将按位操作从Visual Basic转换为C＃

Question

Having mixed results when trying to translate a function using bitwise operations from Visual Basic to C#.

I'm sure I'm missing something really (visually) basic.

Here's the original VB code:

Dim CRCresult As UInt16 = 0
Dim CRC_16_POLY As UInt16 = &HA001

Private Sub CRC16(newByte As Byte)
    CRCresult = CRCresult Xor newByte
    For i As Integer = 0 To 7
        If (CRCresult And &H1) Then
            CRCresult = (CRCresult >> 1) Xor CRC_16_POLY
        Else
            CRCresult = (CRCresult >> 1)
        End If
    Next
End Sub

When I feed it the first 8 terms of this array:

{&H47, &H41, &H50, &H53, &H41, &HC, &H0, &H1, &H0, &H0, &H0, &HFF}

CRCresult appears as follows:

12864, 49395, 31104, 40248, 9949, 23782, 35549, 39307

Below is my translation to C#:

private UInt16 CRCresult = 0;
private UInt16 CRC_16_POLY = 0xA001;

private void CRC16(byte newByte)
{
    CRCresult = (UInt16)(CRCresult ^ newByte);
    for (int i = 0; i <= 7; i++) {
        if((CRCresult & 0x1) != 0)
        {
            CRCresult = (UInt16)((CRCresult >> 1) ^ CRC_16_POLY);
        } else
        {
            CRCresult = (UInt16)(CRCresult >> 1);
        }
    }
}

When I feed it the first 8 terms of this array:

{ 0x47, 0x41, 0x50, 0x53, 0x41, 0xC, 0x0, 0x1, 0x0, 0x0, 0x0, 0xFF }

CRCresult appears as follows:

12864, 49395, 31104, 40248, 57948, 15586, 18876, 29065  

In summary

  newBytes          CRCresult 
  VB |  C#  |      VB   | C# 
-------------    ---------------
&H47 | 0x47 |     12864 | 12864
&H41 | 0x41 |     49395 | 49395
&H50 | 0x50 |     31104 | 31104
&H53 | 0x53 |     40248 | 40248
&H41 | 0x41 |     9949  | 57948
&HC  | 0xC  |     23782 | 15586
&H0  | 0x0  |     35549 | 18876
&H1  | 0x1  |     39307 | 29065
&H0  | 0x0  |
&H0  | 0x0  |
&H0  | 0x0  |
&HFF | 0xFF |

What am I missing in my translation that's causing the differences in the results?

Answer 1

both implementations are correct and produce same results

i found a sequence with a different value at pos 5 (index 4) &H4f instead &H41

thisgenerate your (VB) results:

{&H47, &H41, &H50, &H53, &H4f, &HC, &H0, &H1, &H0, &H0, &H0, &HFF}

and this for (C#) results:

{&H47, &H41, &H50, &H53, &H41, &HC, &H0, &H1, &H0, &H0, &H0, &HFF}

maybe a small typing error in your test data? :-)