Bit Scan Forward and Reverse

Thomas Dybdahl Ahle lobais at
Fri Jan 18 21:01:25 CET 2008

Hi, I'm writing an app in python, and I'm storing some a lot of data in
I need a way to find the first or latest set bit in a 64bit number, and
for that I've implemented a small routine.
Thing is that this routine is not as fast as I'd wish. I know most
processors implement BSF and BSR calls to do this efficiently.
Is there anyway to access those calls from python?
I'd still have my routine as a fallback on nonsupporting architectures.

Med venlig hilsen,
Best regards,

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