checksum.h
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#ifndef __ASM_GENERIC_CHECKSUM_H
#define __ASM_GENERIC_CHECKSUM_H
/*
* 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 __wsum csum_partial(const void *buff, int len, __wsum 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
*/
extern __wsum csum_partial_copy(const void *src, void *dst, int len, __wsum sum);
/*
* the same as csum_partial_copy, but copies from user space.
*
* here even more important to align src and dst on a 32-bit (or even
* better 64-bit) boundary
*/
extern __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
int len, __wsum sum, int *csum_err);
#ifndef csum_partial_copy_nocheck
#define csum_partial_copy_nocheck(src, dst, len, sum) \
csum_partial_copy((src), (dst), (len), (sum))
#endif
#ifndef ip_fast_csum
/*
* This is a version of ip_compute_csum() optimized for IP headers,
* which always checksum on 4 octet boundaries.
*/
extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
#endif
#ifndef csum_fold
/*
* Fold a partial checksum
*/
static inline __sum16 csum_fold(__wsum csum)
{
u32 sum = (__force u32)csum;
sum = (sum & 0xffff) + (sum >> 16);
sum = (sum & 0xffff) + (sum >> 16);
return (__force __sum16)~sum;
}
#endif
#ifndef csum_tcpudp_nofold
/*
* computes the checksum of the TCP/UDP pseudo-header
* returns a 16-bit checksum, already complemented
*/
extern __wsum
csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
unsigned short proto, __wsum sum);
#endif
#ifndef csum_tcpudp_magic
static inline __sum16
csum_tcpudp_magic(__be32 saddr, __be32 daddr, unsigned short len,
unsigned short proto, __wsum sum)
{
return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
}
#endif
/*
* this routine is used for miscellaneous IP-like checksums, mainly
* in icmp.c
*/
extern __sum16 ip_compute_csum(const void *buff, int len);
#endif /* __ASM_GENERIC_CHECKSUM_H */