/*
* Copyright 2004-2009 Analog Devices Inc.
*
* Licensed under the GPL-2 or later.
*
* An implementation of the TCP/IP protocol suite for the LINUX operating
* system. INET is implemented using the BSD Socket interface as the
* means of communication with the user level.
*
*/
#include <linux/module.h>
#include <net/checksum.h>
#include <asm/checksum.h>
#ifdef CONFIG_IP_CHECKSUM_L1
static unsigned short do_csum(const unsigned char *buff, int len)__attribute__((l1_text));
#endif
static unsigned short do_csum(const unsigned char *buff, int len)
{
register unsigned long sum = 0;
int swappem = 0;
if (1 & (unsigned long)buff) {
sum = *buff << 8;
buff++;
len--;
++swappem;
}
while (len > 1) {
sum += *(unsigned short *)buff;
buff += 2;
len -= 2;
}
if (len > 0)
sum += *buff;
/* Fold 32-bit sum to 16 bits */
while (sum >> 16)
sum = (sum & 0xffff) + (sum >> 16);
if (swappem)
sum = ((sum & 0xff00) >> 8) + ((sum & 0x00ff) << 8);
return sum;
}
/*
* This is a version of ip_compute_csum() optimized for IP headers,
* which always checksum on 4 octet boundaries.
*/
__sum16 ip_fast_csum(unsigned char *iph, unsigned int ihl)
{
return (__force __sum16)~do_csum(iph, ihl * 4);
}
EXPORT_SYMBOL(ip_fast_csum);
/*
* 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
*/
__wsum csum_partial(const void *buff, int len, __wsum sum)
{
/*
* Just in case we get nasty checksum data...
* Like 0xffff6ec3 in the case of our IPv6 multicast header.
* We fold to begin with, as well as at the end.
*/
sum = (sum & 0xffff) + (sum >> 16);
sum += do_csum(buff, len);
sum = (sum & 0xffff) + (sum >> 16);
return sum;
}
EXPORT_SYMBOL(csum_partial);
/*
* this routine is used for miscellaneous IP-like checksums, mainly
* in icmp.c
*/
__sum16 ip_compute_csum(const void *buff, int len)
{
return (__force __sum16)~do_csum(buff, len);
}
EXPORT_SYMBOL(ip_compute_csum);
/*
* copy from fs while checksumming, otherwise like csum_partial
*/
__wsum
csum_partial_copy_from_user(const void __user *src, void *dst,
int len, __wsum sum, int *csum_err)
{
if (csum_err)
*csum_err = 0;
memcpy(dst, (__force void *)src, len);
return csum_partial(dst, len, sum);
}
EXPORT_SYMBOL(csum_partial_copy_from_user);
/*
* copy from ds while checksumming, otherwise like csum_partial
*/
__wsum csum_partial_copy(const void *src, void *dst, int len, __wsum sum)
{
memcpy(dst, src, len);
return csum_partial(dst, len, sum);
}
EXPORT_SYMBOL(csum_partial_copy);
