public int DecodeSymbol(ArithmeticModel model)
{
int range;
int cum;
int symbol;
range = (_highBound - _lowBound) + 1;
cum = (((_value - _lowBound) + 1) * model.CumulativeFrequency[0] - 1) / range;
for (symbol = 0; model.CumulativeFrequency[symbol + 1] > cum; symbol++)
{
/* do nothing */
;
}
_highBound = _lowBound + (range * model.CumulativeFrequency[symbol]) / model.CumulativeFrequency[0] - 1;
_lowBound = _lowBound + (range * model.CumulativeFrequency[symbol + 1]) / model.CumulativeFrequency[0];
for (; ;)
{
if (_highBound < ArithmeticCodecConstants.HalfValue)
{
/* do nothing */
}
else if (_lowBound >= ArithmeticCodecConstants.HalfValue)
{
_value -= ArithmeticCodecConstants.HalfValue;
_lowBound -= ArithmeticCodecConstants.HalfValue;
_highBound -= ArithmeticCodecConstants.HalfValue;
}
else if (_lowBound >= ArithmeticCodecConstants.FirstQuarterValue &&
_highBound < ArithmeticCodecConstants.ThirdQuarterValue)
{
_value -= ArithmeticCodecConstants.FirstQuarterValue;
_lowBound -= ArithmeticCodecConstants.FirstQuarterValue;
_highBound -= ArithmeticCodecConstants.FirstQuarterValue;
}
else
{
break;
}
_lowBound = 2 * _lowBound;
_highBound = 2 * _highBound + 1;
_value = 2 * _value + (InputBit() ? 1 : 0);
}
if (model.Adaptive)
{
model.UpdateModel(symbol);
}
return(symbol);
}
public void EncodeSymbol(ArithmeticModel model, int symbol)
{
int range = (_highBound - _lowBound) + 1;
_highBound = _lowBound + (range * model.CumulativeFrequency[symbol]) / model.CumulativeFrequency[0] - 1;
_lowBound = _lowBound + (range * model.CumulativeFrequency[symbol + 1]) / model.CumulativeFrequency[0];
for (; ;)
{
if (_highBound < ArithmeticCodecConstants.HalfValue)
{
BitPlusFollow(false);
}
else if (_lowBound >= ArithmeticCodecConstants.HalfValue)
{
BitPlusFollow(true);
_lowBound -= ArithmeticCodecConstants.HalfValue;
_highBound -= ArithmeticCodecConstants.HalfValue;
}
else if (_lowBound >= ArithmeticCodecConstants.FirstQuarterValue && _highBound < ArithmeticCodecConstants.ThirdQuarterValue)
{
_followBits += 1;
_lowBound -= ArithmeticCodecConstants.FirstQuarterValue;
_highBound -= ArithmeticCodecConstants.FirstQuarterValue;
}
else
{
break;
}
_lowBound = 2 * _lowBound;
_highBound = 2 * _highBound + 1;
}
if (model.Adaptive)
{
model.UpdateModel(symbol);
}
}
