1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
|
/* vim:ts=8:sts=8:sw=4:noai:noexpandtab
*
* portable weak pseudo-random generator.
*
* Copyright (c) 2010 Miru Limited.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef _WIN32
# include <errno.h>
# include <stdio.h>
#endif
#include <impl/framework.h>
//#define RAND_DEBUG
/* locals */
static pgm_rand_t global_rand = { .seed = 0 };
static volatile uint32_t rand_ref_count = 0;
static pgm_mutex_t rand_mutex;
void
pgm_rand_init (void)
{
if (pgm_atomic_exchange_and_add32 (&rand_ref_count, 1) > 0)
return;
pgm_mutex_init (&rand_mutex);
}
void
pgm_rand_shutdown (void)
{
pgm_return_if_fail (pgm_atomic_read32 (&rand_ref_count) > 0);
if (pgm_atomic_exchange_and_add32 (&rand_ref_count, (uint32_t)-1) != 1)
return;
pgm_mutex_free (&rand_mutex);
}
void
pgm_rand_create (
pgm_rand_t* new_rand
)
{
/* pre-conditions */
pgm_assert (NULL != new_rand);
#ifndef _WIN32
/* attempt to read seed from kernel
*/
FILE* fp;
do {
fp = fopen ("/dev/urandom", "rb");
} while (PGM_UNLIKELY(EINTR == errno));
if (fp) {
size_t items_read;
do {
items_read = fread (&new_rand->seed, sizeof(new_rand->seed), 1, fp);
} while (PGM_UNLIKELY(EINTR == errno));
fclose (fp);
if (1 == items_read)
return;
}
#endif /* !_WIN32 */
const pgm_time_t now = pgm_time_update_now();
new_rand->seed = (uint32_t)pgm_to_msecs (now);
}
/* derived from POSIX.1-2001 example implementation of rand()
*/
uint32_t
pgm_rand_int (
pgm_rand_t* r
)
{
/* pre-conditions */
pgm_assert (NULL != r);
r->seed = r->seed * 1103515245 + 12345;
return r->seed;
}
int32_t
pgm_rand_int_range (
pgm_rand_t* r,
int32_t begin,
int32_t end
)
{
/* pre-conditions */
pgm_assert (NULL != r);
return begin + pgm_rand_int (r) % (end - begin);
}
uint32_t
pgm_random_int (void)
{
pgm_mutex_lock (&rand_mutex);
if (PGM_UNLIKELY(!global_rand.seed))
pgm_rand_create (&global_rand);
const uint32_t rand_value = pgm_rand_int (&global_rand);
pgm_mutex_unlock (&rand_mutex);
return rand_value;
}
int32_t
pgm_random_int_range (
int32_t begin,
int32_t end
)
{
const uint32_t rand_value = pgm_random_int();
return begin + rand_value % (end - begin);
}
/* eof */
|
