Question

我正在尝试为我实现的FPGA设计编写C＃串行接口。

作为接口程序的一部分，我需要计算CRC-8校验和。

我试图在较低的水平上做这个（因为这是我更熟悉的水平），但我遇到了问题。

我遇到的问题是第91-95行（例如第91行：TempChecksumBits[7] = ChecksumBits[6];）的作业不仅要分配TempChecksumBits[]，还要更改ChecksumBits[] }值。

任何想法？我非常感谢您的帮助，因为我不熟悉高级语言。

此致麦克

using System;
using System.Collections.Generic;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication2
{
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        byte[] ReadBuffer = new byte[20];
        ReadBuffer[0] = Convert.ToByte("10000001", 2);
        ReadBuffer[1] = Convert.ToByte("00000000", 2);
        ReadBuffer[2] = Convert.ToByte("11000011", 2);
        ReadBuffer[3] = Convert.ToByte("00001111", 2);
        ReadBuffer[4] = Convert.ToByte("01010101", 2);
        ReadBuffer[5] = Convert.ToByte("00001111", 2);
        ReadBuffer[6] = Convert.ToByte("01010101", 2);
        ReadBuffer[7] = Convert.ToByte("00001111", 2);
        ReadBuffer[8] = Convert.ToByte("01010101", 2);
        ReadBuffer[9] = Convert.ToByte("00001111", 2);
        ReadBuffer[10] = Convert.ToByte("01010101", 2);
        ReadBuffer[11] = Convert.ToByte("00001111", 2);
        ReadBuffer[12] = Convert.ToByte("01010101", 2);
        ReadBuffer[13] = Convert.ToByte("00001111", 2);
        ReadBuffer[14] = Convert.ToByte("01010101", 2);
        ReadBuffer[15] = Convert.ToByte("00001111", 2);
        ReadBuffer[16] = Convert.ToByte("01010101", 2);
        ReadBuffer[17] = Convert.ToByte("00001111", 2);
        ReadBuffer[18] = Convert.ToByte("01010101", 2);
        ReadBuffer[19] = Convert.ToByte("11100111", 2);
        CheckDataPacket(ReadBuffer);

    }


           private void CheckDataPacket(byte[] ReadBuffer)
           {
               byte[] Checksum = new byte[1];
               Checksum[0] =   Convert.ToByte("00000000", 2);
               byte[] DataBytes = new byte[18];
               DataBytes[0] = ReadBuffer[2];
               DataBytes[1] = ReadBuffer[3];
               DataBytes[2] = ReadBuffer[4];
               DataBytes[3] = ReadBuffer[5];
               DataBytes[4] = ReadBuffer[6];
               DataBytes[5] = ReadBuffer[7];
               DataBytes[6] = ReadBuffer[8];
               DataBytes[7] = ReadBuffer[9];
               DataBytes[8] = ReadBuffer[10];
               DataBytes[9] = ReadBuffer[11];
               DataBytes[10] = ReadBuffer[12];
               DataBytes[11] = ReadBuffer[13];
               DataBytes[12] = ReadBuffer[14];
               DataBytes[13] = ReadBuffer[15];
               DataBytes[14] = ReadBuffer[16];
               DataBytes[15] = ReadBuffer[17];
               DataBytes[16] = ReadBuffer[18];
               DataBytes[17] = ReadBuffer[1];

               CalculateChecksum(DataBytes, ref Checksum);
               textBox1.Text = (Convert.ToString(Checksum[0]));

           }

           private void CalculateChecksum(byte[] DataBytes, ref byte[] Checksum)
           {
               BitArray ChecksumBits = new BitArray(Checksum);
               BitArray TempChecksumBits = new BitArray(Checksum);

               for (int i = 0; i < 18; i++)
               {
                   byte[] CurrentByte = new byte[1];
                   CurrentByte[0] = DataBytes[i];
                   BitArray DataBits = new BitArray(CurrentByte);

                   for (int k = 0; k < 8; k++)
                   {

                       TempChecksumBits[7] = ChecksumBits[6];
                       TempChecksumBits[6] = ChecksumBits[5];
                       TempChecksumBits[5] = ChecksumBits[4];
                       TempChecksumBits[4] = ChecksumBits[3];
                       TempChecksumBits[3] = ChecksumBits[2];

                       if ((ChecksumBits[7]) == (ChecksumBits[1]))
                       {
                           TempChecksumBits[2] = false;
                       }

                       else
                       {
                           TempChecksumBits[2] = true;
                       }

                       if ((ChecksumBits[7]) == (ChecksumBits[0]))
                       {
                           TempChecksumBits[1] = false;
                       }

                       else
                       {
                           TempChecksumBits[1] = true;
                       }


                       if ((DataBits[7-k]) == (ChecksumBits[7]))
                       {
                           TempChecksumBits[0] = false;
                       }

                       else
                       {
                           TempChecksumBits[0] = true;
                       }
                       ChecksumBits = TempChecksumBits;
                   }
               }
               /////////////// re-form checksum Byte/////////////////////
               for (int j = 0; j < 8; j++)
               {
                   if (ChecksumBits[j] == true)
                   {
                       double Value = Math.Pow(2, j);
                       Checksum[0] += (byte)(Value);
                   }
               }
           }



    }
}

Answer 1

这一行是问题，就在所有if / else块的末尾：

ChecksumBits = TempChecksumBits;

之后，这两个变量引用BitArray的同一个实例。目前尚不清楚你为什么这样做或者尝试实现的目标，但显然没有做你真正想要的事情。

请注意所有块都是这样的：

if ((ChecksumBits[7]) == (ChecksumBits[1]))
{
    TempChecksumBits[2] = false;
}
else
{
    TempChecksumBits[2] = true;
}

可以简化为：

TempChecksumBits[2] = ChecksumBits[7] != ChecksumBits[1];

...这将使您的代码更多更简单。

（我还强烈建议您使用camelCase而不是PascalCase命名本地变量。）

说实话，我很想使用byte和位移/交换技术而不是所有BitArray个对象......

按位运算的赋值问题

1 个答案: