From: Dave Chinner <david@fromorbit.com>
To: Eric Sandeen <sandeen@redhat.com>
Cc: xfs-oss <xfs@oss.sgi.com>
Subject: Re: [PATCH] xfsprogs: fix crc32 build on big endian
Date: Sat, 5 Oct 2013 13:54:59 +1000 [thread overview]
Message-ID: <20131005035459.GN4446@dastard> (raw)
In-Reply-To: <524F7753.8050801@redhat.com>
On Fri, Oct 04, 2013 at 09:20:03PM -0500, Eric Sandeen wrote:
> While kernelspace can test #ifdef __LITTLE_ENDIAN, this
> doesn't work in userspace. __LITTLE_ENDIAN is defined -
> as is __BIG_ENDIAN.
>
> So we build on all boxes as __LITTLE_ENDIAN, and the
> self-test (thankfully!) fails on big endian boxes.
I'm glad I put that self test into the build now. :)
> Fix this by testing __BYTE_ORDER values.
>
> And add an else which should never be hit, but just in case...
>
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
>
> diff --git a/libxfs/crc32.c b/libxfs/crc32.c
> index 1c0d958..0f847d2 100644
> --- a/libxfs/crc32.c
> +++ b/libxfs/crc32.c
> @@ -63,18 +63,20 @@ typedef __u32 u64;
> static inline u32
> crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
> {
> -# ifdef __LITTLE_ENDIAN
> +#if __BYTE_ORDER == __LITTLE_ENDIAN
> # define DO_CRC(x) crc = t0[(crc ^ (x)) & 255] ^ (crc >> 8)
> # define DO_CRC4 (t3[(q) & 255] ^ t2[(q >> 8) & 255] ^ \
> t1[(q >> 16) & 255] ^ t0[(q >> 24) & 255])
> # define DO_CRC8 (t7[(q) & 255] ^ t6[(q >> 8) & 255] ^ \
> t5[(q >> 16) & 255] ^ t4[(q >> 24) & 255])
> -# else
> +# elif __BYTE_ORDER == __BIG_ENDIAN
> # define DO_CRC(x) crc = t0[((crc >> 24) ^ (x)) & 255] ^ (crc << 8)
> # define DO_CRC4 (t0[(q) & 255] ^ t1[(q >> 8) & 255] ^ \
> t2[(q >> 16) & 255] ^ t3[(q >> 24) & 255])
> # define DO_CRC8 (t4[(q) & 255] ^ t5[(q >> 8) & 255] ^ \
> t6[(q >> 16) & 255] ^ t7[(q >> 24) & 255])
> +# else
> +# error What endian are you?
> # endif
> const u32 *b;
> size_t rem_len;
Looks good - it matches the other endian checks in the code.
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2013-10-05 3:55 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-05 2:20 [PATCH] xfsprogs: fix crc32 build on big endian Eric Sandeen
2013-10-05 3:54 ` Dave Chinner [this message]
2013-10-18 17:19 ` Rich Johnston
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