shithub: opus

ref: a847b775c948a80da60c6193ce8e99275d6e9c2a
dir: /libcelt/entdec.c/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stddef.h>
#include "entdec.h"



void ec_byte_readinit(ec_byte_buffer *_b,unsigned char *_buf,long _bytes){
  _b->buf=_b->ptr=_buf;
  _b->storage=_bytes;
}

int ec_byte_look1(ec_byte_buffer *_b){
  ptrdiff_t endbyte;
  endbyte=_b->ptr-_b->buf;
  if(endbyte>=_b->storage)return -1;
  else return _b->ptr[0];
}

int ec_byte_look4(ec_byte_buffer *_b,ec_uint32 *_val){
  ptrdiff_t endbyte;
  endbyte=_b->ptr-_b->buf;
  if(endbyte+4>_b->storage){
    if(endbyte<_b->storage){
      *_val=_b->ptr[0];
      endbyte++;
      if(endbyte<_b->storage){
        *_val|=(ec_uint32)_b->ptr[1]<<8;
        endbyte++;
        if(endbyte<_b->storage)*_val|=(ec_uint32)_b->ptr[2]<<16;
      }
    }
    return -1;
  }
  else{
    *_val=_b->ptr[0];
    *_val|=(ec_uint32)_b->ptr[1]<<8;
    *_val|=(ec_uint32)_b->ptr[2]<<16;
    *_val|=(ec_uint32)_b->ptr[3]<<24;
  }
  return 0;
}

void ec_byte_adv1(ec_byte_buffer *_b){
  _b->ptr++;
}

void ec_byte_adv4(ec_byte_buffer *_b){
  _b->ptr+=4;
}

int ec_byte_read1(ec_byte_buffer *_b){
  ptrdiff_t endbyte;
  endbyte=_b->ptr-_b->buf;
  if(endbyte>=_b->storage)return -1;
  else return *(_b->ptr++);
}

int ec_byte_read4(ec_byte_buffer *_b,ec_uint32 *_val){
  unsigned char *end;
  end=_b->buf+_b->storage;
  if(_b->ptr+4>end){
    if(_b->ptr<end){
      *_val=*(_b->ptr++);
      if(_b->ptr<end){
        *_val|=(ec_uint32)*(_b->ptr++)<<8;
        if(_b->ptr<end)*_val|=(ec_uint32)*(_b->ptr++)<<16;
      }
    }
    return -1;
  }
  else{
    *_val=(*_b->ptr++);
    *_val|=(ec_uint32)*(_b->ptr++)<<8;
    *_val|=(ec_uint32)*(_b->ptr++)<<16;
    *_val|=(ec_uint32)*(_b->ptr++)<<24;
  }
  return 0;
}



ec_uint32 ec_dec_bits(ec_dec *_this,int _ftb){
  ec_uint32 t;
  unsigned  s;
  unsigned  ft;
  t=0;
  while(_ftb>EC_UNIT_BITS){
    s=ec_decode(_this,EC_UNIT_MASK+1);
    ec_dec_update(_this,s,s+1,EC_UNIT_MASK+1);
    t=t<<EC_UNIT_BITS|s;
    _ftb-=EC_UNIT_BITS;
  }
  ft=1U<<_ftb;
  s=ec_decode(_this,ft);
  ec_dec_update(_this,s,s+1,ft);
  t=t<<_ftb|s;
  return t;
}

ec_uint64 ec_dec_bits64(ec_dec *_this,int _ftb){
  ec_uint32 t;
  if(_ftb>32){
    t=ec_dec_bits(_this,_ftb-32);
    _ftb=32;
  }
  else t=0;
  return (ec_uint64)t<<32|ec_dec_bits(_this,_ftb);
}

ec_uint32 ec_dec_uint(ec_dec *_this,ec_uint32 _ft){
  ec_uint32 mask;
  ec_uint32 t;
  unsigned  ft;
  unsigned  s;
  int       ftb;
  t=0;
  _ft--;
  ftb=EC_ILOG(_ft);
  while(ftb>EC_UNIT_BITS){
    ftb-=EC_UNIT_BITS;
    ft=(unsigned)(_ft>>ftb)+1;
    s=ec_decode(_this,ft);
    ec_dec_update(_this,s,s+1,ft);
    t=t<<EC_UNIT_BITS|s;
    if(s<ft-1)return t<<ftb|ec_dec_bits(_this,ftb);
    mask=((ec_uint32)1<<ftb)-1;
    _ft=_ft&mask;
  }
  _ft++;
  s=ec_decode(_this,(unsigned)_ft);
  ec_dec_update(_this,s,s+1,(unsigned)_ft);
  t=t<<ftb|s;
  return t;
}

ec_uint64 ec_dec_uint64(ec_dec *_this,ec_uint64 _ft){
  ec_uint64 mask;
  ec_uint64 t;
  unsigned  ft;
  unsigned  s;
  int       ftb;
  t=0;
  _ft--;
  ftb=EC_ILOG64(_ft);
  while(ftb>EC_UNIT_BITS){
    ftb-=EC_UNIT_BITS;
    ft=(unsigned)(_ft>>ftb)+1;
    s=ec_decode(_this,ft);
    ec_dec_update(_this,s,s+1,ft);
    t=t<<EC_UNIT_BITS|s;
    if(s<ft-1)return t<<ftb|ec_dec_bits64(_this,ftb);
    mask=((ec_uint64)1<<ftb)-1;
    _ft=_ft&mask;
  }
  _ft++;
  s=ec_decode(_this,(unsigned)_ft);
  ec_dec_update(_this,s,s+1,(unsigned)_ft);
  t=t<<ftb|s;
  return t;
}