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Multiplier-free entropy coder

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This commit is contained in:
Timothy B. Terriberry 2007-12-06 15:09:53 +11:00 • committed by Jean-Marc Valin
parent aeb4467d7f
commit 2ec8d9e522
26 changed files with 1597 additions and 2 deletions
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50
libentcode/probenc.c Normal file
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#include <string.h>
#include "probenc.h"
#include "bitrenc.h"
static void ec_probmod_samp_and_update(ec_probmod *_this,ec_probsamp *_samp,
unsigned _sym){
unsigned sz;
sz=_this->sz;
_samp->fs=ec_bitree_get_freq(_this->bitree,_sym);
_samp->fl=ec_bitree_get_cumul(_this->bitree,_sym);
_samp->ft=_this->ft;
ec_bitree_update(_this->bitree,sz,_sym,_this->inc);
_this->ft+=_this->inc;
if(_this->ft>_this->thresh){
ec_bitree_halve(_this->bitree,sz,_this->split);
_this->ft=ec_bitree_get_cumul(_this->bitree,sz);
}
}
static void ec_probmod_samp_and_update_range(ec_probmod *_this,
ec_probsamp *_samp,int _sym,int _lo,int _hi){
unsigned base;
int sz;
sz=_this->sz;
base=ec_bitree_get_cumul(_this->bitree,_lo);
_samp->fs=ec_bitree_get_freq(_this->bitree,_sym);
_samp->fl=ec_bitree_get_cumul(_this->bitree,_sym)-base;
_samp->ft=ec_bitree_get_cumul(_this->bitree,_hi)-base;
ec_bitree_update(_this->bitree,sz,_sym,_this->inc);
_this->ft+=_this->inc;
if(_this->ft>_this->thresh){
ec_bitree_halve(_this->bitree,sz,_this->split);
_this->ft=ec_bitree_get_cumul(_this->bitree,sz);
}
}
void ec_probmod_write(ec_probmod *_this,ec_enc *_enc,int _sym){
ec_probsamp samp;
ec_probmod_samp_and_update(_this,&samp,_sym);
ec_encode(_enc,samp.fl,samp.fl+samp.fs,samp.ft);
}
void ec_probmod_write_range(ec_probmod *_this,ec_enc *_enc,int _sym,
int _lo,int _hi){
ec_probsamp samp;
ec_probmod_samp_and_update_range(_this,&samp,_sym,_lo,_hi);
ec_encode(_enc,samp.fl,samp.fl+samp.fs,samp.ft);
}