计算字符串或字节数组的CRC16的VB.NET示例
计算字符串或字节数组的CRC16的VB.NET示例
提问于 2014-04-11 17:44:17
参考这个链接Calculate CRC32 of an String or Byte Array我修改了代码来计算CRC16而不是CRC32，但是我得到了错误的结果，有人能告诉我错误在哪里吗？
Private Sub Main()
Crc16.ComputeChecksum(Encoding.UTF8.GetBytes("Some string"))
End Sub
Public Class CRC16
Shared table As UShort()
Shared Sub New()
Dim poly As UShort = &HA001US 'calculates CRC-16 using A001 polynomial (modbus)
table = New UShort(255) {}
Dim temp As UShort = 0
For i As UShort = 0 To table.Length - 1
temp = i
For j As Integer = 8 To 1 Step -1
If (temp And 1) = 1 Then
temp = CUShort((temp >> 1) Xor poly)
Else
temp >>= 1
End If
Next
table(i) = temp
Next
End Sub
Public Shared Function ComputeChecksum(ByVal bytes As Byte()) As UShort
Dim crc As UShort = &H0US ' The calculation start with 0x00
For i As Integer = 0 To bytes.Length - 1
Dim index As Byte = CByte(((crc) And &HFF) Xor bytes(i))
crc = CUShort((crc >> 8) Xor table(index))
Next
Return Not crc
End Function
End Class回答 2
Stack Overflow用户
发布于 2014-10-28 21:30:17
试试这个，它是用于仪器控制的VB6代码。(sCommand是一个包含所有字节的临时字符串，结果被添加到sCommand中，Modbus首先使用LSB，TextToString和StringToAscii是用于将可读字符串"FF EE“转换为ASCII码并将其转换回来的函数，因此这里对它们不感兴趣)：
Private Sub cmdCRC16_Click()
Dim sCommand As String
Dim x As Long
Dim y As Long
Dim lCRC As Long
sCommand = TextToString(txtASCII)
'Initial value
lCRC = 65535 '(&HFFFF results in Integer -1)
For x = 1 To Len(sCommand)
lCRC = lCRC Xor Asc(Mid(sCommand, x, 1))
For y = 1 To 8
If (lCRC Mod 2) > 0 Then
lCRC = (lCRC And 65534) / 2
lCRC = lCRC Xor 40961 '(&HA001 results in whatever negative integer)
Else
lCRC = (lCRC And 65534) / 2
End If
Next y
Next x
'Add CRC with LSB first
sCommand = sCommand + Chr(lCRC And 255)
sCommand = sCommand + Chr((lCRC And 65280) / 256)
txtASCII = StringToASCII(sCommand)结束子对象
Stack Overflow用户
发布于 2017-02-25 04:56:48
我也遇到了同样的问题。简单的解决方案是省略结尾的否定，所以只需将"Return Not crc“更改为"Return crc”，就可以了。
CRC-16有多种变体，其中"CRC-16“不是指IBM变体，也称为"ARC”。它使用的XorOut值为零。参见Catalogue of parametrised CRC algorithms with 16 bits。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/23009036
复制相关文章
相似问题
腾讯云开发者
