[A89] Re: Setting bit fields

To: assembly-89@lists.ticalc.org
Subject: [A89] Re: Setting bit fields
From: the_juggernaut@juno.com
Date: Fri, 1 Mar 2002 16:40:42 -0600
Reply-To: assembly-89@lists.ticalc.org


Why do you need to do an AND and an OR? To set bit 6, you just need:
   ori.b    #%01000000,$600015

To clear bit 6:
   andi.b   #%10111111,$600015

To invert bit 6:
   eori.b   #%01000000,$600015

Right?  Wouldn't ANDing a byte with $BF clear bit 6 and leave the rest
alone?

confused,
jk


On Thu, 28 Feb 2002 15:50:20 -0500 "Scott Noveck" <noveck@pluto.njcc.com>
writes: 
> Yup, you should only need two total instructions -- one AND, one OR. 
>  You
> can AND multiple bits in one instruction by ANDing the entire byte 
> with a
> mask (want to reset all but bit 6?  AND the byte with 0xBF); same 
> thing with
> OR.
> 
>     -Scott
> 
> 
> 
> 
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Follow-Ups:

[A89] Re: Setting bit fields

From: Olle Hedman <alh@home.se>