RE: Terminating a C Program

["Richard Jackson" <richardjackson@xxxxxxxxxxxxxxxxxx>]

Simon, nice summary.  Mike doesn't want to use EPM but you didn't come right
out and say that.    Mike, don't even think about EPM, it will make you
crazy - but very very slowly.

There are a few more historical fragments - like the fact that EMP was not
originally built to be sold, it was supposed to be a demonstration.
System/C was suggested to one of the AS/400 system architects by some
meathead.  I think it was at the Fall of 1988 Common meeting.  The Modula
compiler was originally used to rewrite some of the PL/MI into OO forms and
was never released, C was used instead.  The stack handling in EPM did not
use the MI instructions created to do stack handling - they were too slow.
The EPM environment was originally created for Pascal on the 38.  blah blah
blah.

Richard Jackson
mailto:richardjackson@richardjackson.net
www.richardjacksonltd.com
Voice: 1 (303) 808-8058
Fax:   1 (303) 663-4325

-----Original Message-----
From: owner-c400-l@midrange.com [mailto:owner-c400-l@midrange.com]On
Behalf Of Simon Coulter
Sent: Tuesday, August 08, 2000 7:09 AM
To: C400-L@midrange.com
Subject: Re: Terminating a C Program



Hello Mike,

You wrote:
>I have a few problems in understanding the program model that is used for C
>programs, and how the C program acts in the stack when called from RPG.
>In essence I want the C program to behave like an RPG program - ie it stays
>resident until *INLR is set on. Is there a way of doing this in C?
>Alternatively, how do I control the invocation and termination of a C
>program ? My current C program is terminating each time it returns, and I
>need it and it's lower level RPG invocations to stay resident until I'm
>ready to end them..

C doesn't have that concept.  The closest you can come is by declaring
static variables
and using a named activation group.  I haven't tried it but since named
activation
groups persist until explicitly destroyed and static variables maintain
state over
invocations the nett result should be the same.  Exactly what are you trying
to acheive?

>I'm also  bit confused as to which program model I have when I compile my C
>program

C programs since VRM230 are ILE programs.  Prior to that they were EPM or
System/C.

>In my travels through Jennifer Hamilton's book, I saw a reference to
>STREPMENV and ENDEPMENV and I thought this might be the answer to the above
>problems.

These commands refer to the EPM environment which was a stepping stone on
the way to
ILE.  It added multiple entry points, binding, and long names to the system
but since it
was imposed over the standard program model it also had a major performance
impact --
most noticable when starting the environment or invoking the first EPM
program.

>Unfortunately, it turns out I have ILE C program created using the CRTBNDC.
>When I look at the DSPPGM output, I find that this is an ILE program. When
I
>use CRTCMOD/CRTPGM, of course it's an ILE program. I shouldn't have to
>create an EPM program should I?

You don't have any choice.  EPM programs can no longer be created although I
think they
will still run (certainly on Version 3, and possibly on Version 4).  Query
Management
was written in Modula-2 which was an EPM compiler and I don't think it has
been
converted so that would suggest the runtime support is still present.

>I've have looked at the C Programmers Guide, but to no avail.

The C manuals relate to the current ILE dialect.  There used to be an
appendix
discussing migrating from EPM C to ILE C but it may have been removed.

>Any help out there?
Well, that really rather depends doesn't it?  :)

Regards,
Simon Coulter.

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