1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/chess/knight.c Mon Mar 31 11:16:32 2014 +0200
1.3 @@ -0,0 +1,133 @@
1.4 +/*
1.5 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
1.6 + *
1.7 + * Copyright 2014 Mike Becker. All rights reserved.
1.8 + *
1.9 + * Redistribution and use in source and binary forms, with or without
1.10 + * modification, are permitted provided that the following conditions are met:
1.11 + *
1.12 + * 1. Redistributions of source code must retain the above copyright
1.13 + * notice, this list of conditions and the following disclaimer.
1.14 + *
1.15 + * 2. Redistributions in binary form must reproduce the above copyright
1.16 + * notice, this list of conditions and the following disclaimer in the
1.17 + * documentation and/or other materials provided with the distribution.
1.18 + *
1.19 + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
1.20 + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
1.21 + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
1.22 + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
1.23 + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
1.24 + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
1.25 + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
1.26 + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
1.27 + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
1.28 + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
1.29 + * POSSIBILITY OF SUCH DAMAGE.
1.30 + *
1.31 + */
1.32 +
1.33 +#include "knight.h"
1.34 +#include "rules.h"
1.35 +#include <stdlib.h>
1.36 +
1.37 +_Bool knight_chkrules(Move *move) {
1.38 + int dx = abs(move->fromfile - move->tofile);
1.39 + int dy = abs(move->fromrow - move->torow);
1.40 +
1.41 + return (dx == 2 && dy == 1) || (dx == 1 && dy == 2);
1.42 +}
1.43 +
1.44 +static int knight_getloc_fixedrow(Board board, Move *move) {
1.45 + int d = 3 - abs(move->fromrow - move->torow);
1.46 +
1.47 + if (d == 1 || d == 2) {
1.48 + if (move->tofile < 6 &&
1.49 + board[move->fromrow][move->tofile + d] == move->piece) {
1.50 + if (move->fromfile == POS_UNSPECIFIED) {
1.51 + move->fromfile = move->tofile + d;
1.52 + return VALID_MOVE_SYNTAX;
1.53 + } else {
1.54 + return AMBIGUOUS_MOVE;
1.55 + }
1.56 + }
1.57 + if (move->tofile > 1 &&
1.58 + board[move->fromrow][move->tofile - d] == move->piece) {
1.59 + if (move->fromfile == POS_UNSPECIFIED) {
1.60 + move->fromfile = move->tofile - d;
1.61 + return VALID_MOVE_SYNTAX;
1.62 + } else {
1.63 + return AMBIGUOUS_MOVE;
1.64 + }
1.65 + }
1.66 + }
1.67 +
1.68 + return INVALID_POSITION;
1.69 +}
1.70 +
1.71 +static int knight_getloc_fixedfile(Board board, Move *move) {
1.72 + int d = 3 - abs(move->fromfile - move->tofile);
1.73 +
1.74 + if (d == 1 || d == 2) {
1.75 + if (move->torow < 6 &&
1.76 + board[move->torow + d][move->fromfile] == move->piece) {
1.77 + if (move->fromrow == POS_UNSPECIFIED) {
1.78 + move->fromrow = move->torow + d;
1.79 + return VALID_MOVE_SYNTAX;
1.80 + } else {
1.81 + return AMBIGUOUS_MOVE;
1.82 + }
1.83 + }
1.84 + if (move->torow > 1 &&
1.85 + board[move->torow - d][move->fromfile] == move->piece) {
1.86 + if (move->fromrow == POS_UNSPECIFIED) {
1.87 + move->fromrow = move->torow - d;
1.88 + return VALID_MOVE_SYNTAX;
1.89 + } else {
1.90 + return AMBIGUOUS_MOVE;
1.91 + }
1.92 + }
1.93 + }
1.94 +
1.95 + return INVALID_POSITION;
1.96 +}
1.97 +
1.98 +int knight_getlocation(Board board, Move *move) {
1.99 +
1.100 + if (move->fromfile != POS_UNSPECIFIED) {
1.101 + return knight_getloc_fixedfile(board, move);
1.102 + }
1.103 +
1.104 + if (move->fromrow != POS_UNSPECIFIED) {
1.105 + return knight_getloc_fixedrow(board, move);
1.106 + }
1.107 +
1.108 + for (int x = -2 ; x <= 2 ; x++) {
1.109 + if (x == 0) {
1.110 + continue;
1.111 + }
1.112 + for (int y = -2 ; y <= 2 ; y++) {
1.113 + if (y == 0 || y == x) {
1.114 + continue;
1.115 + }
1.116 + uint8_t cx = move->tofile + x;
1.117 + uint8_t cy = move->torow + y;
1.118 +
1.119 + if (isidx(cx) && isidx(cy) && board[cy][cx] == move->piece) {
1.120 + if (move->fromfile == POS_UNSPECIFIED
1.121 + && move->fromrow == POS_UNSPECIFIED) {
1.122 + move->fromfile = cx;
1.123 + move->fromrow = cy;
1.124 + } else {
1.125 + return AMBIGUOUS_MOVE;
1.126 + }
1.127 + }
1.128 + }
1.129 + }
1.130 +
1.131 + if (move->fromfile == POS_UNSPECIFIED || move->fromrow == POS_UNSPECIFIED) {
1.132 + return INVALID_POSITION;
1.133 + } else {
1.134 + return VALID_MOVE_SYNTAX;
1.135 + }
1.136 +}
