🚀 go-pugleaf

Having recieved a few enthousiastic reactions for the Bomb detector program,
here is it. You can run it afterwards whenever a bombing has taken place.
The main pre is that it does not have to be resident and that it is an
ordinary C program (what is ordinary C? :=).

The program is called LASTERR and compiles succesfull on a Lattice-C compiler,
so note that int == 4 bytes, and short == 2 bytes!
It could be cleaned up a bit, replacing the 'magic numbers' by macro's etc.
It is mainly self-explainatory; the data referenced (addresses 0x380 etc.)
have already been filled in by the standard error routine (the one that also 
throws bombs).

------------------------------- CUT HERE --------------------------------------

/* lasterr.c: report last occured error and stack dump. 
 * Copyright L.J.M. de Wit, 1988. 
 * This source and the generated code may be freely distributed, if not used
 * commercially.
 */

#define PEEKB(a)  (*(unsigned char  *)(a))
#define PEEKW(a)  (*(unsigned short *)(a))
#define PEEKL(a)  (*(unsigned long  *)(a))

main()
{
	int ssp, i;

	ssp = gemdos(0x20,0);	/* switch to supervisor mode, save stack pointer */

	if (PEEKL(0x380) != 0x12345678) { /* magic marker */
		printf("No error occured since last reset\n");
	} else {
		static char *errmsg[] = {
			"Reset", "Reset",
			"Bus error",
			"Address error",
			"Illegal instruction",
			"Division by zero",
			"CHK",
			"TRAPV",
			"Privilege violation",
			"Trace"
		};
		short excepno, offset;

		excepno = PEEKB(0x3c4);
		offset = ((excepno == 2) || (excepno == 3)) ? 8 : 0;

		printf("Exception no. %d (%s)\n",excepno,
			(excepno >= sizeof(errmsg)/sizeof(errmsg[0]))
			? "Unassigned" : errmsg[excepno]);

		for (i = 0; i < 8; i++) {
			printf(D%d : %8x\tA%d : %8x\n",
				i, PEEKL(0x384 + 4 * i), i, PEEKL(0x3a4 + 4 * i));
		}
		printf(PC : %8x\tUSP: %8x\nSR : %8x\n",
			PEEKL(0x3ce + offset), PEEKL(0x3c8), PEEKW(0x3cc + offset));

		if (offset == 8) { /* exceptions 2 and 3 */
			short status = PEEKW(0x3cc);
			static char *accmode[] = {
				"unassigned",
				"user mode data reference",
				"user mode program reference",
				"unassigned",
				"unassigned",
				"supervisor mode data reference",
				"supervisor mode program reference",
				"interrupt acknowledge"
			};

			printf("\nRead/Write  : %s\n",
				(status & 16) ? "read" : "write");
			printf("In-/Extern  : %s\n",
				(status & 8) ? "extern" : "intern");
			printf("Access mode : %s\n",accmode[status & 7]);
			printf("Address     : %8x\n", PEEKL(0x3ce));
			printf("Instruction : %8x\n", PEEKW(0x3d2));
		}
	}
	gemdos(0x20,ssp);
}

------------------------------- CUT HERE --------------------------------------

I hope no errors have crept into the source while I was typing it over; but
then, you could use this program to see what bomb was produced ( :=)).
Have fun!

		leo.	(What you C is what you get).