Re: A83: Re: moving background
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Re: A83: Re: moving background
On 18-Jul-98, Chris Hiszpanski wrote:
>Spend 5 minutes to think about it yourself, then read the answer below:
>- ---
>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
>-------------------------------------------------------------
>To Linus:
>Hey, thanks for the help. I still don't get why if you use bc the left most
>row gets trashed.
>From: Chris
>mecad@scv.net
Ah, sorry. I was a bit unclear, the leftmost row will always get trashed. The
"This" in the second sentence refers to the piece of code above.
Linus
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