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 (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /* Copyright (c) 1988 AT&T */
28 /* All Rights Reserved */
29
30 /*
31 * drand48, etc. pseudo-random number generator
32 * This implementation assumes unsigned short integers of at least
33 * 16 bits, long integers of at least 32 bits, and ignores
34 * overflows on adding or multiplying two unsigned integers.
35 * Two's-complement representation is assumed in a few places.
36 * Some extra masking is done if unsigneds are exactly 16 bits
37 * or longs are exactly 32 bits, but so what?
38 * An assembly-language implementation would run significantly faster.
39 */
40 /*
41 * New assumptions (supercede those stated above) for 64-bit work.
42 * Longs are now 64 bits, and we are bound by standards to return
43 * type long, hovever all internal calculations where long was
44 * previously used (32 bit precision) are now using the int32_t
45 * type (32 bit precision in both ILP32 and LP64 worlds).
46 */
47
48 #include "lint.h"
49 #include <mtlib.h>
50 #include <synch.h>
51 #include <thread.h>
52
53 static mutex_t seed_lock = DEFAULTMUTEX;
54
55 #define EXPORT0(TYPE, fn, fnu) TYPE fn() { \
56 TYPE res; \
57 lmutex_lock(&seed_lock); \
58 res = fnu(); \
59 lmutex_unlock(&seed_lock); \
60 return (res); }
61 #define EXPORT1(TYPE, fn, fnu) TYPE fn(unsigned short xsubi[3]) { \
62 TYPE res; \
63 lmutex_lock(&seed_lock); \
64 res = fnu(xsubi); \
65 lmutex_unlock(&seed_lock); \
66 return (res); }
67
68 #define N 16
69 #define MASK ((unsigned)(1 << (N - 1)) + (1 << (N - 1)) - 1)
70 #define LOW(x) ((unsigned)(x) & MASK)
71 #define HIGH(x) LOW((x) >> N)
72 #define MUL(x, y, z) { int32_t l = (int32_t)(x) * (int32_t)(y); \
73 (z)[0] = LOW(l); (z)[1] = HIGH(l); }
74 #define CARRY(x, y) ((int32_t)(x) + (int32_t)(y) > MASK)
75 #define ADDEQU(x, y, z) (z = CARRY(x, (y)), x = LOW(x + (y)))
76 #define X0 0x330E
77 #define X1 0xABCD
78 #define X2 0x1234
79 #define A0 0xE66D
80 #define A1 0xDEEC
81 #define A2 0x5
82 #define C 0xB
83 #define SET3(x, x0, x1, x2) ((x)[0] = (x0), (x)[1] = (x1), (x)[2] = (x2))
84 #define SETLOW(x, y, n) SET3(x, LOW((y)[n]), LOW((y)[(n)+1]), LOW((y)[(n)+2]))
85 #define SEED(x0, x1, x2) (SET3(x, x0, x1, x2), SET3(a, A0, A1, A2), c = C)
86 #define REST(v) for (i = 0; i < 3; i++) { xsubi[i] = x[i]; x[i] = temp[i]; } \
87 return (v)
88 #define NEST(TYPE, f, F) static TYPE f(unsigned short *xsubi) { \
89 int i; TYPE v; unsigned temp[3]; \
90 for (i = 0; i < 3; i++) { temp[i] = x[i]; x[i] = LOW(xsubi[i]); } \
91 v = F(); REST(v); }
92
93 /* Way ugly solution to problem names, but it works */
94 #define x _drand48_x
95 #define a _drand48_a
96 #define c _drand48_c
97 /* End way ugly */
98 static unsigned x[3] = { X0, X1, X2 }, a[3] = { A0, A1, A2 }, c = C;
99 static unsigned short lastx[3];
100 static void next(void);
101
102 static double
_drand48_u(void)103 _drand48_u(void)
104 {
105 static double two16m = 1.0 / ((int32_t)1 << N);
106
107 next();
108 return (two16m * (two16m * (two16m * x[0] + x[1]) + x[2]));
109 }
110
NEST(double,_erand48_u,_drand48_u)111 NEST(double, _erand48_u, _drand48_u)
112
113 static long
114 _lrand48_u(void)
115 {
116 next();
117 return ((long)((int32_t)x[2] << (N - 1)) + (x[1] >> 1));
118 }
119
120 static long
_mrand48_u(void)121 _mrand48_u(void)
122 {
123 next();
124 return ((long)((int32_t)x[2] << N) + x[1]);
125 }
126
127 static void
next(void)128 next(void)
129 {
130 unsigned p[2], q[2], r[2], carry0, carry1;
131
132 MUL(a[0], x[0], p);
133 ADDEQU(p[0], c, carry0);
134 ADDEQU(p[1], carry0, carry1);
135 MUL(a[0], x[1], q);
136 ADDEQU(p[1], q[0], carry0);
137 MUL(a[1], x[0], r);
138 x[2] = LOW(carry0 + carry1 + CARRY(p[1], r[0]) + q[1] + r[1] +
139 a[0] * x[2] + a[1] * x[1] + a[2] * x[0]);
140 x[1] = LOW(p[1] + r[0]);
141 x[0] = LOW(p[0]);
142 }
143
144 void
srand48(long seedval)145 srand48(long seedval)
146 {
147 int32_t fixseed = (int32_t)seedval; /* limit to 32 bits */
148
149 lmutex_lock(&seed_lock);
150 SEED(X0, LOW(fixseed), HIGH(fixseed));
151 lmutex_unlock(&seed_lock);
152 }
153
154 unsigned short *
seed48(unsigned short seed16v[3])155 seed48(unsigned short seed16v[3])
156 {
157 lmutex_lock(&seed_lock);
158 SETLOW(lastx, x, 0);
159 SEED(LOW(seed16v[0]), LOW(seed16v[1]), LOW(seed16v[2]));
160 lmutex_unlock(&seed_lock);
161 return (lastx);
162 }
163
164 void
lcong48(unsigned short param[7])165 lcong48(unsigned short param[7])
166 {
167 lmutex_lock(&seed_lock);
168 SETLOW(x, param, 0);
169 SETLOW(a, param, 3);
170 c = LOW(param[6]);
171 lmutex_unlock(&seed_lock);
172 }
173
NEST(long,_nrand48_u,_lrand48_u)174 NEST(long, _nrand48_u, _lrand48_u)
175
176 NEST(long, _jrand48_u, _mrand48_u)
177
178 EXPORT0(double, drand48, _drand48_u)
179 EXPORT1(double, erand48, _erand48_u)
180
181 EXPORT0(long, lrand48, _lrand48_u)
182 EXPORT1(long, nrand48, _nrand48_u)
183
184 EXPORT0(long, mrand48, _mrand48_u)
185 EXPORT1(long, jrand48, _jrand48_u)
186
187 #ifdef DRIVER
188 /*
189 * This should print the sequences of integers in Tables 2
190 * and 1 of the TM:
191 * 1623, 3442, 1447, 1829, 1305, ...
192 * 657EB7255101, D72A0C966378, 5A743C062A23, ...
193 */
194 #include <stdio.h>
195
196 main()
197 {
198 int i;
199
200 for (i = 0; i < 80; i++) {
201 printf("%4d ", (int)(4096 * drand48()));
202 printf("%.4X%.4X%.4X\n", x[2], x[1], x[0]);
203 }
204 }
205 #endif
206