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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.
91 lines
2.3 KiB
C
91 lines
2.3 KiB
C
/* GStreamer
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* Copyright (C) 2008 Sebastian Dröge <sebastian.droege@collabora.co.uk>
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*
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* gstfastrandom.h: Fast, bad PNRG
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include <glib.h>
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#ifndef __GST_FAST_RANDOM__
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#define __GST_FAST_RANDOM__
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/* transform [0..2^32] -> [0..1] */
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#define GST_RAND_DOUBLE_TRANSFORM 2.3283064365386962890625e-10
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/* This is the base function, implementing a linear congruential generator
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* and returning a pseudo random number between 0 and 2^32 - 1.
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*/
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static inline guint32
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gst_fast_random_uint32 ()
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{
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static guint32 state = 0xdeadbeef;
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return (state = state * 1103515245 + 12345);
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}
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static inline guint32
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gst_fast_random_uint32_range (gint32 start, gint32 end)
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{
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guint64 tmp = gst_fast_random_uint32 ();
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tmp = (tmp * (end - start)) / G_MAXUINT32 + start;
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return (guint32) tmp;
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}
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static inline gint32
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gst_fast_random_int32 (void)
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{
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return (gint32) gst_fast_random_uint32 ();
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}
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static inline gint32
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gst_fast_random_int32_range (gint32 start, gint32 end)
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{
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gint64 tmp = gst_fast_random_uint32 ();
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tmp = (tmp * (end - start)) / G_MAXUINT32 + start;
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return (gint32) tmp;
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}
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static inline gdouble
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gst_fast_random_double (void)
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{
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gdouble ret;
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ret = gst_fast_random_uint32 () * GST_RAND_DOUBLE_TRANSFORM;
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ret = (ret + gst_fast_random_uint32 ()) * GST_RAND_DOUBLE_TRANSFORM;
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if (ret >= 1.0)
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return gst_fast_random_double ();
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return ret;
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}
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static inline gdouble
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gst_fast_random_double_range (gdouble start, gdouble end)
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{
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return gst_fast_random_double () * (end - start) + start;
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}
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#undef GST_RAND_DOUBLE_TRANSFORM
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#endif /* __GST_FAST_RANDOM__ */
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