Mercurial > hg > terminal-chess / file comparison
comparison: src/chess/rules.c
src/chess/rules.c
- changeset 173
- e541b6002933
- parent 170
- bde99d803caf
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| 172:ba1bf80d10cc | 173:e541b6002933 |
|---|---|
| 245 default: | 245 default: |
| 246 return 0; | 246 return 0; |
| 247 } | 247 } |
| 248 } | 248 } |
| 249 | 249 |
| 250 static bool is_stalemate(const GameState *gamestate) { | 250 static bool check_stalemate(const GameState *gamestate) { |
| 251 Color next_player = gamestate->movecount % 2 == 0 ? WHITE : BLACK; | 251 Color next_player = gamestate->movecount % 2 == 0 ? WHITE : BLACK; |
| 252 | 252 |
| 253 /* scan the board for pieces of the next player's color */ | 253 /* scan the board for pieces of the next player's color */ |
| 254 Move moves[QUEEN_MOVES_MAX]; | 254 Move moves[QUEEN_MOVES_MAX]; |
| 255 for (Row r = 0; r < 8; r++) { | 255 for (Row r = 0; r < 8; r++) { |
| 260 } | 260 } |
| 261 } | 261 } |
| 262 } | 262 } |
| 263 | 263 |
| 264 return true; | 264 return true; |
| 265 } | |
| 266 | |
| 267 static size_t fen_len_without_moves(const char *fen) { | |
| 268 size_t len = strlen(fen); | |
| 269 /* find first space that separates the two move counters */ | |
| 270 while (--len > 0 && fen[len] != ' ') {} | |
| 271 /* find second space that separates the move counters from the rest */ | |
| 272 while (--len > 0 && fen[len] != ' ') {} | |
| 273 return len; | |
| 274 } | |
| 275 | |
| 276 bool check_threefold_repetition(const GameState *gamestate) { | |
| 277 if (gamestate->movecount < 3) { | |
| 278 return false; | |
| 279 } | |
| 280 | |
| 281 /* take the part of the FEN that only describes the board */ | |
| 282 const char *fen = gamestate->fen[gamestate->movecount - 1]; | |
| 283 size_t fen_len = fen_len_without_moves(fen); | |
| 284 | |
| 285 // TODO: develop a test case that involves en passant and add support here | |
| 286 | |
| 287 /* count the previous occurrences */ | |
| 288 unsigned c = 0; | |
| 289 for (size_t i = gamestate->movecount - 1; i > 0;) { | |
| 290 const char *other = gamestate->fen[--i]; | |
| 291 size_t other_len = fen_len_without_moves(other); | |
| 292 if (fen_len != other_len) continue; | |
| 293 if (strncmp(fen, other, fen_len) == 0) { | |
| 294 if (++c == 2) return true; | |
| 295 } | |
| 296 } | |
| 297 return false; | |
| 265 } | 298 } |
| 266 | 299 |
| 267 char getpiecechr(Piece piece) { | 300 char getpiecechr(Piece piece) { |
| 268 switch (piece_type(piece)) { | 301 switch (piece_type(piece)) { |
| 269 case ROOK: return 'R'; | 302 case ROOK: return 'R'; |
| 308 case 'K': return mkpiece(KING, color); | 341 case 'K': return mkpiece(KING, color); |
| 309 default: return 0; | 342 default: return 0; |
| 310 } | 343 } |
| 311 } | 344 } |
| 312 | 345 |
| 346 /* applies the move without recalculating gamestate flags */ | |
| 313 static void apply_move_internal(GameState *gamestate, Move *move) { | 347 static void apply_move_internal(GameState *gamestate, Move *move) { |
| 314 /* en passant capture */ | 348 /* en passant capture */ |
| 315 if (move->capture && piece_type(move->piece) == PAWN && | 349 if (move->capture && piece_type(move->piece) == PAWN && |
| 316 piece_at(gamestate, mdst(move)) == 0) { | 350 piece_at(gamestate, mdst(move)) == 0) { |
| 317 piece_remove(gamestate, move->fromrow, move->tofile); | 351 piece_remove(gamestate, move->fromrow, move->tofile); |
| 373 calc_movetime(gamestate, melem); | 407 calc_movetime(gamestate, melem); |
| 374 } | 408 } |
| 375 | 409 |
| 376 /* important: only "add" the move after calculating the time! */ | 410 /* important: only "add" the move after calculating the time! */ |
| 377 gamestate->movecount++; | 411 gamestate->movecount++; |
| 378 | |
| 379 /* did this move checkmate the other king? */ | |
| 380 gamestate->checkmate = move->checkmate; | |
| 381 } | 412 } |
| 382 | 413 |
| 383 void apply_move(GameState *gamestate, Move *move) { | 414 void apply_move(GameState *gamestate, Move *move) { |
| 384 apply_move_internal(gamestate, move); | 415 apply_move_internal(gamestate, move); |
| 385 if (!gamestate->checkmate) { | 416 |
| 386 gamestate->stalemate = is_stalemate(gamestate); | 417 /* calculate gamestate flags in order of efficiency */ |
| 418 if (move->checkmate) { | |
| 419 gamestate->checkmate = true; | |
| 420 } else if (check_threefold_repetition(gamestate)) { | |
| 421 gamestate->threefold = true; | |
| 422 } else if (check_stalemate(gamestate)) { | |
| 423 gamestate->stalemate = true; | |
| 387 } | 424 } |
| 388 } | 425 } |
| 389 | 426 |
| 390 void gamestate_at_move(const GameState *gamestate, | 427 void gamestate_at_move(const GameState *gamestate, |
| 391 unsigned move_number, GameState *replay) { | 428 unsigned move_number, GameState *replay) { |
| 1179 } else { | 1216 } else { |
| 1180 return snprintf(str, 6, "%02u:%02u", minutes, seconds); | 1217 return snprintf(str, 6, "%02u:%02u", minutes, seconds); |
| 1181 } | 1218 } |
| 1182 } | 1219 } |
| 1183 | 1220 |
| 1184 bool check_threefold_repetition(const GameState *gamestate) { | |
| 1185 // TODO: implement threefold repetition detection | |
| 1186 return false; | |
| 1187 } | |
| 1188 | |
| 1189 size_t filter_moves_allowed(const GameState *gamestate, | 1221 size_t filter_moves_allowed(const GameState *gamestate, |
| 1190 Color c, Row r, File f, Move *moves, moves_generator_func func) { | 1222 Color c, Row r, File f, Move *moves, moves_generator_func func) { |
| 1191 | 1223 |
| 1192 /* worst case: the queen has the most moves */ | 1224 /* worst case: the queen has the most moves */ |
| 1193 Move candidates[QUEEN_MOVES_MAX]; | 1225 Move candidates[QUEEN_MOVES_MAX]; |
