Article View: comp.sys.amiga.tech
Article #3783AmigaDos Process structure questions
From: Travers Naran
Date: Mon, 04 Jun 1990 14:09
Date: Mon, 04 Jun 1990 14:09
27 lines
1902 bytes
1902 bytes
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?
--
-------------------------------------------------------------------
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
------------------------------------------------------------------
Technical Details
Message-ID:
<2006@mindlink.UUCP>Path:
arc1-ca.pugleaf.net!utzoo!utgpu!watserv1!watmath!att!ucbvax!van-bc!rsoft!mindlink!a275Show Full Headers
Complete Article Headers
Path: arc1-ca.pugleaf.net!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