A89: Re: Re: Question.


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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)


--kaus






----- Original Message -----
From: Niklas Brunlid <e96nbr@efd.lth.se>
To: <assembly-89@lists.ticalc.org>
Sent: Friday, July 30, 1999 9:12 PM
Subject: A89: Re: Question.


>
> > ok.  in this syntax:
> > move.w 4(a0,d0),d1
> > how do i specify the size of d0? or is it assumed long?
> >
>
> You have two possabilities here:
>
> (Ax,Dy) or 0(Ax, Dy) means Ax + lower 16 bits of Dy sign-extended to 32
> bits.
> d(Ax,Dy) means Ax + d (8 bits) + lower 8 bits of Dy sign-extended to 32
> bits.
>
> AFAIK you can't set Dy in the first case to only use 8 bits, but I
wouldn't
> mind being proved wrong since it would be useful... :o)
>
>
>  / Niklas Brunlid
> Check out Prosit for the TI-89 / TI-92 Plus at http://c625.sparta.lu.se
> Random PQF Quote follows:
>
> "And Howondaland Smith, Balrog Hunter, practic'ly eats the dark for
> his tea."
>         -- Gaspode the wonder dog
>            (Terry Pratchett, Moving Pictures)
>
>
>



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