static int ec_encode(ec_enc *_this,unsigned _fl,unsigned _fh,unsigned _ftb) {
unsigned l;
unsigned r;
int c;
int s;
unsigned d;
unsigned u;
unsigned v;
#if defined(EC_MULT_FREE)
unsigned ft;
#endif
/*printf("0x%08X %2i 0x%04X [0x%04X,0x%04X) {0x%04X}\n",
_this->low,_this->cnt,_this->rng,_fl,_fh,1<<_ftb);*/
l=_this->low;
c=_this->cnt;
r=_this->rng;
#if defined(EC_MULT_FREE)
ft=1<<_ftb;
s=r>=ft<<1;
if(s)ft<<=1;
_fl<<=s;
_fh<<=s;
d=r-ft;
u=_fl+EC_MINI(_fl,d);
v=_fh+EC_MINI(_fh,d);
#else
u=r*_fl>>_ftb;
v=r*_fh>>_ftb;
#endif
r=v-u;
l+=u;
d=16-EC_ILOGNZ_32(r);
s=c+d;
/*TODO: Right now we flush every time we have at least one byte available.
Instead we should use an ec_window and flush right before we're about to
shift bits off the end of the window.
For a 32-bit window this is about the same amount of work, but for a 64-bit
window it should be a fair win.*/
if(s>=0) {
unsigned short *buf;
size_t cbuf;
size_t nbuf;
unsigned m;
buf=_this->buf;
cbuf=_this->cbuf;
nbuf=_this->nbuf;
if(nbuf>=cbuf) {
cbuf=(cbuf<<1)+2;
buf=(unsigned short *)realloc(buf,cbuf*sizeof(*buf));
if(buf==NULL)return -ENOMEM;
}
c+=16;
m=(1<<c)-1;
if(s>=8) {
buf[nbuf++]=(unsigned short)(l>>c);
l&=m;
c-=8;
m>>=8;
}
unsigned ec_decode_bin(ec_dec *_this,unsigned bits){
unsigned s;
ec_uint32 ft;
ft = (ec_uint32)1<<bits;
_this->nrm=_this->rng>>bits;
s=(unsigned)((_this->dif-1)/_this->nrm);
return ft-EC_MINI(s+1,ft);
}
void ec_dec_update(ec_dec *_this,unsigned _fl,unsigned _fh,unsigned _ft){
ec_uint32 fl;
ec_uint32 fh;
ec_uint32 ft;
ec_uint32 r;
ec_uint32 s;
ec_uint32 d;
/*Step 4: Evaluate the two partition function values.*/
fl=(ec_uint32)_fl<<_this->nrm;
fh=(ec_uint32)_fh<<_this->nrm;
ft=(ec_uint32)_ft<<_this->nrm;
d=_this->rng-ft;
r=fh+EC_MINI(fh,d);
s=fl+EC_MINI(fl,d);
/*Step 5: Update the interval.*/
_this->rng=r-s;
_this->dif-=s;
/*Step 6: Normalize the interval.*/
ec_dec_normalize(_this);
}
unsigned ec_decode_bin(ec_dec *_this,unsigned _bits){
unsigned s;
_this->nrm=_this->rng>>_bits;
s=(unsigned)((_this->dif-1)/_this->nrm);
return (1<<_bits)-EC_MINI(s+1,1<<_bits);
}
unsigned ec_decode(ec_dec *_this,unsigned _ft){
unsigned s;
_this->nrm=_this->rng/_ft;
s=(unsigned)((_this->dif-1)/_this->nrm);
return _ft-EC_MINI(s+1,_ft);
}
unsigned ec_decode_bin(ec_dec *_this,unsigned _bits){
unsigned s;
_this->ext=_this->rng>>_bits;
s=(unsigned)(_this->val/_this->ext);
return (1<<_bits)-EC_MINI(s+1,1<<_bits);
}
unsigned ec_decode(ec_dec *_this,unsigned _ft){
unsigned s;
_this->ext=_this->rng/_ft;
s=(unsigned)(_this->val/_this->ext);
return _ft-EC_MINI(s+1,_ft);
}
