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From: siegel@endor.harvard.edu (Rich Siegel)
Newsgroups: comp.sys.mac.programmer
Subject: Re: LSC debugging code resources
Keywords: combining text and graphics.
Message-ID: <906@husc6.harvard.edu>
Date: 3 Jan 89 05:08:01 GMT
References: <221@dalcsug.UUCP> <966@geowhiz.UUCP> <1235@viscous> <896@husc6.harvard.edu> <66569@ti-csl.CSNET> <900@husc6.harvard.edu> <1198@etive.ed.ac.uk>
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Reply-To: siegel@endor.UUCP (Rich Siegel)
Organization: Symantec/THINK Technologies, Bedford, MA
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In article <1198@etive.ed.ac.uk> nick@lfcs.ed.ac.uk (Nick Rothwell) writes:
>	(i)   Can I do this for any code resource?

	The trick allows you to incorporate the code for any code resource
as part of the program's source code, not as a separate resource.

>	(ii)  What about the resource? Does it have to use A4 rather than A5,
>	      if it's actually a bit of the same project? Any restrictions on
>	      access to globals, or anything like that?

	Embedded code resources are actually more flexible than externally
built code resources, since they can use external globals and data; the
application context is much better defined.

>	(iii) What code do you use to perform the patch? Is it in-store,

	The code loads a dummy resource and fills it with the correct
infomation. Suppose you have a procedyre MyDefProc(), which is the code
for an LDEF, embedded in your program. If you wanted to install MyDefProc
as LDEF 128, it would go like this:

typedef struct {
	int jmpInstr;
	Ptr jmpAddr;
} JmpRec, *JmpPtr, **JmpHandle;

extern pascal void MyDefProc();

	void InstallLDEF()
	{
		JmpHandle jH;

		jH = Get1Resource('LDEF', 128);
		(**jH).jmpInstr = 0x4EF9;
		(**jH).jmpAddr = &MyDefProc;
		HNoPurge(jH);
	}

This loads the dummy defproc, patches it to your routine, and makes it
nonpurgeable. You should be sure that the routine is in a segment that is
loaded and will stay loaded.

		--Rich
Rich Siegel
Staff Software Developer
THINK Technologies Division, Symantec Corp.
Internet: siegel@endor.harvard.edu
UUCP: ..harvard!endor!siegel
Phone: (617) 275-4800 x305

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or policies of Symantec Corporation or its employees.