Question

我需要一些帮助来为数组创建tcp数据包的校验和字节。
这是代码正在运行，因为我已经测试过它 string。
问题是我要将一个字节数组传递给它功能。
此刻我通过努力创造了它嵌入时间序列号，否则登录的代码很长到一个设备。
这个值是b1：68：de：3a：15：cd：5b：07用wireshark检查，CRC应该用在线crc检查E2B6 this

现在，为了达到要点，我无法调用此方法，因为此方法需要一些字符串值，并且我已经传递了十六进制值。我怎么能这样做。

Private Sub ConnectTCP_Click(sender As Object, e As EventArgs) Handles ConnectTCP.Click
Dim Serial As UInt32 = "123456789"
Dim time As UInt32 = "987654321"
Dim buffer2() As Byte = BitConverter.GetBytes(time)
Dim buffer3() As Byte = BitConverter.GetBytes(Serial)
Dim array4(buffer2.Length + buffer3.Length - 1) As Byte
Array.Copy(buffer2, array4, buffer2.Length)
Array.Copy(buffer3, 0, array4, buffer2.Length, buffer3.Length)
getCRC16(array4) 'What I need to do here
       end sub

＆＃34; CRC16 CCITT功能＆＃34;＆＃34;

Public Function getCRC16(ByVal strInput As String)
    Dim lngCheck As Long
    Dim Power(7) As Integer
    Dim I As Integer
    Dim J As Integer
    Dim Poly As Long
    Dim CRC As Long
    Dim TestBit As Boolean
    Dim TestBit1 As Boolean
    Dim TestBit2 As Boolean
    Poly = &H1021
    CRC = &HFFFF
    For J = 0 To 7
        Power(J) = 2 ^ J
    Next J
    For I = 1 To Len(strInput)
        lngCheck = Asc(Mid$(strInput, I, 1))
        For J = 7 To 0 Step -1
            If (CRC And 32768) = 32768 Then
                TestBit1 = True
            Else
                TestBit1 = False
            End If
            If (lngCheck And Power(J)) = Power(J) Then
                TestBit2 = True
            Else
                TestBit2 = False
            End If
            TestBit = TestBit1 Xor TestBit2
            CRC = (CRC And 32767) * 2
            If TestBit = True Then
                CRC = CRC Xor Poly
            End If
        Next J
    Next I
    Dim tmp As String
    tmp = Hex(CRC)
    CRCTCP.Text = tmp
    getCRC16 = tmp
End Function

Answer 1

最后，发现它。

Public Class CRC16CCITT
    Public Enum InitialCRCValue
        Zeroes = 0
        NonZero1 = &HFFFF
        NonZero2 = &H1D0F
        'NonZero3 = &H0
    End Enum

    Private Const poly As UShort = &H1021 'polynomial
    Dim table(255) As UShort
    Dim intValue As UShort = 0

    Public Function ComputeCheckSum(ByVal bytes As Byte()) As UShort
        Dim crc As UShort = Me.intValue
        'Dim x As String
        For i As Integer = 0 To bytes.Length - 1
            crc = CUShort(((crc << 8) Xor table(((crc >> 8) Xor (&HFF And bytes(i))))))
            'crc = (crc << 8) ^ (x << 15) ^ (x << 2) ^ x
        Next
        Return crc
    End Function

    Public Function ComputeCheckSumBytes(ByVal bytes As Byte()) As Byte()
        Dim crc As UShort = ComputeCheckSum(bytes)
        Return BitConverter.GetBytes(crc)
    End Function

    Public Sub New(ByVal initialvalue As InitialCRCValue)
        Me.intValue = CUShort(initialvalue)
        Dim temp, a As UShort
        For i As Integer = 0 To table.Length - 1
            temp = 0
            a = CUShort(i << 8)
            For j As Integer = 0 To 7
                If ((temp Xor a) And &H8000) <> 0 Then
                    temp = CUShort((temp << 1) Xor poly)
                Else
                    temp <<= 1
                End If
                a <<= 1
            Next
            table(i) = temp
        Next
    End Sub
End Class

来自字节数组的crc16 ccitt

1 个答案: