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1.1 root 1: /*
2: * Copyright (c) 1988 Regents of the University of California.
3: * 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: *
1.1.1.2 ! root 33: * from: @(#)in_cksum.c 7.3 (Berkeley) 6/28/90
! 34: * in_cksum.c,v 1.3 1993/05/20 03:50:04 cgd Exp
1.1 root 35: */
36:
1.1.1.2 ! root 37: #include "types.h"
! 38: #include "mbuf.h"
1.1 root 39:
40: /*
41: * Checksum routine for Internet Protocol family headers (Portable Version).
42: *
43: * This routine is very heavily used in the network
44: * code and should be modified for each CPU to be as fast as possible.
45: */
46:
47: #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
48: #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
49:
50: in_cksum_c(m, len)
51: register struct mbuf *m;
52: register int len;
53: {
54: register u_short *w;
55: register int sum = 0;
56: register int mlen = 0;
57: int byte_swapped = 0;
58:
59: union {
60: char c[2];
61: u_short s;
62: } s_util;
63: union {
64: u_short s[2];
65: long l;
66: } l_util;
67:
68: for (;m && len; m = m->m_next) {
69: if (m->m_len == 0)
70: continue;
71: w = mtod(m, u_short *);
72: if (mlen == -1) {
73: /*
74: * The first byte of this mbuf is the continuation
75: * of a word spanning between this mbuf and the
76: * last mbuf.
77: *
78: * s_util.c[0] is already saved when scanning previous
79: * mbuf.
80: */
81: s_util.c[1] = *(char *)w;
82: sum += s_util.s;
83: w = (u_short *)((char *)w + 1);
84: mlen = m->m_len - 1;
85: len--;
86: } else
87: mlen = m->m_len;
88: if (len < mlen)
89: mlen = len;
90: len -= mlen;
91: /*
92: * Force to even boundary.
93: */
94: if ((1 & (int) w) && (mlen > 0)) {
95: REDUCE;
96: sum <<= 8;
97: s_util.c[0] = *(u_char *)w;
98: w = (u_short *)((char *)w + 1);
99: mlen--;
100: byte_swapped = 1;
101: }
102: /*
103: * Unroll the loop to make overhead from
104: * branches &c small.
105: */
106: while ((mlen -= 32) >= 0) {
107: sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
108: sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
109: sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
110: sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
111: w += 16;
112: }
113: mlen += 32;
114: while ((mlen -= 8) >= 0) {
115: sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
116: w += 4;
117: }
118: mlen += 8;
119: if (mlen == 0 && byte_swapped == 0)
120: continue;
121: REDUCE;
122: while ((mlen -= 2) >= 0) {
123: sum += *w++;
124: }
125: if (byte_swapped) {
126: REDUCE;
127: sum <<= 8;
128: byte_swapped = 0;
129: if (mlen == -1) {
130: s_util.c[1] = *(char *)w;
131: sum += s_util.s;
132: mlen = 0;
133: } else
134: mlen = -1;
135: } else if (mlen == -1)
136: s_util.c[0] = *(char *)w;
137: }
138: if (len)
139: printf("cksum: out of data\n");
140: if (mlen == -1) {
141: /* The last mbuf has odd # of bytes. Follow the
142: standard (the odd byte may be shifted left by 8 bits
143: or not as determined by endian-ness of the machine) */
144: s_util.c[1] = 0;
145: sum += s_util.s;
146: }
147: REDUCE;
148: return (~sum & 0xffff);
149: }
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