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comparison: other-licenses/7zstub/src/7zip/Common/MSBFDecoder.h
other-licenses/7zstub/src/7zip/Common/MSBFDecoder.h
- branch
- TOR_BUG_9701
- changeset 14
- 925c144e1f1f
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| -1:000000000000 | 0:8a9b41e2290d |
|---|---|
| 1 // MSBFDecoder.h | |
| 2 // the Most Significant Bit of byte is First | |
| 3 | |
| 4 #ifndef __STREAM_MSBFDECODER_H | |
| 5 #define __STREAM_MSBFDECODER_H | |
| 6 | |
| 7 #include "../../Common/Types.h" | |
| 8 #include "../IStream.h" | |
| 9 | |
| 10 namespace NStream { | |
| 11 namespace NMSBF { | |
| 12 | |
| 13 const int kNumBigValueBits = 8 * 4; | |
| 14 const int kNumValueBytes = 3; | |
| 15 const int kNumValueBits = 8 * kNumValueBytes; | |
| 16 | |
| 17 const UInt32 kMask = (1 << kNumValueBits) - 1; | |
| 18 | |
| 19 template<class TInByte> | |
| 20 class CDecoder | |
| 21 { | |
| 22 UInt32 m_BitPos; | |
| 23 UInt32 m_Value; | |
| 24 public: | |
| 25 TInByte m_Stream; | |
| 26 bool Create(UInt32 bufferSize) { return m_Stream.Create(bufferSize); } | |
| 27 void SetStream(ISequentialInStream *inStream) { m_Stream.SetStream(inStream);} | |
| 28 void ReleaseStream() { m_Stream.ReleaseStream();} | |
| 29 | |
| 30 void Init() | |
| 31 { | |
| 32 m_Stream.Init(); | |
| 33 m_BitPos = kNumBigValueBits; | |
| 34 Normalize(); | |
| 35 } | |
| 36 | |
| 37 UInt64 GetProcessedSize() const | |
| 38 { return m_Stream.GetProcessedSize() - (kNumBigValueBits - m_BitPos) / 8; } | |
| 39 UInt32 GetBitPosition() const { return (m_BitPos & 7); } | |
| 40 | |
| 41 void Normalize() | |
| 42 { | |
| 43 for (;m_BitPos >= 8; m_BitPos -= 8) | |
| 44 m_Value = (m_Value << 8) | m_Stream.ReadByte(); | |
| 45 } | |
| 46 | |
| 47 UInt32 GetValue(UInt32 numBits) const | |
| 48 { | |
| 49 // return (m_Value << m_BitPos) >> (kNumBigValueBits - numBits); | |
| 50 return ((m_Value >> (8 - m_BitPos)) & kMask) >> (kNumValueBits - numBits); | |
| 51 } | |
| 52 | |
| 53 void MovePos(UInt32 numBits) | |
| 54 { | |
| 55 m_BitPos += numBits; | |
| 56 Normalize(); | |
| 57 } | |
| 58 | |
| 59 UInt32 ReadBits(UInt32 numBits) | |
| 60 { | |
| 61 UInt32 res = GetValue(numBits); | |
| 62 MovePos(numBits); | |
| 63 return res; | |
| 64 } | |
| 65 }; | |
| 66 | |
| 67 }} | |
| 68 | |
| 69 #endif |
