Question

我将C＃代码转换为VB.NET以进行CRC16计算。但是，我在C＃和VB.NET上得到了不同的结果。我很困惑！有人可以指出我正确的方向吗？

    //C# Codes
    UInt16 CalculateCRC(Byte dchar, UInt16 crc16)
        {
            UInt16 mask = (UInt16) (dchar & 0x00FF);
            crc16 = (UInt16)(crc16 ^ mask);

            for (int i = 0; i < 8; i++)
            {
                UInt16 compare = (UInt16)(crc16 & 0x0001);

                if ( compare == 1)
                {
                    mask = (UInt16)(crc16 / 2);
                    crc16 = (UInt16)(mask ^ 0xA001);
                }
                else 
                {
                    mask = (UInt16)(crc16 / 2);
                    crc16 = mask;
                }
            }

            return crc16;
        }

    'VB.NET Codes
    Private Function CalculateCRC(ByVal dchar As Byte, ByVal crc16 As UInt16) As UInt16
        Dim mask As UInt16 = Convert.ToUInt16((dchar And &HFF))
        crc16 = Convert.ToUInt16((crc16 Xor mask))

        Dim compare As UInt16

        For i As Integer = 0 To 7
            compare = Convert.ToUInt16((crc16 And &H1))

            If compare = 1 Then
                mask = Convert.ToUInt16((crc16 / 2))
                crc16 = Convert.ToUInt16((mask Xor &HA001))
            Else
                mask = Convert.ToUInt16((crc16 / 2))
                crc16 = mask
            End If

        Next

        Return crc16
    End Function

OUTPUT

    dchar = 1

    Variable values for each iteration (0 to 7)

    C#
    COMPARE : 0,     1,     0,     1,     0,     1,    0,     1
    MASK    : 32767, 16383, 20479, 10239, 17407, 8703, 16639, 8319,
    CRC16   : 32767, 40958, 20479, 38414, 17407, 33278, 16639, 32894

    VB.NET
    COMPARE : 0,     1,     1,     1,     1,     1,     1,     1
    MASK    : 32767, 16384, 28672, 26624, 25600, 25088, 24832, 24704
    CRC16   : 32767, 57345, 53249, 51201, 50177, 49665, 49409, 49281

有人可以指出我在VB代码中哪里做错了吗？显然，C＃代码产生了正确的结果。

Answer 1

Jimi在评论中指出，您需要使用整数除法-同样，'CUShort'应该足够：

Private Function CalculateCRC(ByVal dchar As Byte, ByVal crc16 As UInt16) As UInt16
        Dim mask As UInt16 = CUShort(dchar And &HFF)
        crc16 = CUShort(crc16 Xor mask)

        For i As Integer = 0 To 7
            Dim compare As UInt16 = CUShort(crc16 And &H1)

            If compare = 1 Then
                mask = CUShort(crc16 \ 2)
                crc16 = CUShort(mask Xor &HA001)
            Else
                mask = CUShort(crc16 \ 2)
                crc16 = mask
            End If
        Next i

        Return crc16
End Function

为什么我在C＃和VB.NET之间得到不同的CRC16结果？

1 个答案: