Microsoft KB Archive/74670

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

Article ID: 74670

Article Last Modified on 10/20/2003

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APPLIES TO


 * Microsoft Macro Assembler 5.1 Standard Edition, when used with:
 * Microsoft MS-DOS 6.22 Standard Edition
 * Microsoft Macro Assembler 5.1a, when used with:
 * Microsoft MS-DOS 6.22 Standard Edition

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This article was previously published under Q74670



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: kbfix KB74670

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