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Re: 13 year old C source code

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buck <buck@private.mil> writes:
> I haven't programmed in a VERY long time and I never was much good at 
> it anyway.  From this you can accurately imply that I'm the wrong 
> person to be doing this.  However:
>
> I have been tasked to determine the feasibility of updating 13 year 
> old (pre ANSI) ASM and C source code for the purpose of compiling a 
> 64-bit executable.

If it's only 13 years old (1998), I'm a bit surprised that it's
pre-ANSI; the ANSI standard was published 9 years before that
(and re-published as ISO C90 a year later).

> The source code was last modified in November of 1998 and was compiled 
> using C88 v3.03 and ASM88 v1.5, which are copyright Mark DeSmet 1987 
> and 1986 respectively.

Ok, those would be pre-ANSI compilers -- but at least some compilers
back then probably supported prototypes, which are probably the
most significant change ANSI introduced.

On the other hand, K&R-style (non-prototype) function declarations are
still legal, even in C99; I don't think even the C201X draft gets rid of
them.  (A pity, IMHO, but that's beside the point.)

> Are there any utilities that examine old C code and suggest how to 
> make it compliant with current compilers?  I tried splint v3.1.2, but 
> it crashes on line 110 of 824 lines and does not tell me how to 
> correct the errors and warnings it does find.

Personally, I'd just compile the code with whatever modern compiler
I want to use, and go through and fix any errors it reports.
That requires a fairly good knowledge of C, but I can't think of
any approach that doesn't.

Be sure to use a good source control system so you can keep track
of just what changes you've made.

> Are there any utilities that examine 8086 ASM code and explain what to 
> change to make it compile for a 64-bit CPU?  I type 'debug' in a CMD 
> prompt in Vista in order to see the register names, but (of course) 
> Vista has no DEBUG...

Can't help you with that.  It has nothing to do with C, so you'll get
better help elsewhere.

> One of the things I'm completely stuck on is the difference in char.  
> In the existing source code and with C88,
>
> 'static char v[]={-20,-124,-180,-93,-88,-73,-27,-146,9,-38,-179 ...'
>
> works, but the values obviously violate current char (and unsigned 
> char) rules.  If char is changed to long, the values seem to be 
> accepted, but the function is called with a char variable.

That's not a K&R-vs-ANSI issue.  Unless C88 targets some exotic
system with char bigger than 8 bits (unlikely), that code was wrong
to begin with.  As Francois Grieu points out, the values -180,
-146, and -179 are almost certainly outside the range of char.
In practice, they'll most likely be implicitly converted to 76, 110,
and 77, respectively (though that's not guaranteed by the language).
Possibly the only difference is that the older compiler might not
have warned about it.

char probably isn't the right type for the array; given the values,
and assuming you change the out-of-range values as described, it
should prboably be signed char.  Or perhaps unsigned char would
make more sense; then you should change all the negative values as
well (add 256 to each of them).  It depends very much on what it's
being used for.  (Arrays of unsigned char are usually the best way
to represent arbitrary byte sequences.)

> Any suggested resources other than utilities would be appreciated, 
> too.  Google hasn't been much help, so the above includes a request 
> for suggested search phrases.

Most valid pre-ANSI C code should still compile with a modern
compiler, though warnings are likely.  You'll probably have more
problems with (a) use of extensions supported by the old compiler
but not by the newer one, and (b) bad code that the old compiler
didn't diagnose properly.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Nokia
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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13 year old C source code buck <buck@private.mil> - 2011-07-28 19:04 +0000
  Re: 13 year old C source code jacob navia <jacob@spamsink.net> - 2011-07-28 21:30 +0200
    Re: 13 year old C source code Francois Grieu <fgrieu@gmail.com> - 2011-07-28 21:35 +0200
      Re: 13 year old C source code jacob navia <jacob@spamsink.net> - 2011-07-28 21:48 +0200
        Re: 13 year old C source code Keith Thompson <kst-u@mib.org> - 2011-07-28 13:37 -0700
    Re: 13 year old C source code buck <buck@private.mil> - 2011-07-28 20:28 +0000
  Re: 13 year old C source code Francois Grieu <fgrieu@gmail.com> - 2011-07-28 21:31 +0200
  Re: 13 year old C source code Keith Thompson <kst-u@mib.org> - 2011-07-28 13:00 -0700
    Re: 13 year old C source code "Scott Fluhrer" <sfluhrer@ix.netcom.com> - 2011-07-28 18:10 -0400
      Re: 13 year old C source code Keith Thompson <kst-u@mib.org> - 2011-07-28 15:27 -0700
  Re: 13 year old C source code Rich Webb <bbew.ar@mapson.nozirev.ten> - 2011-07-28 15:53 -0400
  Re: 13 year old C source code Roberto Waltman <usenet@rwaltman.com> - 2011-07-28 16:18 -0400
    Re: 13 year old C source code Roberto Waltman <usenet@rwaltman.com> - 2011-07-28 16:34 -0400
  Re: 13 year old C source code Ben Pfaff <blp@cs.stanford.edu> - 2011-07-28 13:36 -0700
  Re: 13 year old C source code gordonb.mgm25@burditt.org (Gordon Burditt) - 2011-07-28 15:37 -0500
    Re: 13 year old C source code Robert Wessel <robertwessel2@yahoo.com> - 2011-07-28 17:33 -0500
      Re: 13 year old C source code gordonb.2omx0@burditt.org (Gordon Burditt) - 2011-07-28 18:48 -0500
        Re: 13 year old C source code Robert Wessel <robertwessel2@yahoo.com> - 2011-07-28 19:26 -0500
    Re: 13 year old C source code BGB <cr88192@hotmail.com> - 2011-07-28 16:09 -0700
  Re: 13 year old C source code Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-08-03 08:17 +0000

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