Use CSTD and remove local CSTD settings which are no longer needed.
[dragonfly.git] / lib / libstand / in_cksum.c
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1/* $NetBSD: in_cksum.c,v 1.6 2000/03/31 19:55:09 castor Exp $ */
2
3/*
4 * Copyright (c) 1992 Regents of the University of California.
5 * All rights reserved.
6 *
7 * This software was developed by the Computer Systems Engineering group
8 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9 * contributed to Berkeley.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. All advertising materials mentioning features or use of this software
20 * must display the following acknowledgement:
21 * This product includes software developed by the University of
22 * California, Lawrence Berkeley Laboratory and its contributors.
23 * 4. Neither the name of the University nor the names of its contributors
24 * may be used to endorse or promote products derived from this software
25 * without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 * SUCH DAMAGE.
38 *
39 * @(#) Header: in_cksum.c,v 1.1 92/09/11 01:15:55 leres Exp (LBL)
1de703da 40 * $FreeBSD: src/lib/libstand/in_cksum.c,v 1.1.1.1.6.1 2002/07/22 09:28:50 peter Exp $
ff2aef30 41 * $DragonFly: src/lib/libstand/in_cksum.c,v 1.3 2005/12/11 02:27:26 swildner Exp $
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42 */
43
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44#include <sys/types.h>
45#include <machine/endian.h>
46
47#include "stand.h"
48
49/*
50 * Checksum routine for Internet Protocol family headers.
51 * This routine is very heavily used in the network
52 * code and should be modified for each CPU to be as fast as possible.
53 * In particular, it should not be this one.
54 */
55int
ff2aef30 56in_cksum(void *p, int len)
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57{
58 int sum = 0, oddbyte = 0, v = 0;
59 u_char *cp = p;
60
61 /* we assume < 2^16 bytes being summed */
62 while (len > 0) {
63 if (oddbyte) {
64 sum += v + *cp++;
65 len--;
66 }
67 if (((long)cp & 1) == 0) {
68 while ((len -= 2) >= 0) {
69 sum += *(u_short *)cp;
70 cp += 2;
71 }
72 } else {
73 while ((len -= 2) >= 0) {
74#if BYTE_ORDER == BIG_ENDIAN
75 sum += *cp++ << 8;
76 sum += *cp++;
77#else
78 sum += *cp++;
79 sum += *cp++ << 8;
80#endif
81 }
82 }
83 if ((oddbyte = len & 1) != 0)
84#if BYTE_ORDER == BIG_ENDIAN
85 v = *cp << 8;
86#else
87 v = *cp;
88#endif
89 }
90 if (oddbyte)
91 sum += v;
92 sum = (sum >> 16) + (sum & 0xffff); /* add in accumulated carries */
93 sum += sum >> 16; /* add potential last carry */
94 return (0xffff & ~sum);
95}