Re: A89: Legal Crash Bug?

To: assembly-89@lists.ticalc.org
Subject: Re: A89: Legal Crash Bug?
From: Jimmy =?iso-8859-1?Q?M=E5rdell?= <yarin@acc.umu.se>
Date: Wed, 23 Jun 1999 00:01:15 +0200
Delivered-To: assembly-89-outgoing@towerguard.unix.edu.sollentuna.se
Delivered-To: assembly-89@lists.ticalc.org
In-Reply-To: <012701bebcee$43d31d60$2102e0c7@desktop>
Reply-To: assembly-89@lists.ticalc.org

At 16:31 1999-06-22 -0400, you wrote:
>
>Try this in your code:
>
>mulu.l #9,d7
>
>Nice little crash - anything from Address Error to Illegal Instruction to
>Line 1111/1010 Emulator errors.  It had me up for a few nights.  Simply
>changing it to mulu.w #9,d7 worked (and shaved off some time which I should
>have done the first time around).
>
>My question: WHY?  It's driving me nuts =)

An error in a68k most likely, which generates the wrong opcode. Multiplication
is always done in words, so the .w isn't necessary, and anything else (.l
or .b) should cause at least a warning when compiling. My guess is that a68k
takes the opcode for mulu #9,d7 and then adds some "standard justification
byte"
for .l, which in this case is not a good idea...

--
Jimmy Mårdell                    "Fear is the path to the dark side
mailto:yarin@acc.umu.se           Fear leads to anger
http://www.acc.umu.se/~yarin/     Anger leads to hate
ICQ #: 14193765                   Hate.... leads to suffering"  /Yoda

Follow-Ups:

Re: A89: Legal Crash Bug?

From: Zoltan Kocsi <zoltan@bendor.com.au>

References:

A89: Legal Crash Bug?

From: "Scott Noveck" <noveck@pluto.njcc.com>