Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!decwrl!purdue!bu-cs!dartvax!eleazar.dartmouth.edu!earleh
From: earleh@eleazar.dartmouth.edu (Earle R. Horton)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Executing a code segement from Lightspeed Pascal?
Message-ID: <10284@dartvax.Dartmouth.EDU>
Date: 5 Oct 88 14:24:47 GMT
References: <8810051239.AA09466@decwrl.dec.com>
Sender: news@dartvax.Dartmouth.EDU
Reply-To: earleh@eleazar.dartmouth.edu (Earle R. Horton)
Organization: Thayer School of Engineering.
Lines: 45

In article <8810051239.AA09466@decwrl.dec.com> harrow@bagels.dec.com 
	(Jeff Harrow, NMSG LKG2-2/Y10 DTN=226-5564) writes:

>I'm trying to  use  the  HelpCompiler  that came over Usenet.  It
>places help text and  a  CODE  resource into a program, which you
>call with the following "C" code:
...
>Now, I tried to convert this to Pascal (Lightspeed, of course) as
>follows:
>
>procedure ShowHelp;
>  var
>   rsrcH : Handle;
>   pp : ProcPtr;
>
> begin
>  if rsrcH = GetResource('code', 2000) then
>   begin
>    HLock(rsrcH);
>    pp := @rsrcH;
>    pp;         <<<<<THIS, nor @PP, nor (@PP) works<<<<<<<<

The data type ProcPtr technically points to an arbitrary type, I think
it is SignedByte in Pascal.  Therefore there is no way to call the
routine directly from Pascal, without using assembly language or
InLine assembly.

Something like the following should work:

PROCEDURE CallCodeResource(theProc: ProcPtr);
INLINE $205F,$4E90;
 {MOVE.L (A7)+,A0 JSR (A0) }

This InLine code pops the ProcPtr off the stack, then does a JSR to
it, putting the real return address on the stack.  You would use it by:

CallCodeResource(pp);

This, of course, assumes that LightSpeed Pascal allows InLine
declarations using the same syntax used by MPW Pascal.


Earle R. Horton. 23 Fletcher Circle, Hanover, NH 03755
(603) 643-4109
Sorry, no fancy stuff, since this program limits my .signature to three