From: Mark Tinguely <tinguely@sgi.com>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 1/2] xfs: add CRC infrastructure
Date: Thu, 08 Nov 2012 08:42:56 -0600 [thread overview]
Message-ID: <509BC4F0.1040304@sgi.com> (raw)
In-Reply-To: <1352295452-4726-2-git-send-email-david@fromorbit.com>
On 11/07/12 07:37, Dave Chinner wrote:
> +/*
> + * Calculate the intermediate checksum for a buffer that has the CRC field
> + * inside it. The offset of the 32bit crc fields is passed as the
> + * cksum_offset parameter.
> + */
> +static inline __uint32_t
> +xfs_start_cksum(char *buffer, size_t length, unsigned long cksum_offset)
> +{
> + __uint32_t zero = 0;
> + __uint32_t crc;
> +
> + /* Calculate CRC up to the checksum. */
> + crc = crc32c(XFS_CRC_SEED, buffer, cksum_offset);
> +
> + /* Skip checksum field */
> + crc = crc32c(crc,&zero, sizeof(__u32));
> +
> + /* Calculate the rest of the CRC. */
> + return crc32c(crc,&buffer[cksum_offset + sizeof(__be32)],
> + length - (cksum_offset + sizeof(__be32)));
> +}
Why not zero the cksum field and then calculate the crc on the whole buffer?
--Mark.
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next prev parent reply other threads:[~2012-11-08 14:41 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-07 13:37 [PATCH 0/2] xfs: CRCs for log buffers Dave Chinner
2012-11-07 13:37 ` [PATCH 1/2] xfs: add CRC infrastructure Dave Chinner
2012-11-07 16:21 ` Andi Kleen
2012-11-07 20:31 ` Dave Chinner
2012-11-07 21:39 ` Andi Kleen
2012-11-07 22:28 ` Dave Chinner
2012-11-08 14:42 ` Mark Tinguely [this message]
2012-11-08 21:22 ` Dave Chinner
2012-11-09 22:09 ` Mark Tinguely
2012-11-11 1:26 ` Dave Chinner
2012-11-11 19:54 ` Mark Tinguely
2012-11-11 22:51 ` Dave Chinner
2012-11-07 13:37 ` [PATCH 2/2] xfs: add CRC checks to the log Dave Chinner
2012-11-11 19:57 ` Mark Tinguely
2012-11-08 0:21 ` [PATCH 0/2] xfs: CRCs for log buffers Dave Chinner
2012-11-09 0:05 ` Ben Myers
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