private void WriteEncoding(int blockContentLength, AnsCodingTable blockTable)
{
ReversedMemoryStream reversedStream = new ReversedMemoryStream();
uint initialState = ConstructMask(blockTable.Denominator);
AnsState stateIn = new AnsState(MaskBits, reversedStream, initialState);
for (int i = 0; i < blockContentLength; i++)
{
int row = stateIn.ToInt();
int symbol = Block[i];
var validRows = blockTable[symbol];
while (!validRows.ContainsKey(row))
{
stateIn.PopLower();
row = stateIn.ToInt();
}
stateIn.Underlying = (uint)validRows[row];
}
stateIn.Flush();
reversedStream.ReadToStream(Output);
}
private void DecodeBlock(BitReader readerIn)
{
int numCodedSymbols = readerIn.ReadInt(23);
//Change to use stack only if the output stream is non-seekable
//If it is seekable, then simply write the number of bytes that will be put into the stream
//Then seek backward, writing them one by one
Stack <int> symbolsStack = new Stack <int>();
AnsCodingTable decodeTable = AnsCodingTable.ReadTable(readerIn, EncryptionKey);
int bitCapacity = BitUtilities.GetNumberBitsToRepresent(decodeTable.Denominator);
AnsState internalsState = new AnsState(bitCapacity, null, 0);
internalsState.Underlying = readerIn.ReadUint(bitCapacity);
KeyValuePair <int, int> symbolRow;
for (int i = 0; i < numCodedSymbols; i++)
{
symbolRow = decodeTable.DecodePoint(internalsState.ToInt());
symbolsStack.Push(symbolRow.Key);
internalsState.Underlying = (uint)symbolRow.Value;
int bitsToRead = bitCapacity - internalsState.Contained;
for (int j = 0; j < bitsToRead; j++)
{
internalsState.PushLower(readerIn.ReadBit());
}
}
//Decoding finished...
BitWriter symbolWriter = new BitWriter(Output);
byte numBitsToWrite;
if (decodeTable.SymbolType == typeof(byte))
{
numBitsToWrite = 8;
}
else if (decodeTable.SymbolType == typeof(short))
{
numBitsToWrite = 16;
}
else
{
numBitsToWrite = 32;
}
while (symbolsStack.Count != 0)
{
int symbol = symbolsStack.Pop();
symbolWriter.WriteLong(symbol, numBitsToWrite);
}
}