games/backgammon/common_source/allow.c

   1 /*
   2  * Copyright (c) 1980, 1993
   3  *      The Regents of the University of California.  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  * @(#)allow.c  8.1 (Berkeley) 5/31/93
  34  * $FreeBSD: src/games/backgammon/common_source/allow.c,v 1.4 1999/11/30 03:48:24 billf Exp $
  35  * $DragonFly: src/games/backgammon/common_source/allow.c,v 1.3 2006/08/08 16:36:11 pavalos Exp $
  36  */
  37
  38 #include "back.h"
  39
  40 int
  41 movallow(void)
  42 {
  43
  44         int             i, m, iold;
  45         int             r;
  46
  47         if (d0)
  48                 swap;
  49         m = (D0 == D1? 4: 2);
  50         for (i = 0; i < 4; i++)
  51                 p[i] = bar;
  52         i = iold = 0;
  53         while (i < m)  {
  54                 if (*offptr == 15)
  55                         break;
  56                 h[i] = 0;
  57                 if (board[bar])  {
  58                         if (i == 1 || m == 4)
  59                                 g[i] = bar+cturn*D1;
  60                         else
  61                                 g[i] = bar+cturn*D0;
  62                         if ((r = makmove(i)) != 0)  {
  63                                 if (d0 || m == 4)
  64                                         break;
  65                                 swap;
  66                                 movback (i);
  67                                 if (i > iold)
  68                                         iold = i;
  69                                 for (i = 0; i < 4; i++)
  70                                         p[i] = bar;
  71                                 i = 0;
  72                         } else
  73                                 i++;
  74                         continue;
  75                 }
  76                 if ((p[i] += cturn) == home)  {
  77                         if (i > iold)
  78                                 iold = i;
  79                         if (m == 2 && i)  {
  80                                 movback(i);
  81                                 p[i--] = bar;
  82                                 if (p[i] != bar)
  83                                         continue;
  84                                 else
  85                                         break;
  86                         }
  87                         if (d0 || m == 4)
  88                                 break;
  89                         swap;
  90                         movback (i);
  91                         for (i = 0; i < 4; i++)
  92                                 p[i] = bar;
  93                         i = 0;
  94                         continue;
  95                 }
  96                 if (i == 1 || m == 4)
  97                         g[i] = p[i]+cturn*D1;
  98                 else
  99                         g[i] = p[i]+cturn*D0;
 100                 if (g[i]*cturn > home)  {
 101                         if (*offptr >= 0)
 102                                 g[i] = home;
 103                         else
 104                                 continue;
 105                 }
 106                 if (board[p[i]]*cturn > 0 && (r = makmove(i)) == 0)
 107                         i++;
 108         }
 109         movback (i);
 110         return (iold > i? iold: i);
 111 }