我如何使用此函数来计算CHECKSUM

Question

我正在尝试计算串行通信的校验和。所以我做了一个字节数组的数据缓冲区。我不知道如何使用此字节的数据缓冲区数组来实现此功能。因为此函数的参数类型是字节指针。如何使用此功能？

byte[] arrayForChecksum // for databuffer

// calculating a checksum for C#
public unsafe static ushort CalcCRC(byte * pDataBuffer, uint usDataLen)
{
        byte nTemp;
        ushort wCRCWord = 0xFFFF;

        while ((usDataLen--) != 0)
        {
            nTemp = (byte)(wCRCWord ^*pDataBuffer++);
            wCRCWord >>= 8;
            wCRCWord ^= TABLE_CRCVALUE[nTemp];
        }

        return wCRCWord;
}


// original code in C
unsigned short CalcCRC(unsigned char* pDataBuffer, unsigned long usDataLen)
{       
    unsigned char nTemp;
    unsigned short wCRCWord = 0xFFFF;

    while (usDataLen--)
   {
        nTemp = wCRCWord ^ *(pDataBuffer++);
        wCRCWord >>= 8;
        wCRCWord ^= TABLE_CRCVALUE[nTemp];
    }

    return wCRCWord;
}

Answer 1

您可以将校验和用于任何内容。例如，您可以将将从数据库中获取的文本转换为字节数组并计算校验和值。

public class Crc16
{
    private const ushort polynomial = 0xA001;
    private static readonly ushort[] refTable = new ushort[256];

    public Crc16()
    {
        GenerateReferanceTable();
    }

    private void GenerateReferanceTable()
    {
        ushort value;
        ushort temp;

        for (ushort i = 0; i < refTable.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;
            }

            refTable[i] = value;
        }
    }

    public ushort Calculate(byte[] bytes)
    { 
        ushort crc = 0; 

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

        return crc;
    }
}

用法：

byte[] bytes = new byte[] { 0, 1, 2, 3, 204, 120 }; 
Crc16 crc16 = new Crc16();
ushort checksum = crc16.Calculate(bytes);


string data = "Calculate Checksum";
byte[] bytesFromString = Encoding.ASCII.GetBytes(someString);
ushort checksumForString = crc16.Calculate(bytesFromString); 

您也可以签出我的项目。

https://github.com/hidayetcolkusu/ChecksumManager