1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/other-licenses/7zstub/src/7zip/Common/MSBFDecoder.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,69 @@
1.4 +// MSBFDecoder.h
1.5 +// the Most Significant Bit of byte is First
1.6 +
1.7 +#ifndef __STREAM_MSBFDECODER_H
1.8 +#define __STREAM_MSBFDECODER_H
1.9 +
1.10 +#include "../../Common/Types.h"
1.11 +#include "../IStream.h"
1.12 +
1.13 +namespace NStream {
1.14 +namespace NMSBF {
1.15 +
1.16 +const int kNumBigValueBits = 8 * 4;
1.17 +const int kNumValueBytes = 3;
1.18 +const int kNumValueBits = 8 * kNumValueBytes;
1.19 +
1.20 +const UInt32 kMask = (1 << kNumValueBits) - 1;
1.21 +
1.22 +template<class TInByte>
1.23 +class CDecoder
1.24 +{
1.25 + UInt32 m_BitPos;
1.26 + UInt32 m_Value;
1.27 +public:
1.28 + TInByte m_Stream;
1.29 + bool Create(UInt32 bufferSize) { return m_Stream.Create(bufferSize); }
1.30 + void SetStream(ISequentialInStream *inStream) { m_Stream.SetStream(inStream);}
1.31 + void ReleaseStream() { m_Stream.ReleaseStream();}
1.32 +
1.33 + void Init()
1.34 + {
1.35 + m_Stream.Init();
1.36 + m_BitPos = kNumBigValueBits;
1.37 + Normalize();
1.38 + }
1.39 +
1.40 + UInt64 GetProcessedSize() const
1.41 + { return m_Stream.GetProcessedSize() - (kNumBigValueBits - m_BitPos) / 8; }
1.42 + UInt32 GetBitPosition() const { return (m_BitPos & 7); }
1.43 +
1.44 + void Normalize()
1.45 + {
1.46 + for (;m_BitPos >= 8; m_BitPos -= 8)
1.47 + m_Value = (m_Value << 8) | m_Stream.ReadByte();
1.48 + }
1.49 +
1.50 + UInt32 GetValue(UInt32 numBits) const
1.51 + {
1.52 + // return (m_Value << m_BitPos) >> (kNumBigValueBits - numBits);
1.53 + return ((m_Value >> (8 - m_BitPos)) & kMask) >> (kNumValueBits - numBits);
1.54 + }
1.55 +
1.56 + void MovePos(UInt32 numBits)
1.57 + {
1.58 + m_BitPos += numBits;
1.59 + Normalize();
1.60 + }
1.61 +
1.62 + UInt32 ReadBits(UInt32 numBits)
1.63 + {
1.64 + UInt32 res = GetValue(numBits);
1.65 + MovePos(numBits);
1.66 + return res;
1.67 + }
1.68 +};
1.69 +
1.70 +}}
1.71 +
1.72 +#endif
