1 /*
2 * Copyright (c) 1988, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Timothy C. Stoehr.
7 *
8 * %sccs.include.redist.c%
9 */
10
11 #ifndef lint
12 static char sccsid[] = "@(#)random.c 8.1 (Berkeley) 05/31/93";
13 #endif /* not lint */
14
15 /*
16 * random.c
17 *
18 * This source herein may be modified and/or distributed by anybody who
19 * so desires, with the following restrictions:
20 * 1.) No portion of this notice shall be removed.
21 * 2.) Credit shall not be taken for the creation of this source.
22 * 3.) This code is not to be traded, sold, or used for personal
23 * gain or profit.
24 *
25 */
26
27 static long rntb[32] = {
28 3, 0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342,
29 0xde3b81e0, 0xdf0a6fb5, 0xf103bc02, 0x48f340fb, 0x7449e56b,
30 0xbeb1dbb0, 0xab5c5918, 0x946554fd, 0x8c2e680f, 0xeb3d799f,
31 0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88, 0xe369735d,
32 0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc,
33 0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e,
34 0x8999220b, 0x27fb47b9
35 };
36
37 static long *fptr = &rntb[4];
38 static long *rptr = &rntb[1];
39 static long *state = &rntb[1];
40 static int rand_type = 3;
41 static int rand_deg = 31;
42 static int rand_sep = 3;
43 static long *end_ptr = &rntb[32];
44
srrandom(x)45 srrandom(x)
46 int x;
47 {
48 register int i;
49 long rrandom();
50
51 state[0] = (long) x;
52 if (rand_type != 0) {
53 for (i = 1; i < rand_deg; i++) {
54 state[i] = 1103515245 * state[i - 1] + 12345;
55 }
56 fptr = &state[rand_sep];
57 rptr = &state[0];
58 for (i = 0; i < 10 * rand_deg; i++) {
59 (void) rrandom();
60 }
61 }
62 }
63
64 long
rrandom()65 rrandom()
66 {
67 long i;
68
69 if (rand_type == 0) {
70 i = state[0] = (state[0]*1103515245 + 12345) & 0x7fffffff;
71 } else {
72 *fptr += *rptr;
73 i = (*fptr >> 1) & 0x7fffffff;
74 if (++fptr >= end_ptr) {
75 fptr = state;
76 ++rptr;
77 } else {
78 if (++rptr >= end_ptr) {
79 rptr = state;
80 }
81 }
82 }
83 return(i);
84 }
85
get_rand(x,y)86 get_rand(x, y)
87 register int x, y;
88 {
89 register int r, t;
90 long lr;
91
92 if (x > y) {
93 t = y;
94 y = x;
95 x = t;
96 }
97 lr = rrandom();
98 lr &= (long) 0x00003fff;
99 r = (int) lr;
100 r = (r % ((y - x) + 1)) + x;
101 return(r);
102 }
103
rand_percent(percentage)104 rand_percent(percentage)
105 register int percentage;
106 {
107 return(get_rand(1, 100) <= percentage);
108 }
109
coin_toss()110 coin_toss()
111 {
112
113 return(((rrandom() & 01) ? 1 : 0));
114 }
115