C#校验和CRC16 CCITT

using System;

public class CRC16CCITT
{
    private const ushort polynomial = 0x1021;
    private ushort[] table = new ushort[256];
    private ushort initialValue = 0xFFFF;

    public CRC16CCITT()
    {
        GenerateTable();
    }

    private void GenerateTable()
    {
        for (ushort i = 0; i < table.Length; ++i)
        {
            ushort value = 0;
            ushort temp = (ushort)(i << 8);
            for (byte j = 0; j < 8; ++j)
            {
                if (((value ^ temp) & 0x8000) != 0)
                {
                    value = (ushort)((value << 1) ^ polynomial);
                }
                else
                {
                    value <<= 1;
                }
                temp <<= 1;
            }
            table[i] = value;
        }
    }

    public ushort ComputeChecksum(byte[] bytes)
    {
        ushort crc = initialValue;
        foreach (byte b in bytes)
        {
            byte index = (byte)((crc >> 8) ^ b);
            crc = (ushort)((crc << 8) ^ table[index]);
        }
        return crc;
    }

    public byte[] ComputeChecksumBytes(byte[] bytes)
    {
        ushort crc = ComputeChecksum(bytes);
        return BitConverter.GetBytes(crc);
    }
}

class Program
{
    static void Main()
    {
        CRC16CCITT crc16 = new CRC16CCITT();
        byte[] data = System.Text.Encoding.ASCII.GetBytes("123456789");
        ushort checksum = crc16.ComputeChecksum(data);
        Console.WriteLine("CRC16-CCITT Checksum: 0x" + checksum.ToString("X4"));
    }
}