToPiece(ToLower(c)))][1] == 0) closure->kind = ImpossibleMove;
1361 if(gameInfo.variant == VariantShogi) {
1362 /* [HGM] Shogi promotions. On input, '=' means defer, '+' promote. Afterwards, c is set to '+' for promotions, NULL other */
1363 if(closure->rfIn != DROP_RANK && closure->kind == NormalMove) {
1364 ChessSquare piece = closure->piece;
1365 if (c == 'd' && (piece == WhiteRook || piece == BlackRook) ||
1366 c == 'h' && (piece == WhiteBishop || piece == BlackBishop) ||
1367 c == 'g' && (piece <= WhiteFerz || piece <= BlackFerz && piece >= BlackPawn) )
1368 c = '+'; // allowed ICS notations
1369 if(c != NULLCHAR && c != '+' && c != '=') closure->kind = IllegalMove; // otherwise specifying a piece is illegal
1370 else if(flags & F_WHITE_ON_MOVE) {
1371 if( (int) piece < (int) WhiteWazir &&
1372 (closure->rf >= BOARD_HEIGHT-(BOARD_HEIGHT/3) || closure->rt >= BOARD_HEIGHT-(BOARD_HEIGHT/3)) ) {
1373 if( (piece == WhitePawn || piece == WhiteQueen) && closure->rt > BOARD_HEIGHT-2 ||
1374 piece == WhiteKnight && closure->rt > BOARD_HEIGHT-3) /* promotion mandatory */
1375 closure->kind = c == '=' ? IllegalMove : WhitePromotion;
1376 else /* promotion optional, default is defer */
1377 closure->kind = c == '+' ? WhitePromotion : WhiteNonPromotion;
1378 } else closure->kind = c == '+' ? IllegalMove : NormalMove;
1380 if( (int) piece < (int) BlackWazir && (closure->rf < BOARD_HEIGHT/3 || closure->rt < BOARD_HEIGHT/3) ) {
1381 if( (piece == BlackPawn || piece == BlackQueen) && closure->rt < 1 ||
1382 piece == BlackKnight && closure->rt < 2 ) /* promotion obligatory */
1383 closure->kind = c == '=' ? IllegalMove : BlackPromotion;
1384 else /* promotion optional, default is defer */
1385 closure->kind = c == '+' ? BlackPromotion : BlackNonPromotion;
1386 } else closure->kind = c == '+' ? IllegalMove : NormalMove;
1389 if(closure->kind == WhitePromotion || closure->kind == BlackPromotion) c = '+'; else
1390 if(closure->kind == WhiteNonPromotion || closure->kind == BlackNonPromotion) c = '=';
1392 if (closure->kind == WhitePromotion || closure->kind == BlackPromotion) {
1393 if(c == NULLCHAR) { // missing promoChar on mandatory promotion; use default for variant
1394 if(gameInfo.variant == VariantShatranj || gameInfo.variant == VariantCourier || gameInfo.variant == VariantMakruk)
1395 c = PieceToChar(BlackFerz);
1396 else if(gameInfo.variant == VariantGreat)
1397 c = PieceToChar(BlackMan);
1399 c = PieceToChar(BlackQueen);
1400 } else if(c == '=') closure->kind = IllegalMove; // no deferral outside Shogi
1401 } else if (c != NULLCHAR) closure->kind = IllegalMove;
1403 closure->promoChar = ToLower(c); // this can be NULLCHAR! Note we keep original promoChar even if illegal.
1404 if(c != '+' && c != '=' && c != NULLCHAR && CharToPiece(flags & F_WHITE_ON_MOVE ? ToUpper(c) : ToLower(c)) == EmptySquare)
1405 closure->kind = ImpossibleMove; // but we cannot handle non-existing piece types!
1406 if (closure->count > 1) {
1407 closure->kind = AmbiguousMove;
1410 /* Note: If more than one illegal move matches, but no legal
1411 moves, we return IllegalMove, not AmbiguousMove. Caller
1412 can look at closure->count to detect this.
1414 closure->kind = IllegalMove;
1416 if (appData.debugMode) {
1417 fprintf(debugFP, "Disambiguate out: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1418 closure->piece,closure->ff,closure->rf,closure->ft,closure->rt,closure->promoChar,
1419 closure->promoChar >= ' ' ? closure->promoChar:'-');
1433 } CoordsToAlgebraicClosure;
1435 extern void CoordsToAlgebraicCallback P((Board board, int flags,
1436 ChessMove kind, int rf, int ff,
1437 int rt, int ft, VOIDSTAR closure));
1439 void CoordsToAlgebraicCallback(board, flags, kind, rf, ff, rt, ft, closure)
1446 register CoordsToAlgebraicClosure *cl =
1447 (CoordsToAlgebraicClosure *) closure;
1449 if ((rt == cl->rt && ft == cl->ft || rt == rf && ft == ff) && // [HGM] null move matches any toSquare
1450 (board[rf][ff] == cl->piece
1451 || PieceToChar(board[rf][ff]) == '~' &&
1452 (ChessSquare) (DEMOTED board[rf][ff]) == cl->piece)
1456 cl->kind = kind; /* this is the move we want */
1458 cl->file++; /* need file to rule out this move */
1462 cl->rank++; /* need rank to rule out this move */
1464 cl->either++; /* rank or file will rule out this move */
1470 /* Convert coordinates to normal algebraic notation.
1471 promoChar must be NULLCHAR or 'x' if not a promotion.
1473 ChessMove CoordsToAlgebraic(board, flags, rf, ff, rt, ft, promoChar, out)
1482 char *outp = out, c;
1483 CoordsToAlgebraicClosure cl;
1485 if (rf == DROP_RANK) {
1486 /* Bughouse piece drop */
1487 *outp++ = ToUpper(PieceToChar((ChessSquare) ff));
1492 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1494 return (flags & F_WHITE_ON_MOVE) ? WhiteDrop : BlackDrop;
1497 if (promoChar == 'x') promoChar = NULLCHAR;
1498 piece = board[rf][ff];
1499 if(PieceToChar(piece)=='~') piece = (ChessSquare)(DEMOTED piece);
1501 if (appData.debugMode)
1502 fprintf(debugFP, "CoordsToAlgebraic, piece=%d (%d,%d)-(%d,%d) %c\n", (int)piece,ff,rf,ft,rt,promoChar >= ' ' ? promoChar : '-');
1506 kind = LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1507 if (kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1508 /* Keep short notation if move is illegal only because it
1509 leaves the player in check, but still return IllegalMove */
1510 kind = LegalityTest(board, flags|F_IGNORE_CHECK, rf, ff, rt, ft, promoChar);
1511 if (kind == IllegalMove) break;
1516 if (ff == ft && board[rt][ft] == EmptySquare) { /* [HGM] Xiangqi has straight noncapts! */
1517 /* Non-capture; use style "e5" */
1520 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1522 /* Capture; use style "exd5" */
1523 if(gameInfo.variant != VariantXiangqi || board[rt][ft] != EmptySquare )
1524 *outp++ = 'x'; /* [HGM] Xiangqi has sideway noncaptures across river! */
1528 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1530 /* Use promotion suffix style "=Q" */
1532 if (appData.debugMode)
1533 fprintf(debugFP, "movetype=%d, promochar=%d=%c\n", (int)kind, promoChar, promoChar >= ' ' ? promoChar : '-');
1534 if (promoChar != NULLCHAR) {
1535 if(gameInfo.variant == VariantShogi) {
1536 /* [HGM] ... but not in Shogi! */
1537 *outp++ = promoChar == '=' ? '=' : '+';
1540 *outp++ = ToUpper(promoChar);
1549 /* Fabien moved code: FRC castling first (if KxR), wild castling second */
1550 /* Code added by Tord: FRC castling. */
1551 if((piece == WhiteKing && board[rt][ft] == WhiteRook) ||
1552 (piece == BlackKing && board[rt][ft] == BlackRook)) {
1554 safeStrCpy(out, "O-O", MOVE_LEN);
1556 safeStrCpy(out, "O-O-O", MOVE_LEN);
1557 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1559 /* End of code added by Tord */
1560 /* Test for castling or ICS wild castling */
1561 /* Use style "O-O" (oh-oh) for PGN compatibility */
1562 else if (rf == rt &&
1563 rf == ((piece == WhiteKing) ? 0 : BOARD_HEIGHT-1) &&
1564 (ft - ff > 1 || ff - ft > 1) && // No castling if legal King move (on narrow boards!)
1565 ((ff == BOARD_WIDTH>>1 && (ft == BOARD_LEFT+2 || ft == BOARD_RGHT-2)) ||
1566 (ff == (BOARD_WIDTH-1)>>1 && (ft == BOARD_LEFT+1 || ft == BOARD_RGHT-3)))) {
1567 if(ft==BOARD_LEFT+1 || ft==BOARD_RGHT-2)
1568 snprintf(out, MOVE_LEN, "O-O%c%c", promoChar ? '/' : 0, ToUpper(promoChar));
1570 snprintf(out, MOVE_LEN, "O-O-O%c%c", promoChar ? '/' : 0, ToUpper(promoChar));
1572 /* This notation is always unambiguous, unless there are
1573 kings on both the d and e files, with "wild castling"
1574 possible for the king on the d file and normal castling
1575 possible for the other. ICS rules for wild 9
1576 effectively make castling illegal for either king in
1577 this situation. So I am not going to worry about it;
1578 I'll just generate an ambiguous O-O in this case.
1580 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1583 /* else fall through */
1591 cl.kind = IllegalMove;
1592 cl.rank = cl.file = cl.either = 0;
1593 GenLegal(board, flags, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1595 if (cl.kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1596 /* Generate pretty moves for moving into check, but
1597 still return IllegalMove.
1599 GenLegal(board, flags|F_IGNORE_CHECK, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1600 if (cl.kind == IllegalMove) break;
1601 cl.kind = IllegalMove;
1604 /* Style is "Nf3" or "Nxf7" if this is unambiguous,
1605 else "Ngf3" or "Ngxf7",
1606 else "N1f3" or "N5xf7",
1607 else "Ng1f3" or "Ng5xf7".
1609 c = PieceToChar(piece) ;
1610 if( c == '~' || c == '+') {
1611 /* [HGM] print nonexistent piece as its demoted version */
1612 piece = (ChessSquare) (DEMOTED piece);
1614 if(c=='+') *outp++ = c;
1615 *outp++ = ToUpper(PieceToChar(piece));
1617 if (cl.file || (cl.either && !cl.rank)) {
1623 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1626 if(board[rt][ft] != EmptySquare)
1632 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1633 if (gameInfo.variant == VariantShogi) {
1634 /* [HGM] in Shogi non-pawns can promote */
1635 *outp++ = promoChar; // Don't bother to correct move type, return value is never used!
1637 else if (gameInfo.variant != VariantSuper && promoChar &&
1638 (piece == WhiteLance || piece == BlackLance) ) { // Lance sometimes represents Pawn
1640 *outp++ = ToUpper(promoChar);
1642 else if (gameInfo.variant == VariantSChess && promoChar) { // and in S-Chess we have gating
1644 *outp++ = ToUpper(promoChar);
1650 /* Moving a nonexistent piece */
1654 /* Not a legal move, even ignoring check.
1655 If there was a piece on the from square,
1656 use style "Ng1g3" or "Ng1xe8";
1657 if there was a pawn or nothing (!),
1658 use style "g1g3" or "g1xe8". Use "x"
1659 if a piece was on the to square, even
1660 a piece of the same color.
1664 if (piece != EmptySquare && piece != WhitePawn && piece != BlackPawn) {
1666 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<=BOARD_RGHT; f++)
1667 c += (board[r][f] == piece); // count on-board pieces of given type
1668 *outp++ = ToUpper(PieceToChar(piece));
1670 if(c != 1) { // [HGM] but if there is only one piece of the mentioned type, no from-square, thank you!
1674 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1676 if (board[rt][ft] != EmptySquare) *outp++ = 'x';
1680 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1681 /* Use promotion suffix style "=Q" */
1682 if (promoChar != NULLCHAR && promoChar != 'x') {
1684 *outp++ = ToUpper(promoChar);
1691 // [HGM] XQ: the following code serves to detect perpetual chasing (Asian rules)
1700 // I guess the following variables logically belong in the closure too, but I was too lazy and used globals
1702 int preyStackPointer, chaseStackPointer;
1705 char rf, ff, rt, ft;
1715 // there are three new callbacks for use with GenLegal: for adding captures, deleting them, and finding a recapture
1717 extern void AtacksCallback P((Board board, int flags, ChessMove kind,
1718 int rf, int ff, int rt, int ft,
1721 void AttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1727 { // For adding captures that can lead to chase indictment to the chaseStack
1728 if(board[rt][ft] == EmptySquare) return; // non-capture
1729 if(board[rt][ft] == WhitePawn && rt < BOARD_HEIGHT/2) return; // Pawn before river can be chased
1730 if(board[rt][ft] == BlackPawn && rt >= BOARD_HEIGHT/2) return; // Pawn before river can be chased
1731 if(board[rf][ff] == WhitePawn || board[rf][ff] == BlackPawn) return; // Pawns are allowed to chase
1732 if(board[rf][ff] == WhiteWazir || board[rf][ff] == BlackWazir) return; // King is allowed to chase
1733 // move cannot be excluded from being a chase trivially (based on attacker and victim); save it on chaseStack
1734 chaseStack[chaseStackPointer].rf = rf;
1735 chaseStack[chaseStackPointer].ff = ff;
1736 chaseStack[chaseStackPointer].rt = rt;
1737 chaseStack[chaseStackPointer].ft = ft;
1738 chaseStackPointer++;
1741 extern void ExistingAtacksCallback P((Board board, int flags, ChessMove kind,
1742 int rf, int ff, int rt, int ft,
1745 void ExistingAttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1751 { // for removing pre-exsting captures from the chaseStack, to be left with newly created ones
1753 register ChaseClosure *cl = (ChaseClosure *) closure; //closure tells us the move played in the repeat loop
1755 if(board[rt][ft] == EmptySquare) return; // no capture
1756 if(rf == cl->rf && ff == cl->ff) { // attacks with same piece from new position are not considered new
1757 rf = cl->rt; ff = cl->ft; // doctor their fromSquare so they will be recognized in chaseStack
1759 // search move in chaseStack, and delete it if it occurred there (as we know now it is not a new capture)
1760 for(i=0; i<chaseStackPointer; i++) {
1761 if(chaseStack[i].rf == rf && chaseStack[i].ff == ff &&
1762 chaseStack[i].rt == rt && chaseStack[i].ft == ft ) {
1763 // move found on chaseStack, delete it by overwriting with move popped from top of chaseStack
1764 chaseStack[i] = chaseStack[--chaseStackPointer];
1770 extern void ProtectedCallback P((Board board, int flags, ChessMove kind,
1771 int rf, int ff, int rt, int ft,
1774 void ProtectedCallback(board, flags, kind, rf, ff, rt, ft, closure)
1780 { // for determining if a piece (given through the closure) is protected
1781 register ChaseClosure *cl = (ChaseClosure *) closure; // closure tells us where to recapture
1783 if(rt == cl->rt && ft == cl->ft) cl->recaptures++; // count legal recaptures to this square
1784 if(appData.debugMode && board[rt][ft] != EmptySquare)
1785 fprintf(debugFP, "try %c%c%c%c=%d\n", ff+AAA, rf+ONE,ft+AAA, rt+ONE, cl->recaptures);
1788 extern char moveList[MAX_MOVES][MOVE_LEN];
1790 int PerpetualChase(int first, int last)
1791 { // this routine detects if the side to move in the 'first' position is perpetually chasing (when not checking)
1794 ChessSquare captured;
1796 preyStackPointer = 0; // clear stack of chased pieces
1797 for(i=first; i<last; i+=2) { // for all positions with same side to move
1798 if(appData.debugMode) fprintf(debugFP, "judge position %i\n", i);
1799 chaseStackPointer = 0; // clear stack that is going to hold possible chases
1800 // determine all captures possible after the move, and put them on chaseStack
1801 GenLegal(boards[i+1], PosFlags(i), AttacksCallback, &cl);
1802 if(appData.debugMode) { int n;
1803 for(n=0; n<chaseStackPointer; n++)
1804 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1805 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1806 fprintf(debugFP, ": all capts\n");
1808 // determine all captures possible before the move, and delete them from chaseStack
1809 cl.rf = moveList[i][1]-ONE; // prepare closure to pass move that led from i to i+1
1810 cl.ff = moveList[i][0]-AAA+BOARD_LEFT;
1811 cl.rt = moveList[i][3]-ONE;
1812 cl.ft = moveList[i][2]-AAA+BOARD_LEFT;
1813 GenLegal(boards[i], PosFlags(i), ExistingAttacksCallback, &cl);
1814 if(appData.debugMode) { int n;
1815 for(n=0; n<chaseStackPointer; n++)
1816 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1817 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1818 fprintf(debugFP, ": new capts after %c%c%c%c\n", cl.ff+AAA, cl.rf+ONE, cl.ft+AAA, cl.rt+ONE);
1820 // chaseSack now contains all captures made possible by the move
1821 for(j=0; j<chaseStackPointer; j++) { // run through chaseStack to identify true chases
1822 int attacker = (int)boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1823 int victim = (int)boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1825 if(attacker >= (int) BlackPawn) attacker = BLACK_TO_WHITE attacker; // convert to white, as piecee type
1826 if(victim >= (int) BlackPawn) victim = BLACK_TO_WHITE victim;
1828 if((attacker == WhiteKnight || attacker == WhiteCannon) && victim == WhiteRook)
1829 continue; // C or H attack on R is always chase; leave on chaseStack
1831 if(attacker == victim) {
1832 if(LegalityTest(boards[i+1], PosFlags(i+1), chaseStack[j].rt,
1833 chaseStack[j].ft, chaseStack[j].rf, chaseStack[j].ff, NULLCHAR) == NormalMove) {
1834 // we can capture back with equal piece, so this is no chase but a sacrifice
1835 chaseStack[j] = chaseStack[--chaseStackPointer]; // delete the capture from the chaseStack
1836 j--; /* ! */ continue;
1841 // the attack is on a lower piece, or on a pinned or blocked equal one
1842 // test if the victim is protected by a true protector. First make the capture.
1843 captured = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1844 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1845 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = EmptySquare;
1846 // Then test if the opponent can recapture
1847 cl.recaptures = 0; // prepare closure to pass recapture square and count moves to it
1848 cl.rt = chaseStack[j].rt;
1849 cl.ft = chaseStack[j].ft;
1850 if(appData.debugMode) {
1851 fprintf(debugFP, "test if we can recapture %c%c\n", cl.ft+AAA, cl.rt+ONE);
1853 GenLegal(boards[i+1], PosFlags(i+1), ProtectedCallback, &cl); // try all moves
1854 // unmake the capture
1855 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1856 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = captured;
1857 // if a recapture was found, piece is protected, and we are not chasing it.
1858 if(cl.recaptures) { // attacked piece was defended by true protector, no chase
1859 chaseStack[j] = chaseStack[--chaseStackPointer]; // so delete from chaseStack
1863 // chaseStack now contains all moves that chased
1864 if(appData.debugMode) { int n;
1865 for(n=0; n<chaseStackPointer; n++)
1866 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1867 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1868 fprintf(debugFP, ": chases\n");
1870 if(i == first) { // copy all people chased by first move of repeat cycle to preyStack
1871 for(j=0; j<chaseStackPointer; j++) {
1872 preyStack[j].rank = chaseStack[j].rt;
1873 preyStack[j].file = chaseStack[j].ft;
1875 preyStackPointer = chaseStackPointer;
1878 for(j=0; j<chaseStackPointer; j++) {
1879 for(k=0; k<preyStackPointer; k++) {
1880 // search the victim of each chase move on the preyStack (first occurrence)
1881 if(chaseStack[j].ft == preyStack[k].file && chaseStack[j].rt == preyStack[k].rank ) {
1882 if(k < tail) break; // piece was already identified as still being chased
1883 preyStack[preyStackPointer] = preyStack[tail]; // move chased piece to bottom part of preyStack
1884 preyStack[tail] = preyStack[k]; // by swapping
1885 preyStack[k] = preyStack[preyStackPointer];
1891 preyStackPointer = tail; // keep bottom part of preyStack, popping pieces unchased on move i.
1892 if(appData.debugMode) { int n;
1893 for(n=0; n<preyStackPointer; n++)
1894 fprintf(debugFP, "%c%c ", preyStack[n].file+AAA, preyStack[n].rank+ONE);
1895 fprintf(debugFP, "always chased upto ply %d\n", i);
1897 // now adjust the location of the chased pieces according to opponent move
1898 for(j=0; j<preyStackPointer; j++) {
1899 if(preyStack[j].rank == moveList[i+1][1]-ONE &&
1900 preyStack[j].file == moveList[i+1][0]-AAA+BOARD_LEFT) {
1901 preyStack[j].rank = moveList[i+1][3]-ONE;
1902 preyStack[j].file = moveList[i+1][2]-AAA+BOARD_LEFT;
1907 return preyStackPointer; // if any piece was left on preyStack, it has been perpetually chased