ipx_cksum.c

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    1 /*-
    2  * Copyright (c) 1982, 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  * 4. 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.
   16  *
   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.
   28  *
   29  * Copyright (c) 1995, Mike Mitchell
   30  *
   31  * Redistribution and use in source and binary forms, with or without
   32  * modification, are permitted provided that the following conditions
   33  * are met:
   34  * 1. Redistributions of source code must retain the above copyright
   35  *    notice, this list of conditions and the following disclaimer.
   36  * 2. Redistributions in binary form must reproduce the above copyright
   37  *    notice, this list of conditions and the following disclaimer in the
   38  *    documentation and/or other materials provided with the distribution.
   39  * 3. All advertising materials mentioning features or use of this software
   40  *    must display the following acknowledgement:
   41  *      This product includes software developed by the University of
   42  *      California, Berkeley and its contributors.
   43  * 4. Neither the name of the University nor the names of its contributors
   44  *    may be used to endorse or promote products derived from this software
   45  *    without specific prior written permission.
   46  *
   47  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   48  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   49  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   50  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   51  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   52  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   53  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   54  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   55  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   56  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   57  * SUCH DAMAGE.
   58  *
   59  *      @(#)ipx_cksum.c
   60  */
   61 
   62 #include <sys/cdefs.h>
   63 __FBSDID("$FreeBSD$");
   64 
   65 #include <sys/param.h>
   66 #include <sys/mbuf.h>
   67 #include <sys/libkern.h>
   68 
   69 #include <netipx/ipx.h>
   70 #include <netipx/ipx_var.h>
   71 
   72 
   73 #define SUMADV  sum += *w++
   74 
   75 u_short
   76 ipx_cksum(struct mbuf *m, int len)
   77 {
   78         u_int32_t sum = 0;
   79         u_char *w;
   80         u_char oldtc;
   81         int mlen, words;
   82         struct ipx *ipx;
   83         union {
   84                 u_char  b[2];
   85                 u_short w;
   86         } buf;
   87 
   88         ipx = mtod(m, struct ipx*);
   89         oldtc = ipx->ipx_tc;
   90         ipx->ipx_tc = 0;
   91         w = (u_char *)&ipx->ipx_len;
   92         len -= 2;
   93         mlen = 2;
   94 
   95         for(;;) {
   96                 mlen = imin(m->m_len - mlen, len);
   97                 words = mlen / 2;
   98                 len -= mlen & ~1;
   99                 while (words >= 16) {
  100                         SUMADV; SUMADV; SUMADV; SUMADV;
  101                         SUMADV; SUMADV; SUMADV; SUMADV;
  102                         SUMADV; SUMADV; SUMADV; SUMADV;
  103                         SUMADV; SUMADV; SUMADV; SUMADV;
  104                         words -= 16;
  105                 }
  106                 while (words--)
  107                         SUMADV;
  108                 if (len == 0)
  109                         break;
  110                 mlen &= 1;
  111                 if (mlen) {
  112                         buf.b[0] = *w;
  113                         if (--len == 0) {
  114                                 buf.b[1] = 0;
  115                                 sum += buf.w;
  116                                 break;
  117                         }
  118                 }
  119                 m = m->m_next;
  120                 if (m == NULL)
  121                         break;
  122                 w = mtod(m, u_char *);
  123                 if (mlen) {
  124                         buf.b[1] = *w;
  125                         sum += buf.w;
  126                         w++;
  127                         if (--len == 0)
  128                                 break;
  129                 }
  130         }
  131 
  132         ipx->ipx_tc = oldtc;
  133 
  134         sum = (sum & 0xffff) + (sum >> 16);
  135         if (sum >= 0x10000)
  136                 sum++;
  137         if (sum)
  138                 sum = ~sum;
  139         return (sum);
  140 }

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FreeBSD/Linux Kernel Cross Reference sys/netipx/ipx_cksum.c

FreeBSD/Linux Kernel Cross Reference
sys/netipx/ipx_cksum.c