board.h

   1 /* probdist.h must be included before the include goard since we require
   2  * proper including order. */
   3 #include "probdist.h"
   4
   5 #ifndef PACHI_BOARD_H
   6 #define PACHI_BOARD_H
   7
   8 #include <inttypes.h>
   9 #include <stdbool.h>
  10 #include <stdint.h>
  11
  12 #include "util.h"
  13 #include "stone.h"
  14 #include "move.h"
  15
  16 struct fbook;
  17
  18
  19 /* Maximum supported board size. (Without the S_OFFBOARD edges.) */
  20 #define BOARD_MAX_SIZE 19
  21
  22
  23 /* The board implementation has bunch of optional features.
  24  * Turn them on below: */
  25
  26 #define WANT_BOARD_C // capturable groups queue
  27
  28 //#define BOARD_SIZE 9 // constant board size, allows better optimization
  29
  30 //#define BOARD_SPATHASH // incremental patternsp.h hashes
  31 #define BOARD_SPATHASH_MAXD 3 // maximal diameter
  32
  33 #define BOARD_PAT3 // incremental 3x3 pattern codes
  34
  35 //#define BOARD_TRAITS 1 // incremental point traits (see struct btraits)
  36 //#define BOARD_TRAIT_SAFE 1 // include btraits.safe (rather expensive, unused)
  37 //#define BOARD_TRAIT_SAFE 2 // include btraits.safe based on full is_bad_selfatari()
  38
  39
  40 #define BOARD_MAX_MOVES (BOARD_MAX_SIZE * BOARD_MAX_SIZE)
  41 #define BOARD_MAX_GROUPS (BOARD_MAX_SIZE * BOARD_MAX_SIZE / 2)
  42
  43
  44 /* Some engines might normalize their reading and skip symmetrical
  45  * moves. We will tell them how can they do it. */
  46 struct board_symmetry {
  47         /* Playground is in this rectangle. */
  48         int x1, x2, y1, y2;
  49         /* d ==  0: Full rectangle
  50          * d ==  1: Top triangle */
  51         int d;
  52         /* General symmetry type. */
  53         /* Note that the above is redundant to this, but just provided
  54          * for easier usage. */
  55         enum {
  56                 SYM_FULL,
  57                 SYM_DIAG_UP,
  58                 SYM_DIAG_DOWN,
  59                 SYM_HORIZ,
  60                 SYM_VERT,
  61                 SYM_NONE
  62         } type;
  63 };
  64
  65
  66 typedef uint64_t hash_t;
  67 #define PRIhash PRIx64
  68
  69 /* XXX: This really belongs in pattern3.h, unfortunately that would mean
  70  * a dependency hell. */
  71 typedef uint32_t hash3_t; // 3x3 pattern hash
  72
  73
  74 /* Note that "group" is only chain of stones that is solidly
  75  * connected for us. */
  76 typedef coord_t group_t;
  77
  78 struct group {
  79         /* We keep track of only up to GROUP_KEEP_LIBS; over that, we
  80          * don't care. */
  81         /* _Combination_ of these two values can make some difference
  82          * in performance - fine-tune. */
  83 #define GROUP_KEEP_LIBS 10
  84         // refill lib[] only when we hit this; this must be at least 2!
  85         // Moggy requires at least 3 - see below for semantic impact.
  86 #define GROUP_REFILL_LIBS 5
  87         coord_t lib[GROUP_KEEP_LIBS];
  88         /* libs is only LOWER BOUND for the number of real liberties!!!
  89          * It denotes only number of items in lib[], thus you can rely
  90          * on it to store real liberties only up to <= GROUP_REFILL_LIBS. */
  91         int libs;
  92 };
  93
  94 struct neighbor_colors {
  95         char colors[S_MAX];
  96 };
  97
  98
  99 /* Point traits bitmap; we update this information incrementally,
 100  * it can be used e.g. for fast pattern features matching. */
 101 struct btraits {
 102         /* Number of neighbors we can capture. 0=this move is
 103          * not capturing, 1..4=this many neighbors we can capture
 104          * (can be multiple neighbors of same group). */
 105         unsigned cap:3;
 106         /* Number of 1-stone neighbors we can capture. */
 107         unsigned cap1:3;
 108 #ifdef BOARD_TRAIT_SAFE
 109         /* Whether it is SAFE to play here. This is essentially just
 110          * cached result of board_safe_to_play(). (Of course the concept
 111          * of "safety" is not perfect here, but it's the cheapest
 112          * reasonable thing we can do.) */
 113         bool safe:1;
 114 #endif
 115         /* Whether we need to re-compute this coordinate; used to
 116          * weed out duplicates. Maintained only for S_BLACK. */
 117         bool dirty:1;
 118 };
 119
 120
 121 /* You should treat this struct as read-only. Always call functions below if
 122  * you want to change it. */
 123
 124 struct board {
 125         int size; /* Including S_OFFBOARD margin - see below. */
 126         int size2; /* size^2 */
 127         int bits2; /* ceiling(log2(size2)) */
 128         int captures[S_MAX];
 129         floating_t komi;
 130         int handicap;
 131         /* The ruleset is currently almost never taken into account;
 132          * the board implementation is basically Chinese rules (handicap
 133          * stones compensation) w/ suicide (or you can look at it as
 134          * New Zealand w/o handi stones compensation), while the engine
 135          * enforces no-suicide, making for real Chinese rules.
 136          * However, we accept suicide moves by the opponent, so we
 137          * should work with rules allowing suicide, just not taking
 138          * full advantage of them. */
 139         enum go_ruleset {
 140                 RULES_CHINESE, /* default value */
 141                 RULES_AGA,
 142                 RULES_NEW_ZEALAND,
 143                 RULES_JAPANESE,
 144                 RULES_STONES_ONLY, /* do not count eyes */
 145                 /* http://home.snafu.de/jasiek/siming.html */
 146                 /* Simplified ING rules - RULES_CHINESE with handicaps
 147                  * counting as points and pass stones. Also should
 148                  * allow suicide, but Pachi will never suicide
 149                  * nevertheless. */
 150                 /* XXX: I couldn't find the point about pass stones
 151                  * in the rule text, but it is Robert Jasiek's
 152                  * interpretation of them... These rules were
 153                  * used e.g. at the EGC2012 13x13 tournament.
 154                  * They are not supported by KGS. */
 155                 RULES_SIMING,
 156         } rules;
 157
 158         char *fbookfile;
 159         struct fbook *fbook;
 160
 161         /* Iterator offsets for foreach_neighbor*() */
 162         int nei8[8], dnei[4];
 163
 164         int moves;
 165         struct move last_move;
 166         struct move last_move2; /* second-to-last move */
 167         struct move last_move3; /* just before last_move2, only set if last_move is pass */
 168         struct move last_move4; /* just before last_move3, only set if last_move & last_move2 are pass */
 169         /* Whether we tried to add a hash twice; board_play*() can
 170          * set this, but it will still carry out the move as well! */
 171         bool superko_violation;
 172
 173         /* The following two structures are goban maps and are indexed by
 174          * coord.pos. The map is surrounded by a one-point margin from
 175          * S_OFFBOARD stones in order to speed up some internal loops.
 176          * Some of the foreach iterators below might include these points;
 177          * you need to handle them yourselves, if you need to. */
 178
 179         /* Stones played on the board */
 180         enum stone *b; /* enum stone */
 181         /* Group id the stones are part of; 0 == no group */
 182         group_t *g;
 183         /* Positions of next stones in the stone group; 0 == last stone */
 184         coord_t *p;
 185         /* Neighboring colors; numbers of neighbors of index color */
 186         struct neighbor_colors *n;
 187         /* Zobrist hash for each position */
 188         hash_t *h;
 189 #ifdef BOARD_SPATHASH
 190         /* For spatial hashes, we use only 24 bits. */
 191         /* [0] is d==1, we don't keep hash for d==0. */
 192         /* We keep hashes for black-to-play ([][0]) and white-to-play
 193          * ([][1], reversed stone colors since we match all patterns as
 194          * black-to-play). */
 195         uint32_t (*spathash)[BOARD_SPATHASH_MAXD][2];
 196 #endif
 197 #ifdef BOARD_PAT3
 198         /* 3x3 pattern code for each position; see pattern3.h for encoding
 199          * specification. The information is only valid for empty points. */
 200         hash3_t *pat3;
 201 #endif
 202 #ifdef BOARD_TRAITS
 203         /* Incrementally matched point traits information, black-to-play
 204          * ([][0]) and white-to-play ([][1]). */
 205         /* The information is only valid for empty points. */
 206         struct btraits (*t)[2];
 207 #endif
 208         /* Cached information on x-y coordinates so that we avoid division. */
 209         uint8_t (*coord)[2];
 210
 211         /* Group information - indexed by gid (which is coord of base group stone) */
 212         struct group *gi;
 213
 214         /* Positions of free positions - queue (not map) */
 215         /* Note that free position here is any valid move; including single-point eyes!
 216          * However, pass is not included. */
 217         coord_t *f; int flen;
 218
 219 #ifdef WANT_BOARD_C
 220         /* Queue of capturable groups */
 221         group_t *c; int clen;
 222 #endif
 223
 224 #ifdef BOARD_TRAITS
 225         /* Queue of positions that need their traits updated */
 226         coord_t *tq; int tqlen;
 227 #endif
 228
 229         /* Symmetry information */
 230         struct board_symmetry symmetry;
 231
 232         /* Last ko played on the board. */
 233         struct move last_ko;
 234         int last_ko_age;
 235
 236         /* Basic ko check */
 237         struct move ko;
 238
 239         /* Engine-specific state; persistent through board development,
 240          * is reset only at clear_board. */
 241         void *es;
 242
 243         /* Playout-specific state; persistent through board development,
 244          * but its lifetime is maintained in play_random_game(); it should
 245          * not be set outside of it. */
 246         void *ps;
 247
 248
 249         /* --- PRIVATE DATA --- */
 250
 251         /* For superko check: */
 252
 253         /* Board "history" - hashes encountered. Size of the hash should be
 254          * >> board_size^2. */
 255 #define history_hash_bits 12
 256 #define history_hash_mask ((1 << history_hash_bits) - 1)
 257 #define history_hash_prev(i) ((i - 1) & history_hash_mask)
 258 #define history_hash_next(i) ((i + 1) & history_hash_mask)
 259         hash_t history_hash[1 << history_hash_bits];
 260         /* Hash of current board position. */
 261         hash_t hash;
 262         /* Hash of current board position quadrants. */
 263         hash_t qhash[4];
 264 };
 265
 266 #ifdef BOARD_SIZE
 267 /* Avoid unused variable warnings */
 268 #define board_size(b_) (((b_) == (b_)) ? BOARD_SIZE + 2 : 0)
 269 #define board_size2(b_) (board_size(b_) * board_size(b_))
 270 #else
 271 #define board_size(b_) ((b_)->size)
 272 #define board_size2(b_) ((b_)->size2)
 273 #endif
 274
 275 /* This is a shortcut for taking different action on smaller
 276  * and large boards (e.g. picking different variable defaults).
 277  * This is of course less optimal than fine-tuning dependency
 278  * function of values on board size, but that is difficult and
 279  * possibly not very rewarding if you are interested just in
 280  * 9x9 and 19x19. */
 281 #define board_large(b_) (board_size(b_)-2 >= 15)
 282
 283 #if BOARD_SIZE == 19
 284 #  define board_bits2(b_) 9
 285 #elif BOARD_SIZE == 13
 286 #  define board_bits2(b_) 8
 287 #elif BOARD_SIZE == 9
 288 #  define board_bits2(b_) 7
 289 #else
 290 #  define board_bits2(b_) ((b_)->bits2)
 291 #endif
 292
 293 #define board_at(b_, c) ((b_)->b[c])
 294 #define board_atxy(b_, x, y) ((b_)->b[(x) + board_size(b_) * (y)])
 295
 296 #define group_at(b_, c) ((b_)->g[c])
 297 #define group_atxy(b_, x, y) ((b_)->g[(x) + board_size(b_) * (y)])
 298
 299 /* Warning! Neighbor count is kept up-to-date for S_NONE! */
 300 #define neighbor_count_at(b_, coord, color) ((b_)->n[coord].colors[(enum stone) color])
 301 #define set_neighbor_count_at(b_, coord, color, count) (neighbor_count_at(b_, coord, color) = (count))
 302 #define inc_neighbor_count_at(b_, coord, color) (neighbor_count_at(b_, coord, color)++)
 303 #define dec_neighbor_count_at(b_, coord, color) (neighbor_count_at(b_, coord, color)--)
 304 #define immediate_liberty_count(b_, coord) (4 - neighbor_count_at(b_, coord, S_BLACK) - neighbor_count_at(b_, coord, S_WHITE) - neighbor_count_at(b_, coord, S_OFFBOARD))
 305
 306 #define trait_at(b_, coord, color) (b_)->t[coord][(color) - 1]
 307
 308 #define groupnext_at(b_, c) ((b_)->p[c])
 309 #define groupnext_atxy(b_, x, y) ((b_)->p[(x) + board_size(b_) * (y)])
 310
 311 #define group_base(g_) (g_)
 312 #define group_is_onestone(b_, g_) (groupnext_at(b_, group_base(g_)) == 0)
 313 #define board_group_info(b_, g_) ((b_)->gi[(g_)])
 314 #define board_group_captured(b_, g_) (board_group_info(b_, g_).libs == 0)
 315 /* board_group_other_lib() makes sense only for groups with two liberties. */
 316 #define board_group_other_lib(b_, g_, l_) (board_group_info(b_, g_).lib[board_group_info(b_, g_).lib[0] != (l_) ? 0 : 1])
 317
 318 #define hash_at(b_, coord, color) ((b_)->h[((color) == S_BLACK ? board_size2(b_) : 0) + coord])
 319
 320 struct board *board_init(char *fbookfile);
 321 struct board *board_copy(struct board *board2, struct board *board1);
 322 void board_done_noalloc(struct board *board);
 323 void board_done(struct board *board);
 324 /* size here is without the S_OFFBOARD margin. */
 325 void board_resize(struct board *board, int size);
 326 void board_clear(struct board *board);
 327
 328 struct FILE;
 329 typedef char *(*board_cprint)(struct board *b, coord_t c, char *s, char *end);
 330 void board_print(struct board *board, FILE *f);
 331 void board_print_custom(struct board *board, FILE *f, board_cprint cprint);
 332
 333 /* Place given handicap on the board; coordinates are printed to f. */
 334 void board_handicap(struct board *board, int stones, FILE *f);
 335
 336 /* Returns group id, 0 on allowed suicide, pass or resign, -1 on error */
 337 int board_play(struct board *board, struct move *m);
 338 /* Like above, but plays random move; the move coordinate is recorded
 339  * to *coord. This method will never fill your own eye. pass is played
 340  * when no move can be played. You can impose extra restrictions if you
 341  * supply your own permit function; the permit function can also modify
 342  * the move coordinate to redirect the move elsewhere. */
 343 typedef bool (*ppr_permit)(void *data, struct board *b, struct move *m);
 344 void board_play_random(struct board *b, enum stone color, coord_t *coord, ppr_permit permit, void *permit_data);
 345
 346 /*Undo, supported only for pass moves. Returns -1 on error, 0 otherwise. */
 347 int board_undo(struct board *board);
 348
 349 /* Returns true if given move can be played. */
 350 static bool board_is_valid_play(struct board *b, enum stone color, coord_t coord);
 351 static bool board_is_valid_move(struct board *b, struct move *m);
 352 /* Returns true if ko was just taken. */
 353 static bool board_playing_ko_threat(struct board *b);
 354 /* Returns 0 or ID of neighboring group in atari. */
 355 static group_t board_get_atari_neighbor(struct board *b, coord_t coord, enum stone group_color);
 356 /* Returns true if the move is not obvious self-atari. */
 357 static bool board_safe_to_play(struct board *b, coord_t coord, enum stone color);
 358
 359 /* Determine number of stones in a group, up to @max stones. */
 360 static int group_stone_count(struct board *b, group_t group, int max);
 361
 362 /* Adjust symmetry information as if given coordinate has been played. */
 363 void board_symmetry_update(struct board *b, struct board_symmetry *symmetry, coord_t c);
 364 /* Check if coordinates are within symmetry base. (If false, they can
 365  * be derived from the base.) */
 366 static bool board_coord_in_symmetry(struct board *b, coord_t c);
 367
 368 /* Returns true if given coordinate has all neighbors of given color or the edge. */
 369 static bool board_is_eyelike(struct board *board, coord_t coord, enum stone eye_color);
 370 /* Returns true if given coordinate could be a false eye; this check makes
 371  * sense only if you already know the coordinate is_eyelike(). */
 372 bool board_is_false_eyelike(struct board *board, coord_t coord, enum stone eye_color);
 373 /* Returns true if given coordinate is a 1-pt eye (checks against false eyes, or
 374  * at least tries to). */
 375 bool board_is_one_point_eye(struct board *board, coord_t c, enum stone eye_color);
 376 /* Returns color of a 1pt eye owner, S_NONE if not an eye. */
 377 enum stone board_get_one_point_eye(struct board *board, coord_t c);
 378
 379 /* board_official_score() is the scoring method for yielding score suitable
 380  * for external presentation. For fast scoring of entirely filled boards
 381  * (e.g. playouts), use board_fast_score(). */
 382 /* Positive: W wins */
 383 /* Compare number of stones + 1pt eyes. */
 384 floating_t board_fast_score(struct board *board);
 385 /* Tromp-Taylor scoring, assuming given groups are actually dead. */
 386 struct move_queue;
 387 floating_t board_official_score(struct board *board, struct move_queue *mq);
 388
 389 /* Set board rules according to given string. Returns false in case
 390  * of unknown ruleset name. */
 391 bool board_set_rules(struct board *board, char *name);
 392
 393 /** Iterators */
 394
 395 #define foreach_point(board_) \
 396         do { \
 397                 coord_t c = 0; \
 398                 for (; c < board_size(board_) * board_size(board_); c++)
 399 #define foreach_point_and_pass(board_) \
 400         do { \
 401                 coord_t c = pass; \
 402                 for (; c < board_size(board_) * board_size(board_); c++)
 403 #define foreach_point_end \
 404         } while (0)
 405
 406 #define foreach_free_point(board_) \
 407         do { \
 408                 int fmax__ = (board_)->flen; \
 409                 for (int f__ = 0; f__ < fmax__; f__++) { \
 410                         coord_t c = (board_)->f[f__];
 411 #define foreach_free_point_end \
 412                 } \
 413         } while (0)
 414
 415 #define foreach_in_group(board_, group_) \
 416         do { \
 417                 struct board *board__ = board_; \
 418                 coord_t c = group_base(group_); \
 419                 coord_t c2 = c; c2 = groupnext_at(board__, c2); \
 420                 do {
 421 #define foreach_in_group_end \
 422                         c = c2; c2 = groupnext_at(board__, c2); \
 423                 } while (c != 0); \
 424         } while (0)
 425
 426 /* NOT VALID inside of foreach_point() or another foreach_neighbor(), or rather
 427  * on S_OFFBOARD coordinates. */
 428 #define foreach_neighbor(board_, coord_, loop_body) \
 429         do { \
 430                 struct board *board__ = board_; \
 431                 coord_t coord__ = coord_; \
 432                 coord_t c; \
 433                 c = coord__ - board_size(board__); do { loop_body } while (0); \
 434                 c = coord__ - 1; do { loop_body } while (0); \
 435                 c = coord__ + 1; do { loop_body } while (0); \
 436                 c = coord__ + board_size(board__); do { loop_body } while (0); \
 437         } while (0)
 438
 439 #define foreach_8neighbor(board_, coord_) \
 440         do { \
 441                 int fn__i; \
 442                 coord_t c = (coord_); \
 443                 for (fn__i = 0; fn__i < 8; fn__i++) { \
 444                         c += (board_)->nei8[fn__i];
 445 #define foreach_8neighbor_end \
 446                 } \
 447         } while (0)
 448
 449 #define foreach_diag_neighbor(board_, coord_) \
 450         do { \
 451                 int fn__i; \
 452                 coord_t c = (coord_); \
 453                 for (fn__i = 0; fn__i < 4; fn__i++) { \
 454                         c += (board_)->dnei[fn__i];
 455 #define foreach_diag_neighbor_end \
 456                 } \
 457         } while (0)
 458
 459
 460 static inline bool
 461 board_is_eyelike(struct board *board, coord_t coord, enum stone eye_color)
 462 {
 463         return (neighbor_count_at(board, coord, eye_color)
 464                 + neighbor_count_at(board, coord, S_OFFBOARD)) == 4;
 465 }
 466
 467 static inline bool
 468 board_is_valid_play(struct board *board, enum stone color, coord_t coord)
 469 {
 470         if (board_at(board, coord) != S_NONE)
 471                 return false;
 472         if (!board_is_eyelike(board, coord, stone_other(color)))
 473                 return true;
 474         /* Play within {true,false} eye-ish formation */
 475         if (board->ko.coord == coord && board->ko.color == color)
 476                 return false;
 477 #ifdef BOARD_TRAITS
 478         /* XXX: Disallows suicide. */
 479         return trait_at(board, coord, color).cap > 0;
 480 #else
 481         int groups_in_atari = 0;
 482         foreach_neighbor(board, coord, {
 483                 group_t g = group_at(board, c);
 484                 groups_in_atari += (board_group_info(board, g).libs == 1);
 485         });
 486         return !!groups_in_atari;
 487 #endif
 488 }
 489
 490 static inline bool
 491 board_is_valid_move(struct board *board, struct move *m)
 492 {
 493         return board_is_valid_play(board, m->color, m->coord);
 494 }
 495
 496 static inline bool
 497 board_playing_ko_threat(struct board *b)
 498 {
 499         return !is_pass(b->ko.coord);
 500 }
 501
 502 static inline group_t
 503 board_get_atari_neighbor(struct board *b, coord_t coord, enum stone group_color)
 504 {
 505 #ifdef BOARD_TRAITS
 506         if (!trait_at(b, coord, stone_other(group_color)).cap) return 0;
 507 #endif
 508         foreach_neighbor(b, coord, {
 509                 group_t g = group_at(b, c);
 510                 if (g && board_at(b, c) == group_color && board_group_info(b, g).libs == 1)
 511                         return g;
 512                 /* We return first match. */
 513         });
 514         return 0;
 515 }
 516
 517 static inline bool
 518 board_safe_to_play(struct board *b, coord_t coord, enum stone color)
 519 {
 520         /* number of free neighbors */
 521         int libs = immediate_liberty_count(b, coord);
 522         if (libs > 1)
 523                 return true;
 524
 525 #ifdef BOARD_TRAITS
 526         /* number of capturable enemy groups */
 527         if (trait_at(b, coord, color).cap > 0)
 528                 return true; // XXX: We don't account for snapback.
 529         /* number of non-capturable friendly groups */
 530         int noncap_ours = neighbor_count_at(b, coord, color) - trait_at(b, coord, stone_other(color)).cap;
 531         if (noncap_ours < 1)
 532                 return false;
 533 /*#else see below */
 534 #endif
 535
 536         /* ok, but we need to check if they don't have just two libs. */
 537         coord_t onelib = -1;
 538         foreach_neighbor(b, coord, {
 539 #ifndef BOARD_TRAITS
 540                 if (board_at(b, c) == stone_other(color) && board_group_info(b, group_at(b, c)).libs == 1)
 541                         return true; // can capture; no snapback check
 542 #endif
 543                 if (board_at(b, c) != color) continue;
 544                 group_t g = group_at(b, c);
 545                 if (board_group_info(b, g).libs == 1) continue; // in atari
 546                 if (board_group_info(b, g).libs == 2) { // two liberties
 547                         if (libs > 0) return true; // we already have one real liberty
 548                         /* we might be connecting two 2-lib groups, which is ok;
 549                          * so remember the other liberty and just make sure it's
 550                          * not the same one */
 551                         if (onelib >= 0 && c != onelib) return true;
 552                         onelib = board_group_other_lib(b, g, c);
 553                         continue;
 554                 }
 555                 // many liberties
 556                 return true;
 557         });
 558         // no good support group
 559         return false;
 560 }
 561
 562 static inline int
 563 group_stone_count(struct board *b, group_t group, int max)
 564 {
 565         int n = 0;
 566         foreach_in_group(b, group) {
 567                 n++;
 568                 if (n >= max) return max;
 569         } foreach_in_group_end;
 570         return n;
 571 }
 572
 573 static inline bool
 574 board_coord_in_symmetry(struct board *b, coord_t c)
 575 {
 576         if (coord_y(c, b) < b->symmetry.y1 || coord_y(c, b) > b->symmetry.y2)
 577                 return false;
 578         if (coord_x(c, b) < b->symmetry.x1 || coord_x(c, b) > b->symmetry.x2)
 579                 return false;
 580         if (b->symmetry.d) {
 581                 int x = coord_x(c, b);
 582                 if (b->symmetry.type == SYM_DIAG_DOWN)
 583                         x = board_size(b) - 1 - x;
 584                 if (x > coord_y(c, b))
 585                         return false;
 586         }
 587         return true;
 588
 589 }
 590
 591 #endif