Masm32 assembly error

So I decided to go through the Tutorials after installing MASM32…

Console Demos 1 — 4 (and 6-7 too), worked just fine using «Project» —> «Console Assemble & Link» in the Quick Editor.
But when I tried Demo5 (numbers.asm), even if I use a simple build.bat file instead of the Quick Editor, it keeps giving me this Assembly error either way:

error A2006: undefined symbol : crt_atol
 sval(2): Macro Called From … numbers.asm

The numbers.exe file that came with it works fine, and I checked where «crt_atol» is defined and don’t see any problems there! So what’s wrong??!  PLEASE TRY running this yourself using the latest MASM32 install from the website. The line of code involved in the file is:

    mov var1, sval(input("Enter a number : "))
UPDATE: Since the file itself notes that the code above was a combination of macros, I went ahead and split them, in that case the error message is still about this line of code:

    mov var1, sval(str1)

error A2006: undefined symbol : crt_atol
 sval(2): Macro Called From
  C:masm32tutorialconsoledemo5numbers.asm(74): Main Line Code

Dan.

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Hi Dan,

atol

is a function exported by msvcrt.dll  To avoid naming conflicts with some reserved Masm keywords, the msvcrt functions are prepended with the symbol

crt_

You need to add the two lines below to the source code :

include masm32includemsvcrt.inc
includelib masm32libmsvcrt.lib
Part of masm32includemsvcrt.inc :

externdef _imp__atol:PTR c_msvcrt
crt_atol equ <_imp__atol>


« Last Edit: December 08, 2020, 05:33:29 AM by Vortex »

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Or, a bit simpler, after line 22:

    include masm32macrosmacros.asm       ; MASM support macros
    uselib msvcrt

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First, Thank you for your replies!  Tested the code all different ways as suggested, works fine now!

atol is a function exported by msvcrt.dll  To avoid naming conflicts with some reserved Masm keywords, the msvcrt functions are prepended with the symbol vc_

Part of masm32includemsvcrt.inc :

externdef _imp__atol:PTR c_msvcrt
crt_atol equ <_imp__atol>


I just found a number of replies from Hutch about this on 16 NOV 2020 (in «Re: scanf macro and printf macro»), so I guess that’s why Demo5‘s

numbers.asm

file hasn’t been changed yet?  Or was this change requiring «msvcrt» much earlier?

Regarding the comment: «… the msvcrt functions are prepended with the symbol

vc_

,» I still don’t quite understand what that «

vc_

» has to do with the definition of

sval()

(and the «

crt_atol

» in macros.asm) and a number of capitalized «VC_»s I see in various examples. However, now that I’ve looked thoroughly, I see the only definition of «

crt_atol

» in all of the MASM32 files is in: msvcrt.inc. So it’s rather obvious it must be included in the

numbers.asm

file.

As I wrote in my first post’s later comments, most of the work I did with assembly was reversing raw hex into straight-forward assembly instructions, so many ‘masm macros’ are still just a bunch of crazy meaningless symbols to me.

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Hi Dan,

My apologies, the 32-bit version of msvcrt.inc is using the suffix

crt_

  The 64-bit version of the same file :

vc_

I corrected this in my previous message.

masm32include64msvcrt.inc :

externdef __imp_atol:PPROC
vc_atol equ <__imp_atol>
There are some Masm specific keywords like div and FABS which could collide with the sane named msvcrt functions. To avoid those confusions, Hutch prepended the functions names with

crt_

and

vc_

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Dan,

The general drift is while you are getting up to speed, use the system as its designed. The masm32rt.inc file has all the the correct include files, the main macro file and the matching libraries. Also don’t be afraid to use the help files, they document the library procedures and the available macros you can use. Once you are up to pace you can be creative, write your own libraries, macros and architecture.

; ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤
    include masm32includemasm32rt.inc
; ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤

comment * ——————————————————
                        Build this  template with
                       «CONSOLE ASSEMBLE AND LINK»
        —————————————————— *

    testproc PROTO :DWORD,:DWORD,:DWORD

    .code

start:

   ; ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤

    call main
    exit

; ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤

main proc

    invoke testproc,1,2,3

    ret

main endp

; ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤

testproc proc arg1:DWORD,arg2:DWORD,arg3:DWORD

    LOCAL var1  :DWORD
    LOCAL var2  :DWORD
    LOCAL var3  :DWORD

    mov eax, var1
    mov ecx, var2
    mov edx, var3

    ret

testproc endp

; ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤

end start

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Answers

• If you are sure that you did that then I would have to come to the conclusion that your install of VC Express is corrupt somehow.

  Here, when I enable the build customization, it immediately allows asm files to be built using masm.

  

  

  The reason why I took so long this time was because I was testing it out properly. I was using VS to do this, so I was being sure that there was no differences between the VS IDE and the VC Express IDE. Those two screenshots were taken using VC Express though,
  so the relationship does still hold, if masm is enabled in build customizations then the compile option gets enabled, if masm isn’t enabled then compile doesn’t occur and things start falling apart.

  So at this point I would suggest trying it out on another computer if possible to rule out VC Express being the problem. Also, as a bit of a thought, did you install service pack 1? I am using fully updated versions of VS so there could be a bug that was
  fixed getting in the way.

  ---

  This is a signature

  Any samples given are not meant to have error checking or show best practices. They are meant to just illustrate a point. I may also give inefficient code or introduce some problems to discourage copy/paste coding. This is because the major point of my posts
  is to aid in the learning process.

  • Marked as answer by

    Monday, February 6, 2012 9:15 AM