1 /* Copyright (C) 1995, 1996, 1997, 1998, 2001 Free Software Foundation, Inc.
2 This file is part of the GNU C Library and the VMIPS testsuite.
3 Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, August 1995.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
18 MA 02110-1301, USA. */
19
20 /* (brg) This file consists mostly of bits and pieces from the GNU C
21 Library version 2.2.4. The pieces come from stdlib/drand48-iter.c,
22 stdlib/stdlib.h, stdlib/nrand48_r.c, and stdlib/lrand48.c. */
23
24 typedef unsigned long long uint64_t;
25 typedef unsigned int uint32_t;
26
27 /* Data structure for communication with thread safe versions. This
28 type is to be regarded as opaque. It's only exported because users
29 have to allocate objects of this type. */
30 struct drand48_data
31 {
32 unsigned short int __x[3]; /* Current state. */
33 unsigned short int __old_x[3]; /* Old state. */
34 unsigned short int __c; /* Additive const. in congruential formula. */
35 unsigned short int __init; /* Flag for initializing. */
36 unsigned long long int __a; /* Factor in congruential formula. */
37 };
38
39 /* Global state for non-reentrant functions. */
40 struct drand48_data __libc_drand48_data;
41
42 int
__drand48_iterate(xsubi,buffer)43 __drand48_iterate (xsubi, buffer)
44 unsigned short int xsubi[3];
45 struct drand48_data *buffer;
46 {
47 uint64_t X;
48 uint64_t result;
49
50 /* Initialize buffer, if not yet done. */
51 if (!buffer->__init)
52 {
53 buffer->__a = 0x5deece66dull;
54 buffer->__c = 0xb;
55 buffer->__init = 1;
56 }
57
58 /* Do the real work. We choose a data type which contains at least
59 48 bits. Because we compute the modulus it does not care how
60 many bits really are computed. */
61
62 X = (uint64_t) xsubi[2] << 32 | (uint32_t) xsubi[1] << 16 | xsubi[0];
63
64 result = X * buffer->__a + buffer->__c;
65
66 xsubi[0] = result & 0xffff;
67 xsubi[1] = (result >> 16) & 0xffff;
68 xsubi[2] = (result >> 32) & 0xffff;
69
70 return 0;
71 }
72
73 int
__nrand48_r(xsubi,buffer,result)74 __nrand48_r (xsubi, buffer, result)
75 unsigned short int xsubi[3];
76 struct drand48_data *buffer;
77 long int *result;
78 {
79 /* Compute next state. */
80 if (__drand48_iterate (xsubi, buffer) < 0)
81 return -1;
82
83 /* Store the result. */
84 if (sizeof (unsigned short int) == 2)
85 *result = xsubi[2] << 15 | xsubi[1] >> 1;
86 else
87 *result = xsubi[2] >> 1;
88
89 return 0;
90 }
91
92 long int
lrand48()93 lrand48 ()
94 {
95 long int result;
96
97 (void) __nrand48_r (__libc_drand48_data.__x, &__libc_drand48_data, &result);
98
99 return result;
100 }
101