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1.1 root 1: /*
2: * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
3: *
4: * @APPLE_LICENSE_HEADER_START@
5: *
6: * Portions Copyright (c) 1999 Apple Computer, Inc. All Rights
7: * Reserved. This file contains Original Code and/or Modifications of
8: * Original Code as defined in and that are subject to the Apple Public
9: * Source License Version 1.1 (the "License"). You may not use this file
10: * except in compliance with the License. Please obtain a copy of the
11: * License at http://www.apple.com/publicsource and read it before using
12: * this file.
13: *
14: * The Original Code and all software distributed under the License are
15: * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
16: * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
17: * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
18: * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
19: * License for the specific language governing rights and limitations
20: * under the License.
21: *
22: * @APPLE_LICENSE_HEADER_END@
23: */
24:
25: /*
26: * Copyright (c) 1982, 1992, 1993
27: * The Regents of the University of California. All rights reserved.
28: *
29: * Redistribution and use in source and binary forms, with or without
30: * modification, are permitted provided that the following conditions
31: * are met:
32: * 1. Redistributions of source code must retain the above copyright
33: * notice, this list of conditions and the following disclaimer.
34: * 2. Redistributions in binary form must reproduce the above copyright
35: * notice, this list of conditions and the following disclaimer in the
36: * documentation and/or other materials provided with the distribution.
37: * 3. All advertising materials mentioning features or use of this software
38: * must display the following acknowledgement:
39: * This product includes software developed by the University of
40: * California, Berkeley and its contributors.
41: * 4. Neither the name of the University nor the names of its contributors
42: * may be used to endorse or promote products derived from this software
43: * without specific prior written permission.
44: *
45: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
46: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
47: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
48: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
49: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
50: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
51: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
52: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
53: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
54: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
55: * SUCH DAMAGE.
56: *
57: * @(#)ns_cksum.c 8.1 (Berkeley) 6/10/93
58: */
59:
60: #include <sys/param.h>
61: #include <sys/mbuf.h>
62:
63: /*
64: * Checksum routine for Network Systems Protocol Packets (Big-Endian).
65: *
66: * This routine is very heavily used in the network
67: * code and should be modified for each CPU to be as fast as possible.
68: */
69:
70: #define ADDCARRY(x) { if ((x) > 65535) (x) -= 65535; }
71: #define FOLD(x) {l_util.l = (x); (x) = l_util.s[0] + l_util.s[1]; ADDCARRY(x);}
72:
73: u_short
74: ns_cksum(m, len)
75: register struct mbuf *m;
76: register int len;
77: {
78: register u_short *w;
79: register int sum = 0;
80: register int mlen = 0;
81: register int sum2;
82:
83: union {
84: u_short s[2];
85: long l;
86: } l_util;
87:
88: for (;m && len; m = m->m_next) {
89: if (m->m_len == 0)
90: continue;
91: /*
92: * Each trip around loop adds in
93: * word from one mbuf segment.
94: */
95: w = mtod(m, u_short *);
96: if (mlen == -1) {
97: /*
98: * There is a byte left from the last segment;
99: * ones-complement add it into the checksum.
100: */
101: #if BYTE_ORDER == BIG_ENDIAN
102: sum += *(u_char *)w;
103: #else
104: sum += *(u_char *)w << 8;
105: #endif
106: sum += sum;
107: w = (u_short *)(1 + (char *)w);
108: mlen = m->m_len - 1;
109: len--;
110: FOLD(sum);
111: } else
112: mlen = m->m_len;
113: if (len < mlen)
114: mlen = len;
115: len -= mlen;
116: /*
117: * We can do a 16 bit ones complement sum using
118: * 32 bit arithmetic registers for adding,
119: * with carries from the low added
120: * into the high (by normal carry-chaining)
121: * so long as we fold back before 16 carries have occured.
122: */
123: if (1 & (int) w)
124: goto uuuuglyy;
125: #ifndef TINY
126: /* -DTINY reduces the size from 1250 to 550, but slows it down by 22% */
127: while ((mlen -= 32) >= 0) {
128: sum += w[0]; sum += sum; sum += w[1]; sum += sum;
129: sum += w[2]; sum += sum; sum += w[3]; sum += sum;
130: sum += w[4]; sum += sum; sum += w[5]; sum += sum;
131: sum += w[6]; sum += sum; sum += w[7]; sum += sum;
132: FOLD(sum);
133: sum += w[8]; sum += sum; sum += w[9]; sum += sum;
134: sum += w[10]; sum += sum; sum += w[11]; sum += sum;
135: sum += w[12]; sum += sum; sum += w[13]; sum += sum;
136: sum += w[14]; sum += sum; sum += w[15]; sum += sum;
137: FOLD(sum);
138: w += 16;
139: }
140: mlen += 32;
141: #endif
142: while ((mlen -= 8) >= 0) {
143: sum += w[0]; sum += sum; sum += w[1]; sum += sum;
144: sum += w[2]; sum += sum; sum += w[3]; sum += sum;
145: FOLD(sum);
146: w += 4;
147: }
148: mlen += 8;
149: while ((mlen -= 2) >= 0) {
150: sum += *w++; sum += sum;
151: }
152: goto commoncase;
153: uuuuglyy:
154: #if BYTE_ORDER == BIG_ENDIAN
155: #define ww(n) (((u_char *)w)[n + n + 1])
156: #define vv(n) (((u_char *)w)[n + n])
157: #else
158: #if BYTE_ORDER == LITTLE_ENDIAN
159: #define vv(n) (((u_char *)w)[n + n + 1])
160: #define ww(n) (((u_char *)w)[n + n])
161: #endif
162: #endif
163: sum2 = 0;
164: #ifndef TINY
165: while ((mlen -= 32) >= 0) {
166: sum += ww(0); sum += sum; sum += ww(1); sum += sum;
167: sum += ww(2); sum += sum; sum += ww(3); sum += sum;
168: sum += ww(4); sum += sum; sum += ww(5); sum += sum;
169: sum += ww(6); sum += sum; sum += ww(7); sum += sum;
170: FOLD(sum);
171: sum += ww(8); sum += sum; sum += ww(9); sum += sum;
172: sum += ww(10); sum += sum; sum += ww(11); sum += sum;
173: sum += ww(12); sum += sum; sum += ww(13); sum += sum;
174: sum += ww(14); sum += sum; sum += ww(15); sum += sum;
175: FOLD(sum);
176: sum2 += vv(0); sum2 += sum2; sum2 += vv(1); sum2 += sum2;
177: sum2 += vv(2); sum2 += sum2; sum2 += vv(3); sum2 += sum2;
178: sum2 += vv(4); sum2 += sum2; sum2 += vv(5); sum2 += sum2;
179: sum2 += vv(6); sum2 += sum2; sum2 += vv(7); sum2 += sum2;
180: FOLD(sum2);
181: sum2 += vv(8); sum2 += sum2; sum2 += vv(9); sum2 += sum2;
182: sum2 += vv(10); sum2 += sum2; sum2 += vv(11); sum2 += sum2;
183: sum2 += vv(12); sum2 += sum2; sum2 += vv(13); sum2 += sum2;
184: sum2 += vv(14); sum2 += sum2; sum2 += vv(15); sum2 += sum2;
185: FOLD(sum2);
186: w += 16;
187: }
188: mlen += 32;
189: #endif
190: while ((mlen -= 8) >= 0) {
191: sum += ww(0); sum += sum; sum += ww(1); sum += sum;
192: sum += ww(2); sum += sum; sum += ww(3); sum += sum;
193: FOLD(sum);
194: sum2 += vv(0); sum2 += sum2; sum2 += vv(1); sum2 += sum2;
195: sum2 += vv(2); sum2 += sum2; sum2 += vv(3); sum2 += sum2;
196: FOLD(sum2);
197: w += 4;
198: }
199: mlen += 8;
200: while ((mlen -= 2) >= 0) {
201: sum += ww(0); sum += sum;
202: sum2 += vv(0); sum2 += sum2;
203: w++;
204: }
205: sum += (sum2 << 8);
206: commoncase:
207: if (mlen == -1) {
208: #if BYTE_ORDER == BIG_ENDIAN
209: sum += *(u_char *)w << 8;
210: #else
211: sum += *(u_char *)w;
212: #endif
213: }
214: FOLD(sum);
215: }
216: if (mlen == -1) {
217: /* We had an odd number of bytes to sum; assume a garbage
218: byte of zero and clean up */
219: sum += sum;
220: FOLD(sum);
221: }
222: /*
223: * sum has already been kept to low sixteen bits.
224: * just examine result and exit.
225: */
226: if(sum==0xffff) sum = 0;
227: return (sum);
228: }
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