From: "David S. Miller" <davem@davemloft.net>
To: drepper@redhat.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: ntohs/ntohl and bitops
Date: Wed, 11 Jan 2006 00:00:20 -0800 (PST) [thread overview]
Message-ID: <20060111.000020.25886635.davem@davemloft.net> (raw)
In-Reply-To: <43C42F0C.10008@redhat.com>
From: Ulrich Drepper <drepper@redhat.com>
Date: Tue, 10 Jan 2006 14:02:52 -0800
> I just saw this in a patch:
>
> + if (ntohs(ih->frag_off) & IP_OFFSET)
> + return EBT_NOMATCH;
>
> This isn't optimal, it requires a byte switch little endian machines.
> The compiler isn't smart enough. It would be better to use
>
> if (ih->frag_off & ntohs(IP_OFFSET))
>
> where the byte-swap can be done at compile time. This is kind of ugly,
> I guess, so maybe a dedicate macro
>
> net_host_bit_p(ih->frag_off, IP_OFFSET)
The first suggestion isn't considered ugly, and the best form is:
if (ih->frag_off & __constant_htons(IP_OFFSET))
I'll fix that up when I get a chance, thanks for catching it Uli.
next prev parent reply other threads:[~2006-01-11 8:00 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-10 22:02 ntohs/ntohl and bitops Ulrich Drepper
2006-01-11 8:00 ` David S. Miller [this message]
2006-01-11 8:13 ` Arjan van de Ven
2006-01-11 8:36 ` David S. Miller
2006-01-11 8:36 ` Ulrich Drepper
2006-01-11 8:44 ` David S. Miller
2006-01-11 9:48 ` Jakub Jelinek
2006-01-11 18:35 ` Jan Engelhardt
2006-01-11 18:45 ` Ulrich Drepper
2006-01-11 20:19 ` David S. Miller
2006-01-12 1:04 ` Pavel Machek
2006-01-14 9:52 ` YOSHIFUJI Hideaki / 吉藤英明
2006-01-15 1:46 ` David S. Miller
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