C# CRC-CCITT (Kermit)校验方法

using System;

public enum Crc16Mode : ushort { Standard = 0xA001, CcittKermit = 0x8408 }

public class Crc16 {
    static ushort[] table = new ushort[256];

    public ushort ComputeChecksum( params byte[] bytes ) {
        ushort crc = 0;
        for(int i = 0; i < bytes.Length; ++i) {
            byte index = (byte)(crc ^ bytes[i]);
            crc = (ushort)((crc >> 8) ^ table[index]);
        }
        return crc;
    }

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

    public Crc16( Crc16Mode mode ) {
        ushort polynomial = (ushort)mode;
        ushort value;
        ushort temp;
        for(ushort i = 0; i < table.Length; ++i) {
            value = 0;
            temp = i;
            for(byte j = 0; j < 8; ++j) {
                if(((value ^ temp) & 0x0001) != 0) {
                    value = (ushort)((value >> 1) ^ polynomial);
                }else {
                    value >>= 1;
                }
                temp >>= 1;
            }
            table[i] = value;
        }
    }
}