1 /**
2 * collectd - src/utils_random.c
3 * Copyright (C) 2013 Florian Forster
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining a
6 * copy of this software and associated documentation files (the "Software"),
7 * to deal in the Software without restriction, including without limitation
8 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
9 * and/or sell copies of the Software, and to permit persons to whom the
10 * Software is furnished to do so, subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be included in
13 * all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
21 * DEALINGS IN THE SOFTWARE.
22 *
23 * Authors:
24 * Florian Forster <octo at collectd.org>
25 **/
26
27 #include "collectd.h"
28
29 #include "utils_random.h"
30 #include "utils_time.h"
31
32 #include <pthread.h>
33
34 #ifdef WIN32
erand48(unsigned short unused[3])35 double erand48(unsigned short unused[3]) {
36 return (double)rand() / (double)RAND_MAX;
37 }
38
jrand48(unsigned short unused[3])39 long int jrand48(unsigned short unused[3]) { return rand(); }
40 #endif
41
42 static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
43 static bool have_seed;
44 static unsigned short seed[3];
45
cdrand_seed(void)46 static void cdrand_seed(void) {
47 cdtime_t t;
48
49 if (have_seed)
50 return;
51
52 t = cdtime();
53
54 seed[0] = (unsigned short)t;
55 seed[1] = (unsigned short)(t >> 16);
56 seed[2] = (unsigned short)(t >> 32);
57
58 #ifdef WIN32
59 srand((unsigned)t);
60 #endif
61
62 have_seed = true;
63 }
64
cdrand_d(void)65 double cdrand_d(void) {
66 double r;
67
68 pthread_mutex_lock(&lock);
69 cdrand_seed();
70 r = erand48(seed);
71 pthread_mutex_unlock(&lock);
72
73 return r;
74 }
75
cdrand_u(void)76 uint32_t cdrand_u(void) {
77 long r;
78
79 pthread_mutex_lock(&lock);
80 cdrand_seed();
81 r = jrand48(seed);
82 pthread_mutex_unlock(&lock);
83
84 return (uint32_t)r;
85 }
86
cdrand_range(long min,long max)87 long cdrand_range(long min, long max) {
88 long range;
89 long r;
90
91 range = 1 + max - min;
92
93 r = (long)(0.5 + (cdrand_d() * range));
94 r += min;
95
96 return r;
97 }
98