Microsoft KB Archive/94751

= FIX: ORG Behavior Different with Span-Dependent Value =

Article ID: 94751

Article Last Modified on 10/22/2003

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APPLIES TO


 * Microsoft Macro Assembler 6.0 Standard Edition
 * Microsoft Macro Assembler 6.0a
 * Microsoft Macro Assembler 6.0b

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This article was previously published under Q94751



SYMPTOMS
In Microsoft Macro Assembler (MASM) versions 6.0, 6.0a, and 6.0b, if the offset for an ORG directive depends on the difference between two labels (a span-dependent value), the assembled code differs from that produces by previous versions of MASM.



CAUSE
The offset for the ORG directive depends on label values that are not yet determined in the first assembly pass.



RESOLUTION
Modify the code to remove span-dependent values in an ORG directive in code assembled with MASM versions 6.0, 6.0a, or 6.0b.



STATUS
Microsoft has confirmed this to be a problem in MASM version 6.0, 6.0a, and 6.0b for MS-DOS and OS/2. This problem was corrected in MASM version 6.1 for MS-DOS.



MORE INFORMATION
This problem usually occurs when a forward reference occurs between the two labels. The assembler adds padding bytes for the forward reference and eliminates these bytes during a subsequent assembly pass. When this occurs, the second label has a larger value during the first assembly pass than it does in subsequent passes.

The sample code below demonstrates this behavior.

Sample Code
; Assemble options needed: none

tst1 SEGMENT para public ASSUME cs:tst1 start: jmp SHORT forward forward: mov ax, 4C00h int 21h tst1 ENDS

count = offset forward - offset start

tst2 SEGMENT para public DB 1 ORG count ; This assembles as ORG 10 in MASM versions 6.0, 6.0a, and ; 6.0b. It assembles as ORG 2 in MASM versions 5.1 and 6.1. xxx DB 1 tst2 ENDS

END start

Additional query words: 6.00 6.00a 6.00b buglist6.00 buglist6.00a buglist6.00b fixlist6.10

Keywords: kbfix KB94751

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