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From: jwwalker@opusc.csd.scarolina.edu (Jim Walker)
Newsgroups: comp.sys.mac.programmer
Subject: Re: trap patches
Message-ID: <1990Dec1.233546.20813@opusc.csd.scarolina.edu>
Date: 1 Dec 90 23:35:46 GMT
References: <1990Nov26.040223.8193@ucselx.sdsu.edu> <46831@apple.Apple.COM> <2818@polari.UUCP>
Organization: Univ. of South Carolina, Columbia
Lines: 77

In article <2818@polari.UUCP> robert@polari.UUCP (robert) writes:
[stuff deleted]
>
>    This example looks very useful, but my BIG problem right now is
> that what I need to do requires patching routines in the Standard File
> package. Pack3 is a complex trap. Apparently, calls to Pack3 involve
> passing a routine "selector" of some kind. I haven't found any 
> documentation on this. Does anyone have any information? Any examples
> or pointers to examples? A sharp razor?
>
>                                            Robert Riebman

(I tried to mail this reply, but it bounced.)

Here is some THINK C code for the relevant parts of a Pack3 patch I wrote.

typedef enum {
	SFPut = 1,
	SFGet,
	SFPPut,
	SFPGet
};

pascal void my_SF()
{
	int		selector;
	register Point	*where;
	int			dlog_id;
	
	/* since this is a trap routine, we must preserve the registers */
	asm {
		movem.l	a1-a5/d0-d7, -(SP)	; a7 is SP
		LEA 	main, A4		; set up globals
		move.w	8(A6), selector
	}
	
	
	switch (selector)
	{
		case SFGet:
			asm {
				lea	32(A6), where
			}
			dlog_id = getDlgID;
			break;
		case SFPut:
			asm {
				LEA	26(A6), where
			}
			dlog_id = putDlgID;
			break;
		case SFPPut:
			asm {
				lea	32(A6), where
				move.w	14(A6), dlog_id
			}
			break;
		case SFPGet:
			asm {
				LEA	38(A6), where
				move.w	14(A6), dlog_id
			}
			break;
	}
	
	/*  Most of your patch goes here */
	
	asm {
		move.l	Old_SF, A0
		movem.l	(SP)+, a1-a5/d0-d7	; restore registers
		unlk	A6
		JMP	(A0)			; jump to Old_SF
	}
}

-- 
  -- Jim Walker 76367.2271@compuserve.com