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allow.c revision 1.1 
      1 /*
      2  * Copyright (c) 1980 Regents of the University of California.
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #ifndef lint
     35 static char sccsid[] = "@(#)allow.c	5.4 (Berkeley) 6/1/90";
     36 #endif /* not lint */
     37 
     38 #include "back.h"
     39 
     40 movallow ()  {
     41 
     42 	register int	i, m, iold;
     43 	int		r;
     44 
     45 	if (d0)
     46 		swap;
     47 	m = (D0 == D1? 4: 2);
     48 	for (i = 0; i < 4; i++)
     49 		p[i] = bar;
     50 	i = iold = 0;
     51 	while (i < m)  {
     52 		if (*offptr == 15)
     53 			break;
     54 		h[i] = 0;
     55 		if (board[bar])  {
     56 			if (i == 1 || m == 4)
     57 				g[i] = bar+cturn*D1;
     58 			else
     59 				g[i] = bar+cturn*D0;
     60 			if (r = makmove(i))  {
     61 				if (d0 || m == 4)
     62 					break;
     63 				swap;
     64 				movback (i);
     65 				if (i > iold)
     66 					iold = i;
     67 				for (i = 0; i < 4; i++)
     68 					p[i] = bar;
     69 				i = 0;
     70 			} else
     71 				i++;
     72 			continue;
     73 		}
     74 		if ((p[i] += cturn) == home)  {
     75 			if (i > iold)
     76 				iold = i;
     77 			if (m == 2 && i)  {
     78 				movback(i);
     79 				p[i--] = bar;
     80 				if (p[i] != bar)
     81 					continue;
     82 				else
     83 					break;
     84 			}
     85 			if (d0 || m == 4)
     86 				break;
     87 			swap;
     88 			movback (i);
     89 			for (i = 0; i < 4; i++)
     90 				p[i] = bar;
     91 			i = 0;
     92 			continue;
     93 		}
     94 		if (i == 1 || m == 4)
     95 			g[i] = p[i]+cturn*D1;
     96 		else
     97 			g[i] = p[i]+cturn*D0;
     98 		if (g[i]*cturn > home)  {
     99 			if (*offptr >= 0)
    100 				g[i] = home;
    101 			else
    102 				continue;
    103 		}
    104 		if (board[p[i]]*cturn > 0 && (r = makmove(i)) == 0)
    105 			i++;
    106 	}
    107 	movback (i);
    108 	return (iold > i? iold: i);
    109 }
    110