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From: cg@myrias.UUCP (Chris Gray)
Newsgroups: comp.sys.amiga
Subject: Format of loadable object files
Message-ID: <510@myrias.UUCP>
Date: Mon, 29-Jun-87 14:40:29 EDT
Article-I.D.: myrias.510
Posted: Mon Jun 29 14:40:29 1987
Date-Received: Wed, 1-Jul-87 02:56:56 EDT
Organization: Myrias Research, Edmonton
Lines: 22
Keywords: object files format dynamic loading

As of yesterday, I finished off (hopefully) the world-creation program for
my 'Explore' D&D system. My next step is the supervisor program for running
the scenarios. For this I need to dynamically load the code for the scenario.
I managed to get it working, but ran into something that's puzzling me. It
seems that in order for the system (presumeably 'LoadSeg') to recognize a
file as a valid object file, the file has to start with a hunk with a 'jmp'
in it. I haven't done experiments to see exactly what is needed, but a file
with just a Draco routine wasn't accepted, even though BLink didn't complain
when it linked it. When I tried to run it directly, I got error number 121
(not an object file). To kludge it to work, I made the following stub:

	IDNT	"explore.startup"
	XREF	exploreEntry
	JMP	exploreEntry
	END

and BLink'ed with that object + the one I wanted, with its entry point renamed
as 'exploreEntry'. Then all was well. Has anyone figured out just what IS
needed?
-- 
Chris Gray		Myrias Research, Edmonton	+1 403 432 1616
	{seismo!mnetor,ubc-vision,watmath,vax135}!alberta!myrias!cg