Subj : Re: faster approach to division
To   : comp.programming
From : goose
Date : Tue Jul 12 2005 09:02 pm

Mark P wrote:
> 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

I've had need for something similar in the past, I've found
that the fastest way for me to do it was by #define a macro
to do the division.

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