checksum.h

嵌入式ARM的一些源代码

#ifndef _PPC_CHECKSUM_H
#define _PPC_CHECKSUM_H


/*
 *	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);

/*
 * 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);

/*
 * the same as csum_partial, but copies from src while it
 * checksums
 *
 * here even more important to align src and dst on a 32-bit (or even
 * better 64-bit) boundary
 */
unsigned int csum_partial_copy( const char *src, char *dst, int len, int sum);

/*
 * the same as csum_partial, but copies from user space (but on the alpha
 * we have just one address space, so this is identical to the above)
 */
#define csum_partial_copy_fromuser csum_partial_copy


/*
 * this routine is used for miscellaneous IP-like checksums, mainly
 * in icmp.c
A */

extern unsigned short ip_compute_csum(unsigned char * buff, int len);

#endif