Q74532: FIX: Near Call Between Segments Within a Group May Fail

Article: Q74532
Product(s): Microsoft Macro Assembler
Version(s): 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), version 6.0 
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SYMPTOMS
========

The Microsoft Macro Assembler (MASM) version 6.0 may generate incorrect code
when a near call is made to a procedure in another segment. When a call is made
from an offset greater that 0FDh in the calling segment to a procedure declared
in the same source file, the call is made to an incorrect offset.

RESOLUTION
==========

To work around this problem, code the procedure in another module and declare it
as external in the problem module.

STATUS
======

Microsoft has confirmed this to be a problem in MASM version 6.0. This problem
was corrected in MASM version 6.0a.

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

The sample program below illustrates this problem. It defines two segments that
are defined in the same group. Calls are being made from different offsets in
the file. All calls after offset 0FDh are made to incorrect addresses rather
than being set up as relocatable calls.

The following is incorrect code generated for the procedure called Generic:

   00F8                           Generic proc    near
   00F8  E8 0000 R                        call    Simple
   00FB  E8 0000 R                        call    Simple
   00FE  E8 11B2                          call    Simple
   0101  E8 5200                          call    Simple
   0104  E8 11B2                          call    Simple
   0107  E8 11B2                          call    Simple
   010A  E8 0854                          call    Simple
   010D                           Generic endp

The correct code that should be generated would appear as follows:

   00F8                           Generic proc    near
   00F8  E8 0000 R                        call    Simple
   00FB  E8 0000 R                        call    Simple
   00FE  E8 0000 R                        call    Simple
   0101  E8 0000 R                        call    Simple
   0104  E8 0000 R                        call    Simple
   0107  E8 0000 R                        call    Simple
   010A  E8 0000 R                        call    Simple
   010D                           Generic endp

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

  ; Assemble options needed: none
  ;

  CGroup  group   Init, Code

  ASSUME CS:CGroup

  Code    segment para public 'CODE'

  Simple  proc    near
          ret
  Simple  endp

  Code    ends

  Init    segment para public 'CODE'
          ORG     0F8h

  Generic proc    near
          call    Simple
          call    Simple
          call    Simple
          call    Simple
          call    Simple
          call    Simple
          call    Simple
  Generic endp

  Init    ends

  END

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

======================================================================
Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper kbMASM600
Version           : MS-DOS:6.0
Solution Type     : kbfix

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