DOCUMENT:Q99336  12-NOV-1999  [win16sdk]
TITLE   :PRB: Combined Windows 3.0 and 3.1 Applications
PRODUCT :Microsoft Windows Software Development Kit
PROD/VER:WINDOWS:3.0
OPER/SYS:
KEYWORDS:kb16bitonly

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The information in this article applies to:

 - Microsoft Windows Software Development Kit (SDK) 3.0 
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When a combined Windows 3.0 and 3.1 application is run under the debugging
version of Windows 3.0, during load time, a Fatal Exit message "Invalid
Ordinal Reference" is displayed on the debug terminal followed by a stack
trace.

Note, however, that the application continues to load and run successfully,
and therefore this error message can be ignored as long as the Windows 3.1
function is not actually called.

CAUSE
=====

While loading an application, the Windows 3.0 kernel attempts to fix up
references to all function calls in the application. At load time, the Windows
3.0 kernel is unaware of the version checking being done on the Windows
3.1-specific calls. The version 3.0 kernel will attempt to fix up the references
to the Windows 3.1 calls too, which are undefined, and therefore the Fatal Exit
message is generated.

RESOLUTION
==========

The Fatal Exit message can be ignored because the application will run
successfully.

If this behavior (the Fatal Exit message) is not satisfactory, use the following
workaround to call Windows 3.1-specific calls in a Windows 3.0 application
without generating any Fatal Exit messages:

   extern BOOL fWin31;
     // Assuming fWin31 is initialized appropriately using GetVersion().

          if (fWin31)
          {
             // Get the address of the Window 3.1-specific function.

            // First, load either USER.EXE, GDI.EXE, or KERNEL.EXE,
            // depending on which DLL the function resides in.
             LoadLibrary(...);

             // Get the address of that function using GetProcAddress().
             lpfnWin31FuncAddr = GetProcAddress(...);

             // Use this address to make the function call.
             (*lpfnWin31FuncAddr)(...);
           }

This method will not generate a Fatal Exit message under the debug version of
Windows 3.0, because there is no direct reference made to a Windows 3.1
function.

For a quick reference on how this method works, please see the DIBVIEW sample
provided with the Windows SDK. The source file PRINT.C adopts this same
technique in the FindGDIFunction() routine before calling any GDI functions
specific to Windows 3.1.

MORE INFORMATION
================

Microsoft Windows version 3.0 applications can be written to conditionally link
to and use Windows version 3.1 functions to take advantage of the newer features
when running under Windows 3.1. This is explained in the "Combined Windows 3.0
and 3.1 Applications" section on page 31 of the Microsoft Windows SDK "Getting
Started" manual for version 3.1.

This behavior may not be suitable for certain applications or could lead to other
problems. For example, on systems that do not have a debug terminal connected to
the COM1 port to receive debug information, Kernel will display a "Cannot write
to device AUX" message box or the system might freeze. The debug message could
be redirected from the AUX device to some other destination, if desired. For
information on how to do this, please query on the following words in the
Microsoft Knowledge Base:

   redirect debug information


Additional query words: 3.10 RIP

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Keywords          : kb16bitonly 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK300
Version           : WINDOWS:3.0

=============================================================================

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