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comparison: other-licenses/7zstub/src/7zip/Common/LSBFDecoder.h
other-licenses/7zstub/src/7zip/Common/LSBFDecoder.h
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| -1:000000000000 | 0:dee299fe3eb4 |
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| 1 // LSBFDecoder.h | |
| 2 | |
| 3 #ifndef __STREAM_LSBFDECODER_H | |
| 4 #define __STREAM_LSBFDECODER_H | |
| 5 | |
| 6 #include "../IStream.h" | |
| 7 | |
| 8 namespace NStream { | |
| 9 namespace NLSBF { | |
| 10 | |
| 11 const int kNumBigValueBits = 8 * 4; | |
| 12 | |
| 13 const int kNumValueBytes = 3; | |
| 14 const int kNumValueBits = 8 * kNumValueBytes; | |
| 15 | |
| 16 const UInt32 kMask = (1 << kNumValueBits) - 1; | |
| 17 | |
| 18 extern Byte kInvertTable[256]; | |
| 19 // the Least Significant Bit of byte is First | |
| 20 | |
| 21 template<class TInByte> | |
| 22 class CBaseDecoder | |
| 23 { | |
| 24 protected: | |
| 25 int m_BitPos; | |
| 26 UInt32 m_Value; | |
| 27 TInByte m_Stream; | |
| 28 public: | |
| 29 UInt32 NumExtraBytes; | |
| 30 bool Create(UInt32 bufferSize) { return m_Stream.Create(bufferSize); } | |
| 31 void SetStream(ISequentialInStream *inStream) { m_Stream.SetStream(inStream); } | |
| 32 void ReleaseStream() { m_Stream.ReleaseStream(); } | |
| 33 void Init() | |
| 34 { | |
| 35 m_Stream.Init(); | |
| 36 m_BitPos = kNumBigValueBits; | |
| 37 m_Value = 0; | |
| 38 NumExtraBytes = 0; | |
| 39 } | |
| 40 UInt64 GetProcessedSize() const | |
| 41 { return m_Stream.GetProcessedSize() - (kNumBigValueBits - m_BitPos) / 8; } | |
| 42 UInt64 GetProcessedBitsSize() const | |
| 43 { return (m_Stream.GetProcessedSize() << 3) - (kNumBigValueBits - m_BitPos); } | |
| 44 int GetBitPosition() const { return (m_BitPos & 7); } | |
| 45 | |
| 46 void Normalize() | |
| 47 { | |
| 48 for (;m_BitPos >= 8; m_BitPos -= 8) | |
| 49 { | |
| 50 Byte b; | |
| 51 if (!m_Stream.ReadByte(b)) | |
| 52 { | |
| 53 b = 0xFF; // check it | |
| 54 NumExtraBytes++; | |
| 55 } | |
| 56 m_Value = (b << (kNumBigValueBits - m_BitPos)) | m_Value; | |
| 57 } | |
| 58 } | |
| 59 | |
| 60 UInt32 ReadBits(int numBits) | |
| 61 { | |
| 62 Normalize(); | |
| 63 UInt32 res = m_Value & ((1 << numBits) - 1); | |
| 64 m_BitPos += numBits; | |
| 65 m_Value >>= numBits; | |
| 66 return res; | |
| 67 } | |
| 68 | |
| 69 bool ExtraBitsWereRead() const | |
| 70 { | |
| 71 if (NumExtraBytes == 0) | |
| 72 return false; | |
| 73 return ((UInt32)(kNumBigValueBits - m_BitPos) < (NumExtraBytes << 3)); | |
| 74 } | |
| 75 }; | |
| 76 | |
| 77 template<class TInByte> | |
| 78 class CDecoder: public CBaseDecoder<TInByte> | |
| 79 { | |
| 80 UInt32 m_NormalValue; | |
| 81 | |
| 82 public: | |
| 83 void Init() | |
| 84 { | |
| 85 CBaseDecoder<TInByte>::Init(); | |
| 86 m_NormalValue = 0; | |
| 87 } | |
| 88 | |
| 89 void Normalize() | |
| 90 { | |
| 91 for (;this->m_BitPos >= 8; this->m_BitPos -= 8) | |
| 92 { | |
| 93 Byte b; | |
| 94 if (!this->m_Stream.ReadByte(b)) | |
| 95 { | |
| 96 b = 0xFF; // check it | |
| 97 this->NumExtraBytes++; | |
| 98 } | |
| 99 m_NormalValue = (b << (kNumBigValueBits - this->m_BitPos)) | m_NormalValue; | |
| 100 this->m_Value = (this->m_Value << 8) | kInvertTable[b]; | |
| 101 } | |
| 102 } | |
| 103 | |
| 104 UInt32 GetValue(int numBits) | |
| 105 { | |
| 106 Normalize(); | |
| 107 return ((this->m_Value >> (8 - this->m_BitPos)) & kMask) >> (kNumValueBits - numBits); | |
| 108 } | |
| 109 | |
| 110 void MovePos(int numBits) | |
| 111 { | |
| 112 this->m_BitPos += numBits; | |
| 113 m_NormalValue >>= numBits; | |
| 114 } | |
| 115 | |
| 116 UInt32 ReadBits(int numBits) | |
| 117 { | |
| 118 Normalize(); | |
| 119 UInt32 res = m_NormalValue & ( (1 << numBits) - 1); | |
| 120 MovePos(numBits); | |
| 121 return res; | |
| 122 } | |
| 123 }; | |
| 124 | |
| 125 }} | |
| 126 | |
| 127 #endif |
