// Decode a bit with modelling
public uint decodeBit(ArithmeticBitModel m)
{
Debug.Assert(m != null);
uint x = m.bit_0_prob * (length >> BM.LengthShift); // product l x p0
uint sym = (value >= x)?1u:0u; // decision
// update & shift interval
if (sym == 0)
{
length = x;
++m.bit_0_count;
}
else
{
value -= x; // shifted interval base = 0
length -= x;
}
if (length < AC.MinLength)
{
renorm_dec_interval(); // renormalization
}
if (--m.bits_until_update == 0)
{
m.update(); // periodic model update
}
return(sym); // return data bit value
}
// Encode a bit with modelling
public void encodeBit(ArithmeticBitModel m, uint bit)
{
Debug.Assert(m != null && (bit <= 1));
uint x = m.bit_0_prob * (length >> BM.LengthShift); // product l x p0
// update interval
if (bit == 0)
{
length = x;
++m.bit_0_count;
}
else
{
uint init_interval_base = interval_base;
interval_base += x;
length -= x;
if (init_interval_base > interval_base)
{
propagate_carry(); // overflow = carry
}
}
if (length < AC.MinLength)
{
renorm_enc_interval(); // renormalization
}
if (--m.bits_until_update == 0)
{
m.update(); // periodic model update
}
}
// Encode a bit with modelling
public void encodeBit(ArithmeticBitModel m, uint bit)
{
Debug.Assert(m!=null&&(bit<=1));
uint x=m.bit_0_prob*(length>>BM.LengthShift); // product l x p0
// update interval
if(bit==0)
{
length=x;
++m.bit_0_count;
}
else
{
uint init_interval_base=interval_base;
interval_base+=x;
length-=x;
if(init_interval_base>interval_base) propagate_carry(); // overflow = carry
}
if(length<AC.MinLength) renorm_enc_interval(); // renormalization
if(--m.bits_until_update==0) m.update(); // periodic model update
}
public void initBitModel(ArithmeticBitModel m)
{
m.init();
}
// Decode a bit with modelling
public uint decodeBit(ArithmeticBitModel m)
{
Debug.Assert(m!=null);
uint x=m.bit_0_prob*(length>>BM.LengthShift); // product l x p0
uint sym=(value>=x)?1u:0u; // decision
// update & shift interval
if(sym==0)
{
length=x;
++m.bit_0_count;
}
else
{
value-=x; // shifted interval base = 0
length-=x;
}
if(length<AC.MinLength) renorm_dec_interval(); // renormalization
if(--m.bits_until_update==0) m.update(); // periodic model update
return sym; // return data bit value
}
public void initBitModel(ArithmeticBitModel m)
{
m.init();
}
