/*
* Copyright (c) 2000-2018 Apple Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this
* file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_LICENSE_HEADER_END@
*/
/*
* Copyright (c) 1988, 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
*/
#include <sys/param.h>
#include "in_cksum.h"
typedef union {
char c[2];
u_short s;
} short_union_t;
typedef union {
u_short s[2];
long l;
} long_union_t;
static __inline__ void
reduce(int * sum)
{
long_union_t l_util;
l_util.l = *sum;
*sum = l_util.s[0] + l_util.s[1];
if (*sum > 65535) {
*sum -= 65535;
}
return;
}
#include <stdio.h>
unsigned short
in_cksum(void * pkt, int len)
{
u_short * w;
int sum = 0;
w = (u_short *)pkt;
while ((len -= 32) >= 0) {
sum += w[0]; sum += w[1];
sum += w[2]; sum += w[3];
sum += w[4]; sum += w[5];
sum += w[6]; sum += w[7];
sum += w[8]; sum += w[9];
sum += w[10]; sum += w[11];
sum += w[12]; sum += w[13];
sum += w[14]; sum += w[15];
w += 16;
}
len += 32;
while ((len -= 8) >= 0) {
sum += w[0]; sum += w[1];
sum += w[2]; sum += w[3];
w += 4;
}
len += 8;
if (len) {
reduce(&sum);
while ((len -= 2) >= 0) {
sum += *w++;
}
}
if (len == -1) { /* odd-length packet */
short_union_t s_util;
s_util.s = 0;
s_util.c[0] = *((char *)w);
s_util.c[1] = 0;
sum += s_util.s;
}
reduce(&sum);
return ~sum & 0xffff;
}