C++To ruby,...

gistfile1.txt

  def self.crc16(buf)
    crc = 0xffff
    buf.each_byte do |b|
      crc = (crc >> 8) ^ CRC_LOOKUP[(crc ^ b) & 0xff]
    end
    ~crc
  end

gistfile2.txt

U16 GetCrc16(const U8* pData, size_t nLength)
{
	U16 fcs = 0xffff; // initialization
	while(nLength>0){
		fcs = (fcs >> 8) ^ crctab16[(fcs ^ *pData) & 0xff];
		nLength--;
		pData++;
	}
	return ~fcs; // negated
}