1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright 1996 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /* Copyright (c) 1984 AT&T */
28 /* All Rights Reserved */
29
30 #pragma ident "%Z%%M% %I% %E% SMI"
31
32 /*LINTLIBRARY*/
33 /*
34 * drand48, etc. pseudo-random number generator
35 * This implementation assumes unsigned short integers of at least
36 * 16 bits, long integers of at least 32 bits, and ignores
37 * overflows on adding or multiplying two unsigned integers.
38 * Two's-complement representation is assumed in a few places.
39 * Some extra masking is done if unsigneds are exactly 16 bits
40 * or longs are exactly 32 bits, but so what?
41 * An assembly-language implementation would run significantly faster.
42 */
43 #define N 16
44 #define MASK ((unsigned)(1 << (N - 1)) + (1 << (N - 1)) - 1)
45 #define LOW(x) ((unsigned)(x) & MASK)
46 #define HIGH(x) LOW((x) >> N)
47 #define MUL(x, y, z) { long l = (long)(x) * (long)(y); \
48 (z)[0] = LOW(l); (z)[1] = HIGH(l); }
49 #define CARRY(x, y) ((long)(x) + (long)(y) > MASK)
50 #define ADDEQU(x, y, z) (z = CARRY(x, (y)), x = LOW(x + (y)))
51 #define X0 0x330E
52 #define X1 0xABCD
53 #define X2 0x1234
54 #define A0 0xE66D
55 #define A1 0xDEEC
56 #define A2 0x5
57 #define C 0xB
58 #define SET3(x, x0, x1, x2) ((x)[0] = (x0), (x)[1] = (x1), (x)[2] = (x2))
59 #define SETLOW(x, y, n) SET3(x, LOW((y)[n]), LOW((y)[(n)+1]), LOW((y)[(n)+2]))
60 #define SEED(x0, x1, x2) (SET3(x, x0, x1, x2), SET3(a, A0, A1, A2), c = C)
61 #define REST(v) \
62 for (i = 0; i < 3; i++) { \
63 xsubi[i] = x[i]; \
64 x[i] = temp[i]; \
65 } \
66 return (v)
67
68 #define NEST(TYPE, f, F) \
69 TYPE f(xsubi) \
70 register unsigned short *xsubi; \
71 { \
72 register int i; \
73 register TYPE v; \
74 unsigned temp[3]; \
75 \
76 for (i = 0; i < 3; i++) { \
77 temp[i] = x[i]; \
78 x[i] = LOW(xsubi[i]); \
79 } \
80 v = F(); \
81 REST(v); \
82 }
83
84 static unsigned x[3] = { X0, X1, X2 }, a[3] = { A0, A1, A2 }, c = C;
85 static unsigned short lastx[3];
86 static void next();
87
88 double
drand48()89 drand48()
90 {
91 static double two16m = 1.0 / (1L << N);
92
93 next();
94 return (two16m * (two16m * (two16m * x[0] + x[1]) + x[2]));
95 }
96
NEST(double,erand48,drand48)97 NEST(double, erand48, drand48)
98
99 long
100 lrand48()
101 {
102 next();
103 return (((long)x[2] << (N - 1)) + (x[1] >> 1));
104 }
105
106 long
mrand48()107 mrand48()
108 {
109 next();
110 return (((long)x[2] << N) + x[1]);
111 }
112
113 static void
next()114 next()
115 {
116 unsigned p[2], q[2], r[2], carry0, carry1;
117
118 MUL(a[0], x[0], p);
119 ADDEQU(p[0], c, carry0);
120 ADDEQU(p[1], carry0, carry1);
121 MUL(a[0], x[1], q);
122 ADDEQU(p[1], q[0], carry0);
123 MUL(a[1], x[0], r);
124 x[2] = LOW(carry0 + carry1 + CARRY(p[1], r[0]) + q[1] + r[1] +
125 a[0] * x[2] + a[1] * x[1] + a[2] * x[0]);
126 x[1] = LOW(p[1] + r[0]);
127 x[0] = LOW(p[0]);
128 }
129
130 void
srand48(seedval)131 srand48(seedval)
132 long seedval;
133 {
134 SEED(X0, LOW(seedval), HIGH(seedval));
135 }
136
137 unsigned short *
seed48(seed16v)138 seed48(seed16v)
139 unsigned short seed16v[3];
140 {
141 SETLOW(lastx, x, 0);
142 SEED(LOW(seed16v[0]), LOW(seed16v[1]), LOW(seed16v[2]));
143 return (lastx);
144 }
145
146 void
lcong48(param)147 lcong48(param)
148 unsigned short param[7];
149 {
150 SETLOW(x, param, 0);
151 SETLOW(a, param, 3);
152 c = LOW(param[6]);
153 }
154
NEST(long,nrand48,lrand48)155 NEST(long, nrand48, lrand48)
156
157 NEST(long, jrand48, mrand48)
158
159 #ifdef DRIVER
160 /*
161 * This should print the sequences of integers in Tables 2
162 * and 1 of the TM:
163 * 1623, 3442, 1447, 1829, 1305, ...
164 * 657EB7255101, D72A0C966378, 5A743C062A23, ...
165 */
166 #include <stdio.h>
167
168 main()
169 {
170 int i;
171
172 for (i = 0; i < 80; i++) {
173 printf("%4d ", (int)(4096 * drand48()));
174 printf("%.4X%.4X%.4X\n", x[2], x[1], x[0]);
175 }
176 }
177 #endif
178