Re: A89: LCD memory manipulation (in asm)
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Re: A89: LCD memory manipulation (in asm)
On Tue, Jan 23, 2001, reukidodo wrote:
>
> Thank you for the information! Was this in a documentation that I missed
> somewhere?
You're welcome. The information can be found in various hardware docs at
http://alh.dhs.org/ti89/ . I believe the documents (esp. mine) can be quite
hard to understand though.
> I had originally planned to use the extra memory around the visible LCD as a
> buffer, in order to make easy smooth scrolling, but now I can't figure out
> how to scroll left/right using lsl and lsr... are there other commands that
> let the end bit be carried over into the next byte?
Use the ROXL and ROXR instructions, they rotate through the X flag.
Eg.: The following loop "scrolls" an arbitrary amount of data one pixel to
the right. The leftmost pixel is set to 0.
move #0,ccr ; X=0
\loop
roxr.w (a0)+ ; X -> (a0) -> new X
dbra d0,\loop
--
Johan Eilert
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