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From: ts@cup.portal.com (Tim W Smith)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Surviving a Bus Error
Message-ID: <28001@cup.portal.com>
Date: 18 Mar 90 09:18:49 GMT
References: <1990Mar13.192544.1617@asterix.drev.dnd.ca>
Organization: The Portal System (TM)
Lines: 34

Try something like this:

	long saveBusErrorVector;

	if ( setjmp( something ) )
	{
		*(long *)8 = saveBusErrorVector;
		return GOT_A_BUS_ERROR;
	}
	saveBusErrorVector = *(long *)8;
	*(long *)8 = MyBusErrorHandler();

	/* access your board */

	*(long *)8 = saveBusErrorVector;
	return DID_NOT_GET_A_BUS_ERROR;

The function MyBusErrorHandler would look something like this:

	SetupA5();		/* or whatever your development
				 * system uses */
	longjmp( something );

Check the Motorola manual to see what bus error does to the interrupt
level.  I would guess that it is treated like a level 7 interrupt, and
thus sets the interupt level to 7.  If so, you will have to do something
about this.  This will require assembly language.

					Tim Smith

ps: when I say "this will require assembly language", I am assuming
we are all gentle people who would not even think of casting a string
pointer to a function pointer and calling it, or any other such things
best not mentioned in polite company...