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