1*479ab7f0SSascha Wildner /* $NetBSD: in_cksum.c,v 1.6 2000/03/31 19:55:09 castor Exp $ */
2*479ab7f0SSascha Wildner
3*479ab7f0SSascha Wildner /*
4*479ab7f0SSascha Wildner * Copyright (c) 1992 Regents of the University of California.
5*479ab7f0SSascha Wildner * All rights reserved.
6*479ab7f0SSascha Wildner *
7*479ab7f0SSascha Wildner * This software was developed by the Computer Systems Engineering group
8*479ab7f0SSascha Wildner * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9*479ab7f0SSascha Wildner * contributed to Berkeley.
10*479ab7f0SSascha Wildner *
11*479ab7f0SSascha Wildner * Redistribution and use in source and binary forms, with or without
12*479ab7f0SSascha Wildner * modification, are permitted provided that the following conditions
13*479ab7f0SSascha Wildner * are met:
14*479ab7f0SSascha Wildner * 1. Redistributions of source code must retain the above copyright
15*479ab7f0SSascha Wildner * notice, this list of conditions and the following disclaimer.
16*479ab7f0SSascha Wildner * 2. Redistributions in binary form must reproduce the above copyright
17*479ab7f0SSascha Wildner * notice, this list of conditions and the following disclaimer in the
18*479ab7f0SSascha Wildner * documentation and/or other materials provided with the distribution.
19*479ab7f0SSascha Wildner * 3. Neither the name of the University nor the names of its contributors
20*479ab7f0SSascha Wildner * may be used to endorse or promote products derived from this software
21*479ab7f0SSascha Wildner * without specific prior written permission.
22*479ab7f0SSascha Wildner *
23*479ab7f0SSascha Wildner * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24*479ab7f0SSascha Wildner * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25*479ab7f0SSascha Wildner * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26*479ab7f0SSascha Wildner * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27*479ab7f0SSascha Wildner * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28*479ab7f0SSascha Wildner * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29*479ab7f0SSascha Wildner * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30*479ab7f0SSascha Wildner * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31*479ab7f0SSascha Wildner * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32*479ab7f0SSascha Wildner * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33*479ab7f0SSascha Wildner * SUCH DAMAGE.
34*479ab7f0SSascha Wildner *
35*479ab7f0SSascha Wildner * @(#) Header: in_cksum.c,v 1.1 92/09/11 01:15:55 leres Exp (LBL)
36*479ab7f0SSascha Wildner * $FreeBSD: src/lib/libstand/in_cksum.c,v 1.1.1.1.6.1 2002/07/22 09:28:50 peter Exp $
37*479ab7f0SSascha Wildner * $DragonFly: src/lib/libstand/in_cksum.c,v 1.3 2005/12/11 02:27:26 swildner Exp $
38*479ab7f0SSascha Wildner */
39*479ab7f0SSascha Wildner
40*479ab7f0SSascha Wildner #include <sys/types.h>
41*479ab7f0SSascha Wildner #include <machine/endian.h>
42*479ab7f0SSascha Wildner
43*479ab7f0SSascha Wildner #include "stand.h"
44*479ab7f0SSascha Wildner
45*479ab7f0SSascha Wildner /*
46*479ab7f0SSascha Wildner * Checksum routine for Internet Protocol family headers.
47*479ab7f0SSascha Wildner * This routine is very heavily used in the network
48*479ab7f0SSascha Wildner * code and should be modified for each CPU to be as fast as possible.
49*479ab7f0SSascha Wildner * In particular, it should not be this one.
50*479ab7f0SSascha Wildner */
51*479ab7f0SSascha Wildner int
in_cksum(void * p,int len)52*479ab7f0SSascha Wildner in_cksum(void *p, int len)
53*479ab7f0SSascha Wildner {
54*479ab7f0SSascha Wildner int sum = 0, oddbyte = 0, v = 0;
55*479ab7f0SSascha Wildner u_char *cp = p;
56*479ab7f0SSascha Wildner
57*479ab7f0SSascha Wildner /* we assume < 2^16 bytes being summed */
58*479ab7f0SSascha Wildner while (len > 0) {
59*479ab7f0SSascha Wildner if (oddbyte) {
60*479ab7f0SSascha Wildner sum += v + *cp++;
61*479ab7f0SSascha Wildner len--;
62*479ab7f0SSascha Wildner }
63*479ab7f0SSascha Wildner if (((long)cp & 1) == 0) {
64*479ab7f0SSascha Wildner while ((len -= 2) >= 0) {
65*479ab7f0SSascha Wildner sum += *(u_short *)cp;
66*479ab7f0SSascha Wildner cp += 2;
67*479ab7f0SSascha Wildner }
68*479ab7f0SSascha Wildner } else {
69*479ab7f0SSascha Wildner while ((len -= 2) >= 0) {
70*479ab7f0SSascha Wildner #if BYTE_ORDER == BIG_ENDIAN
71*479ab7f0SSascha Wildner sum += *cp++ << 8;
72*479ab7f0SSascha Wildner sum += *cp++;
73*479ab7f0SSascha Wildner #else
74*479ab7f0SSascha Wildner sum += *cp++;
75*479ab7f0SSascha Wildner sum += *cp++ << 8;
76*479ab7f0SSascha Wildner #endif
77*479ab7f0SSascha Wildner }
78*479ab7f0SSascha Wildner }
79*479ab7f0SSascha Wildner if ((oddbyte = len & 1) != 0)
80*479ab7f0SSascha Wildner #if BYTE_ORDER == BIG_ENDIAN
81*479ab7f0SSascha Wildner v = *cp << 8;
82*479ab7f0SSascha Wildner #else
83*479ab7f0SSascha Wildner v = *cp;
84*479ab7f0SSascha Wildner #endif
85*479ab7f0SSascha Wildner }
86*479ab7f0SSascha Wildner if (oddbyte)
87*479ab7f0SSascha Wildner sum += v;
88*479ab7f0SSascha Wildner sum = (sum >> 16) + (sum & 0xffff); /* add in accumulated carries */
89*479ab7f0SSascha Wildner sum += sum >> 16; /* add potential last carry */
90*479ab7f0SSascha Wildner return (0xffff & ~sum);
91*479ab7f0SSascha Wildner }
92