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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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98
libentcode/entenc.c Normal file
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#include <stdlib.h>
#include <string.h>
#include "entenc.h"
#define EC_BUFFER_INCREMENT (256)
void ec_byte_writeinit(ec_byte_buffer *_b){
_b->ptr=_b->buf=malloc(EC_BUFFER_INCREMENT);
_b->storage=EC_BUFFER_INCREMENT;
}
void ec_byte_writetrunc(ec_byte_buffer *_b,long _bytes){
_b->ptr=_b->buf+_bytes;
}
void ec_byte_write1(ec_byte_buffer *_b,unsigned _value){
ptrdiff_t endbyte;
endbyte=_b->ptr-_b->buf;
if(endbyte>=_b->storage){
_b->buf=realloc(_b->buf,_b->storage+EC_BUFFER_INCREMENT);
_b->storage+=EC_BUFFER_INCREMENT;
_b->ptr=_b->buf+endbyte;
}
*(_b->ptr++)=(unsigned char)_value;
}
void ec_byte_write4(ec_byte_buffer *_b,ec_uint32 _value){
ptrdiff_t endbyte;
endbyte=_b->ptr-_b->buf;
if(endbyte+4>_b->storage){
_b->buf=realloc(_b->buf,_b->storage+EC_BUFFER_INCREMENT);
_b->storage+=EC_BUFFER_INCREMENT;
_b->ptr=_b->buf+endbyte;
}
*(_b->ptr++)=(unsigned char)_value;
_value>>=8;
*(_b->ptr++)=(unsigned char)_value;
_value>>=8;
*(_b->ptr++)=(unsigned char)_value;
_value>>=8;
*(_b->ptr++)=(unsigned char)_value;
}
void ec_byte_writecopy(ec_byte_buffer *_b,void *_source,long _bytes){
ptrdiff_t endbyte;
endbyte=_b->ptr-_b->buf;
if(endbyte+_bytes>_b->storage){
_b->storage=endbyte+_bytes+EC_BUFFER_INCREMENT;
_b->buf=realloc(_b->buf,_b->storage);
_b->ptr=_b->buf+endbyte;
}
memmove(_b->ptr,_source,_bytes);
_b->ptr+=_bytes;
}
void ec_byte_writeclear(ec_byte_buffer *_b){
free(_b->buf);
}
void ec_enc_bits(ec_enc *_this,ec_uint32 _fl,int _ftb){
unsigned fl;
unsigned ft;
while(_ftb>EC_UNIT_BITS){
_ftb-=EC_UNIT_BITS;
fl=(unsigned)(_fl>>_ftb)&EC_UNIT_MASK;
ec_encode(_this,fl,fl+1,EC_UNIT_MASK+1);
}
ft=1<<_ftb;
fl=_fl&ft-1;
ec_encode(_this,fl,fl+1,ft);
}
void ec_enc_uint(ec_enc *_this,ec_uint32 _fl,ec_uint32 _ft){
ec_uint32 mask;
ec_uint32 ft;
unsigned fl;
int ftb;
_ft--;
ftb=EC_ILOG(_ft);
while(ftb>EC_UNIT_BITS){
ftb-=EC_UNIT_BITS;
ft=(_ft>>ftb)+1;
fl=(unsigned)(_fl>>ftb);
ec_encode(_this,fl,fl+1,ft);
if(fl<ft-1){
ec_enc_bits(_this,_fl,ftb);
return;
}
mask=((ec_uint32)1<<ftb)-1;
_fl=_fl&mask;
_ft=_ft&mask;
}
ec_encode(_this,_fl,_fl+1,_ft+1);
}