private uint DecodeSymbol()
{
Range = (ulong)(High - Low) + 1;
uint code_sum = (uint)(((ulong)(Code - Low + 1) * arithmeticModel.GetSymbolTotalSum() - 1) / Range);
uint symbol = arithmeticModel.GetSymbolForSpecifiedSum(code_sum);
High = Low + (uint)((Range * arithmeticModel.GetSymbolSumLimitH(symbol)) / arithmeticModel.GetSymbolTotalSum() - 1);
Low = Low + (uint)((Range * arithmeticModel.GetSymbolSumLimitL(symbol)) / arithmeticModel.GetSymbolTotalSum());
for (; ;)
{
if ((High & firstShiftingMask) == (Low & firstShiftingMask))
{
Low <<= 1;
High <<= 1;
High |= 1;
Code = (Code << 1) | reader.ReadNBits(1);
}
else if ((Low & secondShiftingMask) == 0x40000000 && (High & secondShiftingMask) == 0x80000000)
{
Code = ((Code ^ 0x40000000) << 1) | reader.ReadNBits(1);
High = ((High | 0x40000000) << 1) | 1;
Low = (Low & 0x3FFFFFFF) << 1;
}
else
{
break;
}
}
return(symbol);
}
private void EncodeSymbol(uint symbol)
{
Range = (ulong)High - Low + 1;
High = Low + (uint)((Range * arithmeticModel.GetSymbolSumLimitH(symbol)) / arithmeticModel.GetSymbolTotalSum() - 1);
Low = Low + (uint)((Range * arithmeticModel.GetSymbolSumLimitL(symbol)) / arithmeticModel.GetSymbolTotalSum());
for (; ;)
{
// Test First shift MSB(H) = MSB(L) = 0 or MSB(H) = MSB(L) = 1
if ((High & firstShiftingMask) == (Low & firstShiftingMask))
{
// Send the stabilized bit and the shiftings
uint msbFromHigh = (High >> 31);
WriteBitAndUnderflowBits(msbFromHigh);
// Set the last bit from High and Low
High <<= 1;
High |= 1;
Low <<= 1;
}
// Test Second shift (first 2 semnificative bits of H = 10; L = 01;)
else if ((Low & secondShigtingMask) == 0x40000000 && (High & secondShigtingMask) == 0x80000000)
{
UnderflowBits++;
High |= 0x40000000;
Low &= 0x3FFFFFFF;
// Set the last bit from High and Low
High <<= 1;
High |= 1;
Low <<= 1;
}
else
{
return;
}
}
}
