src/chess/rook.c

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2016 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
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 */

#include "rules.h"
#include "rook.h"

bool rook_chkrules(const Move *move) {
    return move->torank == move->fromrank || move->tofile == move->fromfile;
}

bool rook_isblocked(const GameState *gamestate, const Move *move) {
    
    if (move->torank == move->fromrank) {
        int d = move->tofile > move->fromfile ? 1 : -1;
        File f = move->fromfile;
        while (f != move->tofile-d) {
            f += d;
            if (gamestate->board[move->fromrank][f]) {
                return true;
            }
        }
    } else {
        int d = move->torank > move->fromrank ? 1 : -1;
        Rank r = move->fromrank;
        while (r != move->torank - d) {
            r += d;
            if (gamestate->board[r][move->fromfile]) {
                return true;
            }
        }
    }
    
    return false;
}

size_t rook_moves(const GameState *gamestate,
        Color c, File f, Rank r, Move *moves) {
    size_t count = 0;
    const int directions[4][2] = {
        { 1,  0},
        {-1,  0},
        { 0,  1},
        { 0, -1}
    };

    for (size_t i = 0 ; i < 4 ; i++) {
        Rank rank = r + directions[i][0];
        File file = f + directions[i][1];

        while (isidx(rank) && isidx(file)) {
            moves[count] = (Move){0};
            moves[count].piece = mkpiece(ROOK, c);
            moves[count].fromrank = r;
            moves[count].fromfile = f;
            moves[count].torank = rank;
            moves[count].tofile = file;
            moves[count].capture = piece_at(gamestate, file, rank) != 0;
            count++;

            rank += directions[i][0];
            file += directions[i][1];
        }
    }

    return count;
}