1 /* $NetBSD: allow.c,v 1.9 2024/08/22 20:46:40 rillig 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[] = "@(#)allow.c 8.1 (Berkeley) 5/31/93";
36 #else
37 __RCSID("$NetBSD: allow.c,v 1.9 2024/08/22 20:46:40 rillig Exp $");
38 #endif
39 #endif /* not lint */
40
41 #include "back.h"
42
43 int
movallow(struct move * mm)44 movallow(struct move *mm)
45 {
46 int i, m, iold;
47
48 if (mm->d0)
49 mswap(mm);
50 m = (mm->D0 == mm->D1 ? 4 : 2);
51 for (i = 0; i < 4; i++)
52 mm->p[i] = bar;
53 i = iold = 0;
54 while (i < m) {
55 if (*offptr == 15)
56 break;
57 mm->h[i] = 0;
58 if (board[bar]) {
59 if (i == 1 || m == 4)
60 mm->g[i] = bar + cturn * mm->D1;
61 else
62 mm->g[i] = bar + cturn * mm->D0;
63 if (makmove(mm, i) != 0) {
64 if (mm->d0 || m == 4)
65 break;
66 mswap(mm);
67 movback(mm, i);
68 if (i > iold)
69 iold = i;
70 for (i = 0; i < 4; i++)
71 mm->p[i] = bar;
72 i = 0;
73 } else
74 i++;
75 continue;
76 }
77 if ((mm->p[i] += cturn) == home) {
78 if (i > iold)
79 iold = i;
80 if (m == 2 && i) {
81 movback(mm, i);
82 mm->p[i--] = bar;
83 if (mm->p[i] != bar)
84 continue;
85 else
86 break;
87 }
88 if (mm->d0 || m == 4)
89 break;
90 mswap(mm);
91 movback(mm, i);
92 for (i = 0; i < 4; i++)
93 mm->p[i] = bar;
94 i = 0;
95 continue;
96 }
97 if (i == 1 || m == 4)
98 mm->g[i] = mm->p[i] + cturn * mm->D1;
99 else
100 mm->g[i] = mm->p[i] + cturn * mm->D0;
101 if (mm->g[i] * cturn > home) {
102 if (*offptr >= 0)
103 mm->g[i] = home;
104 else
105 continue;
106 }
107 if (board[mm->p[i]] * cturn > 0 && makmove(mm, i) == 0)
108 i++;
109 }
110 movback(mm, i);
111 return (iold > i ? iold : i);
112 }
113