source: rtems/c/src/exec/libnetworking/netinet/in_cksum.c @ 887618b0

4.104.114.84.9
Last change on this file since 887618b0 was 887618b0, checked in by Joel Sherrill <joel.sherrill@…>, on Jan 26, 1999 at 1:49:56 AM

Switched from printf() to puts().

  • Property mode set to 100644
File size: 4.5 KB
Line 
1/*
2 * Copyright (c) 1988, 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 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *      This product includes software developed by the University of
16 *      California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
34 * $Id$
35 */
36
37#include <sys/param.h>
38#include <sys/mbuf.h>
39
40/*
41 *  Try to use a CPU specific version, then punt to the portable C one.
42 */
43
44#if (defined(__GNUC__) && (defined(__mc68000__) || defined(__m68k__)))
45
46#include "in_cksum_m68k.c"
47
48#elif (defined(__GNUC__) && defined(__i386__))
49
50#include "in_cksum_i386.c"
51
52#else
53
54/*
55 * Checksum routine for Internet Protocol family headers (Portable Version).
56 *
57 * This routine is very heavily used in the network
58 * code and should be modified for each CPU to be as fast as possible.
59 */
60
61#define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
62#define REDUCE \
63  {l_util.l = sum; sum = l_util.s[0] + l_util.s[1];  ADDCARRY(sum);}
64
65int
66in_cksum(m, len)
67        register struct mbuf *m;
68        register int len;
69{
70        register u_short *w;
71        register int sum = 0;
72        register int mlen = 0;
73        int byte_swapped = 0;
74
75        union {
76                char    c[2];
77                u_short s;
78        } s_util;
79        union {
80                u_short s[2];
81                long    l;
82        } l_util;
83
84        for (;m && len; m = m->m_next) {
85                if (m->m_len == 0)
86                        continue;
87                w = mtod(m, u_short *);
88                if (mlen == -1) {
89                        /*
90                         * The first byte of this mbuf is the continuation
91                         * of a word spanning between this mbuf and the
92                         * last mbuf.
93                         *
94                         * s_util.c[0] is already saved when scanning previous
95                         * mbuf.
96                         */
97                        s_util.c[1] = *(char *)w;
98                        sum += s_util.s;
99                        w = (u_short *)((char *)w + 1);
100                        mlen = m->m_len - 1;
101                        len--;
102                } else
103                        mlen = m->m_len;
104                if (len < mlen)
105                        mlen = len;
106                len -= mlen;
107                /*
108                 * Force to even boundary.
109                 */
110                if ((1 & (int) w) && (mlen > 0)) {
111                        REDUCE;
112                        sum <<= 8;
113                        s_util.c[0] = *(u_char *)w;
114                        w = (u_short *)((char *)w + 1);
115                        mlen--;
116                        byte_swapped = 1;
117                }
118                /*
119                 * Unroll the loop to make overhead from
120                 * branches &c small.
121                 */
122                while ((mlen -= 32) >= 0) {
123                        sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
124                        sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
125                        sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
126                        sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
127                        w += 16;
128                }
129                mlen += 32;
130                while ((mlen -= 8) >= 0) {
131                        sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
132                        w += 4;
133                }
134                mlen += 8;
135                if (mlen == 0 && byte_swapped == 0)
136                        continue;
137                REDUCE;
138                while ((mlen -= 2) >= 0) {
139                        sum += *w++;
140                }
141                if (byte_swapped) {
142                        REDUCE;
143                        sum <<= 8;
144                        byte_swapped = 0;
145                        if (mlen == -1) {
146                                s_util.c[1] = *(char *)w;
147                                sum += s_util.s;
148                                mlen = 0;
149                        } else
150                                mlen = -1;
151                } else if (mlen == -1)
152                        s_util.c[0] = *(char *)w;
153        }
154        if (len)
155                puts("cksum: out of data");
156        if (mlen == -1) {
157                /* The last mbuf has odd # of bytes. Follow the
158                   standard (the odd byte may be shifted left by 8 bits
159                   or not as determined by endian-ness of the machine) */
160                s_util.c[1] = 0;
161                sum += s_util.s;
162        }
163        REDUCE;
164        return (~sum & 0xffff);
165}
166#endif
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