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  * SPDX-License-Identifier: BSD-4-Clause
    5  *
    6  * Copyright (c) 1988, 1992, 1993
    7  *      The Regents of the University of California.  All rights reserved.
    8  * Copyright (c) 1996
    9  *      Matt Thomas <matt@3am-software.com>
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  * 3. All advertising materials mentioning features or use of this software
   20  *    must display the following acknowledgement:
   21  *      This product includes software developed by the University of
   22  *      California, Berkeley and its contributors.
   23  * 4. Neither the name of the University nor the names of its contributors
   24  *    may be used to endorse or promote products derived from this software
   25  *    without specific prior written permission.
   26  *
   27  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   28  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   30  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   31  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   32  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   33  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   34  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   35  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   36  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   37  * SUCH DAMAGE.
   38  *
   39  *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
   40  */
   41 
   42 #include <sys/cdefs.h>                  /* RCS ID & Copyright macro defns */
   43 __FBSDID("$FreeBSD$");
   44 
   45 #include <sys/param.h>
   46 #include <sys/mbuf.h>
   47 #include <sys/systm.h>
   48 #include <netinet/in_systm.h>
   49 #include <netinet/in.h>
   50 #include <netinet/ip.h>
   51 #include <machine/in_cksum.h>
   52 
   53 /*
   54  * Checksum routine for Internet Protocol family headers
   55  *    (Portable Alpha 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 REDUCE32                                                          \
   63     {                                                                     \
   64         q_util.q = sum;                                                   \
   65         sum = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3];      \
   66     }
   67 #define REDUCE16                                                          \
   68     {                                                                     \
   69         q_util.q = sum;                                                   \
   70         l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \
   71         sum = l_util.s[0] + l_util.s[1];                                  \
   72         ADDCARRY(sum);                                                    \
   73     }
   74 
   75 union l_util {
   76         u_int16_t s[2];
   77         u_int32_t l;
   78 };
   79 union q_util {
   80         u_int16_t s[4];
   81         u_int32_t l[2];
   82         u_int64_t q;
   83 };
   84 
   85 u_short
   86 in_addword(u_short a, u_short b)
   87 {
   88         u_int64_t sum = a + b;
   89 
   90         ADDCARRY(sum);
   91         return (sum);
   92 }
   93 
   94 static
   95 uint64_t _do_cksum(void *addr, int len)
   96 {
   97         uint64_t sum;
   98         union q_util q_util;
   99 
  100         sum = do_cksum(addr, len);
  101         REDUCE32;
  102         return (sum);
  103 }
  104 
  105 u_short
  106 in_cksum_skip(struct mbuf *m, int len, int skip)
  107 {
  108         u_int64_t sum = 0;
  109         int mlen = 0;
  110         int clen = 0;
  111         caddr_t addr;
  112         union q_util q_util;
  113         union l_util l_util;
  114 
  115         len -= skip;
  116         for (; skip && m; m = m->m_next) {
  117                 if (m->m_len > skip) {
  118                         mlen = m->m_len - skip;
  119                         addr = mtod(m, caddr_t) + skip;
  120                         goto skip_start;
  121                 } else {
  122                         skip -= m->m_len;
  123                 }
  124         }
  125 
  126         for (; m && len; m = m->m_next) {
  127                 if (m->m_len == 0)
  128                         continue;
  129                 mlen = m->m_len;
  130                 addr = mtod(m, caddr_t);
  131 skip_start:
  132                 if (len < mlen)
  133                         mlen = len;
  134 
  135                 if ((clen ^ (int) addr) & 1)
  136                     sum += _do_cksum(addr, mlen) << 8;
  137                 else
  138                     sum += _do_cksum(addr, mlen);
  139 
  140                 clen += mlen;
  141                 len -= mlen;
  142         }
  143         REDUCE16;
  144         return (~sum & 0xffff);
  145 }
  146 
  147 u_int in_cksum_hdr(const struct ip *ip)
  148 {
  149         u_int64_t sum = do_cksum(ip, sizeof(struct ip));
  150         union q_util q_util;
  151         union l_util l_util;
  152         REDUCE16;
  153         return (~sum & 0xffff);
  154 }

Cache object: 0bc80eed8018c48fbde3a0f8e609ec35


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