1/*	$OpenBSD: odds.c,v 1.7 2016/01/08 13:40:05 tb 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 "back.h"
33
34void
35odds(int r1, int r2, int val)
36{
37	int     i, j;
38
39	if (r1 == 0) {
40		for (i = 0; i < 6; i++)
41			for (j = 0; j < 6; j++)
42				table[i][j] = 0;
43		return;
44	} else {
45		r1--;
46		if (r2-- == 0) {
47			for (i = 0; i < 6; i++) {
48				table[i][r1] += val;
49				table[r1][i] += val;
50			}
51		} else {
52			table[r2][r1] += val;
53			table[r1][r2] += val;
54		}
55	}
56}
57
58int
59count(void)
60{
61	int     i, j, total;
62
63	total = 0;
64	for (i = 0; i < 6; i++)
65		for (j = 0; j < 6; j++)
66			total += table[i][j];
67	return(total);
68}
69
70int
71canhit(int i, int c)
72{
73	int     j, k, b;
74	int     a, diff, place, addon, menstuck;
75
76	if (c == 0)
77		odds(0, 0, 0);
78	if (board[i] > 0) {
79		a = -1;
80		b = 25;
81	} else {
82		a = 1;
83		b = 0;
84	}
85	place = abs(25 - b - i);
86	menstuck = abs(board[b]);
87	for (j = b; j != i; j += a) {
88		if (board[j] * a > 0) {
89			diff = abs(j - i);
90			addon = place + ((board[j] * a > 2 || j == b) ? 5 : 0);
91			if ((j == b && menstuck == 1) ||
92			    (j != b && menstuck == 0))
93				for (k = 1; k < diff; k++)
94					if (k < 7 && diff - k < 7 &&
95					    (board[i + a * k] * a >= 0 ||
96					     board[i + a * (diff - k)] >= 0))
97						odds(k, diff - k, addon);
98			if ((j == b || menstuck < 2) && diff < 7)
99				odds(diff, 0, addon);
100		}
101		if (j == b && menstuck > 1)
102			break;
103	}
104	return(count());
105}
106