Remove some unnecessary inclusions of <sys/cdefs.h> across the tree.
[dragonfly.git] / lib / libatm / ip_checksum.c
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1/*
2 *
3 * ===================================
4 * HARP | Host ATM Research Platform
5 * ===================================
6 *
7 *
8 * This Host ATM Research Platform ("HARP") file (the "Software") is
9 * made available by Network Computing Services, Inc. ("NetworkCS")
10 * "AS IS". NetworkCS does not provide maintenance, improvements or
11 * support of any kind.
12 *
13 * NETWORKCS MAKES NO WARRANTIES OR REPRESENTATIONS, EXPRESS OR IMPLIED,
14 * INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY
15 * AND FITNESS FOR A PARTICULAR PURPOSE, AS TO ANY ELEMENT OF THE
16 * SOFTWARE OR ANY SUPPORT PROVIDED IN CONNECTION WITH THIS SOFTWARE.
17 * In no event shall NetworkCS be responsible for any damages, including
18 * but not limited to consequential damages, arising from or relating to
19 * any use of the Software or related support.
20 *
21 * Copyright 1994-1998 Network Computing Services, Inc.
22 *
23 * Copies of this Software may be made, however, the above copyright
24 * notice must be reproduced on all copies.
25 *
26 * @(#) $FreeBSD: src/lib/libatm/ip_checksum.c,v 1.3.2.1 2001/09/28 16:52:10 dillon Exp $
27 *
28 */
29
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30/*
31 * User Space Library Functions
32 * ----------------------------
33 *
34 * IP checksum computation
35 *
36 */
37
38#include <sys/types.h>
39#include <sys/param.h>
40#include <sys/socket.h>
41#include <net/if.h>
42#include <netinet/in.h>
43#include <netatm/port.h>
44#include <netatm/atm.h>
45#include <netatm/atm_if.h>
46#include <netatm/atm_sap.h>
47#include <netatm/atm_sys.h>
48#include <netatm/atm_ioctl.h>
49
50#include "libatm.h"
51
52/*
53 * Compute an IP checksum
54 *
55 * This code was taken from RFC 1071.
56 *
57 * "The following "C" code algorithm computes the checksum with an inner
58 * loop that sums 16 bits at a time in a 32-bit accumulator."
59 *
60 * Arguments:
61 * addr pointer to the buffer whose checksum is to be computed
62 * count number of bytes to include in the checksum
63 *
64 * Returns:
65 * the computed checksum
66 *
67 */
68short
d797dc5d 69ip_checksum(char *addr, int count)
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70{
71 /* Compute Internet Checksum for "count" bytes
72 * beginning at location "addr".
73 */
660c873b 74 long sum = 0;
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75
76 while( count > 1 ) {
77 /* This is the inner loop */
78 sum += ntohs(* (unsigned short *) addr);
79 addr += sizeof(unsigned short);
80 count -= sizeof(unsigned short);
81 }
82
83 /* Add left-over byte, if any */
84 if( count > 0 )
85 sum += * (unsigned char *) addr;
86
87 /* Fold 32-bit sum to 16 bits */
88 while (sum>>16)
89 sum = (sum & 0xffff) + (sum >> 16);
90
91 return((short)~sum);
92}