src/chess/rules.h

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2014 Mike Becker. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */

#ifndef RULES_H
#define	RULES_H

#include <stdint.h>

#define VALID_MOVE_SYNTAX   0
#define INVALID_MOVE_SYNTAX 1
#define INVALID_POSITION    2
#define AMBIGUOUS_MOVE      3
#define NEED_PROMOTION      4


#define PIECE_MASK       0x0F
#define COLOR_MASK       0x30
#define ENPASSANT_THREAT 0x40

#define WHITE 0x10
#define BLACK 0x20

#define PAWN   0x01
#define ROOK   0x02
#define KNIGHT 0x03
#define BISHOP 0x04
#define QUEEN  0x05
#define KING   0x06

#define WPAWN   (WHITE|PAWN)
#define WROOK   (WHITE|ROOK)
#define WKNIGHT (WHITE|KNIGHT)
#define WBISHOP (WHITE|BISHOP)
#define WQUEEN  (WHITE|QUEEN)
#define WKING   (WHITE|KING)
#define BPAWN   (BLACK|PAWN)
#define BROOK   (BLACK|ROOK)
#define BKNIGHT (BLACK|KNIGHT)
#define BBISHOP (BLACK|BISHOP)
#define BQUEEN  (BLACK|QUEEN)
#define BKING   (BLACK|KING)

typedef uint8_t Board[8][8];


typedef struct {
    uint8_t piece;
    uint8_t fromfile;
    uint8_t fromrow;
    uint8_t tofile;
    uint8_t torow;
    uint8_t promotion;
    _Bool check;
    _Bool capture;
} Move;

typedef struct MoveList MoveList;

struct MoveList {
    Move move;
    MoveList* next;
};

typedef struct {
    Board board;
    uint8_t mycolor;
    MoveList* movelist;
    MoveList* lastmove;
    _Bool checkmate;
    _Bool stalemate;
} GameState;

#define opponent_color(color) ((color)==WHITE?BLACK:WHITE)

#define POS_UNSPECIFIED UINT8_MAX
#define mdst(b,m) b[(m)->torow][(m)->tofile]
#define msrc(b,m) b[(m)->fromrow][(m)->fromfile]

#define isidx(idx) ((uint8_t)idx < 8)

#define isfile(file) (file >= 'a' && file <= 'h')
#define isrow(row) (row >= '1' && row <= '8')

#define rowidx(row) (row-'1')
#define fileidx(file) (file-'a')

#define rowchr(row) (row+'1')
#define filechr(file) (file+'a')

#define chkidx(move) (isidx((move)->fromfile) && isidx((move)->fromrow) && \
        isidx((move)->tofile) && isidx((move)->torow))

/* secure versions - use, if index is not checked with isidx() */
#define fileidx_s(c) (isfile(c)?fileidx(c):POS_UNSPECIFIED)
#define rowidx_s(c) (isrow(c)?rowidx(c):POS_UNSPECIFIED)

void gamestate_cleanup(GameState *gamestate);

/**
 * Maps a character to a piece.
 * 
 * Does not work for pawns, since they don't have a character.
 * 
 * @param c one of R,N,B,Q,K
 * @return numeric value for the specified piece
 */
uint8_t getpiece(char c);

/**
 * Maps a piece to a character.
 * 
 * Does not work for pawns, scince they don't have a character.
 * 
 * @param piece one of ROOK, KNIGHT, BISHOP, QUEEN, KING
 * @return character value for the specified piece
 */
char getpiecechr(uint8_t piece);

/**
 * Checks, if a specified field is covered by a piece of a certain color.
 * 
 * @param gamestate the current game state
 * @param row row of the field to check
 * @param file file of the field to check
 * @param color the color of the piece that should cover the field
 * @return TRUE, if any piece of the specified color threatens the specified
 * field (i.e. could capture an opponent piece)
 */
_Bool is_covered(GameState *gamestate,uint8_t row,uint8_t file,uint8_t color);

/**
 * Evaluates a move syntactically and stores the move data in the specified
 * object.
 * 
 * @param gamestate the current game state
 * @param mstr the input string to parse
 * @param move a pointer to object where the move data shall be stored
 * @return status code (see rules/rules.h for the list of codes)
 */
int eval_move(GameState *gamestate, char *mstr, Move *move);

/**
 * Validates move by applying chess rules.
 * @param gamestate the current game state
 * @param move the move to validate
 * @return TRUE, if the move complies to chess rules, FALSE otherwise
 */
_Bool validate_move(GameState *gamestate, Move *move);

/**
 * Applies a move and deletes captured pieces.
 * 
 * @param gamestate the current game state
 * @param move the move to apply
 */
void apply_move(GameState *gamestate, Move *move);

#endif	/* RULES_H */