/*
* File: arch/blackfin/lib/checksum.c
* Based on: none - original work
* Author:
*
* Created:
* Description: 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.
*
* Modified:
* Copyright 2004-2006 Analog Devices Inc.
*
* Bugs: Enter bugs at http://blackfin.uclinux.org/
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see the file COPYING, or write
* to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include
#include
#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.
*/
unsigned short ip_fast_csum(unsigned char *iph, unsigned int ihl)
{
return ~do_csum(iph, ihl * 4);
}
/*
* 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)
{
/*
* 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;
}
/*
* this routine is used for miscellaneous IP-like checksums, mainly
* in icmp.c
*/
unsigned short ip_compute_csum(const unsigned char *buff, int len)
{
return ~do_csum(buff, len);
}
/*
* copy from fs while checksumming, otherwise like csum_partial
*/
unsigned int
csum_partial_copy_from_user(const unsigned char *src, unsigned char *dst,
int len, int sum, int *csum_err)
{
if (csum_err)
*csum_err = 0;
memcpy(dst, src, len);
return csum_partial(dst, len, sum);
}
/*
* copy from ds while checksumming, otherwise like csum_partial
*/
unsigned int csum_partial_copy(const unsigned char *src, unsigned char *dst,
int len, int sum)
{
memcpy(dst, src, len);
return csum_partial(dst, len, sum);
}