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1 // ZlibDecoder.cpp
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2
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3 #include "StdAfx.h"
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4
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5 #include "../Common/StreamUtils.h"
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6
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7 #include "DeflateDecoder.h"
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8 #include "ZlibDecoder.h"
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9
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10 namespace NCompress {
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11 namespace NZlib {
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12
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13 #define DEFLATE_TRY_BEGIN try {
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14 #define DEFLATE_TRY_END } \
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15 catch(...) { return S_FALSE; }
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16
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17 #define ADLER_MOD 65521
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18 #define ADLER_LOOP_MAX 5550
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19
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20 static UInt32 Adler32_Update(UInt32 adler, const Byte *buf, size_t size)
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21 {
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22 UInt32 a = adler & 0xFFFF;
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23 UInt32 b = (adler >> 16) & 0xFFFF;
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24 while (size > 0)
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25 {
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26 unsigned curSize = (size > ADLER_LOOP_MAX) ? ADLER_LOOP_MAX : (unsigned )size;
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27 unsigned i;
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28 for (i = 0; i < curSize; i++)
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29 {
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30 a += buf[i];
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31 b += a;
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32 }
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33 buf += curSize;
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34 size -= curSize;
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35 a %= ADLER_MOD;
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36 b %= ADLER_MOD;
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37 }
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38 return (b << 16) + a;
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39 }
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40
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41 STDMETHODIMP COutStreamWithAdler::Write(const void *data, UInt32 size, UInt32 *processedSize)
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42 {
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43 HRESULT result = _stream->Write(data, size, &size);
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44 _adler = Adler32_Update(_adler, (const Byte *)data, size);
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45 if (processedSize != NULL)
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46 *processedSize = size;
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47 return result;
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48 }
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49
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50 STDMETHODIMP CDecoder::Code(ISequentialInStream *inStream, ISequentialOutStream *outStream,
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51 const UInt64 *inSize, const UInt64 *outSize, ICompressProgressInfo *progress)
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52 {
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53 DEFLATE_TRY_BEGIN
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54 if (!AdlerStream)
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55 {
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56 AdlerSpec = new COutStreamWithAdler;
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57 AdlerStream = AdlerSpec;
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58 }
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59 if (!DeflateDecoder)
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60 {
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61 DeflateDecoderSpec = new NCompress::NDeflate::NDecoder::CCOMCoder;
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62 DeflateDecoderSpec->ZlibMode = true;
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63 DeflateDecoder = DeflateDecoderSpec;
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64 }
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65
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66 Byte buf[2];
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67 RINOK(ReadStream_FALSE(inStream, buf, 2));
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68 int method = buf[0] & 0xF;
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69 if (method != 8)
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70 return S_FALSE;
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71 // int dicSize = buf[0] >> 4;
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72 if ((((UInt32)buf[0] << 8) + buf[1]) % 31 != 0)
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73 return S_FALSE;
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74 if ((buf[1] & 0x20) != 0) // dictPresent
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75 return S_FALSE;
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76 // int level = (buf[1] >> 6);
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77
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78 AdlerSpec->SetStream(outStream);
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79 AdlerSpec->Init();
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80 HRESULT res = DeflateDecoder->Code(inStream, AdlerStream, inSize, outSize, progress);
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81 AdlerSpec->ReleaseStream();
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82
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83 if (res == S_OK)
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84 {
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85 const Byte *p = DeflateDecoderSpec->ZlibFooter;
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86 UInt32 adler = ((UInt32)p[0] << 24) | ((UInt32)p[1] << 16) | ((UInt32)p[2] << 8) | p[3];
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87 if (adler != AdlerSpec->GetAdler())
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88 return S_FALSE;
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89 }
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90 return res;
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91 DEFLATE_TRY_END
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92 }
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93
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94 }}
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