dcmjpls/libcharls/encodstr.h

//
// (C) Jan de Vaan 2007-2010, all rights reserved. See the accompanying "License.txt" for licensed use.
//

#ifndef CHARLS_ENCODERSTRATEGY
#define CHARLS_ENCODERSTRATEGY

#include "dcmtk/ofstd/ofaptr.h"
#include "procline.h"
#include "decodstr.h"

// Implements encoding to stream of bits. In encoding mode JpegLsCodec inherits from EncoderStrategy

class EncoderStrategy
{

public:
    explicit EncoderStrategy(const JlsParameters& info) :
         _qdecoder(0),
         _info(info),
         _processLine(0),
         valcurrent(0),
         bitpos(0),
         _isFFWritten(false),
         _bytesWritten(0)

    {
    }

    virtual ~EncoderStrategy()
    {
    }

    LONG PeekByte();

    void OnLineBegin(LONG cpixel, void* ptypeBuffer, LONG pixelStride)
    {
        _processLine->NewLineRequested(ptypeBuffer, cpixel, pixelStride);
    }

    void OnLineEnd(LONG /*cpixel*/, void* /*ptypeBuffer*/, LONG /*pixelStride*/) { }

    virtual void SetPresets(const JlsCustomParameters& presets) = 0;

    virtual size_t EncodeScan(const void* pvoid, void* pvoidOut, size_t byteCount, void* pvoidCompare) = 0;

protected:

    void Init(BYTE* compressedBytes, size_t byteCount)
    {
        bitpos = 32;
        valcurrent = 0;
        _position = compressedBytes;
        _compressedLength = byteCount;
    }


    void AppendToBitStream(LONG value, LONG length)
    {
        ASSERT(length < 32 && length >= 0);

        ASSERT((_qdecoder.get() == NULL) || (length == 0 && value == 0) ||( _qdecoder->ReadLongValue(length) == value));

#ifndef NDEBUG
        if (length < 32)
        {
            int mask = (1 << (length)) - 1;
            ASSERT((value | mask) == mask);
        }
#endif

        bitpos -= length;
        if (bitpos >= 0)
        {
            valcurrent = valcurrent | (value << bitpos);
            return;
        }
        valcurrent |= value >> -bitpos;

        Flush();

        ASSERT(bitpos >=0);
        valcurrent |= value << bitpos;

    }

    void EndScan()
    {
        Flush();

        // if a 0xff was written, Flush() will force one unset bit anyway
        if (_isFFWritten)
            AppendToBitStream(0, (bitpos - 1) % 8);
        else
            AppendToBitStream(0, bitpos % 8);

        Flush();
        ASSERT(bitpos == 0x20);
    }

    void Flush()
    {
        for (LONG i = 0; i < 4; ++i)
        {
            if (bitpos >= 32)
                break;

            if (_isFFWritten)
            {
                // insert highmost bit
                *_position = BYTE(valcurrent >> 25);
                valcurrent = valcurrent << 7;
                bitpos += 7;
                _isFFWritten = false;
            }
            else
            {
                *_position = BYTE(valcurrent >> 24);
                valcurrent = valcurrent << 8;
                bitpos += 8;
                _isFFWritten = *_position == 0xFF;
            }

            _position++;
            _compressedLength--;
            _bytesWritten++;

        }

    }

    size_t GetLength()
    {
        return _bytesWritten - (bitpos -32)/8;
    }


    inlinehint void AppendOnesToBitStream(LONG length)
    {
        AppendToBitStream((1 << length) - 1, length);
    }


    OFauto_ptr<DecoderStrategy> _qdecoder;

protected:
    JlsParameters _info;
    OFauto_ptr<ProcessLine> _processLine;
private:

    unsigned int valcurrent;
    LONG bitpos;
    size_t _compressedLength;

    // encoding
    BYTE* _position;
    bool _isFFWritten;
    size_t _bytesWritten;

};

#endif

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