checksum.h

xen 3.2.2 源码

#ifndef _ASM_IA64_CHECKSUM_H
#define _ASM_IA64_CHECKSUM_H

/*
 * Modified 1998, 1999
 *	David Mosberger-Tang <[e-mail]>, Hewlett-Packard Co
 */

/*
 * This is a version of ip_compute_csum() optimized for IP headers,
 * which always checksum on 4 octet boundaries.
 */
extern unsigned short ip_fast_csum (unsigned char * iph, unsigned int ihl);

/*
 * Computes the checksum of the TCP/UDP pseudo-header returns a 16-bit
 * checksum, already complemented
 */
extern unsigned short int csum_tcpudp_magic (unsigned long saddr,
					     unsigned long daddr,
					     unsigned short len,
					     unsigned short proto,
					     unsigned int sum);

extern unsigned int csum_tcpudp_nofold (unsigned long saddr,
					unsigned long daddr,
					unsigned short len,
					unsigned short proto,
					unsigned int sum);

/*
 * Computes the checksum of a memory block at buff, length len,
 * and adds in "sum" (32-bit)
 *
 * returns a 32-bit number suitable for feeding into itself
 * or csum_tcpudp_magic
 *
 * this function must be called with even lengths, except
 * for the last fragment, which may be odd
 *
 * it's best to have buff aligned on a 32-bit boundary
 */
extern unsigned int csum_partial (const unsigned char * buff, int len,
				  unsigned int sum);

/*
 * Same as csum_partial, but copies from src while it checksums.
 *
 * Here it is even more important to align src and dst on a 32-bit (or
 * even better 64-bit) boundary.
 */
extern unsigned int csum_partial_copy_from_user (const char *src, char *dst,
						 int len, unsigned int sum,
						 int *errp);

extern unsigned int csum_partial_copy_nocheck (const char *src, char *dst,
					       int len, unsigned int sum);

/*
 * This routine is used for miscellaneous IP-like checksums, mainly in
 * icmp.c
 */
extern unsigned short ip_compute_csum (unsigned char *buff, int len);

/*
 * Fold a partial checksum without adding pseudo headers.
 */
static inline unsigned short
csum_fold (unsigned int sum)
{
	sum = (sum & 0xffff) + (sum >> 16);
	sum = (sum & 0xffff) + (sum >> 16);
	return ~sum;
}

#endif /* _ASM_IA64_CHECKSUM_H */