/*      $OpenBSD: allow.c,v 1.6 2015/11/30 08:19:25 tb Exp $    */

/*
 * Copyright (c) 1980, 1993
 *      The Regents of the University of California.  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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 */

#include "back.h"

int
movallow(void)
{
        int     i, m, iold, r;

        if (d0)
                swap;
        m = (D0 == D1 ? 4 : 2);
        for (i = 0; i < 4; i++)
                p[i] = bar;
        i = iold = 0;
        while (i < m) {
                if (*offptr == 15)
                        break;
                h[i] = 0;
                if (board[bar]) {
                        if (i == 1 || m == 4)
                                g[i] = bar + cturn * D1;
                        else
                                g[i] = bar + cturn * D0;
                        if ((r = makmove(i))) {
                                if (d0 || m == 4)
                                        break;
                                swap;
                                movback(i);
                                if (i > iold)
                                        iold = i;
                                for (i = 0; i < 4; i++)
                                        p[i] = bar;
                                i = 0;
                        } else
                                i++;
                        continue;
                }
                if ((p[i] += cturn) == home) {
                        if (i > iold)
                                iold = i;
                        if (m == 2 && i) {
                                movback(i);
                                p[i--] = bar;
                                if (p[i] != bar)
                                        continue;
                                else
                                        break;
                        }
                        if (d0 || m == 4)
                                break;
                        swap;
                        movback(i);
                        for (i = 0; i < 4; i++)
                                p[i] = bar;
                        i = 0;
                        continue;
                }
                if (i == 1 || m == 4)
                        g[i] = p[i] + cturn * D1;
                else
                        g[i] = p[i] + cturn * D0;
                if (g[i] * cturn > home) {
                        if (*offptr >= 0)
                                g[i] = home;
                        else
                                continue;
                }
                if (board[p[i]] * cturn > 0 && (r = makmove(i)) == 0)
                        i++;
        }
        movback(i);
        return (iold > i ? iold : i);
}