Re: [Boost-users] run-time integer log2

Subject: Re: [Boost-users] run-time integer log2
From: Vicente Botet Escriba (vicente.botet_at_[hidden])
Date: 2010-07-13 09:31:27

Joel Falcou-3 wrote:
> 
> Tim Blechmann wrote:
>> i see, maybe it would be an interesting addition to boost.integer to
>> provide 
>> a generic and efficient version, based on bsr/ffs or the like ...
>>   
> There is a lot of branchless or SWAR algorithm to salvaged from there 
> and to be indeed made generic or at least platform independant w/r to 
> various things. Other thign we never did is benching all of the versions 
> of a given algorithm (with/without branch) on different platform to add 
> a proper #ifdef/else to maximize performance.
> _______________________________________________
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> Boost-users_at_[hidden]
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> 
> 

Hi,

there is a GSOC project "Bits and Ints" that is working on a lot off this
kind of branch less algorithms. I can suggest him to include the integer
runtime variant of some math functions, as log2.

Anyway, on the meantime, for the run-time you can use the cmath header
working on floats and then convert to an integer if this is what you need.

Best,
Vicente

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