1/*	$NetBSD: odds.c,v 1.6 2005/07/01 01:12:39 jmc 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
35static char sccsid[] = "@(#)odds.c	8.1 (Berkeley) 5/31/93";
36#else
37__RCSID("$NetBSD: odds.c,v 1.6 2005/07/01 01:12:39 jmc Exp $");
38#endif
39#endif /* not lint */
40
41#include "back.h"
42
43void
44odds(int r1, int r2, int val)
45{
46	int     i, j;
47
48	if (r1 == 0) {
49		for (i = 0; i < 6; i++)
50			for (j = 0; j < 6; j++)
51				table[i][j] = 0;
52		return;
53	} else {
54		r1--;
55		if (r2-- == 0) {
56			for (i = 0; i < 6; i++) {
57				table[i][r1] += val;
58				table[r1][i] += val;
59			}
60		} else {
61			table[r2][r1] += val;
62			table[r1][r2] += val;
63		}
64	}
65}
66
67int
68count(void)
69{
70	int     i;
71	int     j;
72	int     total;
73
74	total = 0;
75	for (i = 0; i < 6; i++)
76		for (j = 0; j < 6; j++)
77			total += table[i][j];
78	return (total);
79}
80
81int
82canhit(int i, int c)
83{
84	int     j, k, b;
85	int     a, diff, place, addon, menstuck;
86
87	if (c == 0)
88		odds(0, 0, 0);
89	if (board[i] > 0) {
90		a = -1;
91		b = 25;
92	} else {
93		a = 1;
94		b = 0;
95	}
96	place = abs(25 - b - i);
97	menstuck = abs(board[b]);
98	for (j = b; j != i; j += a) {
99		if (board[j] * a > 0) {
100			diff = abs(j - i);
101			addon = place + ((board[j] * a > 2 || j == b) ? 5 : 0);
102			if ((j == b && menstuck == 1) ||
103			    (j != b && menstuck == 0))
104				for (k = 1; k < diff; k++)
105					if (k < 7 && diff - k < 7 &&
106					    (board[i + a * k] * a >= 0 ||
107						board[i + a * (diff - k)] >= 0))
108						odds(k, diff - k, addon);
109			if ((j == b || menstuck < 2) && diff < 7)
110				odds(diff, 0, addon);
111		}
112		if (j == b && menstuck > 1)
113			break;
114	}
115	return (count());
116}
117