From: "H. Peter Anvin" <hpa@zytor.com>
To: Soumyadip Das Mahapatra <dip_kernel@yahoo.co.in>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Improved Swapping Method In sort.c
Date: Thu, 01 May 2008 22:05:16 -0700 [thread overview]
Message-ID: <481AA10C.9080705@zytor.com> (raw)
In-Reply-To: <988568.21908.qm@web94102.mail.in2.yahoo.com>
Soumyadip Das Mahapatra wrote:
> Hello everybody,
> The swapping method (in function void u32_swap() line no.. 14 to 16) in lib/sort.c can be improved by using the following code
> *(u32 *)b ^= *(u32 *)a ^= *(u32 *)b ^= *(u32 *)a instead of the code given. This code
> is not using third variable thus not consuming another memory. And I dont see any significance in
> using *int size* argument. so the function should be
> static void u32_swap(void *a, void *b)
> {
> *(u32 *)b ^= *(u32 *)a ^= *(u32 *)b ^= *(u32 *)a;
> }
>
Not only is this invalid C, but it produces massively worse code.
-hpa
prev parent reply other threads:[~2008-05-02 5:08 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-30 17:09 Improved Swapping Method In sort.c Soumyadip Das Mahapatra
2008-04-30 17:30 ` Jan Engelhardt
2008-04-30 17:33 ` Jan Engelhardt
2008-04-30 18:03 ` Sami Farin
2008-04-30 18:46 ` David Newall
2008-05-02 5:05 ` H. Peter Anvin [this message]
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