Return-Path: <cyrus@holtmann.org>
From: "Christian Hoene" <hoene@uni-tuebingen.de>
To: "'Marcel Holtmann'" <marcel@holtmann.org>,
        "'Siarhei Siamashka'" <siarhei.siamashka@nokia.com>
Cc: <linux-bluetooth@vger.kernel.org>
References: <200901290310.03440.siarhei.siamashka@nokia.com> <1233214058.2139.6.camel@violet>
In-Reply-To: <1233214058.2139.6.camel@violet>
Subject: RE: [PATCH] SBC encoder scale factors calculation optimized with __builtin_clz
Date: Thu, 29 Jan 2009 16:00:11 +0100
Message-ID: <021801c98222$4a1726e0$de4574a0$@de>
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List-ID: <linux-bluetooth.vger.kernel.org>

> 
> > The attached patch contains optimization for scale factors calculation
which
> > provides additional SBC encoder speedup.
> >
> > For non-gcc compilers, CLZ function is implemented with a very simple
and
> > slow straightforward code (but it is still faster than current git code
even
> > if used instead of __builtin_clz). Something better could be done like:
> > http://groups.google.com/group/comp.sys.arm/msg/5ae56e3a95a2345e?hl=en
> > But I'm not sure about license/copyright of the code at this link and
> decided
> > not to touch it. Anyway, I don't think that gcc implementation of
> > __builtin_clz for the CPU cores which do not support CLZ instruction is
any
> > worse.
> 
> personally I don't really care about non-gcc compilers. I think that
> some of the BlueZ source might not even compile without gcc.
> 
> Anyway, patch has been applied. Thanks.

The testing results are not positive. It is better to revoke the patch.
http://net.cs.uni-tuebingen.de/html/nexgenvoip/
http://net.cs.uni-tuebingen.de/html/nexgenvoip/html/encoder.bluez.03.wav


Greetings

 Christian