如何编写Copymem Lib" Kernel32" Alias" Rtlmovememory"在Vb.Net

时间:2015-02-04 09:42:43

标签: vb.net visual-studio-2010 vb6 copymemory

下面是我的vb6代码

    Private Declare Sub CopyMem Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)


Public Property Let Key(New_Value As String)

  Dim i As Long
  Dim j As Long
  Dim K As Long
  Dim dataX As Long
  Dim datal As Long
  Dim datar As Long
  Dim Key() As Byte
  Dim KeyLength As Long

  'Do nothing if the key is buffered
  If (m_KeyValue = New_Value) Then Exit Property
  m_KeyValue = New_Value

  'Convert the new key into a bytearray
  KeyLength = Len(New_Value)
  Key() = StrConv(New_Value, vbFromUnicode)

  'Create key-dependant p-boxes
  j = 0
  For i = 0 To (ROUNDS + 1)
    dataX = 0
    For K = 0 To 3
      Call CopyMem(ByVal VarPtr(dataX) + 1, dataX, 3) 'the problem is here
      dataX = (dataX Or Key(j))
      j = j + 1
      If (j >= KeyLength) Then j = 0
    Next
    m_pBox(i) = m_pBox(i) Xor dataX
  Next

End Property

CopyMem sub lib我如何在vb.net中使用它

现在这里是我的vb.net代码相同的

  Private Declare Sub CopyMem Lib "KERNEL32" Alias "RtlMoveMemory" (ByVal pDst As Object, ByVal pSrc As Object, ByVal ByteLen As Integer)


 Public WriteOnly Property Key() As String
        Set(ByVal Value As String)

            Dim i As Long
            Dim j As Long
            Dim K As Long
            Dim dataX As Long
            Dim datal As Long
            Dim datar As Long
            Dim Key() As Byte
            Dim KeyLength As Long

            'Do nothing if the key is buffered
            If (m_KeyValue = Value) Then Exit Property
            m_KeyValue = Value

            'Convert the new key into a bytearray
            KeyLength = Len(Value)

            Key = System.Text.Encoding.Unicode.GetBytes(Value)

            'Create key-dependant p-boxes
            j = 0

            For i = 0 To (ROUNDS + 1)
                dataX = 0
                For K = 0 To 3


                    CopyMem(VarPtr(dataX) + 1, dataX, 3) ' the problem is here
                    dataX = (dataX Or Key(j))
                    j = j + 1
                    If (j >= KeyLength) Then j = 0

                Next
                m_pBox(i) = m_pBox(i) Xor dataX
            Next
 End Property

这是VarPtr

的代码
Public Function VarPtr(ByVal e As Object) As Object
        Dim GC As GCHandle = GCHandle.Alloc(e, GCHandleType.Pinned)
        Dim GC2 As Integer = GC.AddrOfPinnedObject.ToInt32
        GC.Free()
        Return GC2
    End Function

我已提到Equivalent of CopyMemory in .NET

但我仍然没有得到这个

请有人帮忙!!!

1 个答案:

答案 0 :(得分:3)

如果要使用.NET中的指针访问数据,则需要在整个操作期间将它们固定。 VarPtr方法在获取对象的地址时固定对象,但随后它会取消对象。这意味着在进行CopyMem调用时可以移动对象。大多数情况下,对象没有被移动,所以看起来效果很好,但是当它被移动时,CopyMem操作可能会改变其他一些数据。这可能会使应用程序中的任何对象行为异常,或者使应用程序崩溃。

无论如何,使用内存复制对于在整数中移动几位来说肯定是过度的。 (顺便说一句,VB 6中的Long数据类型对应于VB.NET中的Integer数据类型。)

您可以将整数转换为字节数组,使用Array.Copy方法,然后将其转换回来:

Dim temp As Byte() = BitConverter.GetBytes(dataX)
Array.Copy(temp, 0, temp, 1, 3)
dataX = BitConverter.ToInt32(temp, 0)

您也可以使用位操作:

dataX = (dataX And &HFF) Or (dataX << 8)

附注:Encoding.Unicode用于UTF-16编码。这意味着GetBytes返回的字节数组将是字符串长度的两倍,因此您只使用字符串的一半。