[linux.git] / fs / xfs / xfs_cksum.h

#ifndef _XFS_CKSUM_H
#define _XFS_CKSUM_H 1

#define XFS_CRC_SEED	(~(__uint32_t)0)

/*
 * 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)));
}

/*
 * Convert the intermediate checksum to the final ondisk format.
 *
 * The CRC32c calculation uses LE format even on BE machines, but returns the
 * result in host endian format. Hence we need to byte swap it back to LE format
 * so that it is consistent on disk.
 */
static inline __le32
xfs_end_cksum(__uint32_t crc)
{
	return ~cpu_to_le32(crc);
}

/*
 * Helper to generate the checksum for a buffer.
 */
static inline void
xfs_update_cksum(char *buffer, size_t length, unsigned long cksum_offset)
{
	__uint32_t crc = xfs_start_cksum(buffer, length, cksum_offset);

	*(__le32 *)(buffer + cksum_offset) = xfs_end_cksum(crc);
}

/*
 * Helper to verify the checksum for a buffer.
 */
static inline int
xfs_verify_cksum(char *buffer, size_t length, unsigned long cksum_offset)
{
	__uint32_t crc = xfs_start_cksum(buffer, length, cksum_offset);

	return *(__le32 *)(buffer + cksum_offset) == xfs_end_cksum(crc);
}

#endif /* _XFS_CKSUM_H */
Commit	Line	Data
bc02e869 CH	1	#ifndef _XFS_CKSUM_H
	2	#define _XFS_CKSUM_H 1
	3
	4	#define XFS_CRC_SEED (~(__uint32_t)0)
	5
	6	/*
	7	* Calculate the intermediate checksum for a buffer that has the CRC field
	8	* inside it. The offset of the 32bit crc fields is passed as the
	9	* cksum_offset parameter.
	10	*/
	11	static inline __uint32_t
	12	xfs_start_cksum(char *buffer, size_t length, unsigned long cksum_offset)
	13	{
	14	__uint32_t zero = 0;
	15	__uint32_t crc;
	16
	17	/* Calculate CRC up to the checksum. */
	18	crc = crc32c(XFS_CRC_SEED, buffer, cksum_offset);
	19
	20	/* Skip checksum field */
	21	crc = crc32c(crc, &zero, sizeof(__u32));
	22
	23	/* Calculate the rest of the CRC. */
	24	return crc32c(crc, &buffer[cksum_offset + sizeof(__be32)],
	25	length - (cksum_offset + sizeof(__be32)));
	26	}
	27
	28	/*
	29	* Convert the intermediate checksum to the final ondisk format.
	30	*
	31	* The CRC32c calculation uses LE format even on BE machines, but returns the
	32	* result in host endian format. Hence we need to byte swap it back to LE format
	33	* so that it is consistent on disk.
	34	*/
	35	static inline __le32
	36	xfs_end_cksum(__uint32_t crc)
	37	{
	38	return ~cpu_to_le32(crc);
	39	}
	40
	41	/*
	42	* Helper to generate the checksum for a buffer.
	43	*/
	44	static inline void
	45	xfs_update_cksum(char *buffer, size_t length, unsigned long cksum_offset)
	46	{
	47	__uint32_t crc = xfs_start_cksum(buffer, length, cksum_offset);
	48
	49	(__le32 )(buffer + cksum_offset) = xfs_end_cksum(crc);
	50	}
	51
	52	/*
	53	* Helper to verify the checksum for a buffer.
	54	*/
	55	static inline int
	56	xfs_verify_cksum(char *buffer, size_t length, unsigned long cksum_offset)
	57	{
	58	__uint32_t crc = xfs_start_cksum(buffer, length, cksum_offset);
	59
	60	return (__le32 )(buffer + cksum_offset) == xfs_end_cksum(crc);
	61	}
	62
	63	#endif /* _XFS_CKSUM_H */