1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/chess/rules.c Mon Mar 31 11:16:32 2014 +0200
1.3 @@ -0,0 +1,303 @@
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 "rules.h"
1.34 +#include "chess.h"
1.35 +#include <string.h>
1.36 +
1.37 +char getpiecechr(uint8_t piece) {
1.38 + switch (piece & PIECE_MASK) {
1.39 + case ROOK: return 'R';
1.40 + case KNIGHT: return 'N';
1.41 + case BISHOP: return 'B';
1.42 + case QUEEN: return 'Q';
1.43 + case KING: return 'K';
1.44 + default: return '\0';
1.45 + }
1.46 +}
1.47 +
1.48 +uint8_t getpiece(char c) {
1.49 + switch (c) {
1.50 + case 'R': return ROOK;
1.51 + case 'N': return KNIGHT;
1.52 + case 'B': return BISHOP;
1.53 + case 'Q': return QUEEN;
1.54 + case 'K': return KING;
1.55 + default: return 0;
1.56 + }
1.57 +}
1.58 +
1.59 +/**
1.60 + * Guesses the location of a piece for short algebraic notation.
1.61 + *
1.62 + * @param board the current state of the board
1.63 + * @param move the move date to operate on
1.64 + * @return status code (see rules/rules.h for the codes)
1.65 + */
1.66 +static int getlocation(Board board, Move *move) {
1.67 + uint8_t piece = move->piece & PIECE_MASK;
1.68 + switch (piece) {
1.69 + case PAWN: return pawn_getlocation(board, move);
1.70 + case ROOK: return rook_getlocation(board, move);
1.71 + case KNIGHT: return knight_getlocation(board, move);
1.72 + case BISHOP: return bishop_getlocation(board, move);
1.73 + case QUEEN: return queen_getlocation(board, move);
1.74 + case KING: return king_getlocation(board, move);
1.75 + default: return INVALID_MOVE_SYNTAX;
1.76 + }
1.77 +}
1.78 +
1.79 +
1.80 +void apply_move(Board board, Move *move) {
1.81 + uint8_t piece = move->piece & PIECE_MASK;
1.82 + uint8_t color = move->piece & COLOR_MASK;
1.83 +
1.84 + /* en passant capture */
1.85 + if (move->capture && piece == PAWN &&
1.86 + mdst(board, move) == 0) {
1.87 + board[move->fromrow][move->tofile] = 0;
1.88 + }
1.89 +
1.90 + /* remove old en passant threats */
1.91 + for (uint8_t file = 0 ; file < 8 ; file++) {
1.92 + board[3][file] &= ~ENPASSANT_THREAT;
1.93 + board[4][file] &= ~ENPASSANT_THREAT;
1.94 + }
1.95 +
1.96 + /* add new en passant threat */
1.97 + if (piece == PAWN && (
1.98 + (move->fromrow == 1 && move->torow == 3) ||
1.99 + (move->fromrow == 6 && move->torow == 4))) {
1.100 + move->piece |= ENPASSANT_THREAT;
1.101 + }
1.102 +
1.103 + /* move (and maybe capture or promote) */
1.104 + msrc(board, move) = 0;
1.105 + if (move->promotion) {
1.106 + mdst(board, move) = move->promotion;
1.107 + } else {
1.108 + mdst(board, move) = move->piece;
1.109 + }
1.110 +
1.111 + /* castling */
1.112 + if (piece == KING &&
1.113 + move->fromfile == fileidx('e')) {
1.114 +
1.115 + if (move->tofile == fileidx('g')) {
1.116 + board[move->torow][fileidx('h')] = 0;
1.117 + board[move->torow][fileidx('f')] = color|ROOK;
1.118 + } else if (move->tofile == fileidx('c')) {
1.119 + board[move->torow][fileidx('a')] = 0;
1.120 + board[move->torow][fileidx('d')] = color|ROOK;
1.121 + }
1.122 + }
1.123 +}
1.124 +
1.125 +_Bool validate_move(Board board, Move *move) {
1.126 + _Bool result;
1.127 +
1.128 + /* validate indices (don't trust opponent) */
1.129 + if (!chkidx(move)) {
1.130 + return 0;
1.131 + }
1.132 +
1.133 + /* does piece exist */
1.134 + result = msrc(board, move) == move->piece;
1.135 +
1.136 + /* can't capture own pieces */
1.137 + if ((mdst(board, move) & COLOR_MASK) == (move->piece & COLOR_MASK)) {
1.138 + return 0;
1.139 + }
1.140 +
1.141 + /* validate individual rules */
1.142 + switch (move->piece & PIECE_MASK) {
1.143 + case PAWN:
1.144 + result = result && pawn_chkrules(board, move);
1.145 + result = result && !pawn_isblocked(board, move);
1.146 + break;
1.147 + case ROOK:
1.148 + result = result && rook_chkrules(move);
1.149 + result = result && !rook_isblocked(board, move);
1.150 + break;
1.151 + case KNIGHT:
1.152 + result = result && knight_chkrules(move);
1.153 + result = result && !knight_isblocked(board, move);
1.154 + break;
1.155 + case BISHOP:
1.156 + result = result && bishop_chkrules(move);
1.157 + result = result && !bishop_isblocked(board, move);
1.158 + break;
1.159 + case QUEEN:
1.160 + result = result && queen_chkrules(move);
1.161 + result = result && !queen_isblocked(board, move);
1.162 + break;
1.163 + case KING:
1.164 + result = result && king_chkrules(board, move);
1.165 + result = result && !king_isblocked(board, move);
1.166 + break;
1.167 + default:
1.168 + result = 0;
1.169 + }
1.170 +
1.171 + /* is piece pinned */
1.172 + // TODO: make it so
1.173 +
1.174 + /* correct check and checkmate flags */
1.175 + // TODO: make it so
1.176 +
1.177 + return result;
1.178 +}
1.179 +
1.180 +int eval_move(Board board, uint8_t mycolor, char *mstr, Move *move) {
1.181 + memset(move, 0, sizeof(Move));
1.182 + move->fromfile = POS_UNSPECIFIED;
1.183 + move->fromrow = POS_UNSPECIFIED;
1.184 +
1.185 + size_t len = strlen(mstr);
1.186 +
1.187 + /* evaluate check/checkmate flags */
1.188 + if (mstr[len-1] == '+') {
1.189 + len--; mstr[len] = '\0';
1.190 + move->check = 1;
1.191 + } else if (mstr[len-1] == '#') {
1.192 + len--; mstr[len] = '\0';
1.193 + move->checkmate = 1;
1.194 + }
1.195 +
1.196 + /* evaluate promotion */
1.197 + if (len > 3 && mstr[len-2] == '=') {
1.198 + move->promotion = getpiece(mstr[len-1]);
1.199 + if (!move->promotion) {
1.200 + return INVALID_MOVE_SYNTAX;
1.201 + } else {
1.202 + move->promotion |= mycolor;
1.203 + len -= 2;
1.204 + mstr[len] = 0;
1.205 + }
1.206 + }
1.207 +
1.208 + if (len == 2) {
1.209 + /* pawn move (e.g. "e4") */
1.210 + move->piece = PAWN;
1.211 + move->tofile = fileidx(mstr[0]);
1.212 + move->torow = rowidx(mstr[1]);
1.213 + } else if (len == 3) {
1.214 + if (strcmp(mstr, "O-O") == 0) {
1.215 + /* king side castling */
1.216 + move->piece = KING;
1.217 + move->fromfile = fileidx('e');
1.218 + move->tofile = fileidx('g');
1.219 + move->fromrow = move->torow = mycolor == WHITE ? 0 : 7;
1.220 + } else {
1.221 + /* move (e.g. "Nf3") */
1.222 + move->piece = getpiece(mstr[0]);
1.223 + move->tofile = fileidx(mstr[1]);
1.224 + move->torow = rowidx(mstr[2]);
1.225 + }
1.226 +
1.227 + } else if (len == 4) {
1.228 + move->piece = getpiece(mstr[0]);
1.229 + if (!move->piece) {
1.230 + move->piece = PAWN;
1.231 + move->fromfile = fileidx(mstr[0]);
1.232 + }
1.233 + if (mstr[1] == 'x') {
1.234 + /* capture (e.g. "Nxf3", "dxe5") */
1.235 + move->capture = 1;
1.236 + } else {
1.237 + /* move (e.g. "Ndf3", "N2c3", "e2e4") */
1.238 + if (isfile(mstr[1])) {
1.239 + move->fromfile = fileidx(mstr[1]);
1.240 + if (move->piece == PAWN) {
1.241 + move->piece = 0;
1.242 + }
1.243 + } else {
1.244 + move->fromrow = rowidx(mstr[1]);
1.245 + }
1.246 + }
1.247 + move->tofile = fileidx(mstr[2]);
1.248 + move->torow = rowidx(mstr[3]);
1.249 + } else if (len == 5) {
1.250 + if (strcmp(mstr, "O-O-O") == 0) {
1.251 + /* queen side castling "O-O-O" */
1.252 + move->piece = KING;
1.253 + move->fromfile = fileidx('e');
1.254 + move->tofile = fileidx('c');
1.255 + move->fromrow = move->torow = mycolor == WHITE ? 0 : 7;
1.256 + } else {
1.257 + move->piece = getpiece(mstr[0]);
1.258 + if (mstr[2] == 'x') {
1.259 + move->capture = 1;
1.260 + if (move->piece) {
1.261 + /* capture (e.g. "Ndxf3") */
1.262 + move->fromfile = fileidx(mstr[1]);
1.263 + } else {
1.264 + /* long notation capture (e.g. "e5xf6") */
1.265 + move->piece = PAWN;
1.266 + move->fromfile = fileidx(mstr[0]);
1.267 + move->fromrow = rowidx(mstr[1]);
1.268 + }
1.269 + } else {
1.270 + /* long notation move (e.g. "Nc5a4") */
1.271 + move->fromfile = fileidx(mstr[1]);
1.272 + move->fromrow = rowidx(mstr[2]);
1.273 + }
1.274 + move->tofile = fileidx(mstr[3]);
1.275 + move->torow = rowidx(mstr[4]);
1.276 + }
1.277 + } else if (len == 6) {
1.278 + /* long notation capture (e.g. "Nc5xf3") */
1.279 + if (mstr[3] == 'x') {
1.280 + move->capture = 1;
1.281 + move->piece = getpiece(mstr[0]);
1.282 + move->fromfile = fileidx(mstr[1]);
1.283 + move->fromrow = rowidx(mstr[2]);
1.284 + move->tofile = fileidx(mstr[4]);
1.285 + move->torow = rowidx(mstr[5]);
1.286 + }
1.287 + }
1.288 +
1.289 +
1.290 + if (move->piece) {
1.291 + if (move->piece == PAWN && move->torow == (mycolor==WHITE?7:0)
1.292 + && !move->promotion) {
1.293 + return NEED_PROMOTION;
1.294 + }
1.295 +
1.296 + move->piece |= mycolor;
1.297 + if (move->fromfile == POS_UNSPECIFIED
1.298 + || move->fromrow == POS_UNSPECIFIED) {
1.299 + return getlocation(board, move);
1.300 + } else {
1.301 + return chkidx(move) ? VALID_MOVE_SYNTAX : INVALID_POSITION;
1.302 + }
1.303 + } else {
1.304 + return INVALID_MOVE_SYNTAX;
1.305 + }
1.306 +}
