How to Call DLL Functions Inside ABAP

"-Begin-----------------------------------------------------------------
  Program zCallDLL.

    "-TypePools---------------------------------------------------------
      Type-Pools OLE2 .

    "-Constants---------------------------------------------------------
      Constants CrLf(2) Type c Value %_CR_LF.
      Constants OUTPUT_CONSOLE Type i Value 0.
      Constants OUTPUT_WINDOW Type i Value 1.
      Constants OUTPUT_BUFFER Type i Value 2.

    "-Variables---------------------------------------------------------
      Data PS Type OLE2_OBJECT.
      Data Result Type i Value 0.
      Data strResult Type String Value ''.
      Data tabResult Type Table Of String.
      Data PSCode Type String Value ''.

    "-Macros------------------------------------------------------------
      Define _.
        Concatenate PSCode &1 CrLf Into PSCode.
      End-Of-Definition.

    "-Main--------------------------------------------------------------
      Create Object PS 'SAPIEN.ActiveXPoSH'.
      If sy-subrc = 0 And PS-Handle <> 0 And PS-Type = 'OLE2'.

        Call Method Of PS 'Init' = Result Exporting #1 = 0.
        If Result = 0.

          Call Method Of PS 'IsPowerShellInstalled' = Result.
          If Result <> 0.
            Set Property Of PS 'OutputMode' = OUTPUT_BUFFER.

_ '$sig = @"'.
_ '[DllImport("User32.dll")]'.
_ 'public static extern int MessageBoxA(int hWnd, String Text, String Caption, int Type);'.
_ '"@;'.
_ '$DLL_User32 = Add-Type PBexpMsgBox -MemberDefinition $sig -PassThru'.
_ '$DLL_User32::MessageBoxA(0, "Hello World", "From WinAPI", 0);'.

            Call Method Of PS 'Execute' Exporting
              #1 = PSCode.

            Call Method Of PS 'OutputString' = strResult.

            Split strResult At cl_abap_char_utilities=>cr_lf
              Into Table tabResult.
            Loop At tabResult Into strResult.
              Write: / strResult.
            EndLoop.

          EndIf.

        EndIf.

        Free Object PS.

      EndIf.

"-End-------------------------------------------------------------------