Calling the DLL Function

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Once you have obtained the address of the target DLL function, you can call it from APP16 using the CallProcEx32W function.

These examples call MyPrint, passing two arguments, a string and a window handle. All parameters must be 32-bit values. Therefore, the string is declared using a FAR pointer, as shown here:

char FAR *TestString = "Hello there";

You must convert the 16-bit window handle to a 32-bit window handle using the WOWHandle32 function, as shown here:

// Convert the window handle.
DWORD hWnd32;
hWnd32 = WOWHandle32(hWnd, WOW_TYPE_HWND);

The following example uses CallProcEx32W.

// Call the MyPrint routine in the Win32-based DLL
CallProcEx32W( 2 | CPEX_DEST_STDCALL, 
                                   2, 
                               hProc, 
                  (DWORD) TestString, 
                              hWnd32);

A mask of 2 (0x10) is given because we want to pass TestString by reference and hProc by value. The system translates the pointer for us.

If you are isolating your thunking code into DLL16, put the call to CallProcEx32W in the MyPrint function of the DLL16 code.