50 lines
1.9 KiB
C
50 lines
1.9 KiB
C
|
/*
|
||
|
|
* This file is part of the libpayload project
|
||
|
|
*
|
||
|
|
* Copyright (c) 2001 Charles Mott <cm@linktel.net>
|
||
|
|
* All rights reserved.
|
||
|
|
*
|
||
|
|
* Redistribution and use in source and binary forms, with or without
|
||
|
|
* modification, are permitted provided that the following conditions
|
||
|
|
* are met:
|
||
|
|
* 1. Redistributions of source code must retain the above copyright
|
||
|
|
* notice, this list of conditions and the following disclaimer.
|
||
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
||
|
|
* notice, this list of conditions and the following disclaimer in the
|
||
|
|
* documentation and/or other materials provided with the distribution.
|
||
|
|
*
|
||
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
||
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
||
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
||
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
||
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
||
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
||
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
||
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
||
|
|
* SUCH DAMAGE.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <libpayload.h>
|
||
|
|
|
||
|
|
unsigned short ipchksum(const unsigned short *ptr, unsigned long nbytes)
|
||
|
|
{
|
||
|
|
int sum, oddbyte;
|
||
|
|
|
||
|
|
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);
|
||
|
|
return (~sum);
|
||
|
|
}
|