1199767f8SToomas Soome /* $NetBSD: in_cksum.c,v 1.6 2000/03/31 19:55:09 castor Exp $ */
2199767f8SToomas Soome
3199767f8SToomas Soome /*
4199767f8SToomas Soome * Copyright (c) 1992 Regents of the University of California.
5199767f8SToomas Soome * All rights reserved.
6199767f8SToomas Soome *
7199767f8SToomas Soome * This software was developed by the Computer Systems Engineering group
8199767f8SToomas Soome * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9199767f8SToomas Soome * contributed to Berkeley.
10199767f8SToomas Soome *
11199767f8SToomas Soome * Redistribution and use in source and binary forms, with or without
12199767f8SToomas Soome * modification, are permitted provided that the following conditions
13199767f8SToomas Soome * are met:
14199767f8SToomas Soome * 1. Redistributions of source code must retain the above copyright
15199767f8SToomas Soome * notice, this list of conditions and the following disclaimer.
16199767f8SToomas Soome * 2. Redistributions in binary form must reproduce the above copyright
17199767f8SToomas Soome * notice, this list of conditions and the following disclaimer in the
18199767f8SToomas Soome * documentation and/or other materials provided with the distribution.
190384eafeSToomas Soome * 3. Neither the name of the University nor the names of its contributors
20199767f8SToomas Soome * may be used to endorse or promote products derived from this software
21199767f8SToomas Soome * without specific prior written permission.
22199767f8SToomas Soome *
23199767f8SToomas Soome * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24199767f8SToomas Soome * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25199767f8SToomas Soome * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26199767f8SToomas Soome * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27199767f8SToomas Soome * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28199767f8SToomas Soome * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29199767f8SToomas Soome * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30199767f8SToomas Soome * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31199767f8SToomas Soome * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32199767f8SToomas Soome * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33199767f8SToomas Soome * SUCH DAMAGE.
34199767f8SToomas Soome *
35199767f8SToomas Soome * @(#) Header: in_cksum.c,v 1.1 92/09/11 01:15:55 leres Exp (LBL)
36199767f8SToomas Soome */
37199767f8SToomas Soome
38199767f8SToomas Soome #include <sys/cdefs.h>
39199767f8SToomas Soome
40199767f8SToomas Soome #include <sys/types.h>
41199767f8SToomas Soome #include <machine/endian.h>
42199767f8SToomas Soome
43199767f8SToomas Soome #include "stand.h"
44199767f8SToomas Soome
45199767f8SToomas Soome /*
46199767f8SToomas Soome * Checksum routine for Internet Protocol family headers.
47199767f8SToomas Soome * This routine is very heavily used in the network
48199767f8SToomas Soome * code and should be modified for each CPU to be as fast as possible.
49199767f8SToomas Soome * In particular, it should not be this one.
50199767f8SToomas Soome */
51199767f8SToomas Soome int
in_cksum(void * p,int len)520384eafeSToomas Soome in_cksum(void *p, int len)
53199767f8SToomas Soome {
54199767f8SToomas Soome int sum = 0, oddbyte = 0, v = 0;
550384eafeSToomas Soome uchar_t *cp = p;
56199767f8SToomas Soome
57199767f8SToomas Soome /* we assume < 2^16 bytes being summed */
58199767f8SToomas Soome while (len > 0) {
59199767f8SToomas Soome if (oddbyte) {
60199767f8SToomas Soome sum += v + *cp++;
61199767f8SToomas Soome len--;
62199767f8SToomas Soome }
63199767f8SToomas Soome if (((long)cp & 1) == 0) {
64199767f8SToomas Soome while ((len -= 2) >= 0) {
650384eafeSToomas Soome sum += *(ushort_t *)cp;
66199767f8SToomas Soome cp += 2;
67199767f8SToomas Soome }
68199767f8SToomas Soome } else {
69199767f8SToomas Soome while ((len -= 2) >= 0) {
70199767f8SToomas Soome #if BYTE_ORDER == BIG_ENDIAN
71199767f8SToomas Soome sum += *cp++ << 8;
72199767f8SToomas Soome sum += *cp++;
73199767f8SToomas Soome #else
74199767f8SToomas Soome sum += *cp++;
75199767f8SToomas Soome sum += *cp++ << 8;
76199767f8SToomas Soome #endif
77199767f8SToomas Soome }
78199767f8SToomas Soome }
79199767f8SToomas Soome if ((oddbyte = len & 1) != 0)
80199767f8SToomas Soome #if BYTE_ORDER == BIG_ENDIAN
81199767f8SToomas Soome v = *cp << 8;
82199767f8SToomas Soome #else
83199767f8SToomas Soome v = *cp;
84199767f8SToomas Soome #endif
85199767f8SToomas Soome }
86199767f8SToomas Soome if (oddbyte)
87199767f8SToomas Soome sum += v;
88199767f8SToomas Soome sum = (sum >> 16) + (sum & 0xffff); /* add in accumulated carries */
89199767f8SToomas Soome sum += sum >> 16; /* add potential last carry */
90199767f8SToomas Soome return (0xffff & ~sum);
91199767f8SToomas Soome }
92