Re: A83: moving background

To: Olle Hedman <assembly-83@lists.ticalc.org>
Subject: Re: A83: moving background
From: Linus Akesson <lairfight@softhome.net>
Date: Fri, 17 Jul 1998 18:21:48 +0100
Delivered-To: assembly-83-outgoing@towerguard.unix.edu.sollentuna.se
In-Reply-To: <3.0.3.32.19980716214944.00769304@hem.passagen.se>
Reply-To: assembly-83@lists.ticalc.org


Sorry, I wasn't thinking... =)

Linus

On 16-Jul-98, Olle Hedman wrote:

>Remove the ld b,0 's  and get it a little bit faster :)

>//Olle

>>
>>Just rotate every byte in the graph buffer through carry, like this:
>>
>>        ld    hl,PLOTSSCREEN
>>        ld    b,0
>>loop1:  rr    (hl)
>>        djnz  loop1
>>        ld    b,0
>>loop2:  rr    (hl)
>>        djnz  loop2
>>        ld    b,0
>>loop3:  rr    (hl)
>>        djnz  loop3
>>        ret
>>
>>That's optimized for speed, optimizing for size would use bc to loop through
>>all of the buffer at once. This will scroll everything to the right one
>>pixel, leaving the leftmost row trashed.
>>
>>Linus
>>
>>

References:

Re: A83: moving background

From: Olle Hedman <oh@hem.passagen.se>