Re: [stella] I'm back! :) ...

Subject: Re: [stella] I'm back! :) ...
From: Ben Larson <wazzapfool@xxxxxxxxx>
Date: Mon, 7 Oct 2002 10:08:24 -0700 (PDT)
--- Ben Larson <wazzapfool@xxxxxxxxx> wrote:
> I really want to do this, but I'm having a hard time
> coming up with a simple bitmasking routine for the
> whole screen (The fact that I'm packing both PF0
> nibbles into one byte probably doesn't help the
> situation.) to use for a given X value.  If I could
> come up with something here, that would probably
> also
> enable me to simplify the initial terrain drawing
> routing as well.

OK, actually I sat down and thought it out, and I
suppose it wouldn't be as hard as I originally
thought...basically just treat the whole 40 column
playfield as a giant register and just do ROLs and
RORs to get the masking bit where I want it.  The fact
that the PF0 bits are packed into one byte will be a
minor inconvenience, but shouldn't be anything too

I suppose I will try to implement this strategy first
for the playfield drawing routine, since that's a big
ROM hog right now...


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