1 /*
2 * Copyright (c) 1988 The Regents of the University of California.
3 * All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Timothy C. Stoehr.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37 #ifndef lint
38 static char sccsid[] = "@(#)random.c 5.3 (Berkeley) 6/1/90";
39 #endif /* not lint */
40
41 /*
42 * random.c
43 *
44 * This source herein may be modified and/or distributed by anybody who
45 * so desires, with the following restrictions:
46 * 1.) No portion of this notice shall be removed.
47 * 2.) Credit shall not be taken for the creation of this source.
48 * 3.) This code is not to be traded, sold, or used for personal
49 * gain or profit.
50 *
51 */
52
53 static long rntb[32] = {
54 3, 0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342,
55 0xde3b81e0, 0xdf0a6fb5, 0xf103bc02, 0x48f340fb, 0x7449e56b,
56 0xbeb1dbb0, 0xab5c5918, 0x946554fd, 0x8c2e680f, 0xeb3d799f,
57 0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88, 0xe369735d,
58 0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc,
59 0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e,
60 0x8999220b, 0x27fb47b9
61 };
62
63 static long *fptr = &rntb[4];
64 static long *rptr = &rntb[1];
65 static long *state = &rntb[1];
66 static int rand_type = 3;
67 static int rand_deg = 31;
68 static int rand_sep = 3;
69 static long *end_ptr = &rntb[32];
70
srrandom(x)71 srrandom(x)
72 int x;
73 {
74 register int i;
75 long rrandom();
76
77 state[0] = (long) x;
78 if (rand_type != 0) {
79 for (i = 1; i < rand_deg; i++) {
80 state[i] = 1103515245 * state[i - 1] + 12345;
81 }
82 fptr = &state[rand_sep];
83 rptr = &state[0];
84 for (i = 0; i < 10 * rand_deg; i++) {
85 (void) rrandom();
86 }
87 }
88 }
89
90 long
rrandom()91 rrandom()
92 {
93 long i;
94
95 if (rand_type == 0) {
96 i = state[0] = (state[0]*1103515245 + 12345) & 0x7fffffff;
97 } else {
98 *fptr += *rptr;
99 i = (*fptr >> 1) & 0x7fffffff;
100 if (++fptr >= end_ptr) {
101 fptr = state;
102 ++rptr;
103 } else {
104 if (++rptr >= end_ptr) {
105 rptr = state;
106 }
107 }
108 }
109 return(i);
110 }
111
get_rand(x,y)112 get_rand(x, y)
113 register int x, y;
114 {
115 register int r, t;
116 long lr;
117
118 if (x > y) {
119 t = y;
120 y = x;
121 x = t;
122 }
123 lr = rrandom();
124 lr &= (long) 0x00003fff;
125 r = (int) lr;
126 r = (r % ((y - x) + 1)) + x;
127 return(r);
128 }
129
rand_percent(percentage)130 rand_percent(percentage)
131 register int percentage;
132 {
133 return(get_rand(1, 100) <= percentage);
134 }
135
coin_toss()136 coin_toss()
137 {
138
139 return(((rrandom() & 01) ? 1 : 0));
140 }
141