switch-coreboot/lib/compute_ip_checksum.c
Stefan Reinauer 6220b632e7 Now version 3: LinuxBIOS -> coreboot rename.
- I left LB_TAG_ intact because they are used by the payloads
- file renames are still missing. see next commit
- some lb_ renames might be missing. feel free to provide patches.

Signed-off-by: Stefan Reinauer <stepan@coresystems.de>
Acked-by: Stefan Reinauer <stepan@coresystems.de>



git-svn-id: svn://coreboot.org/repository/coreboot-v3@564 f3766cd6-281f-0410-b1cd-43a5c92072e9
2008-01-27 18:54:57 +00:00

104 lines
2.5 KiB
C

/*
* This file is part of the coreboot project.
*
* It was taken from kexec-tools 1.101.
*
* Copyright (C) 2003,2004 Eric Biederman <ebiederm@xmission.com>
*
* 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; version 2 of the License.
*
* 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, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <types.h>
#include <ip_checksum.h>
#include <string.h>
unsigned long compute_ip_checksum(void *addr, unsigned long length)
{
u16 *ptr;
unsigned long sum;
unsigned long len;
unsigned long laddr;
/* compute an ip style checksum */
laddr = (unsigned long )addr;
sum = 0;
if (laddr & 1) {
u16 buffer;
unsigned char *ptr;
/* copy the first byte into a 2 byte buffer.
* This way automatically handles the endian question
* of which byte (low or high) the last byte goes in.
*/
buffer = 0;
ptr = addr;
memcpy(&buffer, ptr, 1);
sum += buffer;
if (sum > 0xFFFF)
sum -= 0xFFFF;
length -= 1;
addr = ptr +1;
}
len = length >> 1;
ptr = addr;
while (len--) {
sum += *(ptr++);
if (sum > 0xFFFF)
sum -= 0xFFFF;
}
addr = ptr;
if (length & 1) {
u16 buffer;
unsigned char *ptr;
/* copy the last byte into a 2 byte buffer.
* This way automatically handles the endian question
* of which byte (low or high) the last byte goes in.
*/
buffer = 0;
ptr = addr;
memcpy(&buffer, ptr, 1);
sum += buffer;
if (sum > 0xFFFF)
sum -= 0xFFFF;
}
return (~sum) & 0xFFFF;
}
unsigned long add_ip_checksums(unsigned long offset, unsigned long sum, unsigned long new)
{
unsigned long checksum;
sum = ~sum & 0xFFFF;
new = ~new & 0xFFFF;
if (offset & 1) {
/* byte swap the sum if it came from an odd offset
* since the computation is endian independant this
* works.
*/
new = ((new >> 8) & 0xff) | ((new << 8) & 0xff00);
}
checksum = sum + new;
if (checksum > 0xFFFF) {
checksum -= 0xFFFF;
}
return (~checksum) & 0xFFFF;
}
unsigned long negate_ip_checksum(unsigned long sum)
{
sum = ~sum & 0xFFFF;
sum = 0xFFFF - sum;
return ~sum & 0xFFFF;
}