Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!unmvax!tut.cis.ohio-state.edu!att!pegasus!ech
From: ech@pegasus.ATT.COM (Edward C Horvath)
Newsgroups: comp.sys.mac.programmer
Subject: Re: help with sublaunching
Message-ID: <2856@pegasus.ATT.COM>
Date: 3 May 89 20:18:56 GMT
References: <9410@j.cc.purdue.edu>
Distribution: usa
Organization: AT&T ISL Middletown NJ USA
Lines: 46

From article <9410@j.cc.purdue.edu>, by aib@j.cc.purdue.edu (coleman):
> HELP !!

>   I am having major problems with sublaunching...

> pascal OSErr LaunchIt( pLnch) /* < 0 means error */
> pLaunchStruct pLnch ;
> {
> 	asm {
> 	 MOVE.L  (A7)+,A0
> 	  _Launch
> 	  MOVE.W  D0,(A7)  ; since it MAY return */
> 	}
> }

Depending on how your C compiler works -- I assume this is LSC from the
asm{...} -- you have either one or two longwords on the stack on top of
the address of the launch parameters, namely the return address, and
perhaps the old value of A6.  There is also no need for the pascal
keyword, since d0 is where _Launch leaves its result code, and where a
C caller expects to find it.  LSC also lets you access parameters
symbolically.  Thus, the following:

OSErr LaunchIt (pLnch)
	pLaunchStruct (pLnch);
{
	asm {
		move.l	pLnch,a0
		_Launch
	}
}

That's it.  In fact, if you have the LaunchStruct, you can embed the
trap right in your other routine:

	LaunchStruct Lnch;
	OSErr rslt;
...
	/* set up Lnch */
	asm {
		lea	Lnch,a0
		_Launch
		move.w	d0,rslt
	}

=Ned Horvath=