A89: Re: Re: Re: Question.

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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?


 / Niklas Brunlid
Check out Prosit for the TI-89 / TI-92 Plus at http://c625.sparta.lu.se
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