terminal-chess: src/chess/king.c@3ab0c2e1a4e2

     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 "king.h"

    32 #include <stdlib.h>

    34 static _Bool king_castling_chkmoved(GameState *gamestate,

    35     uint8_t row, uint8_t file) {

    37     MoveList *ml = gamestate->movelist;

    38     while (ml) {

    39         if (ml->move.fromfile == file && ml->move.fromrow == row) {

    40             return 1;

    41         }

    42         ml = ml->next;

    43     }

    45     return 0;

    46 }

    48 _Bool king_chkrules(GameState *gamestate, Move* move) {

    49     if (abs(move->torow - move->fromrow) <= 1 &&

    50         abs(move->tofile - move->fromfile) <= 1) {

    51         return 1;

    52     } else {

    53         /* castling */

    54         if (move->fromrow == move->torow &&

    55             move->fromrow == ((move->piece&COLOR_MASK) == WHITE ? 0 : 7) &&

    56             move->fromfile == fileidx('e') &&

    57             (move->tofile == fileidx('c') || move->tofile == fileidx('g'))) {

    59             return !king_castling_chkmoved(gamestate,

    60                 move->fromrow, move->fromfile) &&

    61                 !king_castling_chkmoved(gamestate, move->fromrow,

    62                 move->tofile == fileidx('c') ? 0 : 7);

    63         } else {

    64             return 0;

    65         }

    66     }

    67 }

    69 _Bool king_isblocked(GameState *gamestate, Move *move) {

    71     uint8_t opponent_color = opponent_color(move->piece&COLOR_MASK);

    72     _Bool blocked = is_covered(gamestate, move->torow, move->tofile,

    73         opponent_color);

    75     if (abs(move->tofile - move->fromfile) == 2) {

    76         if (move->tofile == fileidx('c')) {

    77             blocked |= gamestate->board[move->torow][fileidx('b')];

    78         }

    79         uint8_t midfile = (move->tofile+move->fromfile)/2;

    80         blocked |= gamestate->lastmove->move.check ||

    81             gamestate->board[move->torow][midfile] ||

    82             is_covered(gamestate, move->torow, midfile, opponent_color);

    83     }

    85     return blocked;

    86 }

    88 int king_getlocation(GameState *gamestate, Move *move) {

    90     uint8_t file, row;

    92     for (int f = -1 ; f <= 1 ; f++) {

    93         for (int r = -1 ; r <= 1 ; r++) {

    94             if (f == 0 && r == 0) {

    95                 continue;

    96             }

    97             file = move->tofile + f;

    98             row = move->torow + r;

    99             if (isidx(file) && isidx(row)) {

   100                 if (gamestate->board[row][file] == move->piece) {

   101                     if ((move->fromfile != POS_UNSPECIFIED

   102                         && move->fromfile != file) ||

   103                         (move->fromrow != POS_UNSPECIFIED

   104                         && move->fromrow != row)) {

   105                         return INVALID_POSITION;

   106                     }

   107                     move->fromfile = file;

   108                     move->fromrow = row;

   109                     return VALID_MOVE_SYNTAX;

   110                 }

   111             }

   112         }

   113     }

   115     return INVALID_POSITION;

   116 }

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