core/src/fxcodec/jbig2/JBig2_BitStream.h

// Copyright 2014 PDFium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com

#ifndef _JBIG2_BIT_STREAM_H_
#define _JBIG2_BIT_STREAM_H_
#include "JBig2_Define.h"
class CJBig2_BitStream : public CJBig2_Object
{
public:

    CJBig2_BitStream(FX_BYTE *pBuffer, FX_DWORD dwLength);

    CJBig2_BitStream(CJBig2_BitStream &bs);

    ~CJBig2_BitStream();

    FX_INT32 readNBits(FX_DWORD nBits, FX_DWORD *dwResult);

    FX_INT32 readNBits(FX_DWORD nBits, FX_INT32 *nResult);

    FX_INT32 read1Bit(FX_DWORD *dwResult);

    FX_INT32 read1Bit(FX_BOOL  *bResult);

    FX_INT32 read1Byte(FX_BYTE *cResult);

    FX_INT32 readInteger(FX_DWORD *dwResult);

    FX_INT32 readShortInteger(FX_WORD *wResult);

    void alignByte();

    void align4Byte();

    FX_BYTE getAt(FX_DWORD dwOffset);

    FX_BYTE getCurByte();

    FX_BYTE getNextByte();

    FX_INT32 incByteIdx();

    FX_BYTE getCurByte_arith();

    FX_BYTE getNextByte_arith();

    FX_DWORD getOffset();

    void setOffset(FX_DWORD dwOffset);

    FX_DWORD getBitPos();

    void setBitPos(FX_DWORD dwBitPos);

    FX_BYTE *getBuf();

    FX_DWORD getLength()
    {
        return m_dwLength;
    }

    FX_BYTE *getPointer();

    void offset(FX_DWORD dwOffset);

    FX_DWORD getByteLeft();
private:

    FX_BYTE *m_pBuf;

    FX_DWORD m_dwLength;

    FX_DWORD m_dwByteIdx;

    FX_DWORD m_dwBitIdx;
};
inline CJBig2_BitStream::CJBig2_BitStream(FX_BYTE *pBuffer, FX_DWORD dwLength)
{
    m_pBuf = pBuffer;
    m_dwLength = dwLength;
    m_dwByteIdx = 0;
    m_dwBitIdx  = 0;
    if (m_dwLength > 256 * 1024 * 1024) {
        m_dwLength = 0;
        m_pBuf = NULL;
    }
}
inline CJBig2_BitStream::CJBig2_BitStream(CJBig2_BitStream &bs)
{
    m_pBuf = bs.m_pBuf;
    m_dwLength = bs.m_dwLength;
    m_dwByteIdx = bs.m_dwByteIdx;
    m_dwBitIdx = bs.m_dwBitIdx;
}
inline CJBig2_BitStream::~CJBig2_BitStream()
{
}
inline FX_INT32 CJBig2_BitStream::readNBits(FX_DWORD dwBits, FX_DWORD *dwResult)
{
    FX_DWORD dwTemp = (m_dwByteIdx << 3) + m_dwBitIdx;
    if(dwTemp <= (m_dwLength << 3)) {
        *dwResult = 0;
        if(dwTemp + dwBits <= (m_dwLength << 3)) {
            dwTemp = dwBits;
        } else {
            dwTemp = (m_dwLength << 3) - dwTemp;
        }
        while(dwTemp > 0) {
            *dwResult = (*dwResult << 1) | ((m_pBuf[m_dwByteIdx] >> (7 - m_dwBitIdx)) & 0x01);
            if(m_dwBitIdx == 7) {
                m_dwByteIdx ++;
                m_dwBitIdx = 0;
            } else {
                m_dwBitIdx ++;
            }
            dwTemp --;
        }
        return 0;
    } else {
        return -1;
    }
}
inline FX_INT32 CJBig2_BitStream::readNBits(FX_DWORD dwBits, FX_INT32 *nResult)
{
    FX_DWORD dwTemp = (m_dwByteIdx << 3) + m_dwBitIdx;
    if(dwTemp <= (m_dwLength << 3)) {
        *nResult = 0;
        if(dwTemp + dwBits <= (m_dwLength << 3)) {
            dwTemp = dwBits;
        } else {
            dwTemp = (m_dwLength << 3) - dwTemp;
        }
        while(dwTemp > 0) {
            *nResult = (*nResult << 1) | ((m_pBuf[m_dwByteIdx] >> (7 - m_dwBitIdx)) & 0x01);
            if(m_dwBitIdx == 7) {
                m_dwByteIdx ++;
                m_dwBitIdx = 0;
            } else {
                m_dwBitIdx ++;
            }
            dwTemp --;
        }
        return 0;
    } else {
        return -1;
    }
}

inline FX_INT32 CJBig2_BitStream::read1Bit(FX_DWORD *dwResult)
{
    if(m_dwByteIdx < m_dwLength) {
        *dwResult = (m_pBuf[m_dwByteIdx] >> (7 - m_dwBitIdx)) & 0x01;
        if(m_dwBitIdx == 7) {
            m_dwByteIdx ++;
            m_dwBitIdx = 0;
        } else {
            m_dwBitIdx ++;
        }
        return 0;
    } else {
        return -1;
    }
}

inline FX_INT32 CJBig2_BitStream::read1Bit(FX_BOOL *bResult)
{
    if(m_dwByteIdx < m_dwLength) {
        *bResult = (m_pBuf[m_dwByteIdx] >> (7 - m_dwBitIdx)) & 0x01;
        if(m_dwBitIdx == 7) {
            m_dwByteIdx ++;
            m_dwBitIdx = 0;
        } else {
            m_dwBitIdx ++;
        }
        return 0;
    } else {
        return -1;
    }
}
inline FX_INT32 CJBig2_BitStream::read1Byte(FX_BYTE *cResult)
{
    if(m_dwByteIdx < m_dwLength) {
        *cResult = m_pBuf[m_dwByteIdx];
        m_dwByteIdx ++;
        return 0;
    } else {
        return -1;
    }
}

inline FX_INT32 CJBig2_BitStream::readInteger(FX_DWORD *dwResult)
{
    if(m_dwByteIdx + 3 < m_dwLength) {
        *dwResult = (m_pBuf[m_dwByteIdx] << 24) | (m_pBuf[m_dwByteIdx + 1] << 16)
                    | (m_pBuf[m_dwByteIdx + 2] << 8) | m_pBuf[m_dwByteIdx + 3];
        m_dwByteIdx += 4;
        return 0;
    } else {
        return -1;
    }
}

inline FX_INT32 CJBig2_BitStream::readShortInteger(FX_WORD *dwResult)
{
    if(m_dwByteIdx + 1 < m_dwLength) {
        *dwResult = (m_pBuf[m_dwByteIdx] << 8) | m_pBuf[m_dwByteIdx + 1];
        m_dwByteIdx += 2;
        return 0;
    } else {
        return -1;
    }
}
inline void CJBig2_BitStream::alignByte()
{
    if(m_dwBitIdx != 0) {
        m_dwByteIdx ++;
        m_dwBitIdx = 0;
    }
}
inline void CJBig2_BitStream::align4Byte()
{
    if(m_dwBitIdx != 0) {
        m_dwByteIdx ++;
        m_dwBitIdx = 0;
    }
    m_dwByteIdx = (m_dwByteIdx + 3) & -4;
}
inline FX_BYTE CJBig2_BitStream::getAt(FX_DWORD dwOffset)
{
    if(dwOffset < m_dwLength) {
        return m_pBuf[dwOffset];
    } else {
        return 0;
    }
}
inline FX_BYTE CJBig2_BitStream::getCurByte()
{
    if(m_dwByteIdx < m_dwLength) {
        return m_pBuf[m_dwByteIdx];
    } else {
        return 0;
    }
}
inline FX_BYTE CJBig2_BitStream::getNextByte()
{
    if(m_dwByteIdx + 1 < m_dwLength) {
        return m_pBuf[m_dwByteIdx + 1];
    } else {
        return 0;
    }
}
inline FX_INT32 CJBig2_BitStream::incByteIdx()
{
    if(m_dwByteIdx < m_dwLength) {
        m_dwByteIdx ++;
        return 0;
    } else {
        return -1;
    }
}
inline FX_BYTE CJBig2_BitStream::getCurByte_arith()
{
    if(m_dwByteIdx < m_dwLength) {
        return m_pBuf[m_dwByteIdx];
    } else {
        return 0xff;
    }
}
inline FX_BYTE CJBig2_BitStream::getNextByte_arith()
{
    if(m_dwByteIdx + 1 < m_dwLength) {
        return m_pBuf[m_dwByteIdx + 1];
    } else {
        return 0xff;
    }
}
inline FX_DWORD CJBig2_BitStream::getOffset()
{
    return m_dwByteIdx;
}
inline void CJBig2_BitStream::setOffset(FX_DWORD dwOffset)
{
    if (dwOffset > m_dwLength) {
        dwOffset = m_dwLength;
    }
    m_dwByteIdx = dwOffset;
}
inline FX_DWORD CJBig2_BitStream::getBitPos()
{
    return (m_dwByteIdx << 3) + m_dwBitIdx;
}
inline void CJBig2_BitStream::setBitPos(FX_DWORD dwBitPos)
{
    m_dwByteIdx = dwBitPos >> 3;
    m_dwBitIdx = dwBitPos & 7;
}
inline FX_BYTE *CJBig2_BitStream::getBuf()
{
    return m_pBuf;
}
inline FX_BYTE *CJBig2_BitStream::getPointer()
{
    return m_pBuf + m_dwByteIdx;
}
inline void CJBig2_BitStream::offset(FX_DWORD dwOffset)
{
    m_dwByteIdx += dwOffset;
}
inline FX_DWORD CJBig2_BitStream::getByteLeft()
{
    return m_dwLength - m_dwByteIdx;
}
#endif