From: Xavier Leroy <Xavier.Leroy@inria.fr>
To: caml-list@inria.fr
Subject: Re: [Caml-list] Re: Binary logarithm of a power of 2
Date: Fri, 27 May 2011 19:15:11 +0200 [thread overview]
Message-ID: <4DDFDC1F.5050605@inria.fr> (raw)
In-Reply-To: <slrnitv9jo.ks.sylvain@gallu.homelinux.org>
On 05/27/2011 03:26 PM, Sylvain Le Gall wrote:
> Friday afternoon exercice ;-)
Same here :-)
> Here is my code:
[ Recursive & array-based implementation in Caml ]
Simpler and maybe faster:
let logbin (n: int32) =
let n = ref (Int32.add n 0l) and i = ref 0 in
if !n >= 0x10000l then (n := Int32.shift_right !n 16; i := 16);
if !n >= 0x100l then (n := Int32.shift_right !n 8; i := !i + 8);
if !n >= 0x10l then (n := Int32.shift_right !n 4; i := !i + 4);
if !n >= 0x4l then (n := Int32.shift_right !n 2; i := !i + 2);
if !n >= 0x2l then !i + 1 else !i
Have fun,
- Xavier
next prev parent reply other threads:[~2011-05-27 17:15 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-26 15:51 [Caml-list] " Dario Teixeira
2011-05-26 19:28 ` Goswin von Brederlow
2011-05-27 11:50 ` Dario Teixeira
2011-05-27 13:26 ` [Caml-list] " Sylvain Le Gall
2011-05-27 17:15 ` Xavier Leroy [this message]
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
[not found] ` <BANLkTimtMZvoBKHznBYH91czci=YdiRcog@mail.gmail.com>
2011-05-28 21:13 ` Fwd: " Johannes
2011-05-30 11:48 ` Jean-Christophe Filliâtre
2011-05-27 17:21 Dario Teixeira
2011-05-28 5:29 ` Gabriel Kerneis
2011-05-28 16:17 ` Norman Hardy
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