void ec_dec_init(ec_dec *_this,ec_byte_buffer *_buf){
_this->buf=_buf;
_this->rem=ec_dec_in(_this);
_this->rng=1U<<EC_CODE_EXTRA;
_this->dif=_this->rng-(_this->rem>>EC_SYM_BITS-EC_CODE_EXTRA);
/*Normalize the interval.*/
ec_dec_normalize(_this);
}
void ec_dec_init(ec_dec *_this,ec_byte_buffer *_buf){
_this->buf=_buf;
_this->rem=ec_dec_in(_this);
_this->rng=1U<<EC_CODE_EXTRA;
_this->dif=_this->rng-(_this->rem>>EC_SYM_BITS-EC_CODE_EXTRA);
/*Normalize the interval.*/
ec_dec_normalize(_this);
/*_this->end_byte=ec_byte_look_at_end(_this->buf);*/
_this->end_bits_left=0;
_this->nb_end_bits=0;
}
/*Normalizes the contents of dif and rng so that rng lies entirely in the
high-order symbol.*/
static inline void ec_dec_normalize(ec_dec *_this){
/*If the range is too small, rescale it and input some bits.*/
while(_this->rng<=EC_CODE_BOT){
int sym;
_this->rng<<=EC_SYM_BITS;
/*Use up the remaining bits from our last symbol.*/
sym=_this->rem<<EC_CODE_EXTRA&EC_SYM_MAX;
/*Read the next value from the input.*/
_this->rem=ec_dec_in(_this);
/*Take the rest of the bits we need from this new symbol.*/
sym|=_this->rem>>EC_SYM_BITS-EC_CODE_EXTRA;
_this->dif=(_this->dif<<EC_SYM_BITS)+sym&EC_CODE_MASK;
/*dif can never be larger than EC_CODE_TOP.
This is equivalent to the slightly more readable:
if(_this->dif>EC_CODE_TOP)_this->dif-=EC_CODE_TOP;*/
_this->dif^=_this->dif&_this->dif-1&EC_CODE_TOP;
}
}
