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// ZlibDecoder.h
#ifndef __ZLIB_DECODER_H
#define __ZLIB_DECODER_H
#include "DeflateDecoder.h"
namespace NCompress {
namespace NZlib {
const UInt32 ADLER_INIT_VAL = 1;
class COutStreamWithAdler:
public ISequentialOutStream,
public CMyUnknownImp
{
CMyComPtr<ISequentialOutStream> _stream;
UInt32 _adler;
UInt64 _size;
public:
MY_UNKNOWN_IMP
STDMETHOD(Write)(const void *data, UInt32 size, UInt32 *processedSize);
void SetStream(ISequentialOutStream *stream) { _stream = stream; }
void ReleaseStream() { _stream.Release(); }
void Init() { _adler = ADLER_INIT_VAL; _size = 0; }
UInt32 GetAdler() const { return _adler; }
UInt64 GetSize() const { return _size; }
};
class CDecoder:
public ICompressCoder,
public CMyUnknownImp
{
COutStreamWithAdler *AdlerSpec;
CMyComPtr<ISequentialOutStream> AdlerStream;
NCompress::NDeflate::NDecoder::CCOMCoder *DeflateDecoderSpec;
CMyComPtr<ICompressCoder> DeflateDecoder;
public:
STDMETHOD(Code)(ISequentialInStream *inStream, ISequentialOutStream *outStream,
const UInt64 *inSize, const UInt64 *outSize, ICompressProgressInfo *progress);
UInt64 GetInputProcessedSize() const { return DeflateDecoderSpec->GetInputProcessedSize() + 2; }
UInt64 GetOutputProcessedSize() const { return AdlerSpec->GetSize(); }
MY_UNKNOWN_IMP
};
static bool inline IsZlib(const Byte *p)
{
if ((p[0] & 0xF) != 8) // method
return false;
if (((unsigned)p[0] >> 4) > 7) // logar_window_size minus 8.
return false;
if ((p[1] & 0x20) != 0) // dictPresent
return false;
if ((((UInt32)p[0] << 8) + p[1]) % 31 != 0)
return false;
return true;
}
// IsZlib_3bytes checks 2 bytes of zlib header and starting byte of Deflate stream
static bool inline IsZlib_3bytes(const Byte *p)
{
if (!IsZlib(p))
return false;
unsigned val = p[2];
unsigned blockType = (val >> 1) & 0x3;
if (blockType == 3) // unsupported block type for deflate
return false;
if (blockType == NCompress::NDeflate::NBlockType::kStored && (val >> 3) != 0)
return false;
return true;
}
}}
#endif
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