1 /*-
2 * Copyright (c) 1982, 1992, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * Copyright (c) 1995, Mike Mitchell
30 *
31 * Redistribution and use in source and binary forms, with or without
32 * modification, are permitted provided that the following conditions
33 * are met:
34 * 1. Redistributions of source code must retain the above copyright
35 * notice, this list of conditions and the following disclaimer.
36 * 2. Redistributions in binary form must reproduce the above copyright
37 * notice, this list of conditions and the following disclaimer in the
38 * documentation and/or other materials provided with the distribution.
39 * 3. All advertising materials mentioning features or use of this software
40 * must display the following acknowledgement:
41 * This product includes software developed by the University of
42 * California, Berkeley and its contributors.
43 * 4. Neither the name of the University nor the names of its contributors
44 * may be used to endorse or promote products derived from this software
45 * without specific prior written permission.
46 *
47 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
48 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
49 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
50 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
51 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
52 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
53 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
54 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
55 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
56 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
57 * SUCH DAMAGE.
58 *
59 * @(#)ipx_cksum.c
60 */
61
62 #include <sys/cdefs.h>
63 __FBSDID("$FreeBSD: src/sys/netipx/ipx_cksum.c,v 1.15 2007/05/11 10:38:34 rwatson Exp $");
64
65 #include <sys/param.h>
66 #include <sys/mbuf.h>
67 #include <sys/libkern.h>
68
69 #include <netipx/ipx.h>
70 #include <netipx/ipx_var.h>
71
72
73 #define SUMADV sum += *w++
74
75 u_short
76 ipx_cksum(struct mbuf *m, int len)
77 {
78 u_int32_t sum = 0;
79 u_char *w;
80 u_char oldtc;
81 int mlen, words;
82 struct ipx *ipx;
83 union {
84 u_char b[2];
85 u_short w;
86 } buf;
87
88 ipx = mtod(m, struct ipx*);
89 oldtc = ipx->ipx_tc;
90 ipx->ipx_tc = 0;
91 w = (u_char *)&ipx->ipx_len;
92 len -= 2;
93 mlen = 2;
94
95 for(;;) {
96 mlen = imin(m->m_len - mlen, len);
97 words = mlen / 2;
98 len -= mlen & ~1;
99 while (words >= 16) {
100 SUMADV; SUMADV; SUMADV; SUMADV;
101 SUMADV; SUMADV; SUMADV; SUMADV;
102 SUMADV; SUMADV; SUMADV; SUMADV;
103 SUMADV; SUMADV; SUMADV; SUMADV;
104 words -= 16;
105 }
106 while (words--)
107 SUMADV;
108 if (len == 0)
109 break;
110 mlen &= 1;
111 if (mlen) {
112 buf.b[0] = *w;
113 if (--len == 0) {
114 buf.b[1] = 0;
115 sum += buf.w;
116 break;
117 }
118 }
119 m = m->m_next;
120 if (m == NULL)
121 break;
122 w = mtod(m, u_char *);
123 if (mlen) {
124 buf.b[1] = *w;
125 sum += buf.w;
126 w++;
127 if (--len == 0)
128 break;
129 }
130 }
131
132 ipx->ipx_tc = oldtc;
133
134 sum = (sum & 0xffff) + (sum >> 16);
135 if (sum >= 0x10000)
136 sum++;
137 if (sum)
138 sum = ~sum;
139 return (sum);
140 }
141
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