universe@10: /*
universe@10:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
universe@10:  *
universe@10:  * Copyright 2014 Mike Becker. All rights reserved.
universe@10:  *
universe@10:  * Redistribution and use in source and binary forms, with or without
universe@10:  * modification, are permitted provided that the following conditions are met:
universe@10:  *
universe@10:  *   1. Redistributions of source code must retain the above copyright
universe@10:  *      notice, this list of conditions and the following disclaimer.
universe@10:  *
universe@10:  *   2. Redistributions in binary form must reproduce the above copyright
universe@10:  *      notice, this list of conditions and the following disclaimer in the
universe@10:  *      documentation and/or other materials provided with the distribution.
universe@10:  *
universe@10:  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
universe@10:  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
universe@10:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
universe@10:  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
universe@10:  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
universe@10:  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
universe@10:  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
universe@10:  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
universe@10:  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
universe@10:  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
universe@10:  * POSSIBILITY OF SUCH DAMAGE.
universe@10:  *
universe@10:  */
universe@10: 
universe@10: #include "knight.h"
universe@16: #include "rules.h"
universe@19: #include <stdlib.h>
universe@10: 
universe@16: _Bool knight_chkrules(Move *move) {
universe@16:     int dx = abs(move->fromfile - move->tofile);
universe@16:     int dy = abs(move->fromrow - move->torow);
universe@16:     
universe@16:     return (dx == 2 && dy == 1) || (dx == 1 && dy == 2);
universe@10: }
universe@10: 
universe@23: static int knight_getloc_fixedrow(GameState *gamestate, Move *move) {
universe@16:     int d = 3 - abs(move->fromrow - move->torow);
universe@16:     
universe@16:     if (d == 1 || d == 2) {
universe@16:         if (move->tofile < 6 &&
universe@23:             gamestate->board[move->fromrow][move->tofile + d] == move->piece) {
universe@16:             if (move->fromfile == POS_UNSPECIFIED) {
universe@16:                 move->fromfile = move->tofile + d;
universe@16:                 return VALID_MOVE_SYNTAX;
universe@16:             } else {
universe@16:                 return AMBIGUOUS_MOVE;
universe@16:             }
universe@16:         }
universe@16:         if (move->tofile > 1 &&
universe@23:             gamestate->board[move->fromrow][move->tofile - d] == move->piece) {
universe@16:             if (move->fromfile == POS_UNSPECIFIED) {
universe@16:                 move->fromfile = move->tofile - d;
universe@16:                 return VALID_MOVE_SYNTAX;
universe@16:             } else {
universe@16:                 return AMBIGUOUS_MOVE;
universe@16:             }
universe@16:         }
universe@16:     }
universe@16:     
universe@16:     return INVALID_POSITION;
universe@10: }
universe@10: 
universe@23: static int knight_getloc_fixedfile(GameState *gamestate, Move *move) {
universe@16:     int d = 3 - abs(move->fromfile - move->tofile);
universe@16:     
universe@16:     if (d == 1 || d == 2) {
universe@16:         if (move->torow < 6 &&
universe@23:             gamestate->board[move->torow + d][move->fromfile] == move->piece) {
universe@16:             if (move->fromrow == POS_UNSPECIFIED) {
universe@16:                 move->fromrow = move->torow + d;
universe@16:                 return VALID_MOVE_SYNTAX;
universe@16:             } else {
universe@16:                 return AMBIGUOUS_MOVE;
universe@16:             }
universe@16:         }
universe@16:         if (move->torow > 1 &&
universe@23:             gamestate->board[move->torow - d][move->fromfile] == move->piece) {
universe@16:             if (move->fromrow == POS_UNSPECIFIED) {
universe@16:                 move->fromrow = move->torow - d;
universe@16:                 return VALID_MOVE_SYNTAX;
universe@16:             } else {
universe@16:                 return AMBIGUOUS_MOVE;
universe@16:             }
universe@16:         }
universe@16:     }
universe@16:     
universe@16:     return INVALID_POSITION;
universe@10: }
universe@16: 
universe@23: int knight_getlocation(GameState *gamestate, Move *move) {
universe@16:     
universe@16:     if (move->fromfile != POS_UNSPECIFIED) {
universe@23:         return knight_getloc_fixedfile(gamestate, move);
universe@16:     }
universe@16:     
universe@16:     if (move->fromrow != POS_UNSPECIFIED) {
universe@23:         return knight_getloc_fixedrow(gamestate, move);
universe@16:     }
universe@16:     
universe@16:     for (int x = -2 ; x <= 2 ; x++) {
universe@16:         if (x == 0) {
universe@16:             continue;
universe@16:         }
universe@16:         for (int y = -2 ; y <= 2 ; y++) {
universe@16:             if (y == 0 || y == x) {
universe@16:                 continue;
universe@16:             }
universe@16:             uint8_t cx = move->tofile + x;
universe@16:             uint8_t cy = move->torow + y;
universe@16: 
universe@23:             if (isidx(cx) && isidx(cy)
universe@23:                 && gamestate->board[cy][cx] == move->piece) {
universe@16:                 if (move->fromfile == POS_UNSPECIFIED
universe@16:                     && move->fromrow == POS_UNSPECIFIED) {
universe@16:                     move->fromfile = cx;
universe@16:                     move->fromrow = cy;
universe@16:                 } else {
universe@16:                     return AMBIGUOUS_MOVE;
universe@16:                 }
universe@16:             }
universe@16:         }
universe@16:     }
universe@16:     
universe@16:     if (move->fromfile == POS_UNSPECIFIED || move->fromrow == POS_UNSPECIFIED) {
universe@16:         return INVALID_POSITION;
universe@16:     } else {
universe@16:         return VALID_MOVE_SYNTAX;
universe@16:     }
universe@16: }