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