Path: utzoo!mnetor!uunet!mcvax!ukc!mupsy!liv-cs!sqkeith
From: sqkeith@csvax.liv.ac.uk
Newsgroups: comp.os.vms
Subject: Re: question on chaining images
Message-ID: <528@csvax.liv.ac.uk>
Date: 15 Mar 88 10:05:17 GMT
References: <8803130859.AA26863@ucbvax.Berkeley.EDU>
Lines: 26
Organisation: Computer Science CSVAX (VAX1), Liverpool University


In article <8803130859.AA26863@ucbvax.Berkeley.EDU>, MANAGER@SMITH.BITNET (Mary Malmros) writes:
> I am looking for a system service or run-time library routine that
> will allow me to execute a second image.  I want to do this in such
> a way that the flow of control will pass entirely to the second image,
> and will return to the first image at the calling point after the second image
> completes. Neither CREPRC nor LIB$SPAWN seem to do this, which makes sense
> since their purpose is to create another process altogether.  I just want the
> SAME process to start executing a second image.  I'm sure I'm overlooking
> something obvious...

LIB$FIND_IMAGE_SYMBOL (I think that's the name) is the routine you want.
It takes the name of a shareable image and a global symbol name and returns
its value. In doing that, it maps that image into your process space and
activates it. You can get a number of symbols from the image and use them
as the addresses of procedure entry masks from which you can issue the library
routine versions of CALL_S etc..

I'm not sure whether the image is unmapped once you have finished with it
- or how you signal that you have finished with it.

Hope this helps,

Keith Halewood
UUCP: {backbone}!mcvax!ukc!mupsy!liv-cs!sqkeith
Arpa: sqkeith%csvax.liv.ac.uk@nss.cs.ucl.ac.uk
Janet: sqkeith@uk.ac.liv.csvax