1/*	$OpenBSD: allow.c,v 1.6 2015/11/30 08:19:25 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
34int
35movallow(void)
36{
37	int     i, m, iold, r;
38
39	if (d0)
40		swap;
41	m = (D0 == D1 ? 4 : 2);
42	for (i = 0; i < 4; i++)
43		p[i] = bar;
44	i = iold = 0;
45	while (i < m) {
46		if (*offptr == 15)
47			break;
48		h[i] = 0;
49		if (board[bar]) {
50			if (i == 1 || m == 4)
51				g[i] = bar + cturn * D1;
52			else
53				g[i] = bar + cturn * D0;
54			if ((r = makmove(i))) {
55				if (d0 || m == 4)
56					break;
57				swap;
58				movback(i);
59				if (i > iold)
60					iold = i;
61				for (i = 0; i < 4; i++)
62					p[i] = bar;
63				i = 0;
64			} else
65				i++;
66			continue;
67		}
68		if ((p[i] += cturn) == home) {
69			if (i > iold)
70				iold = i;
71			if (m == 2 && i) {
72				movback(i);
73				p[i--] = bar;
74				if (p[i] != bar)
75					continue;
76				else
77					break;
78			}
79			if (d0 || m == 4)
80				break;
81			swap;
82			movback(i);
83			for (i = 0; i < 4; i++)
84				p[i] = bar;
85			i = 0;
86			continue;
87		}
88		if (i == 1 || m == 4)
89			g[i] = p[i] + cturn * D1;
90		else
91			g[i] = p[i] + cturn * D0;
92		if (g[i] * cturn > home) {
93			if (*offptr >= 0)
94				g[i] = home;
95			else
96				continue;
97		}
98		if (board[p[i]] * cturn > 0 && (r = makmove(i)) == 0)
99			i++;
100	}
101	movback(i);
102	return (iold > i ? iold : i);
103}
104