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/* $Id: checksum.h,v 1.3 2000/11/15 17:35:16 bjornw Exp $ */
/* TODO: csum_tcpudp_magic could be speeded up, and csum_fold as well */
#ifndef _CRIS_CHECKSUM_H
#define _CRIS_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
*/
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_nocheck(const char *src, char *dst,
int len, unsigned int sum);
/*
* Fold a partial checksum into a word
*/
static inline unsigned int csum_fold(unsigned int sum)
{
/* the while loop is unnecessary really, it's always enough with two
iterations */
while(sum >> 16)
sum = (sum & 0xffff) + (sum >> 16); /* add in end-around carry */
return ~sum;
}
/* Checksum some values used in TCP/UDP headers.
*
* The gain by doing this in asm is that C will not generate carry-additions
* for the 32-bit components of the checksum, so otherwise we would have had
* to split all of those into 16-bit components, then add.
*/
static inline unsigned int
csum_tcpudp_nofold(unsigned long saddr, unsigned long daddr, unsigned short len,
unsigned short proto, unsigned int sum)
{
int res;
__asm__ ("add.d %2, %0\n\t"
"ax\n\t"
"add.d %3, %0\n\t"
"ax\n\t"
"add.d %4, %0\n\t"
"ax\n\t"
"addq 0, %0\n"
: "=r" (res)
: "0" (sum), "r" (daddr), "r" (saddr), "r" ((ntohs(len) << 16) + (proto << 8)));
return res;
}
/* TODO we need to write this properly to handle userland VM exceptions!! */
#define csum_partial_copy_from_user(a,b,c,d,errptr) csum_partial_copy_nocheck(a,b,c,d)
#if 0
unsigned int csum_partial_copy_from_user(const char *src, char *dst,
int len, unsigned int sum);
#endif
/*
* This is a version of ip_compute_csum() optimized for IP headers,
* which always checksum on 4 octet boundaries.
*
*/
static inline unsigned short ip_fast_csum(unsigned char * iph,
unsigned int ihl)
{
return csum_fold(csum_partial(iph, ihl * 4, 0));
}
/*
* computes the checksum of the TCP/UDP pseudo-header
* returns a 16-bit checksum, already complemented
*/
static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,
unsigned long daddr,
unsigned short len,
unsigned short proto,
unsigned int sum)
{
return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
}
/*
* this routine is used for miscellaneous IP-like checksums, mainly
* in icmp.c
*/
static inline unsigned short ip_compute_csum(unsigned char * buff, int len) {
return csum_fold (csum_partial(buff, len, 0));
}
#endif
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