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 "bishop.h"
universe@16: #include "rules.h"
universe@19: #include <stdlib.h>
universe@10: 
universe@16: _Bool bishop_chkrules(Move* move) {
universe@17:     return abs(move->torow-move->fromrow) == abs(move->tofile-move->fromfile);
universe@17: }
universe@17: 
universe@23: _Bool bishop_isblocked(GameState *gamestate, Move *move) {
universe@17:     int dy = move->torow > move->fromrow ? 1 : -1;
universe@17:     int dx = move->tofile > move->fromfile ? 1 : -1;
universe@17:     
universe@17:     uint8_t y = move->fromrow;
universe@17:     uint8_t x = move->fromfile;
universe@17:     
universe@21:     while (x != move->tofile-dx && y != move->torow-dy) {
universe@17:         x += dx;
universe@17:         y += dy;
universe@23:         if (gamestate->board[y][x]) {
universe@19:             return 1;
universe@17:         }
universe@21:     }
universe@17:     
universe@19:     return 0;
universe@10: }
universe@10: 
universe@23: static int bishop_getloc_fixedfile(GameState *gamestate, Move *move) {
universe@17:     uint8_t d = abs(move->fromfile - move->tofile);
universe@23:     if (gamestate->board[move->torow - d][move->fromfile] == move->piece) {
universe@17:         move->fromrow = move->torow - d;
universe@17:     }
universe@23:     if (gamestate->board[move->torow + d][move->fromfile] == move->piece) {
universe@17:         if (move->fromrow == POS_UNSPECIFIED) {
universe@17:             move->fromrow = move->torow + d;
universe@17:         } else {
universe@17:             return AMBIGUOUS_MOVE; /* rare situation after promotion */
universe@17:         }
universe@17:     }
universe@17:     return move->fromrow == POS_UNSPECIFIED ?
universe@17:         INVALID_POSITION : VALID_MOVE_SYNTAX;
universe@17: }
universe@17: 
universe@23: static int bishop_getloc_fixedrow(GameState *gamestate, Move *move) {
universe@17:     uint8_t d = abs(move->fromrow - move->torow);
universe@23:     if (gamestate->board[move->fromrow][move->tofile - d] == move->piece) {
universe@17:         move->fromfile = move->tofile - d;
universe@17:     }
universe@23:     if (gamestate->board[move->fromrow][move->tofile + d] == move->piece) {
universe@17:         if (move->fromfile == POS_UNSPECIFIED) {
universe@17:             move->fromfile = move->tofile + d;
universe@17:         } else {
universe@17:             return AMBIGUOUS_MOVE; /* rare situation after promotion */
universe@17:         }
universe@17:     }
universe@17:     return move->fromfile == POS_UNSPECIFIED ?
universe@17:         INVALID_POSITION : VALID_MOVE_SYNTAX;
universe@10: }
universe@10: 
universe@23: int bishop_getlocation(GameState *gamestate, Move *move) {
universe@17:     
universe@17:     if (move->fromfile != POS_UNSPECIFIED) {
universe@23:         return bishop_getloc_fixedfile(gamestate, move);
universe@17:     }
universe@17:     
universe@17:     if (move->fromrow != POS_UNSPECIFIED) {
universe@23:         return bishop_getloc_fixedrow(gamestate, move);
universe@17:     }
universe@17:     
universe@19:     _Bool amb = 0;
universe@17:     for (int d = -7 ; d < 8  ; d++) {
universe@17:         uint8_t row = move->torow + d;
universe@17:         if (isidx(row)) {
universe@17:             uint8_t file = move->tofile + d;
universe@23:             if (isidx(file) && gamestate->board[row][file] == move->piece) {
universe@17:                 if (amb) {
universe@17:                     return AMBIGUOUS_MOVE;
universe@17:                 }
universe@19:                 amb = 1;
universe@17:                 move->fromrow = row;
universe@17:                 move->fromfile = file;
universe@17:             }
universe@17:             file = move->tofile - d;
universe@23:             if (isidx(file) && gamestate->board[row][file] == move->piece) {
universe@17:                 if (amb) {
universe@17:                     return AMBIGUOUS_MOVE;
universe@17:                 }
universe@19:                 amb = 1;
universe@17:                 move->fromrow = row;
universe@17:                 move->fromfile = file;
universe@17:             }
universe@17:         }
universe@17:     }
universe@17:     
universe@17:     if (move->fromrow == POS_UNSPECIFIED || move->fromfile == POS_UNSPECIFIED) {
universe@17:         return INVALID_POSITION;
universe@17:     } else {
universe@17:         return VALID_MOVE_SYNTAX;
universe@17:     }
universe@10: }