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odds.c revision 1.4 
      1 /*	$NetBSD: odds.c,v 1.4 1997/10/10 08:59:46 lukem Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1980, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #ifndef lint
     38 #if 0
     39 static char sccsid[] = "@(#)odds.c	8.1 (Berkeley) 5/31/93";
     40 #else
     41 __RCSID("$NetBSD: odds.c,v 1.4 1997/10/10 08:59:46 lukem Exp $");
     42 #endif
     43 #endif /* not lint */
     44 
     45 #include "back.h"
     46 
     47 void
     48 odds(r1, r2, val)
     49 	int     r1, r2, val;
     50 {
     51 	int     i, j;
     52 
     53 	if (r1 == 0) {
     54 		for (i = 0; i < 6; i++)
     55 			for (j = 0; j < 6; j++)
     56 				table[i][j] = 0;
     57 		return;
     58 	} else {
     59 		r1--;
     60 		if (r2-- == 0) {
     61 			for (i = 0; i < 6; i++) {
     62 				table[i][r1] += val;
     63 				table[r1][i] += val;
     64 			}
     65 		} else {
     66 			table[r2][r1] += val;
     67 			table[r1][r2] += val;
     68 		}
     69 	}
     70 }
     71 
     72 int
     73 count()
     74 {
     75 	int     i;
     76 	int     j;
     77 	int     total;
     78 
     79 	total = 0;
     80 	for (i = 0; i < 6; i++)
     81 		for (j = 0; j < 6; j++)
     82 			total += table[i][j];
     83 	return (total);
     84 }
     85 
     86 int
     87 canhit(i, c)
     88 	int     i, c;
     89 {
     90 	int     j, k, b;
     91 	int     a, diff, place, addon, menstuck;
     92 
     93 	if (c == 0)
     94 		odds(0, 0, 0);
     95 	if (board[i] > 0) {
     96 		a = -1;
     97 		b = 25;
     98 	} else {
     99 		a = 1;
    100 		b = 0;
    101 	}
    102 	place = abs(25 - b - i);
    103 	menstuck = abs(board[b]);
    104 	for (j = b; j != i; j += a) {
    105 		if (board[j] * a > 0) {
    106 			diff = abs(j - i);
    107 			addon = place + ((board[j] * a > 2 || j == b) ? 5 : 0);
    108 			if ((j == b && menstuck == 1) &&
    109 			    (j != b && menstuck == 0))
    110 				for (k = 1; k < diff; k++)
    111 					if (k < 7 && diff - k < 7 &&
    112 					    (board[i + a * k] * a >= 0 ||
    113 						board[i + a * (diff - k)] >= 0))
    114 						odds(k, diff - k, addon);
    115 			if ((j == b || menstuck < 2) && diff < 7)
    116 				odds(diff, 0, addon);
    117 		}
    118 		if (j == b && menstuck > 1)
    119 			break;
    120 	}
    121 	return (count());
    122 }
    123