Re: A86: a pretty fast multiply method...
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Re: A86: a pretty fast multiply method...
Kirk Meyer wrote:
> Well if you knew so, why didn't you say so earlier, and we could have had
> this all that time. But apparently I've figured it out independently, which
> is just as well, because whenever you see already-made code you have an
> instinct to try and port it rather than start from scratch.
Well, I only got a TI calculator and started programming in Z80 a week
and a half ago - I didn't know you guys were looking for information like
this :)
But yeah, it's great to try yourself, then look at other people's ideas
after - you may come up with something better that way.
> Anyway, between Jimmy's optimizations and a few tweaks, looks like it's
> gonna come in at about 115 cycles (including ret) with a 1280 byte table.
Looks like there's similarly efficient Z80 version at:
http://www.ffd2.com/fridge/speccy/Spec3D a bit more than half-way down.
Steve Judd managed to do it in 43 cycles on the 6502, and only 25 cycles
if only y changes for further iterations - which can be very common in
3d gfx. Of course, all this wonderful reference material was generated
by a flamewar - and who says nothing good comes from (flame)war?
--
Robin Harbron macbeth@psw.nu
http://www.tbaytel.net/macbeth
http://www.psw.nu/
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