The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/arm/arm/in_cksum.c

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    1 /* $NetBSD: in_cksum.c,v 1.7 1997/09/02 13:18:15 thorpej Exp $ */
    2 
    3 /*-
    4  * Copyright (c) 1988, 1992, 1993
    5  *      The Regents of the University of California.  All rights reserved.
    6  * Copyright (c) 1996
    7  *      Matt Thomas <matt@3am-software.com>
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  * 3. All advertising materials mentioning features or use of this software
   18  *    must display the following acknowledgement:
   19  *      This product includes software developed by the University of
   20  *      California, Berkeley and its contributors.
   21  * 4. Neither the name of the University nor the names of its contributors
   22  *    may be used to endorse or promote products derived from this software
   23  *    without specific prior written permission.
   24  *
   25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   35  * SUCH DAMAGE.
   36  *
   37  *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
   38  */
   39 
   40 #include <sys/cdefs.h>                  /* RCS ID & Copyright macro defns */
   41 __FBSDID("$FreeBSD: releng/9.1/sys/arm/arm/in_cksum.c 160459 2006-07-18 00:07:05Z cognet $");
   42 
   43 #include <sys/param.h>
   44 #include <sys/mbuf.h>
   45 #include <sys/systm.h>
   46 #include <netinet/in_systm.h>
   47 #include <netinet/in.h>
   48 #include <netinet/ip.h>
   49 #include <machine/in_cksum.h>
   50 
   51 /*
   52  * Checksum routine for Internet Protocol family headers
   53  *    (Portable Alpha version).
   54  *
   55  * This routine is very heavily used in the network
   56  * code and should be modified for each CPU to be as fast as possible.
   57  */
   58 
   59 #define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
   60 #define REDUCE32                                                          \
   61     {                                                                     \
   62         q_util.q = sum;                                                   \
   63         sum = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3];      \
   64     }
   65 #define REDUCE16                                                          \
   66     {                                                                     \
   67         q_util.q = sum;                                                   \
   68         l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \
   69         sum = l_util.s[0] + l_util.s[1];                                  \
   70         ADDCARRY(sum);                                                    \
   71     }
   72 
   73 union l_util {
   74         u_int16_t s[2];
   75         u_int32_t l;
   76 };
   77 union q_util {
   78         u_int16_t s[4];
   79         u_int32_t l[2];
   80         u_int64_t q;
   81 };
   82 
   83 u_short
   84 in_addword(u_short a, u_short b)
   85 {
   86         u_int64_t sum = a + b;
   87 
   88         ADDCARRY(sum);
   89         return (sum);
   90 }
   91 
   92 static
   93 uint64_t _do_cksum(void *addr, int len)
   94 {
   95         uint64_t sum;
   96         union q_util q_util;
   97 
   98         sum = do_cksum(addr, len);
   99         REDUCE32;
  100         return (sum);
  101 }
  102 
  103 u_short
  104 in_cksum_skip(struct mbuf *m, int len, int skip)
  105 {
  106         u_int64_t sum = 0;
  107         int mlen = 0;
  108         int clen = 0;
  109         caddr_t addr;
  110         union q_util q_util;
  111         union l_util l_util;
  112 
  113         len -= skip;
  114         for (; skip && m; m = m->m_next) {
  115                 if (m->m_len > skip) {
  116                         mlen = m->m_len - skip;
  117                         addr = mtod(m, caddr_t) + skip;
  118                         goto skip_start;
  119                 } else {
  120                         skip -= m->m_len;
  121                 }
  122         }
  123 
  124         for (; m && len; m = m->m_next) {
  125                 if (m->m_len == 0)
  126                         continue;
  127                 mlen = m->m_len;
  128                 addr = mtod(m, caddr_t);
  129 skip_start:
  130                 if (len < mlen)
  131                         mlen = len;
  132 
  133                 if ((clen ^ (int) addr) & 1)
  134                     sum += _do_cksum(addr, mlen) << 8;
  135                 else
  136                     sum += _do_cksum(addr, mlen);
  137 
  138                 clen += mlen;
  139                 len -= mlen;
  140         }
  141         REDUCE16;
  142         return (~sum & 0xffff);
  143 }
  144 
  145 u_int in_cksum_hdr(const struct ip *ip)
  146 {
  147         u_int64_t sum = do_cksum(ip, sizeof(struct ip));
  148         union q_util q_util;
  149         union l_util l_util;
  150         REDUCE16;
  151         return (~sum & 0xffff);
  152 }                           

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