1*22028508SToomas Soome /* $NetBSD: in_cksum.c,v 1.6 2000/03/31 19:55:09 castor Exp $ */
2*22028508SToomas Soome
3*22028508SToomas Soome /*
4*22028508SToomas Soome * Copyright (c) 1992 Regents of the University of California.
5*22028508SToomas Soome * All rights reserved.
6*22028508SToomas Soome *
7*22028508SToomas Soome * This software was developed by the Computer Systems Engineering group
8*22028508SToomas Soome * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9*22028508SToomas Soome * contributed to Berkeley.
10*22028508SToomas Soome *
11*22028508SToomas Soome * Redistribution and use in source and binary forms, with or without
12*22028508SToomas Soome * modification, are permitted provided that the following conditions
13*22028508SToomas Soome * are met:
14*22028508SToomas Soome * 1. Redistributions of source code must retain the above copyright
15*22028508SToomas Soome * notice, this list of conditions and the following disclaimer.
16*22028508SToomas Soome * 2. Redistributions in binary form must reproduce the above copyright
17*22028508SToomas Soome * notice, this list of conditions and the following disclaimer in the
18*22028508SToomas Soome * documentation and/or other materials provided with the distribution.
19*22028508SToomas Soome * 3. Neither the name of the University nor the names of its contributors
20*22028508SToomas Soome * may be used to endorse or promote products derived from this software
21*22028508SToomas Soome * without specific prior written permission.
22*22028508SToomas Soome *
23*22028508SToomas Soome * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24*22028508SToomas Soome * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25*22028508SToomas Soome * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26*22028508SToomas Soome * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27*22028508SToomas Soome * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28*22028508SToomas Soome * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29*22028508SToomas Soome * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30*22028508SToomas Soome * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31*22028508SToomas Soome * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32*22028508SToomas Soome * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33*22028508SToomas Soome * SUCH DAMAGE.
34*22028508SToomas Soome *
35*22028508SToomas Soome * @(#) Header: in_cksum.c,v 1.1 92/09/11 01:15:55 leres Exp (LBL)
36*22028508SToomas Soome */
37*22028508SToomas Soome
38*22028508SToomas Soome #include <sys/cdefs.h>
39*22028508SToomas Soome
40*22028508SToomas Soome #include <sys/types.h>
41*22028508SToomas Soome #include <machine/endian.h>
42*22028508SToomas Soome
43*22028508SToomas Soome #include "stand.h"
44*22028508SToomas Soome
45*22028508SToomas Soome /*
46*22028508SToomas Soome * Checksum routine for Internet Protocol family headers.
47*22028508SToomas Soome * This routine is very heavily used in the network
48*22028508SToomas Soome * code and should be modified for each CPU to be as fast as possible.
49*22028508SToomas Soome * In particular, it should not be this one.
50*22028508SToomas Soome */
51*22028508SToomas Soome int
in_cksum(void * p,int len)52*22028508SToomas Soome in_cksum(void *p, int len)
53*22028508SToomas Soome {
54*22028508SToomas Soome int sum = 0, oddbyte = 0, v = 0;
55*22028508SToomas Soome uchar_t *cp = p;
56*22028508SToomas Soome
57*22028508SToomas Soome /* we assume < 2^16 bytes being summed */
58*22028508SToomas Soome while (len > 0) {
59*22028508SToomas Soome if (oddbyte) {
60*22028508SToomas Soome sum += v + *cp++;
61*22028508SToomas Soome len--;
62*22028508SToomas Soome }
63*22028508SToomas Soome if (((long)cp & 1) == 0) {
64*22028508SToomas Soome while ((len -= 2) >= 0) {
65*22028508SToomas Soome sum += *(ushort_t *)cp;
66*22028508SToomas Soome cp += 2;
67*22028508SToomas Soome }
68*22028508SToomas Soome } else {
69*22028508SToomas Soome while ((len -= 2) >= 0) {
70*22028508SToomas Soome #if BYTE_ORDER == BIG_ENDIAN
71*22028508SToomas Soome sum += *cp++ << 8;
72*22028508SToomas Soome sum += *cp++;
73*22028508SToomas Soome #else
74*22028508SToomas Soome sum += *cp++;
75*22028508SToomas Soome sum += *cp++ << 8;
76*22028508SToomas Soome #endif
77*22028508SToomas Soome }
78*22028508SToomas Soome }
79*22028508SToomas Soome if ((oddbyte = len & 1) != 0)
80*22028508SToomas Soome #if BYTE_ORDER == BIG_ENDIAN
81*22028508SToomas Soome v = *cp << 8;
82*22028508SToomas Soome #else
83*22028508SToomas Soome v = *cp;
84*22028508SToomas Soome #endif
85*22028508SToomas Soome }
86*22028508SToomas Soome if (oddbyte)
87*22028508SToomas Soome sum += v;
88*22028508SToomas Soome sum = (sum >> 16) + (sum & 0xffff); /* add in accumulated carries */
89*22028508SToomas Soome sum += sum >> 16; /* add potential last carry */
90*22028508SToomas Soome return (0xffff & ~sum);
91*22028508SToomas Soome }
92