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Q97840: FIX: DOSXNT DX1020 Error Using .WHILE and Processor Flag

Article: Q97840
Product(s): Microsoft Macro Assembler
Version(s): 6.1,6.1a; MS-DOS:6.0
Operating System(s): 
Keyword(s): 
Last Modified: 04-MAY-2001

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The information in this article applies to:

- Microsoft Macro Assembler (MASM), versions 6.1, 6.1a 
- Microsoft Macro Assembler (MASM), version 6.0, on platform(s):
   - the operating system: OS/2 
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SYMPTOMS
========

Microsoft Macro Assembler (MASM) version 6.1, and 6.1a may generate a DOSXNT
DX1020 general protection fault when using the .WHILE directive to test the
state of a processor flag (SIGN?, ZERO?, CARRY?, PARITY?, or OVERFLOW?). The
error occurs if the processor flag is tested by itself or is negated and tested.
For example:

  .WHILE SIGN?
  .WHILE !SIGN?

MASM version 6.0 running under OS/2 version 1.21 may generate a trap 13 in the
above situation.

RESOLUTION
==========

To work around this problem, OR the desired processor flag with zero. For
example:

  .WHILE SIGN? || 0

This work around will also work with ZERO?, CARRY?, PARITY?, and OVERFLOW?.

STATUS
======

Microsoft has confirmed this to be a problem in MASM versions 6.0, 6.1, and
6.1a. This problem was corrected in MASM version 6.11.

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

The following sample code can be used to demonstrate the problem.

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

  ; Assemble options needed: none

  .MODEL small
  .STACK 4096

  .DATA

  .CODE
      .startup
      .WHILE SIGN?       ; generates DOSXNT general protection fault
          nop
      .ENDW
      .WHILE SIGN? || 0  ; avoids the protection fault
          nop
      .ENDW
      .exit 0
  END

Additional query words: 6.00 6.10 6.10a unhandled exception buglist6.00 buglist6.10 buglist6.10a fixlist6.11

======================================================================
Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper
Version           : :6.1,6.1a; MS-DOS:6.0
Solution Type     : kbfix

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

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