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Implements ec_enc_patch_initial_bits()

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Timothy B. Terriberry 2011-02-14 14:40:27 -05:00 • committed by Jean-Marc Valin
parent 079b916950
commit b3c05b6be2
1 changed files with 25 additions and 0 deletions
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25
libcelt/entenc.c
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@ -215,6 +215,31 @@ void ec_enc_bits(ec_enc *_this,ec_uint32 _fl,unsigned _bits){
_this->nbits_total+=_bits;
}
int ec_enc_patch_initial_bits(ec_enc *_this,unsigned _val,int _nbits){
int shift;
unsigned mask;
if(_nbits<0||_nbits>EC_SYM_BITS)return -1;
shift=EC_SYM_BITS-_nbits;
mask=(1<<_nbits)-1<<shift;
if(_this->offs>0){
/*The first byte has been finalized.*/
_this->buf[0]=(unsigned char)(_this->buf[0]&~mask|_val<<shift);
}
else if(_this->rem>=0){
/*The first byte is still awaiting carry propagation.*/
_this->rem=_this->rem&~mask|_val<<shift;
}
else if(_this->rng<=EC_CODE_TOP>>shift){
/*The renormalization loop has never been run.*/
_this->val=_this->val&~((ec_uint32)mask<<EC_CODE_SHIFT)|
(ec_uint32)_val<<EC_CODE_SHIFT+shift;
}
/*The encoder hasn't even encoded _nbits of data yet.*/
else return -1;
/*Success!*/
return 0;
}
void ec_enc_shrink(ec_enc *_this,ec_uint32 _size){
celt_assert(_this->offs+_this->end_offs<=_size);
CELT_MOVE(_this->buf+_size-_this->end_offs,