Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!dewey.soe.berkeley.edu!oster
From: oster@dewey.soe.berkeley.edu (David Phillip Oster)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Calling Code resources?
Message-ID: <28734@ucbvax.BERKELEY.EDU>
Date: 8 Apr 89 12:01:22 GMT
References: <11817@ut-emx.UUCP> <6917@hoptoad.uucp>
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Reply-To: oster@dewey.soe.berkeley.edu.UUCP (David Phillip Oster)
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Organization: School of Education, UC-Berkeley
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In article <6917@hoptoad.uucp> tim@hoptoad.UUCP (Tim Maroney) writes:
>In article <11817@ut-emx.UUCP> newman@ut-emx.UUCP (David Newman) writes:
>>how do you call a code resource from another piece of code?  Can it be
>>done from a high-level language?  How might it be done in Pascal?

>In Pascal, you're probably going to need to link in some assembly
>language or at least include some INLINEs.  

Lightspeed Pascal can call other pascal functions two ways:
1.) Pascal allows the parameter of a function to be a procedure,
something like:

PROCEDURE foo( PROCEDURE a( Integer : b));
    BEGIN
     a(3);
    END;
Check your manuals for the exact syntax.
If you call 

foo(POINTER(GetResource('MDEF', 128)^));
the POINTER() will cast the result of the GetResource()^ to a gerneric
pointer that it is legal to pass to anything.  Once again, watch your
locking, code must be loced before you call it.


>Lightspeed C, seems to have some problems with
>casting things to function pointers (actually, K&R seems ambiguous on
>the proper syntax, so I guess we can't blame them):

I've never had any trouble casting things to function pointer in
lightspeed C. But then, I always use typedefs to keep things simple enough
that I can follow them. Examples:

typedef void (*SubrPtr)();
typedef short (*FuncPtr)();
typedef long (*LFuncPtr)();

void CallC(f, arg)SubPtr f;Integer arg;{
	(*f)(arg);
}

The expression ((SubrPtr) *GetResource('CDEF', 128)) is much easier to
understand than (((*void)()) *GetResource('CDEF', 128)).

But that only covers calling procedures that use the C calling sequence.
If you are calling a function that uses the pascal calling sequence, such
as a MDEF, a WDEF, or a CDEF, you can use the routines defined in teh
Lightspeed C file <Pascal.h>  Note, these functions are not documented in
the new LightSpeed C manual. The function pointer goes _after_ all the
arguments:

	CallPascalL(varCode, win, mesg, param, *GetResource('WDEF', 128));
for example.  Once again, make sure the code resource is locked before
you call it.

Lightspeed Pascal probably also implements these CallPascal() functions. I
don't know if Lightspeed Pascal includes a set of CallC() functions, but
I'd be surprised.

------
To Tim Maroney: great pair of postings about ListManager and the usenet
community.

--- David Phillip Oster            --"No doubt about it, time to get
Arpa: oster@dewey.soe.berkeley.edu --a new signature"
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