maint: Allow for EXAMPLES in texi2pod
[qemu/ar7.git] / slirp / cksum.c
blob84c858fafb179bc025d334294b9357366e7c2f7c
1 /*
2 * Copyright (c) 1988, 1992, 1993
3 * The Regents of the University of California. All rights reserved.
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. 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.
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.
29 * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
30 * in_cksum.c,v 1.2 1994/08/02 07:48:16 davidg Exp
33 #include "qemu/osdep.h"
34 #include "slirp.h"
37 * Checksum routine for Internet Protocol family headers (Portable Version).
39 * This routine is very heavily used in the network
40 * code and should be modified for each CPU to be as fast as possible.
42 * XXX Since we will never span more than 1 mbuf, we can optimise this
45 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
46 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; \
47 (void)ADDCARRY(sum);}
49 int cksum(struct mbuf *m, int len)
51 register uint16_t *w;
52 register int sum = 0;
53 register int mlen = 0;
54 int byte_swapped = 0;
56 union {
57 uint8_t c[2];
58 uint16_t s;
59 } s_util;
60 union {
61 uint16_t s[2];
62 uint32_t l;
63 } l_util;
65 if (m->m_len == 0)
66 goto cont;
67 w = mtod(m, uint16_t *);
69 mlen = m->m_len;
71 if (len < mlen)
72 mlen = len;
73 len -= mlen;
75 * Force to even boundary.
77 if ((1 & (uintptr_t)w) && (mlen > 0)) {
78 REDUCE;
79 sum <<= 8;
80 s_util.c[0] = *(uint8_t *)w;
81 w = (uint16_t *)((int8_t *)w + 1);
82 mlen--;
83 byte_swapped = 1;
86 * Unroll the loop to make overhead from
87 * branches &c small.
89 while ((mlen -= 32) >= 0) {
90 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
91 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
92 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
93 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
94 w += 16;
96 mlen += 32;
97 while ((mlen -= 8) >= 0) {
98 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
99 w += 4;
101 mlen += 8;
102 if (mlen == 0 && byte_swapped == 0)
103 goto cont;
104 REDUCE;
105 while ((mlen -= 2) >= 0) {
106 sum += *w++;
109 if (byte_swapped) {
110 REDUCE;
111 sum <<= 8;
112 if (mlen == -1) {
113 s_util.c[1] = *(uint8_t *)w;
114 sum += s_util.s;
115 mlen = 0;
116 } else
118 mlen = -1;
119 } else if (mlen == -1)
120 s_util.c[0] = *(uint8_t *)w;
122 cont:
123 if (len) {
124 DEBUG_ERROR("cksum: out of data");
125 DEBUG_ERROR(" len = %d", len);
127 if (mlen == -1) {
128 /* The last mbuf has odd # of bytes. Follow the
129 standard (the odd byte may be shifted left by 8 bits
130 or not as determined by endian-ness of the machine) */
131 s_util.c[1] = 0;
132 sum += s_util.s;
134 REDUCE;
135 return (~sum & 0xffff);
138 int ip6_cksum(struct mbuf *m)
140 /* TODO: Optimize this by being able to pass the ip6_pseudohdr to cksum
141 * separately from the mbuf */
142 struct ip6 save_ip, *ip = mtod(m, struct ip6 *);
143 struct ip6_pseudohdr *ih = mtod(m, struct ip6_pseudohdr *);
144 int sum;
146 save_ip = *ip;
148 ih->ih_src = save_ip.ip_src;
149 ih->ih_dst = save_ip.ip_dst;
150 ih->ih_pl = htonl((uint32_t)ntohs(save_ip.ip_pl));
151 ih->ih_zero_hi = 0;
152 ih->ih_zero_lo = 0;
153 ih->ih_nh = save_ip.ip_nh;
155 sum = cksum(m, ((int)sizeof(struct ip6_pseudohdr))
156 + ntohl(ih->ih_pl));
158 *ip = save_ip;
160 return sum;