BSD 4_4 release

[unix-history] / usr / src / games / backgammon / common_source / odds.c

/*
* 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. All advertising materials mentioning features or use of this software
*    must display the following acknowledgement:
*      This product includes software developed by the University of
*      California, Berkeley and its contributors.
* 4. 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.
*/

#ifndef lint
static char sccsid[] = "@(#)odds.c      8.1 (Berkeley) 5/31/93";
#endif /* not lint */

#include "back.h"

odds (r1,r2,val)
register int    r1;
int             r2, val;
{
       register int    i, j;

       if (r1 == 0)  {
               for (i = 0; i < 6; i++)  
                       for (j = 0; j < 6; j++)
                               table[i][j] = 0;
               return;
       } else  {
               r1--;
               if (r2-- == 0)
                       for (i = 0; i < 6; i++)  {
                               table[i][r1] += val;
                               table[r1][i] += val;
                       }
               else  {
                       table[r2][r1] += val;
                       table[r1][r2] += val;
               }
       }
}

count ()  {
       register int    i;
       register int    j;
       register int    total;

       total = 0;
       for (i = 0; i < 6; i++)
               for (j = 0; j < 6; j++)
                       total += table[i][j];
       return (total);
}
\f
canhit (i,c)
int     i, c;

{
       register int    j, k, b;
       int             a, d, diff, place, addon, menstuck;

       if (c == 0)
               odds (0,0,0);
       if (board[i] > 0)  {
               a = -1;
               b = 25;
       } else  {
               a = 1;
               b = 0;
       }
       place = abs (25-b-i);
       menstuck = abs (board[b]);
       for (j = b; j != i; j += a)  {
               if (board[j]*a > 0)  {
                       diff = abs(j-i);
                       addon = place+((board[j]*a > 2 || j == b)? 5: 0);
                       if ((j == b && menstuck == 1) &&
                           (j != b && menstuck == 0))
                               for (k = 1; k < diff; k++)
                                       if (k < 7 && diff-k < 7 &&
                                           (board[i+a*k]*a >= 0 ||
                                           board[i+a*(diff-k)] >= 0))
                                               odds (k,diff-k,addon);
                       if ((j == b || menstuck < 2) && diff < 7)
                               odds (diff,0,addon);
               }
               if (j == b && menstuck > 1)
                       break;
       }
       return (count());
}