Simone
d074cc7c07
Plugin: ns7zip v2.0.0 Architectures: x86-ansi, x86-unicode, amd64-unicode License: LGPL-2.1-or-later
91 lines
2.1 KiB
C++
91 lines
2.1 KiB
C++
// BitmEncoder.h -- the Most Significant Bit of byte is First
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#ifndef ZIP7_INC_BITM_ENCODER_H
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#define ZIP7_INC_BITM_ENCODER_H
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#include "../IStream.h"
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template<class TOutByte>
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class CBitmEncoder
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{
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unsigned _bitPos; // 0 < _bitPos <= 8 : number of non-filled low bits in _curByte
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unsigned _curByte; // low (_bitPos) bits are zeros
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// high (8 - _bitPos) bits are filled
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TOutByte _stream;
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public:
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bool Create(UInt32 bufferSize) { return _stream.Create(bufferSize); }
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void SetStream(ISequentialOutStream *outStream) { _stream.SetStream(outStream);}
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UInt64 GetProcessedSize() const { return _stream.GetProcessedSize() + ((8 - _bitPos + 7) >> 3); }
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void Init()
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{
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_stream.Init();
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_bitPos = 8;
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_curByte = 0;
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}
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HRESULT Flush()
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{
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if (_bitPos < 8)
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{
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_stream.WriteByte((Byte)_curByte);
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_bitPos = 8;
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_curByte = 0;
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}
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return _stream.Flush();
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}
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// required condition: (value >> numBits) == 0
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// numBits == 0 is allowed
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void WriteBits(UInt32 value, unsigned numBits)
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{
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do
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{
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unsigned bp = _bitPos;
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unsigned curByte = _curByte;
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if (numBits < bp)
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{
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bp -= numBits;
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_curByte = curByte | (value << bp);
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_bitPos = bp;
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return;
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}
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numBits -= bp;
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const UInt32 hi = (value >> numBits);
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value -= (hi << numBits);
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_stream.WriteByte((Byte)(curByte | hi));
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_bitPos = 8;
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_curByte = 0;
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}
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while (numBits);
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}
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void WriteByte(unsigned b)
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{
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const unsigned bp = _bitPos;
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const unsigned a = _curByte | (b >> (8 - bp));
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_curByte = b << bp;
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_stream.WriteByte((Byte)a);
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}
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void WriteBytes(const Byte *data, size_t num)
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{
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const unsigned bp = _bitPos;
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#if 1 // 1 for optional speed-optimized code branch
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if (bp == 8)
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{
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_stream.WriteBytes(data, num);
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return;
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}
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#endif
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unsigned c = _curByte;
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const unsigned bp_rev = 8 - bp;
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for (size_t i = 0; i < num; i++)
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{
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const unsigned b = data[i];
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_stream.WriteByte((Byte)(c | (b >> bp_rev)));
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c = b << bp;
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}
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_curByte = c;
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}
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};
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#endif
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