Path: utzoo!attcan!uunet!unisoft!bdt!david
From: david@bdt.UUCP (David Beckemeyer)
Newsgroups: comp.sys.atari.st
Subject: Re: argv[0] and Sozobon C
Summary: argv[0] MT C-Shell, MWC, and the ST
Message-ID: <529@bdt.UUCP>
Date: 15 Mar 89 20:02:06 GMT
References: <737@stag.UUCP>
Reply-To: david@bdt.UUCP (David Beckemeyer)
Organization: Beckemeyer Development Tools, Oakland, CA
Lines: 60


I've seen enough un-truths about this subject already so here is
the story behind argv[0] and MT C-Shell.

First the history that got us here:  Way back in 1986 I developed
and released the first version of MT C-Shell V1.0.   This was
before MWC, back when the only C compilers were the DRI/Alcyon
package from Atari and Megamax.  neither of these implemented
argv[0] handling at the time (they just full it it with some
static string).

MT C-Shell needed more than the 128 bytes that Pexec gives you
for arguments, so I invented a method for passing a larger
number of arguments, using the enviroment space.   This was
the first method of extended arguement passing and argv[0]
handling.

Along comes Mark Williams Co. and MWC.   They implement another
(incompatible) method for passing argv[0] and extended arguments
also using the enviroment space.    Since they're bigger than I
am (and because they're way was probably better than mine anyway)
I adopt MT C-Shell and all my utilities to be compatible with this
newly established argument passing method.  At this time Mark
Williams Co., myself, and representatives from Manx and Megamax
approach Atari with the idea of defining a "standard" method for
extended arguments.    Since Atari basically said "we don't care
what you do," we simply agreed that the MWC method would be the
de-facto "standard".   MT C-Shell Versions 1.10 and above and
Micro C-Shell Versions 2.70 and above use this MWC "standard"
method of argv[0] and extendend argument passing.

The "conversion" programs that are often talked about only apply
to *very* old versions of MT C-Shell and Micro C-Shell (prior to
V1.10 MT and V2.70 Micro C-Shell, or about Fall 1986).   Probably
nobody needs these conversion programs anymore; they cloud the
issue.

After all this, many new compilers and libraries have arisen for the
ST.  It seems that along with them came some more techniques for
argument passing.  MT C-Shell does not support any methods other than
that adopted in 1986 (the MWC format).   I do *not* have plans to
implement other methods of argument passing, unless one is *finally*
adopted as the "official" standard.

The method used by MT C-Shell and MWC starts with an environment variable
ARGV, whose value is a "iovector" describing the standard handles.
After this the arguments are appended (each null terminated) starting
with argv[0].   The list of arguments is terminated with a empty
string (a double null), which marks the end of the enviromnent.  The
basepage "tail" is also filled with the first 127 bytes of the arguments
in standard TOS Pexec format, without argv[0].  The ARGV variable is
placed after the "real" environment variables and is always followed
by the command arguments.

I do not know if Sozobon C is compatible with this method or not.
-- 
David Beckemeyer (david@bdt.UUCP)	| "Lester Moore - Four slugs from a .44
Beckemeyer Development Tools		|  no Les, no more."
478 Santa Clara Ave. Oakland, CA 94610	|   - Headstone at Boot Hill
UUCP: {uunet,ucbvax}!unisoft!bdt!david	|     Tombstone, AZ