private static void Encode(Stream input, Stream output)
{
using (PaddedStream paddedInput = new PaddedStream(input, 32, PaddedStreamMode.Read))
{
using (XorStream xorPaddedInput = new XorStream(paddedInput))
{
using (MemoryStream normalOutput = new MemoryStream())
{
using (MemoryStream xorOutput = new MemoryStream())
{
long initialPosition = input.Position;
long inputLength = input.Length - initialPosition;
// Compress using normal encoding
EncodeInternal(paddedInput, normalOutput, false, inputLength);
// Reset the input stream and compress using XOR encoding
input.Position = initialPosition;
EncodeInternal(xorPaddedInput, xorOutput, true, inputLength);
long normalOutputLength = normalOutput.Length;
long xorOutputLength = xorOutput.Length;
using (PaddedStream paddedOutput = new PaddedStream(output, 2, PaddedStreamMode.Write))
{
byte[] outputBytes =
(normalOutputLength <= xorOutputLength ? normalOutput : xorOutput).ToArray();
paddedOutput.Write(outputBytes, 0, outputBytes.Length);
}
}
}
}
}
}
private static void Decode(Stream input, Stream output, Endianness endianness)
{
using (PaddedStream paddedInput = new PaddedStream(input, 2, PaddedStreamMode.Read))
{
byte packetLength = NeutralEndian.Read1(paddedInput);
var readBitfield = GetBitfieldReader(NeutralEndian.Read1(paddedInput));
ushort incrementingValue;
ushort commonValue;
InputBitStream <ushort> bitStream;
Action <Stream, ushort> write2;
if (endianness == Endianness.BigEndian)
{
incrementingValue = BigEndian.Read2(paddedInput);
commonValue = BigEndian.Read2(paddedInput);
bitStream = new UInt16BE_E_L_InputBitStream(paddedInput);
write2 = Write2BE;
}
else
{
incrementingValue = LittleEndian.Read2(paddedInput);
commonValue = LittleEndian.Read2(paddedInput);
bitStream = new UInt16LE_E_L_InputBitStream(paddedInput);
write2 = Write2LE;
}
// Loop until the end-of-data marker is found (if it is not found before the end of the stream, UInt8InputBitStream
// will throw an exception)
for (; ;)
{
if (bitStream.Get())
{
int mode = bitStream.Read(2);
int count = bitStream.Read(4);
switch (mode)
{
case 0:
case 1:
{
ushort flags = readBitfield(bitStream);
ushort outv = (ushort)(bitStream.Read(packetLength) | flags);
do
{
write2(output, outv);
outv += (ushort)mode;
} while (--count >= 0);
}
break;
case 2:
mode = -1;
goto case 0;
case 3:
{
// End of compressed data
if (count == 0xf)
{
return;
}
do
{
ushort flags = readBitfield(bitStream);
ushort outv = bitStream.Read(packetLength);
write2(output, (ushort)(outv | flags));
} while (--count >= 0);
}
break;
}
}
else
{
bool mode = bitStream.Get();
int count = bitStream.Read(4);
if (mode)
{
do
{
write2(output, commonValue);
} while (--count >= 0);
}
else
{
do
{
write2(output, incrementingValue++);
} while (--count >= 0);
}
}
}
}
}
