cntlzw
Matt Sealey
matt at genesi-usa.com
Fri Jun 6 19:53:13 EST 2008
It's in the Compiler Writer's Guide with explanation; section 5-10.
http://www-01.ibm.com/chips/techlib/techlib.nsf/techdocs/852569B20050FF7785256996007558C6
There are lots of clever examples in there, it's definitely recommended
reading (I should make a cheat sheet of chapter 5 though so I can pin it
to my wall)
--
Matt Sealey <matt at genesi-usa.com>
Genesi, Manager, Developer Relations
Scott Wood wrote:
> Kevin Diggs wrote:
>> Hi,
>>
>> x86 has bsf and bsr. PPC has cntlzw which I think is equivalent to
>> bsr. Anyone know of a sneaky algorithm to do bsf?
>
> wordsize - 1 - cntlzw(x & ~(x - 1));
>
> -Scott
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