mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-11-25 11:11:08 +00:00
ef5004e56e
Original commit message from CVS: * gst/audioconvert/audioconvert.h: * gst/audioconvert/gstaudioquantize.c: (gst_audio_quantize_setup_dither), (gst_audio_quantize_free_dither): * gst/audioconvert/gstfastrandom.h: Implement a linear congruential generator as pseudo random number generator for the dither noise. This is about 2 times faster than using GLib's mersenne twister. Also this uses only integer math for generating integers while GLib internally uses floating point math.
90 lines
2.3 KiB
C
90 lines
2.3 KiB
C
/* 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__ */
|
|
|