Extract can frame data signal

extract_can_signal.cpp

#define MASK32(nbits) ((0xffffffff)>> (32-nbits))

uint32_t extractSignal(uint8_t* frame, uint8_t startbit, uint8_t length, bool is_big_endian)
{
    uint8_t startByte = startbit/8;
    uint8_t startBitInByte = startbit % 8;
    uint8_t endByte = 0;
    uint8_t count = 0;
    uint8_t target = frame[startByte] >> startBitInByte;
    uint8_t currentTargetLength = (8-startBitInByte);

    if(is_big_endian) // (big endian)
    {
        endByte = startByte - ((length-(8-startBitInByte))/8); // wow if this works???

        for(count = startByte-1; count > endByte; count --)
        {
            target |= frame[count] << currentTargetLength;
            currentTargetLength += 8;
        }
    }
    else // Intel (little endian)
    {
        endByte = (startbit+length) / 8;

        for(count = startByte+1; count < endByte; count ++)
        {
            target |= frame[count] << currentTargetLength;
            currentTargetLength += 8;
        }
    }

    target &= MASK32(length);
    return target;
}