usr/src/games/backgammon/common_source/allow.c

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that this notice is preserved and that due credit is given
 * to the University of California at Berkeley. The name of the University
 * may not be used to endorse or promote products derived from this
 * software without specific prior written permission. This software
 * is provided ``as is'' without express or implied warranty.
 */

#ifndef lint
static char sccsid[] = "@(#)allow.c     5.2 (Berkeley) %G%";
#endif /* not lint */

#include "back.h"

movallow ()  {

        register int    i, m, iold;
        int             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);
}