DOCUMENT:Q38216  06-MAY-2001  [masm]
TITLE   :PRB: Possible Cause of L2002 for Mixed C, MASM in Large Model
PRODUCT :Microsoft Macro Assembler
PROD/VER::5.0,5.1,5.1a,6.0,6.0a,6.0b
OPER/SYS:
KEYWORDS:

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Macro Assembler (MASM), versions 5.0, 5.1, 5.1a, 6.0, 6.0a, 6.0b 
-------------------------------------------------------------------------------

SYMPTOMS
========

If a variable is referenced externally in an assembler routine in the following
manner:

      .model large, c

      .data
      EXTRN Var:WORD

and declared globally in a large model C program as follows:

      int Var;

the following error is generated:

   error L2002: fixup overflow

CAUSE
=====

This error occurs because the assembler would expect to find Var in the segment
_DATA in DGROUP. The C declaration, however, will put var in the segment
FAR_BSS, since it is an uninitialized global data item in the large memory
model.

Note that the same is true for the compact memory model.

RESOLUTION
==========

One way to eliminate this error is to initialize Var in the C code:

      int Var=0;

This will put it in the _DATA logical segment in DGROUP.

Another work-around is to delcare Var in the Assembly code so that the assembler
would expect to find Var in FAR_BSS, as follows:

      .model large, c

      .fardata?
      EXTERN Var:WORD

In addition, be sure to use a segment override to access Var:

      MOV ax, SEG Var
      MOV es, ax
      MOV bx, es:Var

Additional query words: 5.00 5.10 5.10a 6.00 6.00a 6.00b

======================================================================
Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper kbMASM510 kbMASM600 kbMASM500 kbMASM600a kbMASM510a kbMASM600b
Version           : :5.0,5.1,5.1a,6.0,6.0a,6.0b

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

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2001.