public DeflateStream(Stream stream, ZLibMode mode, ZLibCompLevel level, bool leaveOpen)
{
NativeMethods.CheckZLibLoaded();
_zstream = new ZStream();
_zstreamPtr = GCHandle.Alloc(_zstream, GCHandleType.Pinned);
_leaveOpen = leaveOpen;
_baseStream = stream;
_mode = mode;
_internalBufPos = 0;
Debug.Assert(0 < NativeMethods.BufferSize, "Internal Logic Error at DeflateStream");
_internalBuf = new byte[NativeMethods.BufferSize];
ZLibReturnCode ret;
if (_mode == ZLibMode.Compress)
{
ret = NativeMethods.DeflateInit(_zstream, level, WriteType);
}
else
{
ret = NativeMethods.InflateInit(_zstream, OpenType);
}
ZLibException.CheckZLibOK(ret, _zstream);
}
public override int Read(byte[] buffer, int offset, int count)
{
if (_mode != ZLibMode.Decompress)
{
throw new NotSupportedException("Read() not supported on compression");
}
ValidateReadWriteArgs(buffer, offset, count);
int readLen = 0;
if (_internalBufPos != -1)
{
using (PinnedArray pinRead = new PinnedArray(_internalBuf)) // [In] Compressed
using (PinnedArray pinWrite = new PinnedArray(buffer)) // [Out] Will-be-decompressed
{
_zstream.NextIn = pinRead[_internalBufPos];
_zstream.NextOut = pinWrite[offset];
_zstream.AvailOut = (uint)count;
while (0 < _zstream.AvailOut)
{
if (_zstream.AvailIn == 0)
{ // Compressed Data is no longer available in array, so read more from _stream
int baseReadSize = _baseStream.Read(_internalBuf, 0, _internalBuf.Length);
_internalBufPos = 0;
_zstream.NextIn = pinRead;
_zstream.AvailIn = (uint)baseReadSize;
TotalIn += baseReadSize;
}
uint inCount = _zstream.AvailIn;
uint outCount = _zstream.AvailOut;
// flush method for inflate has no effect
ZLibReturnCode ret = NativeMethods.Inflate(_zstream, ZLibFlush.NO_FLUSH);
_internalBufPos += (int)(inCount - _zstream.AvailIn);
readLen += (int)(outCount - _zstream.AvailOut);
if (ret == ZLibReturnCode.STREAM_END)
{
_internalBufPos = -1; // magic for StreamEnd
break;
}
ZLibException.CheckZLibOK(ret, _zstream);
}
TotalOut += readLen;
}
}
return(readLen);
}
public override void Write(byte[] buffer, int offset, int count)
{
if (_mode != ZLibMode.Compress)
{
throw new NotSupportedException("Write() not supported on decompression");
}
TotalIn += count;
using (PinnedArray pinRead = new PinnedArray(buffer))
using (PinnedArray pinWrite = new PinnedArray(_internalBuf))
{
_zstream.NextIn = pinRead[offset];
_zstream.AvailIn = (uint)count;
_zstream.NextOut = pinWrite[_internalBufPos];
_zstream.AvailOut = (uint)(_internalBuf.Length - _internalBufPos);
while (_zstream.AvailIn != 0)
{
uint outCount = _zstream.AvailOut;
ZLibReturnCode ret = NativeMethods.Deflate(_zstream, ZLibFlush.NO_FLUSH);
_internalBufPos += (int)(outCount - _zstream.AvailOut);
if (_zstream.AvailOut == 0)
{
_baseStream.Write(_internalBuf, 0, _internalBuf.Length);
TotalOut += _internalBuf.Length;
_internalBufPos = 0;
_zstream.NextOut = pinWrite;
_zstream.AvailOut = (uint)_internalBuf.Length;
}
ZLibException.CheckZLibOK(ret, _zstream);
}
}
}
