terminal-chess: src/chess/rules.c@efeb98bc69c9

     1 /*

     2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

     3  *

     4  * Copyright 2014 Mike Becker. All rights reserved.

     5  *

     6  * Redistribution and use in source and binary forms, with or without

     7  * modification, are permitted provided that the following conditions are met:

     8  *

     9  *   1. Redistributions of source code must retain the above copyright

    10  *      notice, this list of conditions and the following disclaimer.

    11  *

    12  *   2. Redistributions in binary form must reproduce the above copyright

    13  *      notice, this list of conditions and the following disclaimer in the

    14  *      documentation and/or other materials provided with the distribution.

    15  *

    16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

    17  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

    18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

    19  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE

    20  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

    21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

    22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

    23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

    24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

    25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

    26  * POSSIBILITY OF SUCH DAMAGE.

    27  *

    28  */

    30 #include "rules.h"

    31 #include "chess.h"

    32 #include <string.h>

    33 #include <stdlib.h>

    35 void gamestate_cleanup(GameState *gamestate) {

    36     MoveList *elem;

    37     elem = gamestate->movelist;

    38     while (elem) {

    39         MoveList *cur = elem;

    40         elem = elem->next;

    41         free(cur);

    42     };

    43 }

    45 static void addmove(GameState* gamestate, Move *move) {

    46     MoveList *elem = malloc(sizeof(MoveList));

    47     elem->next = NULL;

    48     elem->move = *move;

    50     if (gamestate->lastmove) {

    51         gamestate->lastmove->next = elem;

    52         gamestate->lastmove = elem;

    53     } else {

    54         gamestate->movelist = gamestate->lastmove = elem;

    55     }

    56 }

    58 char getpiecechr(uint8_t piece) {

    59     switch (piece & PIECE_MASK) {

    60     case ROOK: return 'R';

    61     case KNIGHT: return 'N';

    62     case BISHOP: return 'B';

    63     case QUEEN: return 'Q';

    64     case KING: return 'K';

    65     default: return '\0';

    66     }

    67 }

    69 uint8_t getpiece(char c) {

    70     switch (c) {

    71         case 'R': return ROOK;

    72         case 'N': return KNIGHT;

    73         case 'B': return BISHOP;

    74         case 'Q': return QUEEN;

    75         case 'K': return KING;

    76         default: return 0;

    77     }

    78 }

    80 static int getlocation(GameState *gamestate, Move *move) {

    81     uint8_t piece = move->piece & PIECE_MASK;

    82     switch (piece) {

    83         case PAWN: return pawn_getlocation(gamestate, move);

    84         case ROOK: return rook_getlocation(gamestate, move);

    85         case KNIGHT: return knight_getlocation(gamestate, move);

    86         case BISHOP: return bishop_getlocation(gamestate, move);

    87         case QUEEN: return queen_getlocation(gamestate, move);

    88         case KING: return king_getlocation(gamestate, move);

    89         default: return INVALID_MOVE_SYNTAX;

    90     }

    91 }

    93 _Bool is_covered(GameState *gamestate,uint8_t row,uint8_t file,uint8_t color) {

    94     Move threats[16];

    95     int threatcount = 0;

    96     for (uint8_t r = 0 ; r < 8 ; r++) {

    97         for (uint8_t f = 0 ; f < 8 ; f++) {

    98             if ((gamestate->board[r][f] & COLOR_MASK) == color) {

    99                 threats[threatcount].piece = gamestate->board[r][f];

   100                 threats[threatcount].fromrow = r;

   101                 threats[threatcount].fromfile = f;

   102                 threats[threatcount].torow = row;

   103                 threats[threatcount].tofile = file;

   104                 threatcount++;

   105             }

   106         }

   107     }

   109     for (int i = 0 ; i < threatcount ; i++) {

   110         if (validate_move(gamestate, &(threats[i]))) {

   111             return 1;

   112         }

   113     }

   115     return 0;

   116 }

   118 void apply_move(GameState *gamestate, Move *move) {

   119     uint8_t piece = move->piece & PIECE_MASK;

   120     uint8_t color = move->piece & COLOR_MASK;

   122     /* en passant capture */

   123     if (move->capture && piece == PAWN &&

   124         mdst(gamestate->board, move) == 0) {

   125         gamestate->board[move->fromrow][move->tofile] = 0;

   126     }

   128     /* remove old en passant threats */

   129     for (uint8_t file = 0 ; file < 8 ; file++) {

   130         gamestate->board[3][file] &= ~ENPASSANT_THREAT;

   131         gamestate->board[4][file] &= ~ENPASSANT_THREAT;

   132     }

   134     /* add new en passant threat */

   135     if (piece == PAWN && (

   136         (move->fromrow == 1 && move->torow == 3) ||

   137         (move->fromrow == 6 && move->torow == 4))) {

   138         move->piece |= ENPASSANT_THREAT;

   139     }

   141     /* move (and maybe capture or promote) */

   142     msrc(gamestate->board, move) = 0;

   143     if (move->promotion) {

   144         mdst(gamestate->board, move) = move->promotion;

   145     } else {

   146         mdst(gamestate->board, move) = move->piece;

   147     }

   149     /* castling */

   150     if (piece == KING &&

   151         move->fromfile == fileidx('e')) {

   153         if (move->tofile == fileidx('g')) {

   154             gamestate->board[move->torow][fileidx('h')] = 0;

   155             gamestate->board[move->torow][fileidx('f')] = color|ROOK;

   156         } else if (move->tofile == fileidx('c')) {

   157             gamestate->board[move->torow][fileidx('a')] = 0;

   158             gamestate->board[move->torow][fileidx('d')] = color|ROOK;

   159         }

   160     }

   162     addmove(gamestate, move);

   163 }

   165 _Bool validate_move(GameState *gamestate, Move *move) {

   166     _Bool result;

   168     /* validate indices (don't trust opponent) */

   169     if (!chkidx(move)) {

   170         return 0;

   171     }

   173     /* must move */

   174     if (move->fromfile == move->tofile && move->fromrow == move->torow) {

   175         return 0;

   176     }

   178     /* does piece exist */

   179     result = msrc(gamestate->board, move) == move->piece;

   181     /* can't capture own pieces */

   182     if ((mdst(gamestate->board, move) & COLOR_MASK)

   183         == (move->piece & COLOR_MASK)) {

   184         return 0;

   185     }

   187     /* validate individual rules */

   188     switch (move->piece & PIECE_MASK) {

   189     case PAWN:

   190         result = result && pawn_chkrules(gamestate, move);

   191         result = result && !pawn_isblocked(gamestate, move);

   192         break;

   193     case ROOK:

   194         result = result && rook_chkrules(move);

   195         result = result && !rook_isblocked(gamestate, move);

   196         break;

   197     case KNIGHT:

   198         result = result && knight_chkrules(move);

   199         result = result && !knight_isblocked(gamestate, move);

   200         break;

   201     case BISHOP:

   202         result = result && bishop_chkrules(move);

   203         result = result && !bishop_isblocked(gamestate, move);

   204         break;

   205     case QUEEN:

   206         result = result && queen_chkrules(move);

   207         result = result && !queen_isblocked(gamestate, move);

   208         break;

   209     case KING:

   210         result = result && king_chkrules(gamestate, move);

   211         result = result && !king_isblocked(gamestate, move);

   212         break;

   213     default:

   214         result = 0;

   215     }

   217     /* cancel processing to avoid recursion overflow with is_covered() */

   218     if (!result) {

   219         return 0;

   220     }

   222     /* is piece pinned */

   223     // TODO: make it so

   225     /* correct check and checkmate flags (move is still valid) */

   226     // TODO: make it so

   228     return result;

   229 }

   231 int eval_move(GameState *gamestate, char *mstr, Move *move) {

   232     memset(move, 0, sizeof(Move));

   233     move->fromfile = POS_UNSPECIFIED;

   234     move->fromrow = POS_UNSPECIFIED;

   236     size_t len = strlen(mstr);

   238     /* evaluate check/checkmate flags */

   239     if (mstr[len-1] == '+') {

   240         len--; mstr[len] = '\0';

   241         move->check = 1;

   242     } else if (mstr[len-1] == '#') {

   243         len--; mstr[len] = '\0';

   244         /* ignore - validation should set game state */

   245     }

   247     /* evaluate promotion */

   248     if (len > 3 && mstr[len-2] == '=') {

   249         move->promotion = getpiece(mstr[len-1]);

   250         if (!move->promotion) {

   251             return INVALID_MOVE_SYNTAX;

   252         } else {

   253             move->promotion |= gamestate->mycolor;

   254             len -= 2;

   255             mstr[len] = 0;

   256         }

   257     }

   259     if (len == 2) {

   260         /* pawn move (e.g. "e4") */

   261         move->piece = PAWN;

   262         move->tofile = fileidx(mstr[0]);

   263         move->torow = rowidx(mstr[1]);

   264     } else if (len == 3) {

   265         if (strcmp(mstr, "O-O") == 0) {

   266             /* king side castling */

   267             move->piece = KING;

   268             move->fromfile = fileidx('e');

   269             move->tofile = fileidx('g');

   270             move->fromrow = move->torow = gamestate->mycolor == WHITE ? 0 : 7;

   271         } else {

   272             /* move (e.g. "Nf3") */

   273             move->piece = getpiece(mstr[0]);

   274             move->tofile = fileidx(mstr[1]);

   275             move->torow = rowidx(mstr[2]);

   276         }

   278     } else if (len == 4) {

   279         move->piece = getpiece(mstr[0]);

   280         if (!move->piece) {

   281             move->piece = PAWN;

   282             move->fromfile = fileidx(mstr[0]);

   283         }

   284         if (mstr[1] == 'x') {

   285             /* capture (e.g. "Nxf3", "dxe5") */

   286             move->capture = 1;

   287         } else {

   288             /* move (e.g. "Ndf3", "N2c3", "e2e4") */

   289             if (isfile(mstr[1])) {

   290                 move->fromfile = fileidx(mstr[1]);

   291                 if (move->piece == PAWN) {

   292                     move->piece = 0;

   293                 }

   294             } else {

   295                 move->fromrow = rowidx(mstr[1]);

   296             }

   297         }

   298         move->tofile = fileidx(mstr[2]);

   299         move->torow = rowidx(mstr[3]);

   300     } else if (len == 5) {

   301         if (strcmp(mstr, "O-O-O") == 0) {

   302             /* queen side castling "O-O-O" */

   303             move->piece = KING;

   304             move->fromfile = fileidx('e');

   305             move->tofile = fileidx('c');

   306             move->fromrow = move->torow = gamestate->mycolor == WHITE ? 0 : 7;

   307         } else {

   308             move->piece = getpiece(mstr[0]);

   309             if (mstr[2] == 'x') {

   310                 move->capture = 1;

   311                 if (move->piece) {

   312                     /* capture (e.g. "Ndxf3") */

   313                     move->fromfile = fileidx(mstr[1]);

   314                 } else {

   315                     /* long notation capture (e.g. "e5xf6") */

   316                     move->piece = PAWN;

   317                     move->fromfile = fileidx(mstr[0]);

   318                     move->fromrow = rowidx(mstr[1]);

   319                 }

   320             } else {

   321                 /* long notation move (e.g. "Nc5a4") */

   322                 move->fromfile = fileidx(mstr[1]);

   323                 move->fromrow = rowidx(mstr[2]);

   324             }

   325             move->tofile = fileidx(mstr[3]);

   326             move->torow = rowidx(mstr[4]);

   327         }

   328     } else if (len == 6) {

   329         /* long notation capture (e.g. "Nc5xf3") */

   330         if (mstr[3] == 'x') {

   331             move->capture = 1;

   332             move->piece = getpiece(mstr[0]);

   333             move->fromfile = fileidx(mstr[1]);

   334             move->fromrow = rowidx(mstr[2]);

   335             move->tofile = fileidx(mstr[4]);

   336             move->torow = rowidx(mstr[5]);

   337         }

   338     }

   341     if (move->piece) {

   342         if (move->piece == PAWN

   343             && move->torow == (gamestate->mycolor==WHITE?7:0)

   344             && !move->promotion) {

   345             return NEED_PROMOTION;

   346         }

   348         move->piece |= gamestate->mycolor;

   349         if (move->fromfile == POS_UNSPECIFIED

   350             || move->fromrow == POS_UNSPECIFIED) {

   351             return getlocation(gamestate, move);

   352         } else {

   353             return chkidx(move) ? VALID_MOVE_SYNTAX : INVALID_POSITION;

   354         }

   355     } else {

   356         return INVALID_MOVE_SYNTAX;

   357     }

   358 }

Mercurial > hg > terminal-chess / file revision

src/chess/rules.c@efeb98bc69c9

src/chess/rules.c