A89: Re: Re: Re: Re: Question.


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A89: Re: Re: Re: Re: Question.





----- Original Message -----
From: Niklas Brunlid <e96nbr@efd.lth.se>
To: <assembly-89@lists.ticalc.org>
Sent: Saturday, July 31, 1999 4:18 AM
Subject: A89: Re: Re: Re: Question.


>
>
> ----- Original Message -----
> From: Kaus <kaus@cybrzn.com>
> To: <assembly-89@lists.ticalc.org>
> Sent: Saturday, July 31, 1999 4:23 AM
> Subject: A89: Re: Re: Question.
>
>
> >
> > thank you. you have answered my question presisely.
> > and as to yours, i beleive that the a68k assembler that i use anyway can
> > turn off something, letr me check..
> > yep. the -n switch. but it turns off all sorts of stuff
> > here is all it does:
> >
> > --backword references to labels within the curent CODE section will be
> > converted to PC relatve addressing with displacement if this mode is
legal
> > for the instruction.
> > -this is turned off, so the conversion here wont happen with the -n
switch
> >
> > --if a movem instruciton only specifies one resiter is is converted to
the
> > corresponding move instruction.
> > -feature disabled by the -n switch  (i dont think this is that big a
deal
> > though :)
> >
> > --add, sub, move instructions will be converted to addq, subq, and moveq
> > respecivelt if possible.
> > -turned off by the -n switch. rough on bytes, probly, unless you
> explicelty
> > use the addq, subq, and moveq instruction yourself (i dont... :)
> >
> > ----add, cmp, sub, and move to an address reg are converted to adda,
cmpa,
> > suba, and movea unless they have been ocnverted to Q form.
> > -turned off again.  agian, expicit use of the A forms get around this.
> >
> > --the above two things for the I form
> > -again, expicit use of I gets around this being turned off with the -n
> > switch
> >
> > --if both operands of a cmp instruction are postinc mode, gets converted
> to
> > cmpm
> > -gets turned off.  you can use the cmpm instruction yourself if you want
> it
> >
> > so, there are a few disadvantages if you are lazy, but if not then you
are
> > set! :)
> >
> > to get the 8 bits, you would then use the 0(Ax,Dy) form
> > or 0(Ax)
>
> So the -n switch turns off A68k:s automatic detection of the zero operand
> which makes it treat the register as a byte?
> But in the second case here the 0 is then treated as a word, right?
>
as far as i know. :)
and yes, that is what the -n switchdoes.

--kaus




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