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// ZlibDecoder.cpp
#include "StdAfx.h"
#include "../Common/StreamUtils.h"
#include "ZlibDecoder.h"
namespace NCompress {
namespace NZlib {
#define DEFLATE_TRY_BEGIN try {
#define DEFLATE_TRY_END } catch(...) { return S_FALSE; }
#define ADLER_MOD 65521
#define ADLER_LOOP_MAX 5550
UInt32 Adler32_Update(UInt32 adler, const Byte *buf, size_t size)
{
UInt32 a = adler & 0xFFFF;
UInt32 b = (adler >> 16) & 0xFFFF;
while (size > 0)
{
unsigned curSize = (size > ADLER_LOOP_MAX) ? ADLER_LOOP_MAX : (unsigned )size;
unsigned i;
for (i = 0; i < curSize; i++)
{
a += buf[i];
b += a;
}
buf += curSize;
size -= curSize;
a %= ADLER_MOD;
b %= ADLER_MOD;
}
return (b << 16) + a;
}
STDMETHODIMP COutStreamWithAdler::Write(const void *data, UInt32 size, UInt32 *processedSize)
{
HRESULT result = _stream->Write(data, size, &size);
_adler = Adler32_Update(_adler, (const Byte *)data, size);
if (processedSize != NULL)
*processedSize = size;
return result;
}
STDMETHODIMP CDecoder::Code(ISequentialInStream *inStream, ISequentialOutStream *outStream,
const UInt64 *inSize, const UInt64 *outSize, ICompressProgressInfo *progress)
{
DEFLATE_TRY_BEGIN
if (!AdlerStream)
AdlerStream = AdlerSpec = new COutStreamWithAdler;
if (!DeflateDecoder)
{
DeflateDecoderSpec = new NDeflate::NDecoder::CCOMCoder;
DeflateDecoderSpec->ZlibMode = true;
DeflateDecoder = DeflateDecoderSpec;
}
Byte buf[2];
RINOK(ReadStream_FALSE(inStream, buf, 2));
int method = buf[0] & 0xF;
if (method != 8)
return S_FALSE;
// int dicSize = buf[0] >> 4;
if ((((UInt32)buf[0] << 8) + buf[1]) % 31 != 0)
return S_FALSE;
if ((buf[1] & 0x20) != 0) // dictPresent
return S_FALSE;
// int level = (buf[1] >> 6);
AdlerSpec->SetStream(outStream);
AdlerSpec->Init();
HRESULT res = DeflateDecoder->Code(inStream, AdlerStream, inSize, outSize, progress);
AdlerSpec->ReleaseStream();
if (res == S_OK)
{
const Byte *p = DeflateDecoderSpec->ZlibFooter;
UInt32 adler = ((UInt32)p[0] << 24) | ((UInt32)p[1] << 16) | ((UInt32)p[2] << 8) | p[3];
if (adler != AdlerSpec->GetAdler())
return S_FALSE;
}
return res;
DEFLATE_TRY_END
}
}}
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