ghost/libentcode/probenc.c

   1 #include <string.h>
   2 #include "probenc.h"
   3 #include "bitrenc.h"
   4
   5
   6
   7 static void ec_probmod_samp_and_update(ec_probmod *_this,ec_probsamp *_samp,
   8  unsigned _sym){
   9   unsigned sz;
  10   sz=_this->sz;
  11   _samp->fs=ec_bitree_get_freq(_this->bitree,_sym);
  12   _samp->fl=ec_bitree_get_cumul(_this->bitree,_sym);
  13   _samp->ft=_this->ft;
  14   ec_bitree_update(_this->bitree,sz,_sym,_this->inc);
  15   _this->ft+=_this->inc;
  16   if(_this->ft>_this->thresh){
  17     ec_bitree_halve(_this->bitree,sz,_this->split);
  18     _this->ft=ec_bitree_get_cumul(_this->bitree,sz);
  19   }
  20 }
  21
  22 static void ec_probmod_samp_and_update_range(ec_probmod *_this,
  23  ec_probsamp *_samp,int _sym,int _lo,int _hi){
  24   unsigned base;
  25   int      sz;
  26   sz=_this->sz;
  27   base=ec_bitree_get_cumul(_this->bitree,_lo);
  28   _samp->fs=ec_bitree_get_freq(_this->bitree,_sym);
  29   _samp->fl=ec_bitree_get_cumul(_this->bitree,_sym)-base;
  30   _samp->ft=ec_bitree_get_cumul(_this->bitree,_hi)-base;
  31   ec_bitree_update(_this->bitree,sz,_sym,_this->inc);
  32   _this->ft+=_this->inc;
  33   if(_this->ft>_this->thresh){
  34     ec_bitree_halve(_this->bitree,sz,_this->split);
  35     _this->ft=ec_bitree_get_cumul(_this->bitree,sz);
  36   }
  37 }
  38
  39 void ec_probmod_write(ec_probmod *_this,ec_enc *_enc,int _sym){
  40   ec_probsamp samp;
  41   ec_probmod_samp_and_update(_this,&samp,_sym);
  42   ec_encode(_enc,samp.fl,samp.fl+samp.fs,samp.ft);
  43 }
  44
  45 void ec_probmod_write_range(ec_probmod *_this,ec_enc *_enc,int _sym,
  46  int _lo,int _hi){
  47   ec_probsamp samp;
  48   ec_probmod_samp_and_update_range(_this,&samp,_sym,_lo,_hi);
  49   ec_encode(_enc,samp.fl,samp.fl+samp.fs,samp.ft);
  50 }