From: Nir Dremer <mailing@dremer.org>
To: soraberri <421246@posta.unizar.es>
Cc: linux-c-programming@vger.kernel.org
Subject: Re: newby.-interpreting C
Date: Mon, 20 Dec 2004 21:38:09 +0200 [thread overview]
Message-ID: <1103571489.28578.14.camel@localhost> (raw)
In-Reply-To: <cq77vi$1ej$1@sea.gmane.org>
this specific attributes is intended in order to avoid structure
alignment in memory.
The compiler is performing alignment to any allocation to be a
multiplication of 4k.
in order to disable this alignment __attribute__ packed is being used.
usually this is being used when working with networking:
if you have a structure of 5k and you will send it you will actually
send 8k.
attributes information:
http://www.unixwiz.net/techtips/gnu-c-attributes.html
cheers
On Mon, 2004-12-20 at 20:07 +0100, soraberri wrote:
> Hi all,
>
> Anyone could give me the meaning of this definition? Is the
> __attribute__ stuff what scares me. If you feel like I'm too
> desoriented, please tell me what should I know first.
>
> typedef struct {
> uint8_t b[6];
> } __attribute__((packed)) bdaddr_t;
>
> thanks very much
>
> -
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>
next prev parent reply other threads:[~2004-12-20 19:38 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-20 19:07 newby.-interpreting C soraberri
2004-12-20 19:38 ` Nir Dremer [this message]
2004-12-20 21:17 ` Jan-Benedict Glaw
2004-12-21 15:39 ` soraberri
2004-12-30 11:26 ` Glynn Clements
2004-12-30 11:40 ` Jan-Benedict Glaw
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