C# CRC

  public static string CRC16(string cmdString)

        {

            try

            {

                //CRC寄存器

                //int CRCCode = 0;

              

                ushort crc = 0xFFFF;

                for (int i = 0; i < cmdString.Length / 2; i++)

                {

                    ushort cmdHex =(ushort)Convert.ToInt16( cmdString.Substring(i * 2, 2),16);

                    crc = (ushort)(crc ^ (cmdHex));

                    for (int j = 0; j < 8; j++)

                    {

                        crc = (crc & 1) != 0 ? (ushort)((crc >> 1) ^ 0xA001) : (ushort)(crc >> 1);

                    }

                }

                byte hi = (byte)((crc & 0xFF00) >> 8); //高位置

                byte lo = (byte)(crc & 0x00FF); //低位置

                string his = Convert.ToString(hi, 16);

                string los = Convert.ToString(lo, 16);

                string res = los + his;

                return res;              

                  

              

            }

            catch

            {

                throw;

            }

        }