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使用 Visual Basic 通过 32 位 地址访问内存(中英对照)         ★★★★

使用 Visual Basic 通过 32 位 地址访问内存(中英对照)

作者:闵涛 文章来源:闵涛的学习笔记 点击数:2875 更新时间:2009/4/23 16:38:16
OfArray = VarPtrStringArray ( MyArrayOfStrings() )

  '''' gives you the Address of the first element in the Array and First
  '''' character of this element, ie, Address where "C" is located in
  '''' Memory

  '''' *** How about it, you dont have MIDL compiler? or dont want to go
  '''' into a process of creating Type Library and Referencing it manually,
  '''' a simple approach of using StrPtr will be handly enough for you, since
  '''' this function has the capability of getting the Address of a String, and
  '''' each element in an Array of Strings is non other than String, so you
  '''' get the picture clear, you have to point your call to the first element
  '''' of the Array of String and call

  AddressOfArray = StrPtr ( MyArrayOfStrings(0) )

  '''' returns the same result as the above call


 3] ObjPtr - Returns the Address of an Object

  Object Oriented Programming consist of Objects, and these objects also
  stored into Memory together with all of its properties, as a structured
  layout, and to obtain its location you need to call ObjPtr Funtion

  ex.
   '''' You want to know where is your Form1 resides in Memory, this
   '''' Method gives you the Address, in Thread

   Dim objMyObject As New Form1

   MsgBox "Form1 located at : " & Hex( ObjPtr( objMyObject ) )


Ok, from this point, you are thinking on, How in the world should this Address becomes
useful in anyways? well the answer is very clear if you think this way, an Address is
a Location in Memory, and your Variables is a Location in Memory with its own Location
in Memory, confused? well, to make it simple, you can simply think that this Address is
a Location where Datas are stored, and Datas are READABLE and WRITABLE, but you need the
Address to have it Written or Read the Data on it, Hmmm, Is Visual Basic Capable of
doing these things?

Well, not, if you think plain as in Visual Basic Capability, but APIs are functions that
are ready for use by you application, the APIs im blabing about is a RunTime Libararies
called RtlMoveMemory and RtlCopyMemory, exported by KERNEL32.DLL.

Aint it charming? First we have found a way to achieve a Memory Address by converting a
Variable into a Pointer, Now we have ways to Read and Write to anf from these addresses,
but how you may ask? By adding either one of this Declarations to your Application, but not
both, since they funtion the same, i suggest use the second one since it supported by all
Windows System, while RtlCopyMemory is not.


 Private Declare Sub CopyMemory _
                     Lib "kernel32" Alias _
                     "RtlCopyMemory" _
                     (Destination As Any, _
                      Source As Any, _
                      ByVal length As Long)
 '''' RtlCopyMemory copies the contents of one buffer to another.

 '''' OR

 Private Declare Sub CopyMemory _
                     Lib "kernel32" Alias _
                     "RtlMoveMemory" _
                     (Destination As Any, _
                      Source As Any, _
                      ByVal length As Long)

 '''' RtlMoveMemory moves memory either forward or backward, aligned or unaligned,
 '''' in 4-byte blocks, followed by any remaining bytes.

Parameters:

 Destination
  Points to the destination of the move.

 Source
  Points to the memory to be copied.

 Length
  Specifies the number of bytes to be copied.

To make it more easy to Use, Included the File modMemory.bas for Copy and Paste
in this Article:

------------cut here------------------------------------------------------------------

 Attribute VB_Name = "modMemory"
 '''' =============================================================================
 '''' Copy Memory API
 '''' =============================================================================
 Private Declare Sub CopyMemory _
                     Lib "kernel32" Alias _
                     "RtlMoveMemory" _
                     (Destination As Any, _
                      Source As Any, _
                      ByVal length As Long)
                    
 '''' =============================================================================
 '''' Data Sizes
 '''' =============================================================================
 Public Enum e_BinaryData
     DefineByte = 1                          ''''  8 Bits Data
     DefineWord = 2                          '''' 16 Bits Data
     DefineDoubleWord = 4                    '''' 32 Bits Data
     DefineQuadWord = 8                      '''' 64 Bits Data
 End Enum

 '''' =============================================================================
 '''' Allows Direct Reading from Memory Pointed by MemPointer
 '''' with definition of bytes used as in Asm (DB, DW, DD, DX)
 '''' =============================================================================
 Function ReadMem(ByVal MemPointer As Long, _
                  SizeInBytes As e_BinaryData)
     Select Case SizeInBytes
         Case DefineByte
             Dim DB As Byte
             CopyMemory DB, ByVal MemPointer, 1
             ReadMem = DB
         Case DefineWord
             Dim DW As Integer
             CopyMemory DW, ByVal MemPointer, 2
             ReadMem = DW
         Case DefineDoubleWord
             Dim DD As Long
             CopyMemory DD, ByVal MemPointer, 4
             ReadMem = DD
         Case DefineQuadWord
             Dim DX As Double
             CopyMemory DX, ByVal MemPointer, 8
             ReadMem = DX
     End Select
 End Function

 '''' =============================================================================
 '''' Allows Direct Writing to Memory Pointed by MemPointer
 '''' with definition of bytes used as in Asm (DB, DW, DD, DX)
 '''' =============================================================================
 Sub WriteMem(ByVal MemPointer As Long, _
              SizeInBytes As e_BinaryData, _
              ByVal DataToWrite)
   

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