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odds.c revision 1.5 
      1 /*	$NetBSD: odds.c,v 1.5 2003/08/07 09:36:57 agc 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. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #ifndef lint
     34 #if 0
     35 static char sccsid[] = "@(#)odds.c	8.1 (Berkeley) 5/31/93";
     36 #else
     37 __RCSID("$NetBSD: odds.c,v 1.5 2003/08/07 09:36:57 agc Exp $");
     38 #endif
     39 #endif /* not lint */
     40 
     41 #include "back.h"
     42 
     43 void
     44 odds(r1, r2, val)
     45 	int     r1, r2, val;
     46 {
     47 	int     i, j;
     48 
     49 	if (r1 == 0) {
     50 		for (i = 0; i < 6; i++)
     51 			for (j = 0; j < 6; j++)
     52 				table[i][j] = 0;
     53 		return;
     54 	} else {
     55 		r1--;
     56 		if (r2-- == 0) {
     57 			for (i = 0; i < 6; i++) {
     58 				table[i][r1] += val;
     59 				table[r1][i] += val;
     60 			}
     61 		} else {
     62 			table[r2][r1] += val;
     63 			table[r1][r2] += val;
     64 		}
     65 	}
     66 }
     67 
     68 int
     69 count()
     70 {
     71 	int     i;
     72 	int     j;
     73 	int     total;
     74 
     75 	total = 0;
     76 	for (i = 0; i < 6; i++)
     77 		for (j = 0; j < 6; j++)
     78 			total += table[i][j];
     79 	return (total);
     80 }
     81 
     82 int
     83 canhit(i, c)
     84 	int     i, c;
     85 {
     86 	int     j, k, b;
     87 	int     a, diff, place, addon, menstuck;
     88 
     89 	if (c == 0)
     90 		odds(0, 0, 0);
     91 	if (board[i] > 0) {
     92 		a = -1;
     93 		b = 25;
     94 	} else {
     95 		a = 1;
     96 		b = 0;
     97 	}
     98 	place = abs(25 - b - i);
     99 	menstuck = abs(board[b]);
    100 	for (j = b; j != i; j += a) {
    101 		if (board[j] * a > 0) {
    102 			diff = abs(j - i);
    103 			addon = place + ((board[j] * a > 2 || j == b) ? 5 : 0);
    104 			if ((j == b && menstuck == 1) &&
    105 			    (j != b && menstuck == 0))
    106 				for (k = 1; k < diff; k++)
    107 					if (k < 7 && diff - k < 7 &&
    108 					    (board[i + a * k] * a >= 0 ||
    109 						board[i + a * (diff - k)] >= 0))
    110 						odds(k, diff - k, addon);
    111 			if ((j == b || menstuck < 2) && diff < 7)
    112 				odds(diff, 0, addon);
    113 		}
    114 		if (j == b && menstuck > 1)
    115 			break;
    116 	}
    117 	return (count());
    118 }
    119