mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-11-17 18:28:55 +00:00
9b0e35cb48
Move the checksum code out into its own file so it can be used elsewhere. Also use a new version which supports a length which is not a multiple of 2 and add a new function to add two checksums. Signed-off-by: Simon Glass <sjg@chromium.org>
60 lines
1.2 KiB
C
60 lines
1.2 KiB
C
/*
|
|
* This file was originally taken from the FreeBSD project.
|
|
*
|
|
* Copyright (c) 2001 Charles Mott <cm@linktel.net>
|
|
* Copyright (c) 2008 coresystems GmbH
|
|
* All rights reserved.
|
|
*
|
|
* SPDX-License-Identifier: BSD-2-Clause
|
|
*/
|
|
|
|
#include <common.h>
|
|
#include <net.h>
|
|
|
|
unsigned compute_ip_checksum(const void *vptr, unsigned nbytes)
|
|
{
|
|
int sum, oddbyte;
|
|
const unsigned short *ptr = vptr;
|
|
|
|
sum = 0;
|
|
while (nbytes > 1) {
|
|
sum += *ptr++;
|
|
nbytes -= 2;
|
|
}
|
|
if (nbytes == 1) {
|
|
oddbyte = 0;
|
|
((u8 *)&oddbyte)[0] = *(u8 *)ptr;
|
|
((u8 *)&oddbyte)[1] = 0;
|
|
sum += oddbyte;
|
|
}
|
|
sum = (sum >> 16) + (sum & 0xffff);
|
|
sum += (sum >> 16);
|
|
sum = ~sum & 0xffff;
|
|
|
|
return sum;
|
|
}
|
|
|
|
unsigned add_ip_checksums(unsigned offset, unsigned sum, unsigned 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;
|
|
}
|
|
|
|
int ip_checksum_ok(const void *addr, unsigned nbytes)
|
|
{
|
|
return !(compute_ip_checksum(addr, nbytes) & 0xfffe);
|
|
}
|