Q40784: CodeView Does Not Work with Grouped Code Segments

Article: Q40784
Product(s): Microsoft Programming Utilities
Version(s): 2.2,3.0,3.11,3.12,3.14,3.5,4.0,4.01,4.05,4.1
Operating System(s): 
Keyword(s): kb16bitonly
Last Modified: 26-JUN-2001

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The information in this article applies to:

- Microsoft CodeView for MS-DOS, versions 2.2, 3.0, 3.11, 3.14, 4.0, 4.01, 4.05, 4.1 
- Microsoft CodeView for OS/2, versions 2.2, 3.0, 3.11, 3.12, 3.5 
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Using the Microsoft Macro Assembler (MASM), it is possible to
associate various segments into a group; DGROUP is an example of this
technique. Grouped data or stack segments do not affect CodeView but
CodeView does not recognize grouped code segments. The program will
run correctly under CodeView but none of the CodeView functions will
be available on the second and subsequent segments in the code group.

The sample code below illustrates this behavior. Once the program
executes into the _TEXTB segment, all CodeView functionality is lost.
You cannot set any breakpoints or single step through the _TEXTB code.
Any attempt to single trace into _TEXTB will result in CodeView
running all the code in _TEXTB as if you had specified a go or a step

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

  ; Assembler options needed: /Zi

          DOSSEG
  _TEXT   GROUP   _TEXTA, _TEXTB         ; Code group _TEXT

  _DATA   SEGMENT WORD PUBLIC 'DATA'
  msg     DB      "Hello, world.", 13, 10, "$"
  _DATA   ENDS

  _TEXTA  SEGMENT WORD PUBLIC 'CODE'     ; First code segment - this
          ASSUME  cs:_TEXT,ds:_DATA      ;  code may be traced as
  start:  mov     ax, _DATA              ;  expected.
          mov     ds, ax
          call    FAR PTR SayHi
          mov     ax, 4C00h
          int     21h
  _TEXTA  ENDS

  _TEXTB  SEGMENT WORD PUBLIC 'CODE'     ; You cannot trace through
  SayHi   PROC                           ;  this code.
          mov     ah, 9h
          mov     dx, OFFSET msg
          int     21h
          ret
  SayHi   ENDP
  _TEXTB  ENDS

          END     start

Additional query words: kbinf 2.20 3.00 3.50 4.10

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Keywords          : kb16bitonly 
Technology        : kbAudDeveloper kbCodeView kbZNotKeyword3 kbCodeView220DOS kbCodeView300DOS kbCodeView311DOS kbCodeView314DOS kbCodeView400DOS kbCodeView401DOS kbCodeView405DOS kbCodeView410DOS kbCodeView220OS2 kbCodeView300OS2 kbCodeView311OS2 kbCodeView312OS2 kbCodeView350OS2
Version           : :2.2,3.0,3.11,3.12,3.14,3.5,4.0,4.01,4.05,4.1

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