FIX: Relational Operators with MOV May Evaluate Incorrectly (26270)


The information in this article applies to:

  • Microsoft Macro Assembler (MASM) 5.0
  • Microsoft Macro Assembler (MASM) 5.1
  • Microsoft Macro Assembler (MASM) 5.1a
This article was previously published under Q26270

SYMPTOMS

In the Microsoft Macro Assembler (MASM) versions 5.0, 5.1, and 5.1a, some of the relational operators evaluate to the wrong value when used with a MOV instruction.

STATUS

Microsoft has confirmed this to be a problem in MASM versions 5.0, 5.1, and 5.1a. This problem was corrected in MASM version 6.0.

MORE INFORMATION

The following listing-file sections are examples of this problem. It is important to note that FFFF=true, and 0000=false. It is also important to note that when FFFFh is used with the GT, GE, LE, and LT operators, it is interpreted as the largest positive number, not as -1.

Sample Listing File

1                                .MODEL SMALL
2                                .CODE
3 0000  B8 0000                  MOV AX, 0FFFFH GT -1
4 0003  B8 FFFF                  MOV AX, 0FFFFH LE -1
5                                END
*******************************************************

1                                .386
2                                .MODEL SMALL
3                                .CODE
4 0000  66| B8 FFFF              MOV AX, -1  GE  0FFFFFFFFH
5 0004  66| B8 FFFF              MOV AX, 0FFFFFFFFH  LE  -1
6 0008  66| B8 0000              MOV AX, 0FFFFFFFFH  GT  -1
7 000C  66| B8 0000              MOV AX, -1  LT  0FFFFFFFFH
8                                END
Modification Type:MajorLast Reviewed:10/17/2003
Keywords:kbfix KB26270
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