board.c

   1 #include <alloca.h>
   2 #include <assert.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <string.h>
   6
   7 #include "board.h"
   8 #include "debug.h"
   9 #include "random.h"
  10
  11 int board_group_capture(struct board *board, group_t group);
  12
  13 bool random_pass = false;
  14
  15
  16 #if 0
  17 #define profiling_noinline __attribute__((noinline))
  18 #else
  19 #define profiling_noinline
  20 #endif
  21
  22 #define gi_granularity 4
  23 #define gi_allocsize(gids) ((1 << gi_granularity) + ((gids) >> gi_granularity) * (1 << gi_granularity))
  24
  25
  26 static void
  27 board_setup(struct board *b)
  28 {
  29         memset(b, 0, sizeof(*b));
  30
  31         struct move m = { pass, S_NONE };
  32         b->last_move = b->ko = m;
  33 }
  34
  35 struct board *
  36 board_init(void)
  37 {
  38         struct board *b = malloc(sizeof(struct board));
  39         board_setup(b);
  40         return b;
  41 }
  42
  43 struct board *
  44 board_copy(struct board *b2, struct board *b1)
  45 {
  46         memcpy(b2, b1, sizeof(struct board));
  47
  48         int bsize = board_size2(b2) * sizeof(*b2->b);
  49         int gsize = board_size2(b2) * sizeof(*b2->g);
  50         int fsize = board_size2(b2) * sizeof(*b2->f);
  51         int nsize = board_size2(b2) * sizeof(*b2->n);
  52         int psize = board_size2(b2) * sizeof(*b2->p);
  53         int hsize = board_size2(b2) * 2 * sizeof(*b2->h);
  54         int gisize = board_size2(b2) * sizeof(*b2->gi);
  55 #ifdef WANT_BOARD_C
  56         int csize = board_size2(b2) * sizeof(*b2->c);
  57 #else
  58         int csize = 0;
  59 #endif
  60         void *x = malloc(bsize + gsize + fsize + psize + nsize + hsize + gisize + csize);
  61         memcpy(x, b1->b, bsize + gsize + fsize + psize + nsize + hsize + gisize + csize);
  62         b2->b = x; x += bsize;
  63         b2->g = x; x += gsize;
  64         b2->f = x; x += fsize;
  65         b2->p = x; x += psize;
  66         b2->n = x; x += nsize;
  67         b2->h = x; x += hsize;
  68         b2->gi = x; x += gisize;
  69 #ifdef WANT_BOARD_C
  70         b2->c = x; x += csize;
  71 #endif
  72
  73         return b2;
  74 }
  75
  76 void
  77 board_done_noalloc(struct board *board)
  78 {
  79         if (board->b) free(board->b);
  80 }
  81
  82 void
  83 board_done(struct board *board)
  84 {
  85         board_done_noalloc(board);
  86         free(board);
  87 }
  88
  89 void
  90 board_resize(struct board *board, int size)
  91 {
  92 #ifdef BOARD_SIZE
  93         assert(board_size(board) == size + 2);
  94 #else
  95         board_size(board) = size + 2 /* S_OFFBOARD margin */;
  96         board_size2(board) = board_size(board) * board_size(board);
  97 #endif
  98         if (board->b)
  99                 free(board->b);
 100
 101         int bsize = board_size2(board) * sizeof(*board->b);
 102         int gsize = board_size2(board) * sizeof(*board->g);
 103         int fsize = board_size2(board) * sizeof(*board->f);
 104         int nsize = board_size2(board) * sizeof(*board->n);
 105         int psize = board_size2(board) * sizeof(*board->p);
 106         int hsize = board_size2(board) * 2 * sizeof(*board->h);
 107         int gisize = board_size2(board) * sizeof(*board->gi);
 108 #ifdef WANT_BOARD_C
 109         int csize = board_size2(board) * sizeof(*board->c);
 110 #else
 111         int csize = 0;
 112 #endif
 113         void *x = malloc(bsize + gsize + fsize + psize + nsize + hsize + gisize + csize);
 114         memset(x, 0, bsize + gsize + fsize + psize + nsize + hsize + gisize + csize);
 115         board->b = x; x += bsize;
 116         board->g = x; x += gsize;
 117         board->f = x; x += fsize;
 118         board->p = x; x += psize;
 119         board->n = x; x += nsize;
 120         board->h = x; x += hsize;
 121         board->gi = x; x += gisize;
 122 #ifdef WANT_BOARD_C
 123         board->c = x; x += csize;
 124 #endif
 125 }
 126
 127 void
 128 board_clear(struct board *board)
 129 {
 130         int size = board_size(board);
 131
 132         board_done_noalloc(board);
 133         board_setup(board);
 134         board_resize(board, size - 2 /* S_OFFBOARD margin */);
 135
 136         /* Setup initial symmetry */
 137         board->symmetry.d = 1;
 138         board->symmetry.x1 = board->symmetry.y1 = board->size / 2;
 139         board->symmetry.x2 = board->symmetry.y2 = board->size - 1;
 140         board->symmetry.type = SYM_FULL;
 141
 142         /* Draw the offboard margin */
 143         int top_row = board_size2(board) - board_size(board);
 144         int i;
 145         for (i = 0; i < board_size(board); i++)
 146                 board->b[i] = board->b[top_row + i] = S_OFFBOARD;
 147         for (i = 0; i <= top_row; i += board_size(board))
 148                 board->b[i] = board->b[board_size(board) - 1 + i] = S_OFFBOARD;
 149
 150         foreach_point(board) {
 151                 coord_t coord = c;
 152                 if (board_at(board, coord) == S_OFFBOARD)
 153                         continue;
 154                 foreach_neighbor(board, c, {
 155                         inc_neighbor_count_at(board, coord, board_at(board, c));
 156                 } );
 157         } foreach_point_end;
 158
 159         /* First, pass is always a free position. */
 160         board->f[board->flen++] = coord_raw(pass);
 161         /* All positions are free! Except the margin. */
 162         for (i = board_size(board); i < (board_size(board) - 1) * board_size(board); i++)
 163                 if (i % board_size(board) != 0 && i % board_size(board) != board_size(board) - 1)
 164                         board->f[board->flen++] = i;
 165
 166         /* Initialize zobrist hashtable. */
 167         foreach_point(board) {
 168                 int max = (sizeof(hash_t) << history_hash_bits);
 169                 /* fast_random() is 16-bit only */
 170                 board->h[coord_raw(c) * 2] = ((hash_t) fast_random(max))
 171                                 | ((hash_t) fast_random(max) << 16)
 172                                 | ((hash_t) fast_random(max) << 32)
 173                                 | ((hash_t) fast_random(max) << 48);
 174                 if (!board->h[coord_raw(c) * 2])
 175                         /* Would be kinda "oops". */
 176                         board->h[coord_raw(c) * 2] = 1;
 177                 /* And once again for white */
 178                 board->h[coord_raw(c) * 2 + 1] = ((hash_t) fast_random(max))
 179                                 | ((hash_t) fast_random(max) << 16)
 180                                 | ((hash_t) fast_random(max) << 32)
 181                                 | ((hash_t) fast_random(max) << 48);
 182                 if (!board->h[coord_raw(c) * 2 + 1])
 183                         board->h[coord_raw(c) * 2 + 1] = 1;
 184         } foreach_point_end;
 185 }
 186
 187
 188 void
 189 board_print(struct board *board, FILE *f)
 190 {
 191         fprintf(f, "Move: % 3d  Komi: %2.1f  Captures B: %d W: %d\n     ",
 192                 board->moves, board->komi,
 193                 board->captures[S_BLACK], board->captures[S_WHITE]);
 194         int x, y;
 195         char asdf[] = "ABCDEFGHJKLMNOPQRSTUVWXYZ";
 196         for (x = 1; x < board_size(board) - 1; x++)
 197                 fprintf(f, "%c ", asdf[x - 1]);
 198         fprintf(f, "\n   +-");
 199         for (x = 1; x < board_size(board) - 1; x++)
 200                 fprintf(f, "--");
 201         fprintf(f, "+\n");
 202         for (y = board_size(board) - 2; y >= 1; y--) {
 203                 fprintf(f, "%2d | ", y);
 204                 for (x = 1; x < board_size(board) - 1; x++) {
 205                         if (coord_x(board->last_move.coord, board) == x && coord_y(board->last_move.coord, board) == y)
 206                                 fprintf(f, "%c)", stone2char(board_atxy(board, x, y)));
 207                         else
 208                                 fprintf(f, "%c ", stone2char(board_atxy(board, x, y)));
 209                 }
 210                 if (DEBUGL(6)) {
 211                         fprintf(f, "| ");
 212                         for (x = 1; x < board_size(board) - 1; x++) {
 213                                 fprintf(f, "%d ", group_base(group_atxy(board, x, y)));
 214                         }
 215                 }
 216                 fprintf(f, "|\n");
 217         }
 218         fprintf(f, "   +-");
 219         for (x = 1; x < board_size(board) - 1; x++)
 220                 fprintf(f, "--");
 221         fprintf(f, "+\n\n");
 222 }
 223
 224
 225 /* Update board hash with given coordinate. */
 226 static void profiling_noinline
 227 board_hash_update(struct board *board, coord_t coord, enum stone color)
 228 {
 229         board->hash ^= hash_at(board, coord, color);
 230         if (DEBUGL(8))
 231                 fprintf(stderr, "board_hash_update(%d,%d,%d) ^ %llx -> %llx\n", color, coord_x(coord, board), coord_y(coord, board), hash_at(board, coord, color), board->hash);
 232 }
 233
 234 /* Commit current board hash to history. */
 235 static void profiling_noinline
 236 board_hash_commit(struct board *board)
 237 {
 238         if (DEBUGL(8))
 239                 fprintf(stderr, "board_hash_commit %llx\n", board->hash);
 240         if (likely(board->history_hash[board->hash & history_hash_mask]) == 0) {
 241                 board->history_hash[board->hash & history_hash_mask] = board->hash;
 242         } else {
 243                 hash_t i = board->hash;
 244                 while (board->history_hash[i & history_hash_mask]) {
 245                         if (board->history_hash[i & history_hash_mask] == board->hash) {
 246                                 if (DEBUGL(5))
 247                                         fprintf(stderr, "SUPERKO VIOLATION noted at %d,%d\n",
 248                                                 coord_x(board->last_move.coord, board), coord_y(board->last_move.coord, board));
 249                                 board->superko_violation = true;
 250                                 return;
 251                         }
 252                         i = history_hash_next(i);
 253                 }
 254                 board->history_hash[i & history_hash_mask] = board->hash;
 255         }
 256 }
 257
 258
 259 void
 260 board_symmetry_update(struct board *b, struct board_symmetry *symmetry, coord_t c)
 261 {
 262         if (likely(symmetry->type == SYM_NONE)) {
 263                 /* Fully degenerated already. We do not support detection
 264                  * of restoring of symmetry, assuming that this is too rare
 265                  * a case to handle. */
 266                 return;
 267         }
 268
 269         int x = coord_x(c, b), y = coord_y(c, b), t = board_size(b) / 2;
 270         int dx = board_size(b) - 1 - x; /* for SYM_DOWN */
 271         if (DEBUGL(6)) {
 272                 fprintf(stderr, "SYMMETRY [%d,%d,%d,%d|%d=%d] update for %d,%d\n",
 273                         symmetry->x1, symmetry->y1, symmetry->x2, symmetry->y2,
 274                         symmetry->d, symmetry->type, x, y);
 275         }
 276
 277         switch (symmetry->type) {
 278                 case SYM_FULL:
 279                         if (x == t && y == t) {
 280                                 /* Tengen keeps full symmetry. */
 281                                 return;
 282                         }
 283                         /* New symmetry now? */
 284                         if (x == y) {
 285                                 symmetry->type = SYM_DIAG_UP;
 286                                 symmetry->x1 = symmetry->y1 = 1;
 287                                 symmetry->x2 = symmetry->y2 = board_size(b) - 1;
 288                                 symmetry->d = 1;
 289                         } else if (dx == y) {
 290                                 symmetry->type = SYM_DIAG_DOWN;
 291                                 symmetry->x1 = symmetry->y1 = 1;
 292                                 symmetry->x2 = symmetry->y2 = board_size(b) - 1;
 293                                 symmetry->d = 1;
 294                         } else if (x == t) {
 295                                 symmetry->type = SYM_HORIZ;
 296                                 symmetry->y1 = 1;
 297                                 symmetry->y2 = board_size(b) - 1;
 298                                 symmetry->d = 0;
 299                         } else if (y == t) {
 300                                 symmetry->type = SYM_VERT;
 301                                 symmetry->x1 = 1;
 302                                 symmetry->x2 = board_size(b) - 1;
 303                                 symmetry->d = 0;
 304                         } else {
 305 break_symmetry:
 306                                 symmetry->type = SYM_NONE;
 307                                 symmetry->x1 = symmetry->y1 = 1;
 308                                 symmetry->x2 = symmetry->y2 = board_size(b) - 1;
 309                                 symmetry->d = 0;
 310                         }
 311                         break;
 312                 case SYM_DIAG_UP:
 313                         if (x == y)
 314                                 return;
 315                         goto break_symmetry;
 316                 case SYM_DIAG_DOWN:
 317                         if (dx == y)
 318                                 return;
 319                         goto break_symmetry;
 320                 case SYM_HORIZ:
 321                         if (x == t)
 322                                 return;
 323                         goto break_symmetry;
 324                 case SYM_VERT:
 325                         if (y == t)
 326                                 return;
 327                         goto break_symmetry;
 328                 case SYM_NONE:
 329                         assert(0);
 330                         break;
 331         }
 332
 333         if (DEBUGL(6)) {
 334                 fprintf(stderr, "NEW SYMMETRY [%d,%d,%d,%d|%d=%d]\n",
 335                         symmetry->x1, symmetry->y1, symmetry->x2, symmetry->y2,
 336                         symmetry->d, symmetry->type);
 337         }
 338         /* Whew. */
 339 }
 340
 341
 342 void
 343 board_handicap_stone(struct board *board, int x, int y, FILE *f)
 344 {
 345         struct move m;
 346         m.color = S_BLACK;
 347         coord_xy(m.coord, x, y, board);
 348
 349         board_play(board, &m);
 350
 351         char *str = coord2str(m.coord, board);
 352         if (DEBUGL(1))
 353                 fprintf(stderr, "choosing handicap %s (%d,%d)\n", str, x, y);
 354         fprintf(f, "%s ", str);
 355         free(str);
 356 }
 357
 358 void
 359 board_handicap(struct board *board, int stones, FILE *f)
 360 {
 361         int margin = 3 + (board_size(board) >= 13);
 362         int min = margin;
 363         int mid = board_size(board) / 2;
 364         int max = board_size(board) - 1 - margin;
 365         const int places[][2] = {
 366                 { min, min }, { max, max }, { max, min }, { min, max },
 367                 { min, mid }, { max, mid },
 368                 { mid, min }, { mid, max },
 369                 { mid, mid },
 370         };
 371
 372         board->handicap = stones;
 373
 374         if (stones == 5 || stones == 7) {
 375                 board_handicap_stone(board, mid, mid, f);
 376                 stones--;
 377         }
 378
 379         int i;
 380         for (i = 0; i < stones; i++)
 381                 board_handicap_stone(board, places[i][0], places[i][1], f);
 382 }
 383
 384
 385 static void __attribute__((noinline))
 386 check_libs_consistency(struct board *board, group_t g)
 387 {
 388 #ifdef DEBUG
 389         if (!g) return;
 390         struct group *gi = &board_group_info(board, g);
 391         for (int i = 0; i < GROUP_KEEP_LIBS; i++)
 392                 if (gi->lib[i] && board_at(board, gi->lib[i]) != S_NONE) {
 393                         fprintf(stderr, "BOGUS LIBERTY %s of group %d[%s]\n", coord2sstr(gi->lib[i], board), g, coord2sstr(group_base(g), board));
 394                         assert(0);
 395                 }
 396 #endif
 397 }
 398
 399 static void
 400 board_capturable_add(struct board *board, group_t group)
 401 {
 402 #ifdef WANT_BOARD_C
 403         //fprintf(stderr, "add of group %d (%d)\n", group_base(group), board->clen);
 404         assert(group);
 405         assert(board->clen < board_size2(board));
 406         board->c[board->clen++] = group;
 407 #endif
 408 }
 409 static void
 410 board_capturable_rm(struct board *board, group_t group)
 411 {
 412 #ifdef WANT_BOARD_C
 413         //fprintf(stderr, "rm of group %d\n", group_base(group));
 414         for (int i = 0; i < board->clen; i++) {
 415                 if (unlikely(board->c[i] == group)) {
 416                         board->c[i] = board->c[--board->clen];
 417                         return;
 418                 }
 419         }
 420         fprintf(stderr, "rm of bad group %d\n", group_base(group));
 421         assert(0);
 422 #endif
 423 }
 424
 425 static void
 426 board_group_addlib(struct board *board, group_t group, coord_t coord)
 427 {
 428         if (DEBUGL(7)) {
 429                 fprintf(stderr, "Group %d[%s] %d: Adding liberty %s\n",
 430                         group_base(group), coord2sstr(group_base(group), board),
 431                         board_group_info(board, group).libs, coord2sstr(coord, board));
 432         }
 433
 434         check_libs_consistency(board, group);
 435
 436         struct group *gi = &board_group_info(board, group);
 437         if (gi->libs < GROUP_KEEP_LIBS) {
 438                 for (int i = 0; i < GROUP_KEEP_LIBS; i++) {
 439 #if 0
 440                         /* Seems extra branch just slows it down */
 441                         if (!gi->lib[i])
 442                                 break;
 443 #endif
 444                         if (unlikely(gi->lib[i] == coord))
 445                                 return;
 446                 }
 447                 if (gi->libs == 0)
 448                         board_capturable_add(board, group);
 449                 else if (gi->libs == 1)
 450                         board_capturable_rm(board, group);
 451                 gi->lib[gi->libs++] = coord;
 452         }
 453
 454         check_libs_consistency(board, group);
 455 }
 456
 457 static void
 458 board_group_find_extra_libs(struct board *board, group_t group, struct group *gi, coord_t avoid)
 459 {
 460         /* Add extra liberty from the board to our liberty list. */
 461         enum stone watermark[board_size2(board)];
 462         memcpy(watermark, board->b, sizeof(watermark));
 463
 464         for (int i = 0; i < GROUP_KEEP_LIBS - 1; i++)
 465                 watermark[coord_raw(gi->lib[i])] = S_OFFBOARD;
 466         watermark[coord_raw(avoid)] = S_OFFBOARD;
 467
 468         foreach_in_group(board, group) {
 469                 coord_t coord2 = c;
 470                 foreach_neighbor(board, coord2, {
 471                         if (likely(watermark[coord_raw(c)] != S_NONE))
 472                                 continue;
 473                         watermark[coord_raw(c)] = S_OFFBOARD;
 474                         gi->lib[gi->libs++] = c;
 475                         if (unlikely(gi->libs >= GROUP_KEEP_LIBS))
 476                                 return;
 477                 } );
 478         } foreach_in_group_end;
 479 }
 480
 481 static void
 482 board_group_rmlib(struct board *board, group_t group, coord_t coord)
 483 {
 484         if (DEBUGL(7)) {
 485                 fprintf(stderr, "Group %d[%s] %d: Removing liberty %s\n",
 486                         group_base(group), coord2sstr(group_base(group), board),
 487                         board_group_info(board, group).libs, coord2sstr(coord, board));
 488         }
 489
 490         struct group *gi = &board_group_info(board, group);
 491         for (int i = 0; i < GROUP_KEEP_LIBS; i++) {
 492 #if 0
 493                 /* Seems extra branch just slows it down */
 494                 if (!gi->lib[i])
 495                         break;
 496 #endif
 497                 if (likely(gi->lib[i] != coord))
 498                         continue;
 499
 500                 gi->lib[i] = gi->lib[--gi->libs];
 501                 gi->lib[gi->libs] = 0;
 502
 503                 check_libs_consistency(board, group);
 504
 505                 /* Postpone refilling lib[] until we need to. */
 506                 assert(GROUP_REFILL_LIBS > 1);
 507                 if (gi->libs > GROUP_REFILL_LIBS)
 508                         return;
 509                 if (gi->libs == GROUP_REFILL_LIBS)
 510                         board_group_find_extra_libs(board, group, gi, coord);
 511
 512                 if (gi->libs == 1)
 513                         board_capturable_add(board, group);
 514                 else if (gi->libs == 0)
 515                         board_capturable_rm(board, group);
 516                 return;
 517         }
 518
 519         /* This is ok even if gi->libs < GROUP_KEEP_LIBS since we
 520          * can call this multiple times per coord. */
 521         check_libs_consistency(board, group);
 522         return;
 523 }
 524
 525
 526 /* This is a low-level routine that doesn't maintain consistency
 527  * of all the board data structures. Use board_group_capture() from
 528  * your code. */
 529 static void
 530 board_remove_stone(struct board *board, coord_t c)
 531 {
 532         enum stone color = board_at(board, c);
 533         board_at(board, c) = S_NONE;
 534         group_at(board, c) = 0;
 535         board_hash_update(board, c, color);
 536
 537         /* Increase liberties of surrounding groups */
 538         coord_t coord = c;
 539         foreach_neighbor(board, coord, {
 540                 dec_neighbor_count_at(board, c, color);
 541                 group_t g = group_at(board, c);
 542                 if (g)
 543                         board_group_addlib(board, g, coord);
 544         });
 545
 546         if (DEBUGL(6))
 547                 fprintf(stderr, "pushing free move [%d]: %d,%d\n", board->flen, coord_x(c, board), coord_y(c, board));
 548         board->f[board->flen++] = coord_raw(c);
 549 }
 550
 551
 552 static void profiling_noinline
 553 add_to_group(struct board *board, group_t group, coord_t prevstone, coord_t coord)
 554 {
 555         foreach_neighbor(board, coord, {
 556                 if (board_at(board, c) == S_NONE)
 557                         board_group_addlib(board, group, c);
 558         });
 559
 560         group_at(board, coord) = group;
 561         groupnext_at(board, coord) = groupnext_at(board, prevstone);
 562         groupnext_at(board, prevstone) = coord_raw(coord);
 563
 564         if (DEBUGL(8))
 565                 fprintf(stderr, "add_to_group: added (%d,%d ->) %d,%d (-> %d,%d) to group %d\n",
 566                         coord_x(prevstone, board), coord_y(prevstone, board),
 567                         coord_x(coord, board), coord_y(coord, board),
 568                         groupnext_at(board, coord) % board_size(board), groupnext_at(board, coord) / board_size(board),
 569                         group_base(group));
 570 }
 571
 572 static void profiling_noinline
 573 merge_groups(struct board *board, group_t group_to, group_t group_from)
 574 {
 575         if (DEBUGL(7))
 576                 fprintf(stderr, "board_play_raw: merging groups %d -> %d\n",
 577                         group_base(group_from), group_base(group_to));
 578
 579         coord_t last_in_group;
 580         foreach_in_group(board, group_from) {
 581                 last_in_group = c;
 582                 group_at(board, c) = group_to;
 583         } foreach_in_group_end;
 584         groupnext_at(board, last_in_group) = groupnext_at(board, group_base(group_to));
 585         groupnext_at(board, group_base(group_to)) = group_base(group_from);
 586
 587         struct group *gi_from = &board_group_info(board, group_from);
 588         struct group *gi_to = &board_group_info(board, group_to);
 589         if (gi_to->libs < GROUP_KEEP_LIBS) {
 590                 for (int i = 0; i < gi_from->libs; i++) {
 591                         for (int j = 0; j < gi_to->libs; j++)
 592                                 if (gi_to->lib[j] == gi_from->lib[i])
 593                                         goto next_from_lib;
 594                         if (gi_to->libs == 0)
 595                                 board_capturable_add(board, group_to);
 596                         else if (gi_to->libs == 1)
 597                                 board_capturable_rm(board, group_to);
 598                         gi_to->lib[gi_to->libs++] = gi_from->lib[i];
 599                         if (gi_to->libs >= GROUP_KEEP_LIBS)
 600                                 break;
 601 next_from_lib:;
 602                 }
 603         }
 604
 605         if (gi_from->libs == 1)
 606                 board_capturable_rm(board, group_from);
 607         memset(gi_from, 0, sizeof(struct group));
 608
 609         if (DEBUGL(7))
 610                 fprintf(stderr, "board_play_raw: merged group: %d\n",
 611                         group_base(group_to));
 612 }
 613
 614 static group_t profiling_noinline
 615 new_group(struct board *board, coord_t coord)
 616 {
 617         group_t group = coord_raw(coord);
 618         struct group *gi = &board_group_info(board, group);
 619         foreach_neighbor(board, coord, {
 620                 if (board_at(board, c) == S_NONE)
 621                         /* board_group_addlib is ridiculously expensive for us */
 622 #if GROUP_KEEP_LIBS < 4
 623                         if (gi->libs < GROUP_KEEP_LIBS)
 624 #endif
 625                         gi->lib[gi->libs++] = c;
 626         });
 627         if (gi->libs == 1)
 628                 board_capturable_add(board, group);
 629         check_libs_consistency(board, group);
 630
 631         group_at(board, coord) = group;
 632         groupnext_at(board, coord) = 0;
 633
 634         if (DEBUGL(8))
 635                 fprintf(stderr, "new_group: added %d,%d to group %d\n",
 636                         coord_x(coord, board), coord_y(coord, board),
 637                         group_base(group));
 638
 639         return group;
 640 }
 641
 642 static inline group_t
 643 play_one_neighbor(struct board *board,
 644                 coord_t coord, enum stone color, enum stone other_color,
 645                 coord_t c, group_t group)
 646 {
 647         enum stone ncolor = board_at(board, c);
 648         group_t ngroup = group_at(board, c);
 649
 650         inc_neighbor_count_at(board, c, color);
 651
 652         if (!ngroup)
 653                 return group;
 654
 655         board_group_rmlib(board, ngroup, coord);
 656         if (DEBUGL(7))
 657                 fprintf(stderr, "board_play_raw: reducing libs for group %d (%d:%d,%d)\n",
 658                         group_base(ngroup), ncolor, color, other_color);
 659
 660         if (ncolor == color && ngroup != group) {
 661                 if (!group) {
 662                         group = ngroup;
 663                         add_to_group(board, group, c, coord);
 664                 } else {
 665                         merge_groups(board, group, ngroup);
 666                 }
 667         } else if (ncolor == other_color) {
 668                 if (DEBUGL(8)) {
 669                         struct group *gi = &board_group_info(board, ngroup);
 670                         fprintf(stderr, "testing captured group %d[%s]: ", group_base(ngroup), coord2sstr(group_base(ngroup), board));
 671                         for (int i = 0; i < GROUP_KEEP_LIBS; i++)
 672                                 fprintf(stderr, "%s ", coord2sstr(gi->lib[i], board));
 673                         fprintf(stderr, "\n");
 674                 }
 675                 if (unlikely(board_group_captured(board, ngroup)))
 676                         board_group_capture(board, ngroup);
 677         }
 678         return group;
 679 }
 680
 681 /* We played on a place with at least one liberty. We will become a member of
 682  * some group for sure. */
 683 static group_t profiling_noinline
 684 board_play_outside(struct board *board, struct move *m, int f)
 685 {
 686         coord_t coord = m->coord;
 687         enum stone color = m->color;
 688         enum stone other_color = stone_other(color);
 689         group_t group = 0;
 690
 691         board->f[f] = board->f[--board->flen];
 692         if (DEBUGL(6))
 693                 fprintf(stderr, "popping free move [%d->%d]: %d\n", board->flen, f, board->f[f]);
 694
 695         foreach_neighbor(board, coord, {
 696                         group = play_one_neighbor(board, coord, color, other_color, c, group);
 697         });
 698
 699         if (unlikely(!group))
 700                 group = new_group(board, coord);
 701
 702         board_at(board, coord) = color;
 703         board->last_move = *m;
 704         board->moves++;
 705         board_hash_update(board, coord, color);
 706         board_symmetry_update(board, &board->symmetry, coord);
 707         struct move ko = { pass, S_NONE };
 708         board->ko = ko;
 709
 710         return group;
 711 }
 712
 713 /* We played in an eye-like shape. Either we capture at least one of the eye
 714  * sides in the process of playing, or return -1. */
 715 static int profiling_noinline
 716 board_play_in_eye(struct board *board, struct move *m, int f)
 717 {
 718         coord_t coord = m->coord;
 719         enum stone color = m->color;
 720         /* Check ko: Capture at a position of ko capture one move ago */
 721         if (unlikely(color == board->ko.color && coord_eq(coord, board->ko.coord))) {
 722                 if (DEBUGL(5))
 723                         fprintf(stderr, "board_check: ko at %d,%d color %d\n", coord_x(coord, board), coord_y(coord, board), color);
 724                 return -1;
 725         } else if (DEBUGL(6)) {
 726                 fprintf(stderr, "board_check: no ko at %d,%d,%d - ko is %d,%d,%d\n",
 727                         color, coord_x(coord, board), coord_y(coord, board),
 728                         board->ko.color, coord_x(board->ko.coord, board), coord_y(board->ko.coord, board));
 729         }
 730
 731         struct move ko = { pass, S_NONE };
 732
 733         int captured_groups = 0;
 734
 735         foreach_neighbor(board, coord, {
 736                 group_t g = group_at(board, c);
 737                 if (DEBUGL(7))
 738                         fprintf(stderr, "board_check: group %d has %d libs\n",
 739                                 g, board_group_info(board, g).libs);
 740                 captured_groups += (board_group_info(board, g).libs == 1);
 741         });
 742
 743         if (likely(captured_groups == 0)) {
 744                 if (DEBUGL(5)) {
 745                         if (DEBUGL(6))
 746                                 board_print(board, stderr);
 747                         fprintf(stderr, "board_check: one-stone suicide\n");
 748                 }
 749
 750                 return -1;
 751         }
 752
 753         board->f[f] = board->f[--board->flen];
 754         if (DEBUGL(6))
 755                 fprintf(stderr, "popping free move [%d->%d]: %d\n", board->flen, f, board->f[f]);
 756
 757         foreach_neighbor(board, coord, {
 758                 inc_neighbor_count_at(board, c, color);
 759
 760                 group_t group = group_at(board, c);
 761                 if (!group)
 762                         continue;
 763
 764                 board_group_rmlib(board, group, coord);
 765                 if (DEBUGL(7))
 766                         fprintf(stderr, "board_play_raw: reducing libs for group %d\n",
 767                                 group_base(group));
 768
 769                 if (board_group_captured(board, group)) {
 770                         if (board_group_capture(board, group) == 1) {
 771                                 /* If we captured multiple groups at once,
 772                                  * we can't be fighting ko so we don't need
 773                                  * to check for that. */
 774                                 ko.color = stone_other(color);
 775                                 ko.coord = c;
 776                                 if (DEBUGL(5))
 777                                         fprintf(stderr, "guarding ko at %d,%d,%d\n", ko.color, coord_x(ko.coord, board), coord_y(ko.coord, board));
 778                         }
 779                 }
 780         });
 781
 782         board_at(board, coord) = color;
 783
 784         board->last_move = *m;
 785         board->moves++;
 786         board_hash_update(board, coord, color);
 787         board_hash_commit(board);
 788         board_symmetry_update(board, &board->symmetry, coord);
 789         board->ko = ko;
 790
 791         return !!new_group(board, coord);
 792 }
 793
 794 static int __attribute__((flatten))
 795 board_play_f(struct board *board, struct move *m, int f)
 796 {
 797         if (DEBUGL(7)) {
 798                 fprintf(stderr, "board_play(): ---- Playing %d,%d\n", coord_x(m->coord, board), coord_y(m->coord, board));
 799         }
 800         if (likely(!board_is_eyelike(board, &m->coord, stone_other(m->color)))) {
 801                 /* NOT playing in an eye. Thus this move has to succeed. (This
 802                  * is thanks to New Zealand rules. Otherwise, multi-stone
 803                  * suicide might fail.) */
 804                 group_t group = board_play_outside(board, m, f);
 805                 if (unlikely(board_group_captured(board, group))) {
 806                         board_group_capture(board, group);
 807                 }
 808                 board_hash_commit(board);
 809                 return 0;
 810         } else {
 811                 return board_play_in_eye(board, m, f);
 812         }
 813 }
 814
 815 int
 816 board_play(struct board *board, struct move *m)
 817 {
 818         if (unlikely(is_pass(m->coord) || is_resign(m->coord))) {
 819                 board->last_move = *m;
 820                 return 0;
 821         }
 822
 823         int f;
 824         for (f = 0; f < board->flen; f++)
 825                 if (board->f[f] == coord_raw(m->coord))
 826                         return board_play_f(board, m, f);
 827
 828         if (DEBUGL(7))
 829                 fprintf(stderr, "board_check: stone exists\n");
 830         return -1;
 831 }
 832
 833
 834 static inline bool
 835 board_try_random_move(struct board *b, enum stone color, coord_t *coord, int f, ppr_permit permit, void *permit_data)
 836 {
 837         coord_raw(*coord) = b->f[f];
 838         if (unlikely(is_pass(*coord)))
 839                 return random_pass;
 840         struct move m = { *coord, color };
 841         if (DEBUGL(6))
 842                 fprintf(stderr, "trying random move %d: %d,%d\n", f, coord_x(*coord, b), coord_y(*coord, b));
 843         return (likely(!board_is_one_point_eye(b, coord, color)) /* bad idea to play into one, usually */
 844                 && (!permit || permit(permit_data, b, &m))
 845                 && likely(board_play_f(b, &m, f) >= 0));
 846 }
 847
 848 void
 849 board_play_random(struct board *b, enum stone color, coord_t *coord, ppr_permit permit, void *permit_data)
 850 {
 851         int base = fast_random(b->flen);
 852         coord_pos(*coord, base, b);
 853         if (likely(board_try_random_move(b, color, coord, base, permit, permit_data)))
 854                 return;
 855
 856         int f;
 857         for (f = base + 1; f < b->flen; f++)
 858                 if (board_try_random_move(b, color, coord, f, permit, permit_data))
 859                         return;
 860         for (f = 0; f < base; f++)
 861                 if (board_try_random_move(b, color, coord, f, permit, permit_data))
 862                         return;
 863
 864         *coord = pass;
 865 }
 866
 867
 868 bool
 869 board_is_eyelike(struct board *board, coord_t *coord, enum stone eye_color)
 870 {
 871         return (neighbor_count_at(board, *coord, eye_color)
 872                 + neighbor_count_at(board, *coord, S_OFFBOARD)) == 4;
 873 }
 874
 875 bool
 876 board_is_false_eyelike(struct board *board, coord_t *coord, enum stone eye_color)
 877 {
 878         enum stone color_diag_libs[S_MAX] = {0, 0, 0, 0};
 879
 880         /* XXX: We attempt false eye detection but we will yield false
 881          * positives in case of http://senseis.xmp.net/?TwoHeadedDragon :-( */
 882
 883         foreach_diag_neighbor(board, *coord) {
 884                 color_diag_libs[(enum stone) board_at(board, c)]++;
 885         } foreach_diag_neighbor_end;
 886         /* For false eye, we need two enemy stones diagonally in the
 887          * middle of the board, or just one enemy stone at the edge
 888          * or in the corner. */
 889         color_diag_libs[stone_other(eye_color)] += !!color_diag_libs[S_OFFBOARD];
 890         return color_diag_libs[stone_other(eye_color)] >= 2;
 891 }
 892
 893 bool
 894 board_is_one_point_eye(struct board *board, coord_t *coord, enum stone eye_color)
 895 {
 896         return board_is_eyelike(board, coord, eye_color)
 897                 && !board_is_false_eyelike(board, coord, eye_color);
 898 }
 899
 900 enum stone
 901 board_get_one_point_eye(struct board *board, coord_t *coord)
 902 {
 903         if (board_is_one_point_eye(board, coord, S_WHITE))
 904                 return S_WHITE;
 905         else if (board_is_one_point_eye(board, coord, S_BLACK))
 906                 return S_BLACK;
 907         else
 908                 return S_NONE;
 909 }
 910
 911
 912 int profiling_noinline
 913 board_group_capture(struct board *board, group_t group)
 914 {
 915         int stones = 0;
 916
 917         foreach_in_group(board, group) {
 918                 board->captures[stone_other(board_at(board, c))]++;
 919                 board_remove_stone(board, c);
 920                 stones++;
 921         } foreach_in_group_end;
 922
 923         if (board_group_info(board, group).libs == 1)
 924                 board_capturable_rm(board, group);
 925         memset(&board_group_info(board, group), 0, sizeof(struct group));
 926
 927         return stones;
 928 }
 929
 930 bool
 931 board_group_in_atari(struct board *board, group_t group, coord_t *lastlib)
 932 {
 933         if (board_group_info(board, group).libs != 1)
 934                 return false;
 935         *lastlib = board_group_info(board, group).lib[0];
 936         return true;
 937 }
 938
 939 bool
 940 board_group_can_atari(struct board *board, group_t group, coord_t lastlib[2])
 941 {
 942         if (board_group_info(board, group).libs != 2)
 943                 return false;
 944         lastlib[0] = board_group_info(board, group).lib[0];
 945         lastlib[1] = board_group_info(board, group).lib[1];
 946         return true;
 947 }
 948
 949
 950 static enum stone
 951 board_tromp_taylor_owner(struct board *board, coord_t c)
 952 {
 953         int x = coord_x(c, board), y = coord_y(c, board);
 954         enum stone color = S_NONE;
 955 #define TEST_REACH(xx, yy) \
 956         { \
 957                 enum stone c2 = board_atxy(board, xx, yy); \
 958                 if (c2 != S_NONE) { \
 959                         if (color != S_NONE && color != c2) \
 960                                 return S_NONE; \
 961                         color = c2; \
 962                         break; \
 963                 } \
 964         }
 965         for (int i = x; i > 0; i--)
 966                 TEST_REACH(i, y);
 967         for (int i = x; i < board_size(board) - 1; i++)
 968                 TEST_REACH(i, y);
 969         for (int i = y; i > 0; i--)
 970                 TEST_REACH(x, i);
 971         for (int i = y; i < board_size(board) - 1; i++)
 972                 TEST_REACH(x, i);
 973         return color;
 974 }
 975
 976 /* Tromp-Taylor Counting */
 977 float
 978 board_official_score(struct board *board)
 979 {
 980
 981         /* A point P, not colored C, is said to reach C, if there is a path of
 982          * (vertically or horizontally) adjacent points of P's color from P to
 983          * a point of color C.
 984          *
 985          * A player's score is the number of points of her color, plus the
 986          * number of empty points that reach only her color. */
 987
 988         int scores[S_MAX];
 989         memset(scores, 0, sizeof(scores));
 990
 991         foreach_point(board) {
 992                 enum stone color = board_at(board, c);
 993                 if (color == S_NONE)
 994                         color = board_tromp_taylor_owner(board, c);
 995                 scores[color]++;
 996         } foreach_point_end;
 997
 998         return board->komi + board->handicap + scores[S_WHITE] - scores[S_BLACK];
 999 }
1000
1001 float
1002 board_fast_score(struct board *board)
1003 {
1004         int scores[S_MAX];
1005         memset(scores, 0, sizeof(scores));
1006
1007         foreach_point(board) {
1008                 enum stone color = board_at(board, c);
1009                 if (color == S_NONE)
1010                         color = board_get_one_point_eye(board, &c);
1011                 scores[color]++;
1012                 // fprintf(stderr, "%d, %d ++%d = %d\n", coord_x(c, board), coord_y(c, board), color, scores[color]);
1013         } foreach_point_end;
1014
1015         return board->komi + board->handicap + scores[S_WHITE] - scores[S_BLACK];
1016 }
1017
1018
1019 bool
1020 is_selfatari(struct board *b, enum stone color, coord_t to)
1021 {
1022         //fprintf(stderr, "sar check %s %s\n", stone2str(color), coord2sstr(to, b));
1023         /* Assess if we actually gain any liberties by this escape route.
1024          * Note that this is not 100% as we cannot check whether we are
1025          * connecting out or just to ourselves. */
1026         int groupcts[S_MAX] = {};
1027         group_t groupids[S_MAX][4] = {};
1028         foreach_neighbor(b, to, {
1029                 enum stone s = board_at(b, c);
1030                 groupids[s][groupcts[s]++] = group_at(b, c);
1031         });
1032
1033         /* More than one immediate liberty, thumbs up! */
1034         if (groupcts[S_NONE] > 1)
1035                 return false;
1036
1037         /* We may be looking for one extra liberty.
1038          * In that case, @needs_more_lib is id of group
1039          * already providing one, don't consider it again. */
1040         group_t needs_more_lib = 0;
1041         /* ID of the first liberty, providing it again is not
1042          * interesting. */
1043         coord_t needs_more_lib_except = 0;
1044         /* We may be able to gain a liberty by capturing this group. */
1045         group_t can_capture = 0;
1046         for (int i = 0; i < 4; i++) {
1047                 /* We can escape by connecting to this group if it's
1048                  * not in atari. */
1049                 group_t g = groupids[color][i];
1050                 if (g && board_group_info(b, g).libs > 1) {
1051                         /* We could self-atari the group here. */
1052                         if (board_group_info(b, g).libs == 2) {
1053                                 /* We need to get another liberty, and
1054                                  * it must not be the other liberty of
1055                                  * the group. */
1056                                 int lib2 = board_group_info(b, g).lib[0];
1057                                 if (lib2 == to) lib2 = board_group_info(b, g).lib[1];
1058                                 /* Maybe we already looked at another
1059                                  * group providing one liberty? */
1060                                 if (needs_more_lib && needs_more_lib != g
1061                                     && needs_more_lib_except != lib2)
1062                                         return false;
1063                                 /* Can we get the liberty locally? */
1064                                 /* Yes if we are route to more liberties... */
1065                                 if (groupcts[S_NONE] > 1)
1066                                         return false;
1067                                 /* ...or one liberty, but not lib2. */
1068                                 if (groupcts[S_NONE] > 0
1069                                     && abs(lib2 - to) != 1
1070                                     && abs(lib2 - to) != board_size(b))
1071                                         return false;
1072                                 /* ...ok, then we can still contribute a liberty
1073                                  * later by capturing something. */
1074                                 needs_more_lib = g;
1075                                 needs_more_lib_except = lib2;
1076                         } else {
1077                                 return false;
1078                         }
1079                 }
1080
1081                 /* We can escape by capturing this group if it's in atari. */
1082                 g = groupids[stone_other(color)][i];
1083                 if (g && board_group_info(b, g).libs == 1) {
1084                         /* But we need to get to at least two liberties by this;
1085                          * we already have one outside liberty, or the group is
1086                          * more than 1 stone. */
1087                         if (groupcts[S_NONE] > 0 || !group_is_onestone(b, g))
1088                                 return false;
1089                         /* ...or, it's a ko stone. */
1090                         if (neighbor_count_at(b, g, color) == 3)
1091                                 return false;
1092                         /* ...or, we already have one indirect liberty provided
1093                          * by another group. */
1094                         if (can_capture && can_capture != g)
1095                                 return false;
1096                         can_capture = g;
1097                 }
1098
1099                 /* There is another possibility - we can self-atari if it is
1100                  * a nakade: we put an enemy group in atari. */
1101                 /* TODO: Allow to only nakade if the created shape is dead
1102                  * (http://senseis.xmp.net/?Nakade). */
1103                 if (g && board_group_info(b, g).libs == 2) {
1104                         /* We must make sure the other liberty of that group:
1105                          * (i) will capture our group
1106                          * (ii) filling it to capture our group will not gain
1107                          * safety */
1108
1109                         /* (i) is guaranteed; otherwise this move would not be
1110                          * self-atari or the enemy group had >2 liberties. */
1111                         ;
1112
1113                         /* (ii) let's look at the liberty neighbors: */
1114                         int lib2 = board_group_info(b, g).lib[0];
1115                         if (lib2 == to) lib2 = board_group_info(b, g).lib[1];
1116                         foreach_neighbor(b, lib2, {
1117                                 /* This neighbor of course does not contribute
1118                                  * anything to the enemy. */
1119                                 if (board_at(b, c) == S_OFFBOARD)
1120                                         continue;
1121                                 /* If the other liberty has empty neighbor,
1122                                  * it may not yet be an escape path.
1123                                  * This enables eyes falsification:
1124                                  * O O O . .
1125                                  * X X O O .
1126                                  * X . X O .
1127                                  * X X X O O
1128                                  * X O * . . */
1129                                 if (board_at(b, c) == S_NONE)
1130                                         continue;
1131                                 /* If the neighbor is of our color, it must
1132                                  * be our group; if it is a different group,
1133                                  * we won't allow the self-atari. */
1134                                 /* This is the main point of having so
1135                                  * convoluted nakade detection. */
1136                                 /* X X X X We will not allow play on 'a',
1137                                  * X X a X because it would capture two
1138                                  * X O b X different groups, forming two
1139                                  * X X X X eyes. */
1140                                 int g2 = group_at(b, c);
1141                                 if (board_at(b, c) == color) {
1142                                         /* Our group == one of the groups
1143                                          * we (@to) are connected to. */
1144                                         int j;
1145                                         for (j = 0; j < 4; j++)
1146                                                 if (groupids[color][j] == g2)
1147                                                         break;
1148                                         if (j == 4)
1149                                                 goto enemy_capture_gains_liberty;
1150                                 }
1151                                 /* The neighbor is enemy color. It's ok if
1152                                  * this is its only liberty. */
1153                                 if (board_group_info(b, g2).libs == 1)
1154                                         continue;
1155                                 /* Otherwise, it must have the exact same
1156                                  * liberties as the original enemy group. */
1157                                 if (board_group_info(b, g2).libs > 2
1158                                     || board_group_info(b, g2).lib[0] == to
1159                                     || board_group_info(b, g2).lib[1] == to)
1160                                         goto enemy_capture_gains_liberty;
1161                         });
1162                         return false;
1163
1164 enemy_capture_gains_liberty:;
1165                 }
1166         }
1167
1168         //fprintf(stderr, "%d,%d\n", needs_more_lib, can_capture);
1169         if (needs_more_lib && can_capture)
1170                 return false;
1171
1172         /* We are throwing-in to false eye:
1173          * X X X O X X X O X X X X X
1174          * X . * X * O . X * O O . X
1175          * # # # # # # # # # # # # # */
1176         /* We cannot sensibly throw-in into a corner. */
1177         if (neighbor_count_at(b, to, S_OFFBOARD) < 2
1178             && neighbor_count_at(b, to, stone_other(color))
1179                + neighbor_count_at(b, to, S_OFFBOARD) == 3) {
1180                 /* *Any space* we can throw a stone in. Is it
1181                  * a false eye? */
1182                 if (board_is_false_eyelike(b, &to, stone_other(color))) {
1183                         assert(groupcts[color] <= 1);
1184                         /* Single-stone throw-in is ok. */
1185                         if (groupcts[color] == 0)
1186                                 return false;
1187                         /* Bad throwin: we are connected to a group whose
1188                          * other liberty is a connection out
1189                          * X X O X X X O X
1190                          * X . X . O O . X
1191                          * # # # # # # # # */
1192                         group_t g = groupids[color][0];
1193                         assert(board_group_info(b, g).libs <= 2);
1194                         /* Suicide is not ok. */
1195                         if (board_group_info(b, g).libs == 1)
1196                                 return true;
1197                         int lib2 = board_group_info(b, g).lib[0];
1198                         if (lib2 == to) lib2 = board_group_info(b, g).lib[1];
1199                         /* This is actually slightly more general than above,
1200                          * and not perfect (the other group can be in atari),
1201                          * but should be ok. */
1202                         if (neighbor_count_at(b, to, color) + neighbor_count_at(b, to, S_NONE) > 1)
1203                                 return false;
1204                 }
1205         }
1206
1207         /* No way to pull out, no way to connect out. */
1208         return true;
1209 }
1210
1211
1212 bool
1213 board_stone_radar(struct board *b, coord_t coord, int distance)
1214 {
1215         int bounds[4] = {
1216                 coord_x(coord, b) - distance,
1217                 coord_y(coord, b) - distance,
1218                 coord_x(coord, b) + distance,
1219                 coord_y(coord, b) + distance
1220         };
1221         for (int i = 0; i < 4; i++)
1222                 if (bounds[i] < 1)
1223                         bounds[i] = 1;
1224                 else if (bounds[i] > board_size(b) - 2)
1225                         bounds[i] = board_size(b) - 2;
1226         for (int x = bounds[0]; x <= bounds[2]; x++)
1227                 for (int y = bounds[1]; y <= bounds[3]; y++)
1228                         if (board_atxy(b, x, y) != S_NONE) {
1229                                 //fprintf(stderr, "radar %d,%d,%d: %d,%d (%d)\n", coord_x(coord, b), coord_y(coord, b), distance, x, y, board_atxy(b, x, y));
1230                                 return true;
1231                         }
1232         return false;
1233 }