From: Dario Teixeira <darioteixeira@yahoo.com>
To: caml-list@inria.fr, Sylvain Le Gall <sylvain@le-gall.net>
Subject: Re: [Caml-list] Re: Binary logarithm of a power of 2
Date: Fri, 27 May 2011 10:21:09 -0700 (PDT) [thread overview]
Message-ID: <891579.63577.qm@web111515.mail.gq1.yahoo.com> (raw)
Hi,
> The code is not bug proof, you should check it ;-)
Yeap, there's one bug which manifests itself on whole-byte boundaries
(ex: logbin_array 512l, logbin_array 65536l)...
>
> You can except at least 18% increase in term of performance
> on amd64 and a 1% decrease on i386.
In my synthetic benchmark it behaves as well as my initial C-based
but "alloc-happy" solution, so congratulations! (Though it is of
course slower than the C-based "noalloc" version).
Incidentally, I found a web page with lots of cool bit-twiddling hacks,
which includes several solutions to the binary logarithm problem:
http://graphics.stanford.edu/~seander/bithacks.html
Cheers,
Dario
next reply other threads:[~2011-05-27 17:21 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-27 17:21 Dario Teixeira [this message]
2011-05-28 5:29 ` Gabriel Kerneis
2011-05-28 16:17 ` Norman Hardy
-- strict thread matches above, loose matches on Subject: below --
2011-05-26 15:51 [Caml-list] " Dario Teixeira
2011-05-27 11:50 ` Dario Teixeira
2011-05-27 13:26 ` [Caml-list] " Sylvain Le Gall
2011-05-27 17:15 ` Xavier Leroy
2011-05-27 18:04 ` Dario Teixeira
2011-05-27 18:37 ` Till Varoquaux
2011-05-27 18:46 ` Till Varoquaux
2011-05-28 0:28 ` Harrison, John R
2011-05-28 15:58 ` Richard W.M. Jones
2011-05-28 16:04 ` Edgar Friendly
2011-05-28 17:50 ` Matteo Frigo
2011-05-30 11:48 ` Jean-Christophe Filliâtre
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