/// <summary>
/// Initializes a new instance of the BZip2DecoderStream class.
/// </summary>
/// <param name="stream">The compressed input stream.</param>
/// <param name="ownsStream">Whether ownership of stream passes to the new instance.</param>
public BZip2DecoderStream(Stream stream, Ownership ownsStream)
{
_compressedStream = stream;
_ownsCompressed = ownsStream;
_bitstream = new BigEndianBitStream(new BufferedStream(stream));
// The Magic BZh
byte[] magic = new byte[3];
magic[0] = (byte)_bitstream.Read(8);
magic[1] = (byte)_bitstream.Read(8);
magic[2] = (byte)_bitstream.Read(8);
if (magic[0] != 0x42 || magic[1] != 0x5A || magic[2] != 0x68)
{
throw new InvalidDataException("Bad magic at start of stream");
}
// The size of the decompression blocks in multiples of 100,000
int blockSize = (int)_bitstream.Read(8) - 0x30;
if (blockSize < 1 || blockSize > 9)
{
throw new InvalidDataException("Unexpected block size in header: " + blockSize);
}
blockSize *= 100000;
_rleStream = new BZip2RleStream();
_blockDecoder = new BZip2BlockDecoder(blockSize);
_blockBuffer = new byte[blockSize];
if (ReadBlock() == 0)
{
_eof = true;
}
}
public int Process(BitStream bitstream, byte[] outputBuffer, int outputBufferOffset)
{
_crc = 0;
for (int i = 0; i < 4; ++i)
{
_crc = (_crc << 8) | bitstream.Read(8);
}
bool rand = bitstream.Read(1) != 0;
int origPtr = (int)bitstream.Read(24);
int thisBlockSize = ReadBuffer(bitstream, outputBuffer, outputBufferOffset);
_inverseBurrowsWheeler.OriginalIndex = origPtr;
_inverseBurrowsWheeler.Process(outputBuffer, outputBufferOffset, thisBlockSize, outputBuffer, outputBufferOffset);
if (rand)
{
BZip2Randomizer randomizer = new BZip2Randomizer();
randomizer.Process(outputBuffer, outputBufferOffset, thisBlockSize, outputBuffer, outputBufferOffset);
}
return thisBlockSize;
}
public BZip2CombinedHuffmanTrees(BitStream bitstream, int maxSymbols)
{
_bitstream = bitstream;
Initialize(maxSymbols);
}
private static int ReadBuffer(BitStream bitstream, byte[] buffer, int offset)
{
// The MTF state
int numInUse = 0;
MoveToFront moveFrontTransform = new MoveToFront();
bool[] inUseGroups = new bool[16];
for (int i = 0; i < 16; ++i)
{
inUseGroups[i] = bitstream.Read(1) != 0;
}
for (int i = 0; i < 256; ++i)
{
if (inUseGroups[i / 16])
{
if (bitstream.Read(1) != 0)
{
moveFrontTransform.Set(numInUse, (byte)i);
numInUse++;
}
}
}
// Initialize 'virtual' Huffman tree from bitstream
BZip2CombinedHuffmanTrees huffmanTree = new BZip2CombinedHuffmanTrees(bitstream, numInUse + 2);
// Main loop reading data
int readBytes = 0;
while (true)
{
uint symbol = huffmanTree.NextSymbol();
if (symbol < 2)
{
// RLE, with length stored in a binary-style format
uint runLength = 0;
int bitShift = 0;
while (symbol < 2)
{
runLength += (symbol + 1) << bitShift;
bitShift++;
symbol = huffmanTree.NextSymbol();
}
byte b = moveFrontTransform.Head;
while (runLength > 0)
{
buffer[offset + readBytes] = b;
++readBytes;
--runLength;
}
}
if (symbol <= numInUse)
{
// Single byte
byte b = moveFrontTransform.GetAndMove((int)symbol - 1);
buffer[offset + readBytes] = b;
++readBytes;
}
else if (symbol == numInUse + 1)
{
// End of block marker
return readBytes;
}
else
{
throw new InvalidDataException("Invalid symbol from Huffman table");
}
}
}
