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Q74670: FIX: MASM 5.1/5.1a Cause LINK to Put Uninitialized Data in .EXE

Article: Q74670
Product(s): Microsoft Macro Assembler
Version(s): winnt:5.10,5.10a
Operating System(s): 
Keyword(s): 
Last Modified: 19-OCT-2000

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The information in this article applies to:

- Microsoft Macro Assembler (32-bit), versions 5.10, 5.10a, on platform(s):
   - the operating system: MS-DOS 
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SYMPTOMS
========

When using the .DATA? directive with the Microsoft Macro Assembler (MASM)
versions 5.1 and 5.1a, uninitialized data elements may be incorrectly allocated
space in the .EXE file.

STATUS
======

Microsoft has confirmed this to be a problem in MASM versions 5.1 and 5.1a. This
problem was corrected in MASM version 6.0.

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

The .DATA? directive indicates the start of the uninitialized data segment, and
data declared here is not allocated space in the resulting executable file.
However, when declaring an array of structures under .DATA? in MASM 5.1a, space
is incorrectly allocated in the .EXE, and the size of the executable program is
correspondingly increased.

The example code below shows a structure and an array of 100 structure elements
being declared. The resulting .EXE size is 1616 (the size of the code [516] plus
1100 [the data size]). However, This amount should only be the code size, 516,
because these array elements are uninitialized.

Sample Code
-----------

  ; Assemble options needed: none

  .MODEL small

  .DATA?
  testing STRUC
      a DB 3 DUP(?)
      b DB 8 DUP(?)
  testing ENDS

  array testing 100 DUP(<>)

  .CODE
     mov ax,4C00h
     int 21h
  END

Additional query words: 5.10 5.10a 6.00 buglist5.10 buglist5.10a fixlist6.00

======================================================================
Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper
Version           : winnt:5.10,5.10a
Solution Type     : kbfix

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