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
|
/* GStreamer
* Copyright (C) 2008 Sebastian Dröge <sebastian.droege@collabora.co.uk>
*
* gstfastrandom.h: Fast, bad PNRG
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library 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.
*/
#include <glib.h>
#ifndef __GST_FAST_RANDOM__
#define __GST_FAST_RANDOM__
/* transform [0..2^32] -> [0..1] */
#define GST_RAND_DOUBLE_TRANSFORM 2.3283064365386962890625e-10
/* This is the base function, implementing a linear congruential generator
* and returning a pseudo random number between 0 and 2^32 - 1.
*/
static inline guint32
gst_fast_random_uint32 ()
{
static guint32 state = 0xdeadbeef;
return (state = state * 1103515245 + 12345);
}
static inline guint32
gst_fast_random_uint32_range (gint32 start, gint32 end)
{
guint64 tmp = gst_fast_random_uint32 ();
tmp = (tmp * (end - start)) / G_MAXUINT32 + start;
return (guint32) tmp;
}
static inline gint32
gst_fast_random_int32 (void)
{
return (gint32) gst_fast_random_uint32 ();
}
static inline gint32
gst_fast_random_int32_range (gint32 start, gint32 end)
{
gint64 tmp = gst_fast_random_uint32 ();
tmp = (tmp * (end - start)) / G_MAXUINT32 + start;
return (gint32) tmp;
}
static inline gdouble
gst_fast_random_double (void)
{
gdouble ret;
ret = gst_fast_random_uint32 () * GST_RAND_DOUBLE_TRANSFORM;
ret = (ret + gst_fast_random_uint32 ()) * GST_RAND_DOUBLE_TRANSFORM;
if (ret >= 1.0)
return gst_fast_random_double ();
return ret;
}
static inline gdouble
gst_fast_random_double_range (gdouble start, gdouble end)
{
return gst_fast_random_double () * (end - start) + start;
}
#undef GST_RAND_DOUBLE_TRANSFORM
#endif /* __GST_FAST_RANDOM__ */
|
