Path: utzoo!attcan!uunet!know!zaphod.mps.ohio-state.edu!ncar!husc6!endor!siegel
From: siegel@endor.uucp (Rich Siegel)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Known Symantec Think C 4.01 bug and work-around
Message-ID: <4510@husc6.harvard.edu>
Date: 25 Oct 90 11:16:18 GMT
References: <514@tci.UUCP> <STEVE.90Oct23100517@huxley.huxley.bitstream.com>
Sender: news@husc6.harvard.edu
Reply-To: siegel@endor.UUCP (Rich Siegel)
Distribution: comp
Organization: Symantec Language Products Group
Lines: 38

In article <STEVE.90Oct23100517@huxley.huxley.bitstream.com> steve@huxley.huxley.bitstream.com (Steve Stein) writes:
>In article <514@tci.UUCP> mitchell@tci.UUCP (Rob Mitchell) writes:
>
>>   Subj:	Known Symantec Think C 4.01 bug and work-around
>>   BUG:	LLastClick, of List Manager routines, returns a long instead
>>	   of a Cell type as defined in Inside Mac.

	This is not a bug. The reason that LLastClick returns a long is because
functions declared 'pascal' (such as all of the Toolbox routines) in THINK C
may not return structures or any simple type larger than 4 bytes (such as
a result-type of 'double'). The behavior of 'pascal'-declared functions is
not standardized, and is pretty much implementation-dependent. (A future
release of THINK C may support the returning of structured function results
by 'pascal' functions.

One way to deal with LLastClick is to cast the result using a pointer cast;
the compiler will recognize this trick for what it is and generate a simple
move. If you feel more comfortable doing it explicitly, you can try this:

{
	extern LLastClick();

	asm {
		clr.l	-(a7)		; function result
		move.l	myList, -(a7)	; argument
		jsr	LLastClick	; call it
		move.l	(a7)+, theCell	; pop result
	}
}

R.



 Rich Siegel	Software Engineer	Symantec Languages Group
 Internet: siegel@endor.harvard.edu	UUCP: ..harvard!endor!siegel

If you have telekinetic powers, raise my hand.