1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/other-licenses/7zstub/src/7zip/Common/LSBFDecoder.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,127 @@
1.4 +// LSBFDecoder.h
1.5 +
1.6 +#ifndef __STREAM_LSBFDECODER_H
1.7 +#define __STREAM_LSBFDECODER_H
1.8 +
1.9 +#include "../IStream.h"
1.10 +
1.11 +namespace NStream {
1.12 +namespace NLSBF {
1.13 +
1.14 +const int kNumBigValueBits = 8 * 4;
1.15 +
1.16 +const int kNumValueBytes = 3;
1.17 +const int kNumValueBits = 8 * kNumValueBytes;
1.18 +
1.19 +const UInt32 kMask = (1 << kNumValueBits) - 1;
1.20 +
1.21 +extern Byte kInvertTable[256];
1.22 +// the Least Significant Bit of byte is First
1.23 +
1.24 +template<class TInByte>
1.25 +class CBaseDecoder
1.26 +{
1.27 +protected:
1.28 + int m_BitPos;
1.29 + UInt32 m_Value;
1.30 + TInByte m_Stream;
1.31 +public:
1.32 + UInt32 NumExtraBytes;
1.33 + bool Create(UInt32 bufferSize) { return m_Stream.Create(bufferSize); }
1.34 + void SetStream(ISequentialInStream *inStream) { m_Stream.SetStream(inStream); }
1.35 + void ReleaseStream() { m_Stream.ReleaseStream(); }
1.36 + void Init()
1.37 + {
1.38 + m_Stream.Init();
1.39 + m_BitPos = kNumBigValueBits;
1.40 + m_Value = 0;
1.41 + NumExtraBytes = 0;
1.42 + }
1.43 + UInt64 GetProcessedSize() const
1.44 + { return m_Stream.GetProcessedSize() - (kNumBigValueBits - m_BitPos) / 8; }
1.45 + UInt64 GetProcessedBitsSize() const
1.46 + { return (m_Stream.GetProcessedSize() << 3) - (kNumBigValueBits - m_BitPos); }
1.47 + int GetBitPosition() const { return (m_BitPos & 7); }
1.48 +
1.49 + void Normalize()
1.50 + {
1.51 + for (;m_BitPos >= 8; m_BitPos -= 8)
1.52 + {
1.53 + Byte b;
1.54 + if (!m_Stream.ReadByte(b))
1.55 + {
1.56 + b = 0xFF; // check it
1.57 + NumExtraBytes++;
1.58 + }
1.59 + m_Value = (b << (kNumBigValueBits - m_BitPos)) | m_Value;
1.60 + }
1.61 + }
1.62 +
1.63 + UInt32 ReadBits(int numBits)
1.64 + {
1.65 + Normalize();
1.66 + UInt32 res = m_Value & ((1 << numBits) - 1);
1.67 + m_BitPos += numBits;
1.68 + m_Value >>= numBits;
1.69 + return res;
1.70 + }
1.71 +
1.72 + bool ExtraBitsWereRead() const
1.73 + {
1.74 + if (NumExtraBytes == 0)
1.75 + return false;
1.76 + return ((UInt32)(kNumBigValueBits - m_BitPos) < (NumExtraBytes << 3));
1.77 + }
1.78 +};
1.79 +
1.80 +template<class TInByte>
1.81 +class CDecoder: public CBaseDecoder<TInByte>
1.82 +{
1.83 + UInt32 m_NormalValue;
1.84 +
1.85 +public:
1.86 + void Init()
1.87 + {
1.88 + CBaseDecoder<TInByte>::Init();
1.89 + m_NormalValue = 0;
1.90 + }
1.91 +
1.92 + void Normalize()
1.93 + {
1.94 + for (;this->m_BitPos >= 8; this->m_BitPos -= 8)
1.95 + {
1.96 + Byte b;
1.97 + if (!this->m_Stream.ReadByte(b))
1.98 + {
1.99 + b = 0xFF; // check it
1.100 + this->NumExtraBytes++;
1.101 + }
1.102 + m_NormalValue = (b << (kNumBigValueBits - this->m_BitPos)) | m_NormalValue;
1.103 + this->m_Value = (this->m_Value << 8) | kInvertTable[b];
1.104 + }
1.105 + }
1.106 +
1.107 + UInt32 GetValue(int numBits)
1.108 + {
1.109 + Normalize();
1.110 + return ((this->m_Value >> (8 - this->m_BitPos)) & kMask) >> (kNumValueBits - numBits);
1.111 + }
1.112 +
1.113 + void MovePos(int numBits)
1.114 + {
1.115 + this->m_BitPos += numBits;
1.116 + m_NormalValue >>= numBits;
1.117 + }
1.118 +
1.119 + UInt32 ReadBits(int numBits)
1.120 + {
1.121 + Normalize();
1.122 + UInt32 res = m_NormalValue & ( (1 << numBits) - 1);
1.123 + MovePos(numBits);
1.124 + return res;
1.125 + }
1.126 +};
1.127 +
1.128 +}}
1.129 +
1.130 +#endif
