From: Thiemo Seufer <ths@networkno.de>
To: hemanth.venkatesh@wipro.com
Cc: linux-mips@linux-mips.org
Subject: Re: Bit operations work differently on MIPS and IA32
Date: Thu, 20 Jul 2006 17:18:39 +0100 [thread overview]
Message-ID: <20060720161839.GE4350@networkno.de> (raw)
In-Reply-To: <2156B1E923F1A147AABDF4D9FDEAB4CB09D3D8@blr-m2-msg.wipro.com>
hemanth.venkatesh@wipro.com wrote:
> Hi All,
>
>
>
> I ran the below program on an IA32 and AU1100 machine, both being little
> endian machines and got different results. Does anyone know what could
> be the cause of this behaviour. This problem is blocking us from booting
> the cramfs rootfs.
>
>
>
> #include <stdio.h>
>
> typedef unsigned int u32;
>
> main()
>
> {
>
> struct tmp{
>
> u32 namelen:6,offset:26;
>
> }tmp1;
>
> (*(int *)(&tmp1))=0x4c0;
This makes non-portable assumptions about the bitfield layout. The
results are platform-dependent (or rather ABI-dependent). Portable
code needs to avoid acessing bitfields via typecasts.
Thiemo
next prev parent reply other threads:[~2006-07-20 16:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-20 16:02 Bit operations work differently on MIPS and IA32 hemanth.venkatesh
2006-07-20 16:02 ` hemanth.venkatesh
2006-07-20 16:18 ` Thiemo Seufer [this message]
2006-07-20 17:45 ` Jonathan Day
2006-07-21 6:51 ` hemanth.venkatesh
2006-07-21 6:51 ` hemanth.venkatesh
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