Function SetBits

3rdParty/StormLib/src/SBaseFileTable.cpp:149–214

}

void SetBits(
    TBitArray * pArray,
    unsigned int nBitPosition,
    unsigned int nBitLength,
    void * pvBuffer,
    int nResultByteSize)
{
    unsigned char * pbBuffer = (unsigned char *)pvBuffer;
    unsigned int nBytePosition = (nBitPosition / 8);
    unsigned int nBitOffset = (nBitPosition & 0x07);
    unsigned short BitBuffer = 0;
    unsigned short AndMask = 0;
    unsigned short OneByte = 0;

    // Keep compiler happy for platforms where nResultByteSize is not used
    nResultByteSize = nResultByteSize;

#ifndef PLATFORM_LITTLE_ENDIAN
    // Adjust the buffer pointer for big endian platforms
    pbBuffer += (nResultByteSize - 1);
#endif

    // Copy whole bytes, if any
    while(nBitLength > 8)
    {
        // Reload the bit buffer
#ifdef PLATFORM_LITTLE_ENDIAN
        OneByte = *pbBuffer++;
#else
        OneByte = *pbBuffer--;
#endif
        // Update the BitBuffer and AndMask for the bit array
        BitBuffer = (BitBuffer >> 0x08) | (OneByte << nBitOffset);
        AndMask = (AndMask >> 0x08) | (0x00FF << nBitOffset);

        // Update the byte in the array
        pArray->Elements[nBytePosition] = (BYTE)((pArray->Elements[nBytePosition] & ~AndMask) | BitBuffer);

        // Move byte positions and lengths
        nBytePosition++;
        nBitLength -= 0x08;
    }

    if(nBitLength != 0)
    {
        // Reload the bit buffer
        OneByte = *pbBuffer;

        // Update the AND mask for the last bit
        BitBuffer = (BitBuffer >> 0x08) | (OneByte << nBitOffset);
        AndMask = (AndMask >> 0x08) | (SetBitsMask[nBitLength] << nBitOffset);

        // Update the byte in the array
        pArray->Elements[nBytePosition] = (BYTE)((pArray->Elements[nBytePosition] & ~AndMask) | BitBuffer);

        // Update the next byte, if needed
        if(AndMask & 0xFF00)
        {