Subj : faster approach to division
To   : comp.programming
From : Mark P
Date : Mon Jul 11 2005 07:17 pm

I'm working on a problem which involves a fair amount of integer 
division but in essentially all cases the divisor is +/- 1 or +/- 2. 
I'm using C++ and trying to figure out whether I should code this as 
just ordinary division or whether it makes sense to create a special 
class (basically a wrapped enumeration) to hold my possible divisor 
values.  Then I would overload operator/() to recast division as a null 
operation or a sign flip and/or right shift.

Anyone have any intuition on this?  I've tried a few very simple tests 
comparing division and shifting and it's hard to discern a difference, 
but I'm not sure my tests are very effective.  (Are modern machines 
optimized to divide by 1 and 2 quickly?)

Thanks for your advice,
Mark

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