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++) {
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) continue; // classical Alfil
423 rt = rf + rs; // in unknown variant we assume Modern Elephant, which can also do one step
425 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
426 && !SameColor(board[rf][ff], board[rt][ft]))
427 callback(board, flags, NormalMove,
428 rf, ff, rt, ft, closure);
430 if(gameInfo.variant == VariantSpartan)
431 for(fs = -1; fs <= 1; fs += 2) {
433 if (!(ft < BOARD_LEFT || ft >= BOARD_RGHT) && board[rf][ft] == EmptySquare)
434 callback(board, flags, NormalMove, rf, ff, rf, ft, closure);
438 /* Make Dragon-Horse also do Dababba moves outside Shogi, for better disambiguation in variant Fairy */
441 for (d = 0; d <= 1; d++) // Dababba moves that Rook cannot do
442 for (s = -2; s <= 2; s += 4) {
444 ft = ff + s * (1 - d);
445 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
446 if (SameColor(board[rf][ff], board[rt][ft])) continue;
447 callback(board, flags, NormalMove, rf, ff, rt, ft, closure);
450 /* Shogi Dragon Horse has to continue with Wazir after Bishop */
451 case SHOGI WhiteCardinal:
452 case SHOGI BlackCardinal:
455 /* Capablanca Archbishop continues as Knight */
460 /* Shogi Bishops are ordinary Bishops */
461 case SHOGI WhiteBishop:
462 case SHOGI BlackBishop:
465 for (rs = -1; rs <= 1; rs += 2)
466 for (fs = -1; fs <= 1; fs += 2)
470 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
471 if (SameColor(board[rf][ff], board[rt][ft])) break;
472 callback(board, flags, NormalMove,
473 rf, ff, rt, ft, closure);
474 if (board[rt][ft] != EmptySquare) break;
476 if(m==1) goto mounted;
477 if(m==2) goto finishGold;
478 /* Bishop falls through */
481 /* Shogi Lance is unlike anything, and asymmetric at that */
482 case SHOGI WhiteQueen:
486 if (rt >= BOARD_HEIGHT) break;
487 if (SameColor(board[rf][ff], board[rt][ft])) break;
488 callback(board, flags, NormalMove,
489 rf, ff, rt, ft, closure);
490 if (board[rt][ft] != EmptySquare) break;
494 case SHOGI BlackQueen:
499 if (SameColor(board[rf][ff], board[rt][ft])) break;
500 callback(board, flags, NormalMove,
501 rf, ff, rt, ft, closure);
502 if (board[rt][ft] != EmptySquare) break;
506 /* Make Dragon-King Dababba & Rook-like outside Shogi, for better disambiguation in variant Fairy */
509 for (d = 0; d <= 1; d++) // Dababba moves that Rook cannot do
510 for (s = -2; s <= 2; s += 4) {
512 ft = ff + s * (1 - d);
513 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT || board[rf+rt>>1][ff+ft>>1] == EmptySquare) continue;
514 if (SameColor(board[rf][ff], board[rt][ft])) continue;
515 callback(board, flags, NormalMove, rf, ff, rt, ft, closure);
517 if(gameInfo.variant == VariantSpartan) rookRange = 2; // in Spartan Chess restrict range to modern Dababba
520 /* Shogi Dragon King has to continue as Ferz after Rook moves */
521 case SHOGI WhiteDragon:
522 case SHOGI BlackDragon:
525 /* Capablanca Chancellor sets flag to continue as Knight */
529 m += (gameInfo.variant == VariantSpartan); // in Spartan Chess Chancellor is used for Dragon King.
531 /* Shogi Rooks are ordinary Rooks */
532 case SHOGI WhiteRook:
533 case SHOGI BlackRook:
537 for (d = 0; d <= 1; d++)
538 for (s = -1; s <= 1; s += 2)
540 rt = rf + (i * s) * d;
541 ft = ff + (i * s) * (1 - d);
542 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
543 if (SameColor(board[rf][ff], board[rt][ft])) break;
544 callback(board, flags, NormalMove,
545 rf, ff, rt, ft, closure);
546 if (board[rt][ft] != EmptySquare || i == rookRange) break;
548 if(m==1) goto mounted;
549 if(m==2) goto finishSilver;
554 for (rs = -1; rs <= 1; rs++)
555 for (fs = -1; fs <= 1; fs++) {
556 if (rs == 0 && fs == 0) continue;
560 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
561 if (SameColor(board[rf][ff], board[rt][ft])) break;
562 callback(board, flags, NormalMove,
563 rf, ff, rt, ft, closure);
564 if (board[rt][ft] != EmptySquare) break;
569 /* Shogi Pawn and Silver General: first the Pawn move, */
570 /* then the General continues like a Ferz */
572 if(gameInfo.variant != VariantMakruk) goto commoner;
573 case SHOGI WhitePawn:
574 case SHOGI WhiteFerz:
575 if (rf < BOARD_HEIGHT-1 &&
576 !SameColor(board[rf][ff], board[rf + 1][ff]) )
577 callback(board, flags, NormalMove,
578 rf, ff, rf + 1, ff, closure);
579 if(piece != SHOGI WhitePawn) goto finishSilver;
583 if(gameInfo.variant != VariantMakruk) goto commoner;
584 case SHOGI BlackPawn:
585 case SHOGI BlackFerz:
587 !SameColor(board[rf][ff], board[rf - 1][ff]) )
588 callback(board, flags, NormalMove,
589 rf, ff, rf - 1, ff, closure);
590 if(piece == SHOGI BlackPawn) break;
595 /* [HGM] support Shatranj pieces */
596 for (rs = -1; rs <= 1; rs += 2)
597 for (fs = -1; fs <= 1; fs += 2) {
600 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
601 if (!SameColor(board[rf][ff], board[rt][ft]) &&
602 (gameInfo.variant != VariantXiangqi || InPalace(rt, ft) ) )
603 callback(board, flags, NormalMove,
604 rf, ff, rt, ft, closure);
610 m++; // [HGM] superchess: use for Centaur
612 case SHOGI WhiteKing:
613 case SHOGI BlackKing:
617 for (i = -1; i <= 1; i++)
618 for (j = -1; j <= 1; j++) {
619 if (i == 0 && j == 0) continue;
622 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
623 if (SameColor(board[rf][ff], board[rt][ft])) continue;
624 callback(board, flags, NormalMove,
625 rf, ff, rt, ft, closure);
627 if(m==1) goto mounted;
630 case WhiteNightrider:
631 case BlackNightrider:
632 for (i = -1; i <= 1; i += 2)
633 for (j = -1; j <= 1; j += 2)
634 for (s = 1; s <= 2; s++) { int k;
638 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
639 if (SameColor(board[rf][ff], board[rt][ft])) break;
640 callback(board, flags, NormalMove,
641 rf, ff, rt, ft, closure);
642 if (board[rt][ft] != EmptySquare) break;
648 /* First do Bishop,then continue like Chancellor */
649 for (rs = -1; rs <= 1; rs += 2)
650 for (fs = -1; fs <= 1; fs += 2)
654 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
655 if (SameColor(board[rf][ff], board[rt][ft])) break;
656 callback(board, flags, NormalMove,
657 rf, ff, rt, ft, closure);
658 if (board[rt][ft] != EmptySquare) break;
663 // Use Lance as Berolina / Spartan Pawn.
665 if(gameInfo.variant == VariantSuper) goto Amazon;
666 if (rf < BOARD_HEIGHT-1 && BlackPiece(board[rf + 1][ff]))
667 callback(board, flags,
668 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
669 rf, ff, rf + 1, ff, closure);
670 for (s = -1; s <= 1; s += 2) {
671 if (rf < BOARD_HEIGHT-1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT && board[rf + 1][ff + s] == EmptySquare)
672 callback(board, flags,
673 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
674 rf, ff, rf + 1, ff + s, closure);
675 if (rf == 1 && ff + 2*s >= BOARD_LEFT && ff + 2*s < BOARD_RGHT && board[3][ff + 2*s] == EmptySquare )
676 callback(board, flags, NormalMove, rf, ff, 3, ff + 2*s, closure);
681 if(gameInfo.variant == VariantSuper) goto Amazon;
682 if (rf > 0 && WhitePiece(board[rf - 1][ff]))
683 callback(board, flags,
684 rf <= promoRank ? BlackPromotion : NormalMove,
685 rf, ff, rf - 1, ff, closure);
686 for (s = -1; s <= 1; s += 2) {
687 if (rf > 0 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT && board[rf - 1][ff + s] == EmptySquare)
688 callback(board, flags,
689 rf <= promoRank ? BlackPromotion : NormalMove,
690 rf, ff, rf - 1, ff + s, closure);
691 if (rf == BOARD_HEIGHT-2 && ff + 2*s >= BOARD_LEFT && ff + 2*s < BOARD_RGHT && board[rf-2][ff + 2*s] == EmptySquare )
692 callback(board, flags, NormalMove, rf, ff, rf-2, ff + 2*s, closure);
696 case WhiteFalcon: // [HGM] wild: for wildcards, self-capture symbolizes move to anywhere
700 callback(board, flags, NormalMove, rf, ff, rf, ff, closure);
713 extern void GenLegalCallback P((Board board, int flags, ChessMove kind,
714 int rf, int ff, int rt, int ft,
717 void GenLegalCallback(board, flags, kind, rf, ff, rt, ft, closure)
724 register GenLegalClosure *cl = (GenLegalClosure *) closure;
726 if (!(flags & F_IGNORE_CHECK) &&
727 CheckTest(board, flags, rf, ff, rt, ft,
728 kind == WhiteCapturesEnPassant ||
729 kind == BlackCapturesEnPassant)) return;
730 if (flags & F_ATOMIC_CAPTURE) {
731 if (board[rt][ft] != EmptySquare ||
732 kind == WhiteCapturesEnPassant || kind == BlackCapturesEnPassant) {
734 ChessSquare king = (flags & F_WHITE_ON_MOVE) ? WhiteKing : BlackKing;
735 if (board[rf][ff] == king) return;
736 for (r = rt-1; r <= rt+1; r++) {
737 for (f = ft-1; f <= ft+1; f++) {
738 if (r >= 0 && r < BOARD_HEIGHT && f >= BOARD_LEFT && f < BOARD_RGHT &&
739 board[r][f] == king) return;
744 cl->cb(board, flags, kind, rf, ff, rt, ft, cl->cl);
751 int captures; // [HGM] losers
752 } LegalityTestClosure;
755 /* Like GenPseudoLegal, but (1) include castling moves, (2) unless
756 F_IGNORE_CHECK is set in the flags, omit moves that would leave the
757 king in check, and (3) if F_ATOMIC_CAPTURE is set in the flags, omit
758 moves that would destroy your own king. The CASTLE_OK flags are
759 true if castling is not yet ruled out by a move of the king or
760 rook. Return TRUE if the player on move is currently in check and
761 F_IGNORE_CHECK is not set. [HGM] add castlingRights parameter */
762 int GenLegal(board, flags, callback, closure)
765 MoveCallback callback;
769 int ff, ft, k, left, right, swap;
770 int ignoreCheck = (flags & F_IGNORE_CHECK) != 0;
771 ChessSquare wKing = WhiteKing, bKing = BlackKing, *castlingRights = board[CASTLING];
775 GenPseudoLegal(board, flags, GenLegalCallback, (VOIDSTAR) &cl);
778 CheckTest(board, flags, -1, -1, -1, -1, FALSE)) return TRUE;
780 /* Generate castling moves */
781 if(gameInfo.variant == VariantKnightmate) { /* [HGM] Knightmate */
782 wKing = WhiteUnicorn; bKing = BlackUnicorn;
785 for (ff = BOARD_WIDTH>>1; ff >= (BOARD_WIDTH-1)>>1; ff-- /*ics wild 1*/) {
786 if ((flags & F_WHITE_ON_MOVE) &&
787 (flags & F_WHITE_KCASTLE_OK) &&
788 board[0][ff] == wKing &&
789 board[0][ff + 1] == EmptySquare &&
790 board[0][ff + 2] == EmptySquare &&
791 board[0][BOARD_RGHT-3] == EmptySquare &&
792 board[0][BOARD_RGHT-2] == EmptySquare &&
793 board[0][BOARD_RGHT-1] == WhiteRook &&
794 castlingRights[0] != NoRights && /* [HGM] check rights */
795 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
797 (!CheckTest(board, flags, 0, ff, 0, ff + 1, FALSE) &&
798 !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-3, FALSE) &&
799 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-2, FALSE)) &&
800 !CheckTest(board, flags, 0, ff, 0, ff + 2, FALSE)))) {
802 callback(board, flags,
803 ff==BOARD_WIDTH>>1 ? WhiteKingSideCastle : WhiteKingSideCastleWild,
804 0, ff, 0, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
806 if ((flags & F_WHITE_ON_MOVE) &&
807 (flags & F_WHITE_QCASTLE_OK) &&
808 board[0][ff] == wKing &&
809 board[0][ff - 1] == EmptySquare &&
810 board[0][ff - 2] == EmptySquare &&
811 board[0][BOARD_LEFT+2] == EmptySquare &&
812 board[0][BOARD_LEFT+1] == EmptySquare &&
813 board[0][BOARD_LEFT+0] == WhiteRook &&
814 castlingRights[1] != NoRights && /* [HGM] check rights */
815 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
817 (!CheckTest(board, flags, 0, ff, 0, ff - 1, FALSE) &&
818 !CheckTest(board, flags, 0, ff, 0, BOARD_LEFT+3, FALSE) &&
819 !CheckTest(board, flags, 0, ff, 0, ff - 2, FALSE)))) {
821 callback(board, flags,
822 ff==BOARD_WIDTH>>1 ? WhiteQueenSideCastle : WhiteQueenSideCastleWild,
823 0, ff, 0, ff - ((gameInfo.boardWidth+2)>>2), closure);
825 if (!(flags & F_WHITE_ON_MOVE) &&
826 (flags & F_BLACK_KCASTLE_OK) &&
827 board[BOARD_HEIGHT-1][ff] == bKing &&
828 board[BOARD_HEIGHT-1][ff + 1] == EmptySquare &&
829 board[BOARD_HEIGHT-1][ff + 2] == EmptySquare &&
830 board[BOARD_HEIGHT-1][BOARD_RGHT-3] == EmptySquare &&
831 board[BOARD_HEIGHT-1][BOARD_RGHT-2] == EmptySquare &&
832 board[BOARD_HEIGHT-1][BOARD_RGHT-1] == BlackRook &&
833 castlingRights[3] != NoRights && /* [HGM] check rights */
834 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
836 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 1, FALSE) &&
837 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-3, FALSE) &&
838 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-2, FALSE)) &&
839 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 2, FALSE)))) {
841 callback(board, flags,
842 ff==BOARD_WIDTH>>1 ? BlackKingSideCastle : BlackKingSideCastleWild,
843 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
845 if (!(flags & F_WHITE_ON_MOVE) &&
846 (flags & F_BLACK_QCASTLE_OK) &&
847 board[BOARD_HEIGHT-1][ff] == bKing &&
848 board[BOARD_HEIGHT-1][ff - 1] == EmptySquare &&
849 board[BOARD_HEIGHT-1][ff - 2] == EmptySquare &&
850 board[BOARD_HEIGHT-1][BOARD_LEFT+2] == EmptySquare &&
851 board[BOARD_HEIGHT-1][BOARD_LEFT+1] == EmptySquare &&
852 board[BOARD_HEIGHT-1][BOARD_LEFT+0] == BlackRook &&
853 castlingRights[4] != NoRights && /* [HGM] check rights */
854 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
856 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 1, FALSE) &&
857 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_LEFT+3, FALSE) &&
858 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 2, FALSE)))) {
860 callback(board, flags,
861 ff==BOARD_WIDTH>>1 ? BlackQueenSideCastle : BlackQueenSideCastleWild,
862 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - ((gameInfo.boardWidth+2)>>2), closure);
866 if((swap = gameInfo.variant == VariantSChess) || flags & F_FRC_TYPE_CASTLING) {
868 /* generate all potential FRC castling moves (KxR), ignoring flags */
869 /* [HGM] test if the Rooks we find have castling rights */
870 /* In S-Chess we generate RxK for allowed castlings, for gating at Rook square */
873 if ((flags & F_WHITE_ON_MOVE) != 0) {
874 ff = castlingRights[2]; /* King file if we have any rights */
875 if(ff != NoRights && board[0][ff] == WhiteKing) {
876 if (appData.debugMode) {
877 fprintf(debugFP, "FRC castling, %d %d %d %d %d %d\n",
878 castlingRights[0],castlingRights[1],ff,castlingRights[3],castlingRights[4],castlingRights[5]);
880 ft = castlingRights[0]; /* Rook file if we have H-side rights */
882 right = BOARD_RGHT-2;
883 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
884 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
885 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
886 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
887 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
888 if(ft != NoRights && board[0][ft] == WhiteRook)
889 callback(board, flags, WhiteHSideCastleFR, 0, swap ? ft : ff, 0, swap ? ff : ft, closure);
891 ft = castlingRights[1]; /* Rook file if we have A-side rights */
894 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
895 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
896 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
897 if(ff > BOARD_LEFT+2)
898 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
899 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
900 if(ft != NoRights && board[0][ft] == WhiteRook)
901 callback(board, flags, WhiteASideCastleFR, 0, swap ? ft : ff, 0, swap ? ff : ft, closure);
904 ff = castlingRights[5]; /* King file if we have any rights */
905 if(ff != NoRights && board[BOARD_HEIGHT-1][ff] == BlackKing) {
906 ft = castlingRights[3]; /* Rook file if we have H-side rights */
908 right = BOARD_RGHT-2;
909 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
910 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
911 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
912 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
913 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
914 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
915 callback(board, flags, BlackHSideCastleFR, BOARD_HEIGHT-1, swap ? ft : ff, BOARD_HEIGHT-1, swap ? ff : ft, closure);
917 ft = castlingRights[4]; /* Rook file if we have A-side rights */
920 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
921 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
922 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
923 if(ff > BOARD_LEFT+2)
924 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
925 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
926 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
927 callback(board, flags, BlackASideCastleFR, BOARD_HEIGHT-1, swap ? ft : ff, BOARD_HEIGHT-1, swap ? ff : ft, closure);
943 extern void CheckTestCallback P((Board board, int flags, ChessMove kind,
944 int rf, int ff, int rt, int ft,
948 void CheckTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
955 register CheckTestClosure *cl = (CheckTestClosure *) closure;
957 if (rt == cl->rking && ft == cl->fking) cl->check++;
961 /* If the player on move were to move from (rf, ff) to (rt, ft), would
962 he leave himself in check? Or if rf == -1, is the player on move
963 in check now? enPassant must be TRUE if the indicated move is an
964 e.p. capture. The possibility of castling out of a check along the
965 back rank is not accounted for (i.e., we still return nonzero), as
966 this is illegal anyway. Return value is the number of times the
968 int CheckTest(board, flags, rf, ff, rt, ft, enPassant)
971 int rf, ff, rt, ft, enPassant;
974 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
975 ChessSquare captured = EmptySquare;
976 /* Suppress warnings on uninitialized variables */
978 if(gameInfo.variant == VariantXiangqi)
979 king = flags & F_WHITE_ON_MOVE ? WhiteWazir : BlackWazir;
980 if(gameInfo.variant == VariantKnightmate)
981 king = flags & F_WHITE_ON_MOVE ? WhiteUnicorn : BlackUnicorn;
985 captured = board[rf][ft];
986 board[rf][ft] = EmptySquare;
988 captured = board[rt][ft];
990 board[rt][ft] = board[rf][ff];
991 board[rf][ff] = EmptySquare;
992 } else board[rt][ft] = ff; // [HGM] drop
994 /* For compatibility with ICS wild 9, we scan the board in the
995 order a1, a2, a3, ... b1, b2, ..., h8 to find the first king,
996 and we test only whether that one is in check. */
997 for (cl.fking = BOARD_LEFT+0; cl.fking < BOARD_RGHT; cl.fking++)
998 for (cl.rking = 0; cl.rking < BOARD_HEIGHT; cl.rking++) {
999 if (board[cl.rking][cl.fking] == king) {
1000 if(gameInfo.variant == VariantXiangqi) {
1001 /* [HGM] In Xiangqi opposing Kings means check as well */
1003 dir = (king >= BlackPawn) ? -1 : 1;
1004 for( i=cl.rking+dir; i>=0 && i<BOARD_HEIGHT &&
1005 board[i][cl.fking] == EmptySquare; i+=dir );
1006 if(i>=0 && i<BOARD_HEIGHT &&
1007 board[i][cl.fking] == (dir>0 ? BlackWazir : WhiteWazir) )
1011 GenPseudoLegal(board, flags ^ F_WHITE_ON_MOVE, CheckTestCallback, (VOIDSTAR) &cl);
1012 if(gameInfo.variant != VariantSpartan || cl.check == 0) // in Spartan Chess go on to test if other King is checked too
1013 goto undo_move; /* 2-level break */
1020 board[rf][ff] = board[rt][ft];
1022 board[rf][ft] = captured;
1023 board[rt][ft] = EmptySquare;
1025 board[rt][ft] = captured;
1027 } else board[rt][ft] = EmptySquare; // [HGM] drop
1029 return cl.fking < BOARD_RGHT ? cl.check : 1000; // [HGM] atomic: return 1000 if we have no king
1032 ChessMove LegalDrop(board, flags, piece, rt, ft)
1037 { // [HGM] put drop legality testing in separate routine for clarity
1039 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
1040 if(board[rt][ft] != EmptySquare) return ImpossibleMove; // must drop to empty square
1041 n = PieceToNumber(piece);
1042 if(gameInfo.holdingsWidth == 0 || (flags & F_WHITE_ON_MOVE ? board[n][BOARD_WIDTH-1] : board[BOARD_HEIGHT-1-n][0]) != piece)
1043 return ImpossibleMove; // piece not available
1044 if(gameInfo.variant == VariantShogi) { // in Shogi lots of drops are forbidden!
1045 if((piece == WhitePawn || piece == WhiteQueen) && rt == BOARD_HEIGHT-1 ||
1046 (piece == BlackPawn || piece == BlackQueen) && rt == 0 ||
1047 piece == WhiteKnight && rt > BOARD_HEIGHT-3 ||
1048 piece == BlackKnight && rt < 2 ) return IllegalMove; // e.g. where dropped piece has no moves
1049 if(piece == WhitePawn || piece == BlackPawn) {
1051 for(r=1; r<BOARD_HEIGHT-1; r++)
1052 if(board[r][ft] == piece) return IllegalMove; // or there already is a Pawn in file
1053 // should still test if we mate with this Pawn
1055 } else if(gameInfo.variant == VariantSChess) { // only back-rank drops
1056 if (rt != (piece < BlackPawn ? 0 : BOARD_HEIGHT-1)) return IllegalMove;
1058 if( (piece == WhitePawn || piece == BlackPawn) &&
1059 (rt == 0 || rt == BOARD_HEIGHT -1 ) )
1060 return IllegalMove; /* no pawn drops on 1st/8th */
1062 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
1063 if (!(flags & F_IGNORE_CHECK) &&
1064 CheckTest(board, flags, DROP_RANK, piece, rt, ft, FALSE) ) return IllegalMove;
1065 return flags & F_WHITE_ON_MOVE ? WhiteDrop : BlackDrop;
1068 extern void LegalityTestCallback P((Board board, int flags, ChessMove kind,
1069 int rf, int ff, int rt, int ft,
1072 void LegalityTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
1079 register LegalityTestClosure *cl = (LegalityTestClosure *) closure;
1081 // if (appData.debugMode) {
1082 // fprintf(debugFP, "Legality test: %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
1084 if(board[rt][ft] != EmptySquare || kind==WhiteCapturesEnPassant || kind==BlackCapturesEnPassant)
1085 cl->captures++; // [HGM] losers: count legal captures
1086 if (rf == cl->rf && ff == cl->ff && rt == cl->rt && ft == cl->ft)
1090 ChessMove LegalityTest(board, flags, rf, ff, rt, ft, promoChar)
1093 int rf, ff, rt, ft, promoChar;
1095 LegalityTestClosure cl; ChessSquare piece, *castlingRights = board[CASTLING];
1097 if(rf == DROP_RANK) return LegalDrop(board, flags, ff, rt, ft);
1098 piece = board[rf][ff];
1100 if (appData.debugMode) {
1102 for(i=0; i<6; i++) fprintf(debugFP, "%d ", castlingRights[i]);
1103 fprintf(debugFP, "Legality test? %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
1105 /* [HGM] Cobra and Falcon are wildcard pieces; consider all their moves legal */
1106 /* (perhaps we should disallow moves that obviously leave us in check?) */
1107 if(piece == WhiteFalcon || piece == BlackFalcon ||
1108 piece == WhiteCobra || piece == BlackCobra)
1109 return CheckTest(board, flags, rf, ff, rt, ft, FALSE) ? IllegalMove : NormalMove;
1115 cl.kind = IllegalMove;
1116 cl.captures = 0; // [HGM] losers: prepare to count legal captures.
1117 GenLegal(board, flags, LegalityTestCallback, (VOIDSTAR) &cl);
1118 if((flags & F_MANDATORY_CAPTURE) && cl.captures && board[rt][ft] == EmptySquare
1119 && cl.kind != WhiteCapturesEnPassant && cl.kind != BlackCapturesEnPassant)
1120 return(IllegalMove); // [HGM] losers: if there are legal captures, non-capts are illegal
1122 if(promoChar == 'x') promoChar = NULLCHAR; // [HGM] is this ever the case?
1123 if(gameInfo.variant == VariantSChess && promoChar && promoChar != '=' && board[rf][ff] != WhitePawn && board[rf][ff] != BlackPawn) {
1124 if(board[rf][ff] < BlackPawn) { // white
1125 if(rf != 0) return IllegalMove; // must be on back rank
1126 if(board[PieceToNumber(CharToPiece(ToUpper(promoChar)))][BOARD_WIDTH-2] == 0) return ImpossibleMove;// must be in stock
1128 if(rf != BOARD_HEIGHT-1) return IllegalMove;
1129 if(board[BOARD_HEIGHT-1-PieceToNumber(CharToPiece(ToLower(promoChar)))][1] == 0) return ImpossibleMove;
1132 if(gameInfo.variant == VariantShogi) {
1133 /* [HGM] Shogi promotions. '=' means defer */
1134 if(rf != DROP_RANK && cl.kind == NormalMove) {
1135 ChessSquare piece = board[rf][ff];
1137 if(promoChar == PieceToChar(BlackQueen)) promoChar = NULLCHAR; /* [HGM] Kludge */
1138 if(promoChar == 'd' && (piece == WhiteRook || piece == BlackRook) ||
1139 promoChar == 'h' && (piece == WhiteBishop || piece == BlackBishop) ||
1140 promoChar == 'g' && (piece <= WhiteFerz || piece <= BlackFerz && piece >= BlackPawn) )
1141 promoChar = '+'; // allowed ICS notations
1142 if(appData.debugMode)fprintf(debugFP,"SHOGI promoChar = %c\n", promoChar ? promoChar : '-');
1143 if(promoChar != NULLCHAR && promoChar != '+' && promoChar != '=')
1144 return CharToPiece(promoChar) == EmptySquare ? ImpossibleMove : IllegalMove;
1145 else if(flags & F_WHITE_ON_MOVE) {
1146 if( (int) piece < (int) WhiteWazir &&
1147 (rf >= BOARD_HEIGHT*2/3 || rt >= BOARD_HEIGHT*2/3) ) {
1148 if( (piece == WhitePawn || piece == WhiteQueen) && rt > BOARD_HEIGHT-2 ||
1149 piece == WhiteKnight && rt > BOARD_HEIGHT-3) /* promotion mandatory */
1150 cl.kind = promoChar == '=' ? IllegalMove : WhitePromotion;
1151 else /* promotion optional, default is defer */
1152 cl.kind = promoChar == '+' ? WhitePromotion : WhiteNonPromotion;
1153 } else cl.kind = promoChar == '+' ? IllegalMove : NormalMove;
1155 if( (int) piece < (int) BlackWazir && (rf < BOARD_HEIGHT/3 || rt < BOARD_HEIGHT/3) ) {
1156 if( (piece == BlackPawn || piece == BlackQueen) && rt < 1 ||
1157 piece == BlackKnight && rt < 2 ) /* promotion obligatory */
1158 cl.kind = promoChar == '=' ? IllegalMove : BlackPromotion;
1159 else /* promotion optional, default is defer */
1160 cl.kind = promoChar == '+' ? BlackPromotion : BlackNonPromotion;
1161 } else cl.kind = promoChar == '+' ? IllegalMove : NormalMove;
1165 if (promoChar != NULLCHAR) {
1166 if(promoChar == '=') cl.kind = IllegalMove; else // [HGM] shogi: no deferred promotion outside Shogi
1167 if (cl.kind == WhitePromotion || cl.kind == BlackPromotion) {
1168 if(CharToPiece(flags & F_WHITE_ON_MOVE ? ToUpper(promoChar) : ToLower(promoChar)) == EmptySquare)
1169 cl.kind = ImpossibleMove; // non-existing piece
1171 cl.kind = IllegalMove;
1181 extern void MateTestCallback P((Board board, int flags, ChessMove kind,
1182 int rf, int ff, int rt, int ft,
1185 void MateTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
1192 register MateTestClosure *cl = (MateTestClosure *) closure;
1197 /* Return MT_NONE, MT_CHECK, MT_CHECKMATE, or MT_STALEMATE */
1198 int MateTest(board, flags)
1203 int inCheck, r, f, myPieces=0, hisPieces=0, nrKing=0;
1204 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
1206 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) {
1207 // [HGM] losers: Count pieces and kings, to detect other unorthodox winning conditions
1208 nrKing += (board[r][f] == king); // stm has king
1209 if( board[r][f] != EmptySquare ) {
1210 if((int)board[r][f] <= (int)king && (int)board[r][f] >= (int)king - (int)WhiteKing + (int)WhitePawn)
1215 if(appData.debugMode) fprintf(debugFP, "MateTest: K=%d, my=%d, his=%d\n", nrKing, myPieces, hisPieces);
1216 switch(gameInfo.variant) { // [HGM] losers: extinction wins
1217 case VariantShatranj:
1218 if(hisPieces == 1) return myPieces > 1 ? MT_BARE : MT_DRAW;
1222 if(nrKing == 0) return MT_NOKING;
1225 if(myPieces == 1) return MT_BARE;
1228 inCheck = GenLegal(board, flags, MateTestCallback, (VOIDSTAR) &cl);
1229 // [HGM] 3check: yet to do!
1231 return inCheck ? MT_CHECK : MT_NONE;
1233 if(gameInfo.holdingsWidth && gameInfo.variant != VariantSuper && gameInfo.variant != VariantGreat) { // drop game
1234 int r, f, n, holdings = flags & F_WHITE_ON_MOVE ? BOARD_WIDTH-1 : 0;
1235 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) if(board[r][f] == EmptySquare) // all empty squares
1236 for(n=0; n<BOARD_HEIGHT; n++) // all pieces in hand
1237 if(board[n][holdings] != EmptySquare) {
1238 int moveType = LegalDrop(board, flags, board[n][holdings], r, f);
1239 if(moveType == WhiteDrop || moveType == BlackDrop) return (inCheck ? MT_CHECK : MT_NONE); // we have legal drop
1242 if(gameInfo.variant == VariantSuicide) // [HGM] losers: always stalemate, since no check, but result varies
1243 return myPieces == hisPieces ? MT_STALEMATE :
1244 myPieces > hisPieces ? MT_STAINMATE : MT_STEALMATE;
1245 else if(gameInfo.variant == VariantLosers) return inCheck ? MT_TRICKMATE : MT_STEALMATE;
1246 else if(gameInfo.variant == VariantGiveaway) return MT_STEALMATE; // no check exists, stalemated = win
1248 return inCheck ? MT_CHECKMATE
1249 : (gameInfo.variant == VariantXiangqi || gameInfo.variant == VariantShatranj) ?
1250 MT_STAINMATE : MT_STALEMATE;
1255 extern void DisambiguateCallback P((Board board, int flags, ChessMove kind,
1256 int rf, int ff, int rt, int ft,
1259 void DisambiguateCallback(board, flags, kind, rf, ff, rt, ft, closure)
1266 register DisambiguateClosure *cl = (DisambiguateClosure *) closure;
1267 int wildCard = FALSE; ChessSquare piece = board[rf][ff];
1269 // [HGM] wild: for wild-card pieces rt and rf are dummies
1270 if(piece == WhiteFalcon || piece == BlackFalcon ||
1271 piece == WhiteCobra || piece == BlackCobra)
1274 if ((cl->pieceIn == EmptySquare || cl->pieceIn == board[rf][ff]
1275 || PieceToChar(board[rf][ff]) == '~'
1276 && cl->pieceIn == (ChessSquare)(DEMOTED board[rf][ff])
1278 (cl->rfIn == -1 || cl->rfIn == rf) &&
1279 (cl->ffIn == -1 || cl->ffIn == ff) &&
1280 (cl->rtIn == -1 || cl->rtIn == rt || wildCard) &&
1281 (cl->ftIn == -1 || cl->ftIn == ft || wildCard)) {
1284 if(cl->count == 1 || board[rt][ft] != EmptySquare) {
1285 // [HGM] oneclick: if multiple moves, be sure we remember capture
1286 cl->piece = board[rf][ff];
1289 cl->rt = wildCard ? cl->rtIn : rt;
1290 cl->ft = wildCard ? cl->ftIn : ft;
1293 cl->captures += (board[rt][ft] != EmptySquare); // [HGM] oneclick: count captures
1297 void Disambiguate(board, flags, closure)
1300 DisambiguateClosure *closure;
1302 int illegal = 0; char c = closure->promoCharIn;
1304 closure->count = closure->captures = 0;
1305 closure->rf = closure->ff = closure->rt = closure->ft = 0;
1306 closure->kind = ImpossibleMove;
1307 if (appData.debugMode) {
1308 fprintf(debugFP, "Disambiguate in: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1309 closure->pieceIn,closure->ffIn,closure->rfIn,closure->ftIn,closure->rtIn,
1310 closure->promoCharIn, closure->promoCharIn >= ' ' ? closure->promoCharIn : '-');
1312 GenLegal(board, flags, DisambiguateCallback, (VOIDSTAR) closure);
1313 if (closure->count == 0) {
1314 /* See if it's an illegal move due to check */
1316 GenLegal(board, flags|F_IGNORE_CHECK, DisambiguateCallback, (VOIDSTAR) closure);
1317 if (closure->count == 0) {
1318 /* No, it's not even that */
1319 if (appData.debugMode) { int i, j;
1320 for(i=BOARD_HEIGHT-1; i>=0; i--) {
1321 for(j=0; j<BOARD_WIDTH; j++)
1322 fprintf(debugFP, "%3d", (int) board[i][j]);
1323 fprintf(debugFP, "\n");
1330 if (c == 'x') c = NULLCHAR; // get rid of any 'x' (which should never happen?)
1331 if(gameInfo.variant == VariantSChess && c && c != '=' && closure->piece != WhitePawn && closure->piece != BlackPawn) {
1332 if(closure->piece < BlackPawn) { // white
1333 if(closure->rf != 0) closure->kind = IllegalMove; // must be on back rank
1334 if(board[PieceToNumber(CharToPiece(ToUpper(c)))][BOARD_WIDTH-2] == 0) closure->kind = ImpossibleMove;// must be in stock
1336 if(closure->rf != BOARD_HEIGHT-1) closure->kind = IllegalMove;
1337 if(board[BOARD_HEIGHT-1-PieceToNumber(CharToPiece(ToLower(c)))][1] == 0) closure->kind = ImpossibleMove;
1340 if(gameInfo.variant == VariantShogi) {
1341 /* [HGM] Shogi promotions. On input, '=' means defer, '+' promote. Afterwards, c is set to '+' for promotions, NULL other */
1342 if(closure->rfIn != DROP_RANK && closure->kind == NormalMove) {
1343 ChessSquare piece = closure->piece;
1344 if (c == 'd' && (piece == WhiteRook || piece == BlackRook) ||
1345 c == 'h' && (piece == WhiteBishop || piece == BlackBishop) ||
1346 c == 'g' && (piece <= WhiteFerz || piece <= BlackFerz && piece >= BlackPawn) )
1347 c = '+'; // allowed ICS notations
1348 if(c != NULLCHAR && c != '+' && c != '=') closure->kind = IllegalMove; // otherwise specifying a piece is illegal
1349 else if(flags & F_WHITE_ON_MOVE) {
1350 if( (int) piece < (int) WhiteWazir &&
1351 (closure->rf >= BOARD_HEIGHT-(BOARD_HEIGHT/3) || closure->rt >= BOARD_HEIGHT-(BOARD_HEIGHT/3)) ) {
1352 if( (piece == WhitePawn || piece == WhiteQueen) && closure->rt > BOARD_HEIGHT-2 ||
1353 piece == WhiteKnight && closure->rt > BOARD_HEIGHT-3) /* promotion mandatory */
1354 closure->kind = c == '=' ? IllegalMove : WhitePromotion;
1355 else /* promotion optional, default is defer */
1356 closure->kind = c == '+' ? WhitePromotion : WhiteNonPromotion;
1357 } else closure->kind = c == '+' ? IllegalMove : NormalMove;
1359 if( (int) piece < (int) BlackWazir && (closure->rf < BOARD_HEIGHT/3 || closure->rt < BOARD_HEIGHT/3) ) {
1360 if( (piece == BlackPawn || piece == BlackQueen) && closure->rt < 1 ||
1361 piece == BlackKnight && closure->rt < 2 ) /* promotion obligatory */
1362 closure->kind = c == '=' ? IllegalMove : BlackPromotion;
1363 else /* promotion optional, default is defer */
1364 closure->kind = c == '+' ? BlackPromotion : BlackNonPromotion;
1365 } else closure->kind = c == '+' ? IllegalMove : NormalMove;
1368 if(closure->kind == WhitePromotion || closure->kind == BlackPromotion) c = '+'; else
1369 if(closure->kind == WhiteNonPromotion || closure->kind == BlackNonPromotion) c = '=';
1371 if (closure->kind == WhitePromotion || closure->kind == BlackPromotion) {
1372 if(c == NULLCHAR) { // missing promoChar on mandatory promotion; use default for variant
1373 if(gameInfo.variant == VariantShatranj || gameInfo.variant == VariantCourier || gameInfo.variant == VariantMakruk)
1374 c = PieceToChar(BlackFerz);
1375 else if(gameInfo.variant == VariantGreat)
1376 c = PieceToChar(BlackMan);
1378 c = PieceToChar(BlackQueen);
1379 } else if(c == '=') closure->kind = IllegalMove; // no deferral outside Shogi
1380 } else if (c != NULLCHAR) closure->kind = IllegalMove;
1382 closure->promoChar = ToLower(c); // this can be NULLCHAR! Note we keep original promoChar even if illegal.
1383 if(c != '+' && c != '=' && c != NULLCHAR && CharToPiece(flags & F_WHITE_ON_MOVE ? ToUpper(c) : ToLower(c)) == EmptySquare)
1384 closure->kind = ImpossibleMove; // but we cannot handle non-existing piece types!
1385 if (closure->count > 1) {
1386 closure->kind = AmbiguousMove;
1389 /* Note: If more than one illegal move matches, but no legal
1390 moves, we return IllegalMove, not AmbiguousMove. Caller
1391 can look at closure->count to detect this.
1393 closure->kind = IllegalMove;
1395 if (appData.debugMode) {
1396 fprintf(debugFP, "Disambiguate out: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1397 closure->piece,closure->ff,closure->rf,closure->ft,closure->rt,closure->promoChar,
1398 closure->promoChar >= ' ' ? closure->promoChar:'-');
1412 } CoordsToAlgebraicClosure;
1414 extern void CoordsToAlgebraicCallback P((Board board, int flags,
1415 ChessMove kind, int rf, int ff,
1416 int rt, int ft, VOIDSTAR closure));
1418 void CoordsToAlgebraicCallback(board, flags, kind, rf, ff, rt, ft, closure)
1425 register CoordsToAlgebraicClosure *cl =
1426 (CoordsToAlgebraicClosure *) closure;
1428 if ((rt == cl->rt && ft == cl->ft || rt == rf && ft == ff) && // [HGM] null move matches any toSquare
1429 (board[rf][ff] == cl->piece
1430 || PieceToChar(board[rf][ff]) == '~' &&
1431 (ChessSquare) (DEMOTED board[rf][ff]) == cl->piece)
1435 cl->kind = kind; /* this is the move we want */
1437 cl->file++; /* need file to rule out this move */
1441 cl->rank++; /* need rank to rule out this move */
1443 cl->either++; /* rank or file will rule out this move */
1449 /* Convert coordinates to normal algebraic notation.
1450 promoChar must be NULLCHAR or 'x' if not a promotion.
1452 ChessMove CoordsToAlgebraic(board, flags, rf, ff, rt, ft, promoChar, out)
1461 char *outp = out, c;
1462 CoordsToAlgebraicClosure cl;
1464 if (rf == DROP_RANK) {
1465 /* Bughouse piece drop */
1466 *outp++ = ToUpper(PieceToChar((ChessSquare) ff));
1471 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1473 return (flags & F_WHITE_ON_MOVE) ? WhiteDrop : BlackDrop;
1476 if (promoChar == 'x') promoChar = NULLCHAR;
1477 piece = board[rf][ff];
1478 if(PieceToChar(piece)=='~') piece = (ChessSquare)(DEMOTED piece);
1480 if (appData.debugMode)
1481 fprintf(debugFP, "CoordsToAlgebraic, piece=%d (%d,%d)-(%d,%d) %c\n", (int)piece,ff,rf,ft,rt,promoChar >= ' ' ? promoChar : '-');
1485 kind = LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1486 if (kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1487 /* Keep short notation if move is illegal only because it
1488 leaves the player in check, but still return IllegalMove */
1489 kind = LegalityTest(board, flags|F_IGNORE_CHECK, rf, ff, rt, ft, promoChar);
1490 if (kind == IllegalMove) break;
1495 if (ff == ft && board[rt][ft] == EmptySquare) { /* [HGM] Xiangqi has straight noncapts! */
1496 /* Non-capture; use style "e5" */
1499 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1501 /* Capture; use style "exd5" */
1502 if(gameInfo.variant != VariantXiangqi || board[rt][ft] != EmptySquare )
1503 *outp++ = 'x'; /* [HGM] Xiangqi has sideway noncaptures across river! */
1507 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1509 /* Use promotion suffix style "=Q" */
1511 if (appData.debugMode)
1512 fprintf(debugFP, "movetype=%d, promochar=%d=%c\n", (int)kind, promoChar, promoChar >= ' ' ? promoChar : '-');
1513 if (promoChar != NULLCHAR) {
1514 if(gameInfo.variant == VariantShogi) {
1515 /* [HGM] ... but not in Shogi! */
1516 *outp++ = promoChar == '=' ? '=' : '+';
1519 *outp++ = ToUpper(promoChar);
1528 /* Fabien moved code: FRC castling first (if KxR), wild castling second */
1529 /* Code added by Tord: FRC castling. */
1530 if((piece == WhiteKing && board[rt][ft] == WhiteRook) ||
1531 (piece == BlackKing && board[rt][ft] == BlackRook)) {
1533 safeStrCpy(out, "O-O", MOVE_LEN);
1535 safeStrCpy(out, "O-O-O", MOVE_LEN);
1536 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1538 /* End of code added by Tord */
1539 /* Test for castling or ICS wild castling */
1540 /* Use style "O-O" (oh-oh) for PGN compatibility */
1541 else if (rf == rt &&
1542 rf == ((piece == WhiteKing) ? 0 : BOARD_HEIGHT-1) &&
1543 (ft - ff > 1 || ff - ft > 1) && // No castling if legal King move (on narrow boards!)
1544 ((ff == BOARD_WIDTH>>1 && (ft == BOARD_LEFT+2 || ft == BOARD_RGHT-2)) ||
1545 (ff == (BOARD_WIDTH-1)>>1 && (ft == BOARD_LEFT+1 || ft == BOARD_RGHT-3)))) {
1546 if(ft==BOARD_LEFT+1 || ft==BOARD_RGHT-2)
1547 snprintf(out, MOVE_LEN, "O-O%c%c", promoChar ? '/' : 0, ToUpper(promoChar));
1549 snprintf(out, MOVE_LEN, "O-O-O%c%c", promoChar ? '/' : 0, ToUpper(promoChar));
1551 /* This notation is always unambiguous, unless there are
1552 kings on both the d and e files, with "wild castling"
1553 possible for the king on the d file and normal castling
1554 possible for the other. ICS rules for wild 9
1555 effectively make castling illegal for either king in
1556 this situation. So I am not going to worry about it;
1557 I'll just generate an ambiguous O-O in this case.
1559 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1562 /* else fall through */
1570 cl.kind = IllegalMove;
1571 cl.rank = cl.file = cl.either = 0;
1572 GenLegal(board, flags, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1574 if (cl.kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1575 /* Generate pretty moves for moving into check, but
1576 still return IllegalMove.
1578 GenLegal(board, flags|F_IGNORE_CHECK, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1579 if (cl.kind == IllegalMove) break;
1580 cl.kind = IllegalMove;
1583 /* Style is "Nf3" or "Nxf7" if this is unambiguous,
1584 else "Ngf3" or "Ngxf7",
1585 else "N1f3" or "N5xf7",
1586 else "Ng1f3" or "Ng5xf7".
1588 c = PieceToChar(piece) ;
1589 if( c == '~' || c == '+') {
1590 /* [HGM] print nonexistent piece as its demoted version */
1591 piece = (ChessSquare) (DEMOTED piece);
1593 if(c=='+') *outp++ = c;
1594 *outp++ = ToUpper(PieceToChar(piece));
1596 if (cl.file || (cl.either && !cl.rank)) {
1602 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1605 if(board[rt][ft] != EmptySquare)
1611 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1612 if (gameInfo.variant == VariantShogi) {
1613 /* [HGM] in Shogi non-pawns can promote */
1614 *outp++ = promoChar; // Don't bother to correct move type, return value is never used!
1616 else if (gameInfo.variant != VariantSuper && promoChar &&
1617 (piece == WhiteLance || piece == BlackLance) ) { // Lance sometimes represents Pawn
1619 *outp++ = ToUpper(promoChar);
1621 else if (gameInfo.variant == VariantSChess && promoChar) { // and in S-Chess we have gating
1623 *outp++ = ToUpper(promoChar);
1629 /* Moving a nonexistent piece */
1633 /* Not a legal move, even ignoring check.
1634 If there was a piece on the from square,
1635 use style "Ng1g3" or "Ng1xe8";
1636 if there was a pawn or nothing (!),
1637 use style "g1g3" or "g1xe8". Use "x"
1638 if a piece was on the to square, even
1639 a piece of the same color.
1643 if (piece != EmptySquare && piece != WhitePawn && piece != BlackPawn) {
1645 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<=BOARD_RGHT; f++)
1646 c += (board[r][f] == piece); // count on-board pieces of given type
1647 *outp++ = ToUpper(PieceToChar(piece));
1649 if(c != 1) { // [HGM] but if there is only one piece of the mentioned type, no from-square, thank you!
1653 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1655 if (board[rt][ft] != EmptySquare) *outp++ = 'x';
1659 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1660 /* Use promotion suffix style "=Q" */
1661 if (promoChar != NULLCHAR && promoChar != 'x') {
1663 *outp++ = ToUpper(promoChar);
1670 // [HGM] XQ: the following code serves to detect perpetual chasing (Asian rules)
1679 // I guess the following variables logically belong in the closure too, but I was too lazy and used globals
1681 int preyStackPointer, chaseStackPointer;
1684 char rf, ff, rt, ft;
1694 // there are three new callbacks for use with GenLegal: for adding captures, deleting them, and finding a recapture
1696 extern void AtacksCallback P((Board board, int flags, ChessMove kind,
1697 int rf, int ff, int rt, int ft,
1700 void AttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1706 { // For adding captures that can lead to chase indictment to the chaseStack
1707 if(board[rt][ft] == EmptySquare) return; // non-capture
1708 if(board[rt][ft] == WhitePawn && rt < BOARD_HEIGHT/2) return; // Pawn before river can be chased
1709 if(board[rt][ft] == BlackPawn && rt >= BOARD_HEIGHT/2) return; // Pawn before river can be chased
1710 if(board[rf][ff] == WhitePawn || board[rf][ff] == BlackPawn) return; // Pawns are allowed to chase
1711 if(board[rf][ff] == WhiteWazir || board[rf][ff] == BlackWazir) return; // King is allowed to chase
1712 // move cannot be excluded from being a chase trivially (based on attacker and victim); save it on chaseStack
1713 chaseStack[chaseStackPointer].rf = rf;
1714 chaseStack[chaseStackPointer].ff = ff;
1715 chaseStack[chaseStackPointer].rt = rt;
1716 chaseStack[chaseStackPointer].ft = ft;
1717 chaseStackPointer++;
1720 extern void ExistingAtacksCallback P((Board board, int flags, ChessMove kind,
1721 int rf, int ff, int rt, int ft,
1724 void ExistingAttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1730 { // for removing pre-exsting captures from the chaseStack, to be left with newly created ones
1732 register ChaseClosure *cl = (ChaseClosure *) closure; //closure tells us the move played in the repeat loop
1734 if(board[rt][ft] == EmptySquare) return; // no capture
1735 if(rf == cl->rf && ff == cl->ff) { // attacks with same piece from new position are not considered new
1736 rf = cl->rt; ff = cl->ft; // doctor their fromSquare so they will be recognized in chaseStack
1738 // search move in chaseStack, and delete it if it occurred there (as we know now it is not a new capture)
1739 for(i=0; i<chaseStackPointer; i++) {
1740 if(chaseStack[i].rf == rf && chaseStack[i].ff == ff &&
1741 chaseStack[i].rt == rt && chaseStack[i].ft == ft ) {
1742 // move found on chaseStack, delete it by overwriting with move popped from top of chaseStack
1743 chaseStack[i] = chaseStack[--chaseStackPointer];
1749 extern void ProtectedCallback P((Board board, int flags, ChessMove kind,
1750 int rf, int ff, int rt, int ft,
1753 void ProtectedCallback(board, flags, kind, rf, ff, rt, ft, closure)
1759 { // for determining if a piece (given through the closure) is protected
1760 register ChaseClosure *cl = (ChaseClosure *) closure; // closure tells us where to recapture
1762 if(rt == cl->rt && ft == cl->ft) cl->recaptures++; // count legal recaptures to this square
1763 if(appData.debugMode && board[rt][ft] != EmptySquare)
1764 fprintf(debugFP, "try %c%c%c%c=%d\n", ff+AAA, rf+ONE,ft+AAA, rt+ONE, cl->recaptures);
1767 extern char moveList[MAX_MOVES][MOVE_LEN];
1769 int PerpetualChase(int first, int last)
1770 { // this routine detects if the side to move in the 'first' position is perpetually chasing (when not checking)
1773 ChessSquare captured;
1775 preyStackPointer = 0; // clear stack of chased pieces
1776 for(i=first; i<last; i+=2) { // for all positions with same side to move
1777 if(appData.debugMode) fprintf(debugFP, "judge position %i\n", i);
1778 chaseStackPointer = 0; // clear stack that is going to hold possible chases
1779 // determine all captures possible after the move, and put them on chaseStack
1780 GenLegal(boards[i+1], PosFlags(i), AttacksCallback, &cl);
1781 if(appData.debugMode) { int n;
1782 for(n=0; n<chaseStackPointer; n++)
1783 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1784 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1785 fprintf(debugFP, ": all capts\n");
1787 // determine all captures possible before the move, and delete them from chaseStack
1788 cl.rf = moveList[i][1]-ONE; // prepare closure to pass move that led from i to i+1
1789 cl.ff = moveList[i][0]-AAA+BOARD_LEFT;
1790 cl.rt = moveList[i][3]-ONE;
1791 cl.ft = moveList[i][2]-AAA+BOARD_LEFT;
1792 GenLegal(boards[i], PosFlags(i), ExistingAttacksCallback, &cl);
1793 if(appData.debugMode) { int n;
1794 for(n=0; n<chaseStackPointer; n++)
1795 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1796 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1797 fprintf(debugFP, ": new capts after %c%c%c%c\n", cl.ff+AAA, cl.rf+ONE, cl.ft+AAA, cl.rt+ONE);
1799 // chaseSack now contains all captures made possible by the move
1800 for(j=0; j<chaseStackPointer; j++) { // run through chaseStack to identify true chases
1801 int attacker = (int)boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1802 int victim = (int)boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1804 if(attacker >= (int) BlackPawn) attacker = BLACK_TO_WHITE attacker; // convert to white, as piecee type
1805 if(victim >= (int) BlackPawn) victim = BLACK_TO_WHITE victim;
1807 if((attacker == WhiteKnight || attacker == WhiteCannon) && victim == WhiteRook)
1808 continue; // C or H attack on R is always chase; leave on chaseStack
1810 if(attacker == victim) {
1811 if(LegalityTest(boards[i+1], PosFlags(i+1), chaseStack[j].rt,
1812 chaseStack[j].ft, chaseStack[j].rf, chaseStack[j].ff, NULLCHAR) == NormalMove) {
1813 // we can capture back with equal piece, so this is no chase but a sacrifice
1814 chaseStack[j] = chaseStack[--chaseStackPointer]; // delete the capture from the chaseStack
1815 j--; /* ! */ continue;
1820 // the attack is on a lower piece, or on a pinned or blocked equal one
1821 // test if the victim is protected by a true protector. First make the capture.
1822 captured = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1823 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1824 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = EmptySquare;
1825 // Then test if the opponent can recapture
1826 cl.recaptures = 0; // prepare closure to pass recapture square and count moves to it
1827 cl.rt = chaseStack[j].rt;
1828 cl.ft = chaseStack[j].ft;
1829 if(appData.debugMode) {
1830 fprintf(debugFP, "test if we can recapture %c%c\n", cl.ft+AAA, cl.rt+ONE);
1832 GenLegal(boards[i+1], PosFlags(i+1), ProtectedCallback, &cl); // try all moves
1833 // unmake the capture
1834 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1835 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = captured;
1836 // if a recapture was found, piece is protected, and we are not chasing it.
1837 if(cl.recaptures) { // attacked piece was defended by true protector, no chase
1838 chaseStack[j] = chaseStack[--chaseStackPointer]; // so delete from chaseStack
1842 // chaseStack now contains all moves that chased
1843 if(appData.debugMode) { int n;
1844 for(n=0; n<chaseStackPointer; n++)
1845 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1846 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1847 fprintf(debugFP, ": chases\n");
1849 if(i == first) { // copy all people chased by first move of repeat cycle to preyStack
1850 for(j=0; j<chaseStackPointer; j++) {
1851 preyStack[j].rank = chaseStack[j].rt;
1852 preyStack[j].file = chaseStack[j].ft;
1854 preyStackPointer = chaseStackPointer;
1857 for(j=0; j<chaseStackPointer; j++) {
1858 for(k=0; k<preyStackPointer; k++) {
1859 // search the victim of each chase move on the preyStack (first occurrence)
1860 if(chaseStack[j].ft == preyStack[k].file && chaseStack[j].rt == preyStack[k].rank ) {
1861 if(k < tail) break; // piece was already identified as still being chased
1862 preyStack[preyStackPointer] = preyStack[tail]; // move chased piece to bottom part of preyStack
1863 preyStack[tail] = preyStack[k]; // by swapping
1864 preyStack[k] = preyStack[preyStackPointer];
1870 preyStackPointer = tail; // keep bottom part of preyStack, popping pieces unchased on move i.
1871 if(appData.debugMode) { int n;
1872 for(n=0; n<preyStackPointer; n++)
1873 fprintf(debugFP, "%c%c ", preyStack[n].file+AAA, preyStack[n].rank+ONE);
1874 fprintf(debugFP, "always chased upto ply %d\n", i);
1876 // now adjust the location of the chased pieces according to opponent move
1877 for(j=0; j<preyStackPointer; j++) {
1878 if(preyStack[j].rank == moveList[i+1][1]-ONE &&
1879 preyStack[j].file == moveList[i+1][0]-AAA+BOARD_LEFT) {
1880 preyStack[j].rank = moveList[i+1][3]-ONE;
1881 preyStack[j].file = moveList[i+1][2]-AAA+BOARD_LEFT;
1886 return preyStackPointer; // if any piece was left on preyStack, it has been perpetually chased