Path: utzoo!utgpu!watserv1!watmath!att!ucbvax!van-bc!rsoft!mindlink!a275
From: a275@mindlink.UUCP (Travers Naran)
Newsgroups: comp.sys.amiga.tech
Subject: AmigaDos Process structure questions
Message-ID: <2006@mindlink.UUCP>
Date: 4 Jun 90 14:09:04 GMT
Organization: MIND LINK! - British Columbia, Canada
Lines: 27

I was trying to write a replacement for the system() command so I can write
front ends that don't require using 'run'. Anyways, the program works except
for one thing: The Exit() command. Now, I noticed that in the Process structure
there is a pr_ReturnAddr varialbe. So I looked it up  in the AmigaDos Technical
Ref. Manual (1.2) and found this:
"The Exit function uses the value of ReturnAddr which points to just above the
return address on the currently active stack. If a program exits by performing
an RTS on an empty stack, then control passes to the code address pushed on the
stack by CreateProc or by the CLI. If a program terminates with a call to Exit,
then AmigaDOS uses this pointer to extract the same return address."

        Well, my question is this: What the hell does that mean!? I assumed it
meant that pr_ReturnAddr is pointing to the same location the stack pointer
would point to when the code is entered. But I keep guru'ing (CPU Trap #4 -
Illegal instruction so I guess that means it is going to the wrong address). So
to put the question mildly:
        What value should pr_ReturnAddr be set to if I want all Exits to return
back to my calling program?
--
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Travers "T'aran" Naran (I am male)
Simon Fraser University, Computing Science
Whovian, Prober, Treker, Quantum Leaper....
Mailing addresses:
   Usenet  Travers_Naran@mindlink.UUCP
or      uunet!van-bc!rsoft!mindlink!Travers_Naran
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