diff -r 9b2c3c7a1a9c -r 567bb019e3e3 gst_plugins_base/gst/audioconvert/gstfastrandom.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/gst_plugins_base/gst/audioconvert/gstfastrandom.h Tue Aug 31 15:30:33 2010 +0300 @@ -0,0 +1,90 @@ +/* GStreamer + * Copyright (C) 2008 Sebastian Dröge + * + * 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 + +#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__ */ +