Gre7g Luterman wrote:
[...]
Well if size & speed are getting you down, try this:
http://pastie.textmate.org/127218
The calculation takes 22 bytes and executes in 40
clocks. As an assembly-language programmer, having
that extra MOV in the beginning annoys me, but hey, I
try not to break the asm rules.
Regardless, you'd be hard-pressed to get it much
smaller or faster.
Actually, getting it faster (and possibly smaller) shouldn't be that
hard for a _constant_ division like that in a AVR that supports mul
instructions.
To do:
a = c/10;
b = c%10;
you can do:
a = (c * 65534) >> 16;
b = c - (a * 10);
leaving you with no divisions to perform.
The main problem is that the first multiplication should be done with
some hand optimized assembly to perform a 8x16 bit multiplication,
leaving just the upper 8 bits of a 24 bit result, but it should be
doable with just 2 mul instructions and one 16 bit addition.
--
Paulo Marques
Software Development Department - Grupo PIE, S.A.
Phone: +351 252 290600, Fax: +351 252 290601
Web: www.grupopie.com
"The impossible often has a kind of integrity to it which the merely
improbable lacks."
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