/*--------------------------------------------------------------------------
 * Calculate a new CRC16 from the input data shorteger.  Return the current
 * CRC16 and also update the global variable CRC16.
 */
const short oddparity[16] = { 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0 };

unsigned short docrc16(unsigned short data)
{
   data = (data ^ (CRC16 & 0xff)) & 0xff;
   CRC16 >>= 8;
    if (oddparity[data & 0xf] ^ oddparity[data >> 4])
     CRC16 ^= 0xc001;

   data <<= 6;
   CRC16   ^= data;
   data <<= 1;
   CRC16   ^= data;
   return CRC16;
}