Faster divides

I remember someone saying there was a trick to speed up something like this
where you have all long variables and you divide multiple times by the same
value:


long dsh,dtx,dty,dy;
...do some calculations to find values for them...
dsh = (dsh << 16) / dy;
dtx = (dtx << 16) / dy;
dty = (dty << 16) / dy;


I tried using 3 floating-point multiplies, but that is way slower, even on
a Pentium due to the large speed hit of converting back-and-forth from
integer to floating-point.


Does anyone know of an algorithm to speed this up without having to do these
3 very similar divides? It seems like there would be one since you are
dividing by the exact same value!


Thanks for any help you can offer,


Stuart Denman
sdenman@cs.washington.edu
























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