/// <summary>Flushes current chunk.</summary>
private void FlushCurrentChunk()
{
if (_bufferOffset <= 0)
{
return;
}
var compressed = new byte[_bufferOffset];
var compressedLength = _highCompression
? LZ4Codec.EncodeHC(_buffer, 0, _bufferOffset, compressed, 0, _bufferOffset)
: LZ4Codec.Encode(_buffer, 0, _bufferOffset, compressed, 0, _bufferOffset);
if (compressedLength <= 0 || compressedLength >= _bufferOffset)
{
// incompressible block
compressed = _buffer;
compressedLength = _bufferOffset;
}
var isCompressed = compressedLength < _bufferOffset;
if (fileHeaderInfo == null)
{
fileHeaderInfo = new LZ4FileHeaderInfo();
fileHeaderInfo.FrameDescriptor_BD_BlockMaxSize = BlockMaximumSize.Block64K;
fileHeaderInfo.FrameDescriptor_FLG_BChecksum = false;
fileHeaderInfo.FrameDescriptor_FLG_BIndependence = true;
fileHeaderInfo.FrameDescriptor_FLG_ContentChecksum = true;
fileHeaderInfo.FrameDescriptor_FLG_ContentSize = false;
fileHeaderInfo.FrameDescriptor_FLG_Version = 64;
//U32 const xxh = XXH32(header, length, 0);
//return (BYTE)(xxh >> 8);
// *dstPtr = LZ4F_headerChecksum(headerStart, dstPtr - headerStart);
LZ4FileHeaderInfo.WriteHeader(_innerStream, fileHeaderInfo);
}
LZ4HeaderChunkInfo chunkInfo = new LZ4HeaderChunkInfo();
chunkInfo.IsCompressed = true;
chunkInfo.ChunkSize = compressedLength;
LZ4HeaderChunkInfo.WriteHeader(_innerStream, chunkInfo);
_innerStream.Write(compressed, 0, compressedLength);
_bufferOffset = 0;
}
/// <summary>Reads the next chunk from stream.</summary>
/// <returns><c>true</c> if next has been read, or <c>false</c> if it is legitimate end of file.
/// Throws <see cref="EndOfStreamException"/> if end of stream was unexpected.</returns>
private bool AcquireNextChunk()
{
do
{
if (fileHeaderInfo == null)
{
fileHeaderInfo = _formatReader.ReadHeader(_innerStream);
}
if (blockInfo != null && blockInfo.ChunkSize <= 0)
{
return(false);
}
blockInfo = _formatReader.ReadChunkHeader(_innerStream);
int compressedLength = blockInfo.ChunkSize;
if (compressedLength <= 0 || compressedLength > GetBufferSize(fileHeaderInfo.FrameDescriptor_BD_BlockMaxSize))
{
return(false);
}
bool isCompressed = blockInfo.IsCompressed;
var compressed = new byte[compressedLength];
var chunk = ReadBlock(compressed, 0, compressedLength);
if (chunk != compressedLength)
{
throw EndOfStream(); // corrupted
}
if (!isCompressed)
{
_buffer = compressed; // no compression on this chunk
_bufferLength = compressedLength;
}
else
{
int bSize = GetBufferSize(fileHeaderInfo.FrameDescriptor_BD_BlockMaxSize);
if (_buffer == null)
{
_buffer = new byte[bSize];
}
_bufferLength = LZ4Codec.Decode(compressed, 0, compressedLength, _buffer, 0, bSize, false);
}
_bufferOffset = 0;
} while (_bufferLength == 0); // skip empty block (shouldn't happen but...)
return(true);
}
///// <summary>Reads the variable length int. Work with assumption that value is in the stream
///// and throws exception if it isn't. If you want to check if value is in the stream
///// use <see cref="TryReadVarInt"/> instead.</summary>
///// <returns></returns>
//ulong ReadVarInt(Stream stream)
//{
// ulong result;
// if (!TryReadVarInt(stream, out result)) throw new EndOfStreamException();
// return result;
//}
///// <summary>Tries to read variable length int.</summary>
///// <param name="result">The result.</param>
///// <returns><c>true</c> if integer has been read, <c>false</c> if end of stream has been
///// encountered. If end of stream has been encountered in the middle of value
///// <see cref="EndOfStreamException"/> is thrown.</returns>
//bool TryReadVarInt(Stream stream, out ulong result)
//{
// var buffer = new byte[1];
// var count = 0;
// result = 0;
// while (true)
// {
// if (stream.Read(buffer, 0, 1) == 0)
// {
// if (count == 0) return false;
// throw new EndOfStreamException();
// }
// var b = buffer[0];
// result = result + ((ulong)(b & 0x7F) << count);
// count += 7;
// if ((b & 0x80) == 0 || count >= 64) break;
// }
// return true;
//}
public LZ4HeaderChunkInfo ReadChunkHeader(Stream stream)
{
var info = new LZ4HeaderChunkInfo(stream);
return(info);
}
