55c49afc42
* qatar/master: yuv4mpeg: return proper error codes. Give all anonymously typedeffed structs in headers a name fate: Add parseutils test parseutils-test: Drop random colors from parsing test vf_pad/scale: use double precision for aspect ratios. build: error on variable-length arrays ppc: swscale: rework yuv2planeX_altivec() ppc: fmtconvert: kill VLA in float_to_int16_interleave_altivec() x86: dsputil: kill VLA in gmc_mmx() libspeexenc: Updated commentary to reflect recent changes libspeexenc: Add an option for enabling DTX doc/APIchanges: fill in missing dates and hashes. lavr: bump major to 1 and declare it stable. lavr: change the type of the data buffers to uint8_t**. lavc: deprecate the audio resampling API. Conflicts: cmdutils.h configure doc/APIchanges ffplay.c libavcodec/dwt.h libavcodec/libspeexenc.c libavfilter/vf_pad.c libavfilter/vf_scale.c libavformat/asf.h tests/fate/libavutil.mak tests/ref/fate/parseutils Merged-by: Michael Niedermayer <michaelni@gmx.at>
63 lines
1.9 KiB
C
63 lines
1.9 KiB
C
/*
|
|
* Lagged Fibonacci PRNG
|
|
* Copyright (c) 2008 Michael Niedermayer
|
|
*
|
|
* This file is part of FFmpeg.
|
|
*
|
|
* FFmpeg is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Lesser General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2.1 of the License, or (at your option) any later version.
|
|
*
|
|
* FFmpeg 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
|
|
* Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
* License along with FFmpeg; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
#ifndef AVUTIL_LFG_H
|
|
#define AVUTIL_LFG_H
|
|
|
|
typedef struct AVLFG {
|
|
unsigned int state[64];
|
|
int index;
|
|
} AVLFG;
|
|
|
|
void av_lfg_init(AVLFG *c, unsigned int seed);
|
|
|
|
/**
|
|
* Get the next random unsigned 32-bit number using an ALFG.
|
|
*
|
|
* Please also consider a simple LCG like state= state*1664525+1013904223,
|
|
* it may be good enough and faster for your specific use case.
|
|
*/
|
|
static inline unsigned int av_lfg_get(AVLFG *c){
|
|
c->state[c->index & 63] = c->state[(c->index-24) & 63] + c->state[(c->index-55) & 63];
|
|
return c->state[c->index++ & 63];
|
|
}
|
|
|
|
/**
|
|
* Get the next random unsigned 32-bit number using a MLFG.
|
|
*
|
|
* Please also consider av_lfg_get() above, it is faster.
|
|
*/
|
|
static inline unsigned int av_mlfg_get(AVLFG *c){
|
|
unsigned int a= c->state[(c->index-55) & 63];
|
|
unsigned int b= c->state[(c->index-24) & 63];
|
|
return c->state[c->index++ & 63] = 2*a*b+a+b;
|
|
}
|
|
|
|
/**
|
|
* Get the next two numbers generated by a Box-Muller Gaussian
|
|
* generator using the random numbers issued by lfg.
|
|
*
|
|
* @param out array where the two generated numbers are placed
|
|
*/
|
|
void av_bmg_get(AVLFG *lfg, double out[2]);
|
|
|
|
#endif /* AVUTIL_LFG_H */
|