From: Grant Edwards <grante@visi.com>
To: ecos-discuss@sources.redhat.com
Subject: [ECOS] Re: pragma pack
Date: Wed, 09 Jan 2008 23:50:00 -0000 [thread overview]
Message-ID: <fm3mgi$v4$1@ger.gmane.org> (raw)
In-Reply-To: <014701c8530d$ff055940$887ba8c0@PAULD>
On 2008-01-09, Paul D. DeRocco <pderocco@ix.netcom.com> wrote:
>> From: Bronislav Gabrhelik
>>
>> Beware of bad alignment of timestamp field. Some processors
>> might raise an exception/interrupt when you use the int like
>> operation directly on field (including assignment &
>> evaluation). You should copy out/in this by memcpy into/from
>> temporary variable of the same type when you need to do some
>> integer computing on this field. In other case your code
>> might not be portable.
>
> I think that's the point of the __packed__ attribute: it
> forces the compiler for any machine on which it matters to do
> the necessary byte packing/unpacking automagically. I know
> that's what the Gnu ARM compiler does.
The trap snaps shut when you take the address of a field in a
packed struct and pass that to somebody who's expecting a
pointer to a normally aligned value.
--
Grant Edwards grante Yow! I am covered with
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next prev parent reply other threads:[~2008-01-09 23:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-09 14:19 [ECOS] " Alexandre
2008-01-09 14:40 ` Andrew Lunn
2008-01-09 14:51 ` Bernard Fouché
2008-01-09 14:56 ` Alexandre
2008-01-09 21:55 ` Bronislav Gabrhelik
2008-01-09 22:22 ` Paul D. DeRocco
2008-01-09 23:50 ` Grant Edwards [this message]
2008-01-10 0:50 ` [ECOS] " Paul D. DeRocco
2008-01-10 9:43 ` Alexandre
2008-01-10 10:07 ` EXTERNAL Gladis Olaf (Praktikant; CR/AEM)
2008-01-10 10:29 ` Alexandre
2008-01-09 15:02 ` [ECOS] " EXTERNAL Gladis Olaf (Praktikant; CR/AEM)
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