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 **/
27 #include "collectd.h"
28 #include "utils_time.h"
30 #include <pthread.h>
32 static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
33 static _Bool have_seed = 0;
34 static unsigned short seed[3];
36 static void cdrand_seed (void)
37 {
38 cdtime_t t;
40 if (have_seed)
41 return;
43 t = cdtime();
45 seed[0] = (unsigned short) t;
46 seed[1] = (unsigned short) (t >> 16);
47 seed[2] = (unsigned short) (t >> 32);
49 have_seed = 1;
50 }
52 double cdrand_d (void)
53 {
54 double r;
56 pthread_mutex_lock (&lock);
57 cdrand_seed ();
58 r = erand48 (seed);
59 pthread_mutex_unlock (&lock);
61 return (r);
62 }
64 long cdrand_range (long min, long max)
65 {
66 long range;
67 long r;
69 range = 1 + max - min;
71 r = (long) (0.5 + (cdrand_d () * range));
72 r += min;
74 return (r);
75 }