BUG: ALIGN Directive Placement Changes EXE File Size

• Microsoft Macro Assembler for MS-DOS, version 6.1, 6.1a, and 6.11

SYMPTOMS

In an application developed with the Microsoft Macro Assembler (MASM), placing the ALIGN directive before data in a _BSS segment increases the sizes of the object module and of the executable file.

CAUSE

When the ALIGN directive appears at the beginning of a segment, the assembler places the unitialized _BSS segment into the executable file.

RESOLUTION

To work around this problem, modify the source code to remove the ALIGN directive from the beginning of the segment. According to the design of the assembler, the ALIGN directive does not have any effect at the beginning of a segment. The first item of the segment is aligned according to the alignment parameter in the SEGMENT statement.

STATUS

Microsoft has confirmed this to be a problem in MASM versions 6.1, 6.1a, and 6.11. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

Sample Code

; Assemble options needed: None

DOSSEG

_text SEGMENT para public 'CODE' start:

   nop

_bss SEGMENT para public '_BSS'

   align 4
   dw ?

stk SEGMENT para stack 'STACK'

   dw ?

END start