1/*	$NetBSD: random.c,v 1.7 2008/01/14 03:50:02 dholland Exp $	*/
2
3/*
4 * Copyright (c) 1988, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Timothy C. Stoehr.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include <sys/cdefs.h>
36#ifndef lint
37#if 0
38static char sccsid[] = "@(#)random.c	8.1 (Berkeley) 5/31/93";
39#else
40__RCSID("$NetBSD: random.c,v 1.7 2008/01/14 03:50:02 dholland Exp $");
41#endif
42#endif /* not lint */
43
44#include "rogue.h"
45
46/*
47 * random.c
48 *
49 * This source herein may be modified and/or distributed by anybody who
50 * so desires, with the following restrictions:
51 *    1.)  No portion of this notice shall be removed.
52 *    2.)  Credit shall not be taken for the creation of this source.
53 *    3.)  This code is not to be traded, sold, or used for personal
54 *         gain or profit.
55 *
56 */
57
58static long rntb[32] = {
59	         3, 0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342,
60	0xde3b81e0, 0xdf0a6fb5, 0xf103bc02, 0x48f340fb, 0x7449e56b,
61	0xbeb1dbb0, 0xab5c5918, 0x946554fd, 0x8c2e680f, 0xeb3d799f,
62	0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88, 0xe369735d,
63	0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc,
64	0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e,
65	0x8999220b, 0x27fb47b9
66};
67
68static long *fptr = &rntb[4];
69static long *rptr = &rntb[1];
70static long *state = &rntb[1];
71static int rand_type = 3;
72static int rand_deg = 31;
73static int rand_sep = 3;
74static long *end_ptr = &rntb[32];
75
76static long rrandom(void);
77
78void
79srrandom(int x)
80{
81	int i;
82
83	state[0] = x;
84	if (rand_type != 0) {
85		for (i = 1; i < rand_deg; i++) {
86			state[i] = 1103515245 * state[i - 1] + 12345;
87		}
88		fptr = &state[rand_sep];
89		rptr = &state[0];
90		for (i = 0; i < 10 * rand_deg; i++) {
91			(void)rrandom();
92		}
93	}
94}
95
96static long
97rrandom(void)
98{
99	long i;
100
101	if (rand_type == 0) {
102		i = state[0] = (state[0]*1103515245 + 12345) & 0x7fffffff;
103	} else {
104		*fptr += *rptr;
105		i = (*fptr >> 1) & 0x7fffffff;
106		if (++fptr >= end_ptr) {
107			fptr = state;
108			++rptr;
109		} else {
110			if (++rptr >= end_ptr) {
111				rptr = state;
112			}
113		}
114	}
115	return(i);
116}
117
118int
119get_rand(int x, int y)
120{
121	int r, t;
122	long lr;
123
124	if (x > y) {
125		t = y;
126		y = x;
127		x = t;
128	}
129	lr = rrandom();
130	lr &= 0x00003fffL;
131	r = (int)lr;
132	r = (r % ((y - x) + 1)) + x;
133	return(r);
134}
135
136int
137rand_percent(int percentage)
138{
139	return(get_rand(1, 100) <= percentage);
140}
141
142int
143coin_toss(void)
144{
145	return(((rrandom() & 01) ? 1 : 0));
146}
147