/// <summary>
/// Creates a new instance of the <see cref="LZ4EncoderStream"/> class.
/// </summary>
/// <param name="inner">Inner stream.</param>
/// <param name="descriptor">LZ4 descriptor.</param>
/// <param name="encoderFactory">A function to return the appropriate encoder according to the <paramref name="descriptor"/>.</param>
/// <param name="leaveOpen">Indicates whether <paramref name="inner"/> stream should be left open after disposing.</param>
internal LZ4EncoderStream(Stream inner, ILZ4FrameDescriptor descriptor, Func<ILZ4FrameDescriptor, ILZ4Encoder> encoderFactory, bool leaveOpen = false)
{
_inner = inner;
_descriptor = descriptor;
_encoderFactory = encoderFactory;
_leaveOpen = leaveOpen;
}
private void ReadFrame()
{
Read0();
uint? magic = TryRead32();
if (magic != 0x184D2204)
throw new InvalidDataException(RS.ExpectLZ4MagicNumber);
Read0();
ushort flgBd = Read16();
int flg = flgBd & 0xFF;
int bd = (flgBd >> 8) & 0xFF;
int version = (flg >> 6) & 0x11;
if (version != 1)
throw new InvalidDataException(string.Format(RS.LZ4VersionNotSupported, version));
bool blockChaining = ((flg >> 5) & 0x01) == 0;
bool blockChecksum = ((flg >> 4) & 0x01) != 0;
bool hasContentSize = ((flg >> 3) & 0x01) != 0;
bool contentChecksum = ((flg >> 2) & 0x01) != 0;
bool hasDictionary = (flg & 0x01) != 0;
int blockSizeCode = (bd >> 4) & 0x07;
long? contentLength = hasContentSize ? (long?) Read64() : null;
uint? dictionaryId = hasDictionary ? (uint?) Read32() : null;
byte actualHC = (byte)(XXHash32.DigestOf(_buffer16, 0, _index16) >> 8);
byte expectedHC = Read8();
if (actualHC != expectedHC)
throw new InvalidDataException(RS.BadLZ4FrameHeaderChecksum);
int blockSize = MaxBlockSize(blockSizeCode);
if (hasDictionary)
{
// Write32(dictionaryId);
throw new NotImplementedException(string.Format(RS.FeatureNotImplementedInType, "Predefined Dictionaries", GetType().Name));
}
_frameInfo = new LZ4FrameDescriptor(contentLength, contentChecksum, blockChaining, blockChecksum, dictionaryId, blockSize);
_decoder = _decoderFactory(_frameInfo);
_buffer = new byte[blockSize];
}
private void CloseFrame()
{
if (_decoder == null)
return;
try
{
_frameInfo = null;
_buffer = null;
// if you need any exceptions throw them here
_decoder.Dispose();
}
finally
{
_decoder = null;
}
}
