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


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

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

Version: -  FREEBSD  -  FREEBSD-13-STABLE  -  FREEBSD-13-0  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  l41  -  OPENBSD  -  linux-2.6  -  MK84  -  PLAN9  -  xnu-8792 
SearchContext: -  none  -  3  -  10 

    1 /*
    2  * Copyright (c) 1988, 1992, 1993
    3  *      The Regents of the University of California.  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  *
   33  *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
   34  * $FreeBSD: releng/5.0/sys/netinet/in_cksum.c 50477 1999-08-28 01:08:13Z peter $
   35  */
   36 
   37 #include <sys/param.h>
   38 #include <sys/mbuf.h>
   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 int
   51 in_cksum(m, len)
   52         register struct mbuf *m;
   53         register int len;
   54 {
   55         register u_short *w;
   56         register int sum = 0;
   57         register int mlen = 0;
   58         int byte_swapped = 0;
   59 
   60         union {
   61                 char    c[2];
   62                 u_short s;
   63         } s_util;
   64         union {
   65                 u_short s[2];
   66                 long    l;
   67         } l_util;
   68 
   69         for (;m && len; m = m->m_next) {
   70                 if (m->m_len == 0)
   71                         continue;
   72                 w = mtod(m, u_short *);
   73                 if (mlen == -1) {
   74                         /*
   75                          * The first byte of this mbuf is the continuation
   76                          * of a word spanning between this mbuf and the
   77                          * last mbuf.
   78                          *
   79                          * s_util.c[0] is already saved when scanning previous
   80                          * mbuf.
   81                          */
   82                         s_util.c[1] = *(char *)w;
   83                         sum += s_util.s;
   84                         w = (u_short *)((char *)w + 1);
   85                         mlen = m->m_len - 1;
   86                         len--;
   87                 } else
   88                         mlen = m->m_len;
   89                 if (len < mlen)
   90                         mlen = len;
   91                 len -= mlen;
   92                 /*
   93                  * Force to even boundary.
   94                  */
   95                 if ((1 & (int) w) && (mlen > 0)) {
   96                         REDUCE;
   97                         sum <<= 8;
   98                         s_util.c[0] = *(u_char *)w;
   99                         w = (u_short *)((char *)w + 1);
  100                         mlen--;
  101                         byte_swapped = 1;
  102                 }
  103                 /*
  104                  * Unroll the loop to make overhead from
  105                  * branches &c small.
  106                  */
  107                 while ((mlen -= 32) >= 0) {
  108                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  109                         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  110                         sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
  111                         sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
  112                         w += 16;
  113                 }
  114                 mlen += 32;
  115                 while ((mlen -= 8) >= 0) {
  116                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  117                         w += 4;
  118                 }
  119                 mlen += 8;
  120                 if (mlen == 0 && byte_swapped == 0)
  121                         continue;
  122                 REDUCE;
  123                 while ((mlen -= 2) >= 0) {
  124                         sum += *w++;
  125                 }
  126                 if (byte_swapped) {
  127                         REDUCE;
  128                         sum <<= 8;
  129                         byte_swapped = 0;
  130                         if (mlen == -1) {
  131                                 s_util.c[1] = *(char *)w;
  132                                 sum += s_util.s;
  133                                 mlen = 0;
  134                         } else
  135                                 mlen = -1;
  136                 } else if (mlen == -1)
  137                         s_util.c[0] = *(char *)w;
  138         }
  139         if (len)
  140                 printf("cksum: out of data\n");
  141         if (mlen == -1) {
  142                 /* The last mbuf has odd # of bytes. Follow the
  143                    standard (the odd byte may be shifted left by 8 bits
  144                    or not as determined by endian-ness of the machine) */
  145                 s_util.c[1] = 0;
  146                 sum += s_util.s;
  147         }
  148         REDUCE;
  149         return (~sum & 0xffff);
  150 }

Cache object: ba070fe853927bcca6ebbf30f8ab5240


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]


This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.