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From: info-mac@uw-beaver
Newsgroups: fa.info-mac
Subject: additional macsbug commands
Message-ID: <1241@uw-beaver>
Date: Tue, 17-Jul-84 17:38:29 EDT
Article-I.D.: uw-beave.1241
Posted: Tue Jul 17 17:38:29 1984
Date-Received: Fri, 20-Jul-84 04:44:04 EDT
Sender: daemon@uw-beave
Organization: U of Washington Computer Science
Lines: 51

From: Bill Croft <croft@safe>
The "new" macsbug (that uses a window at the bottom of the Mac screen)
that was posted to info-mac a few weeks ago, has some new command syntax.
Here is a note from Bruce Horn explaining the new commands:
----

Here's a summary of the new Macsbug commands:

CL a -- clears the breakpoint at location a.  If a is omitted, all breakpoints
are cleared.

BR a c -- sets a breakpoint at location a for count c.  This allows you to say
"Stop after this location is hit 6 times."

GT a -- is Go Till a. (i.e. sets temporary breakpoint at a and goes.)

T n -- Traces n instructions.

S n -- Steps through n instructions  This is just like the old trace, where
it will actually step into the dispatcher.  Now T, the previous command, will
step OVER a trap.  No more tracing through the dispatcher when you just want
to get back to the main procedure.

MR n -- Looks n bytes down the stack and replaces the longword there (usually
a return address) with a magic address in the debugger.  Instead of returning
normally, this returns control to the debugger which puts back in the real
address.  This is a good way to step across subroutines which you know are
good--just trace one instruction into the routine and type MR.

WH x -- if x<512, prints out the address corresponding to the A-Trap numbered
x.  If >=512, the A-Trap "nearest" the address X will be printed.  This is
useful for finding out what trap was executing when an error occurred.

RX -- Toggles the display mode so that the registers are or are not dumped
during a trace command.  The disassembly at PC will always occur.

I think that's all of the new or changed routines in the improved Macsbug.

Parsing is slightly different, however.  Gone is the DH command, replaced by
the prefix @ for indirect.  So the command DH 4200 is replaced by DM @4200.
An additional symbol, TP (thePort) is also supported.  This is useful for
looking at the Quickdraw globals.

You can reference addresses relative to a given location just by using the +
operator.  You can also use ".", last address referenced, to temporarily have
an anchor from which to reference relative addresses.  For example, DM 14000
will set . to 14000, and then you can say DM .+200, DM .+400, etc.

Bruce
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