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/mips/mips/in_cksum.c

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    1 /*-
    2  * Copyright (c) 1988, 1992, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  * Copyright (c) 1996
    5  *      Matt Thomas <matt@3am-software.com>
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 3. All advertising materials mentioning features or use of this software
   16  *    must display the following acknowledgement:
   17  *      This product includes software developed by the University of
   18  *      California, Berkeley and its contributors.
   19  * 4. Neither the name of the University nor the names of its contributors
   20  *    may be used to endorse or promote products derived from this software
   21  *    without specific prior written permission.
   22  *
   23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   33  * SUCH DAMAGE.
   34  *
   35  *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
   36  */
   37 
   38 #include <sys/cdefs.h>
   39 __FBSDID("$FreeBSD: releng/8.4/sys/mips/mips/in_cksum.c 215938 2010-11-27 12:26:40Z jchandra $");
   40 
   41 #include <sys/param.h>
   42 #include <sys/mbuf.h>
   43 #include <sys/systm.h>
   44 #include <netinet/in_systm.h>
   45 #include <netinet/in.h>
   46 #include <netinet/ip.h>
   47 #include <machine/in_cksum.h>
   48 
   49 /*
   50  * Checksum routine for Internet Protocol family headers
   51  *    (Portable Alpha version).
   52  *
   53  * This routine is very heavily used in the network
   54  * code and should be modified for each CPU to be as fast as possible.
   55  */
   56 
   57 #define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
   58 #define REDUCE32                                                          \
   59     {                                                                     \
   60         q_util.q = sum;                                                   \
   61         sum = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3];      \
   62     }
   63 #define REDUCE16                                                          \
   64     {                                                                     \
   65         q_util.q = sum;                                                   \
   66         l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \
   67         sum = l_util.s[0] + l_util.s[1];                                  \
   68         ADDCARRY(sum);                                                    \
   69     }
   70 
   71 static const u_int32_t in_masks[] = {
   72 #if _BYTE_ORDER == _LITTLE_ENDIAN
   73         /*0 bytes*/ /*1 byte*/  /*2 bytes*/ /*3 bytes*/
   74         0x00000000, 0x000000FF, 0x0000FFFF, 0x00FFFFFF, /* offset 0 */
   75         0x00000000, 0x0000FF00, 0x00FFFF00, 0xFFFFFF00, /* offset 1 */
   76         0x00000000, 0x00FF0000, 0xFFFF0000, 0xFFFF0000, /* offset 2 */
   77         0x00000000, 0xFF000000, 0xFF000000, 0xFF000000, /* offset 3 */
   78 #else
   79         /*0 bytes*/ /*1 byte*/  /*2 bytes*/ /*3 bytes*/
   80         0x00000000, 0xFF000000, 0xFFFF0000, 0xFFFFFF00, /* offset 0 */
   81         0x00000000, 0x00FF0000, 0x00FFFF00, 0x00FFFFFF, /* offset 1 */
   82         0x00000000, 0x0000FF00, 0x0000FFFF, 0x0000FFFF, /* offset 2 */
   83         0x00000000, 0x000000FF, 0x000000FF, 0x000000FF, /* offset 3 */
   84 #endif
   85 };
   86 
   87 union l_util {
   88         u_int16_t s[2];
   89         u_int32_t l;
   90 };
   91 union q_util {
   92         u_int16_t s[4];
   93         u_int32_t l[2];
   94         u_int64_t q;
   95 };
   96 
   97 static u_int64_t
   98 in_cksumdata(const void *buf, int len)
   99 {
  100         const u_int32_t *lw = (const u_int32_t *) buf;
  101         u_int64_t sum = 0;
  102         u_int64_t prefilled;
  103         int offset;
  104         union q_util q_util;
  105 
  106         if ((3 & (long) lw) == 0 && len == 20) {
  107                 sum = (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3] + lw[4];
  108                 REDUCE32;
  109                 return sum;
  110         }
  111 
  112         if ((offset = 3 & (long) lw) != 0) {
  113                 const u_int32_t *masks = in_masks + (offset << 2);
  114                 lw = (u_int32_t *) (((long) lw) - offset);
  115                 sum = *lw++ & masks[len >= 3 ? 3 : len];
  116                 len -= 4 - offset;
  117                 if (len <= 0) {
  118                         REDUCE32;
  119                         return sum;
  120                 }
  121         }
  122 #if 0
  123         /*
  124          * Force to cache line boundary.
  125          */
  126         offset = 32 - (0x1f & (long) lw);
  127         if (offset < 32 && len > offset) {
  128                 len -= offset;
  129                 if (4 & offset) {
  130                         sum += (u_int64_t) lw[0];
  131                         lw += 1;
  132                 }
  133                 if (8 & offset) {
  134                         sum += (u_int64_t) lw[0] + lw[1];
  135                         lw += 2;
  136                 }
  137                 if (16 & offset) {
  138                         sum += (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3];
  139                         lw += 4;
  140                 }
  141         }
  142 #endif
  143         /*
  144          * access prefilling to start load of next cache line.
  145          * then add current cache line
  146          * save result of prefilling for loop iteration.
  147          */
  148         prefilled = lw[0];
  149         while ((len -= 32) >= 4) {
  150                 u_int64_t prefilling = lw[8];
  151                 sum += prefilled + lw[1] + lw[2] + lw[3]
  152                         + lw[4] + lw[5] + lw[6] + lw[7];
  153                 lw += 8;
  154                 prefilled = prefilling;
  155         }
  156         if (len >= 0) {
  157                 sum += prefilled + lw[1] + lw[2] + lw[3]
  158                         + lw[4] + lw[5] + lw[6] + lw[7];
  159                 lw += 8;
  160         } else {
  161                 len += 32;
  162         }
  163         while ((len -= 16) >= 0) {
  164                 sum += (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3];
  165                 lw += 4;
  166         }
  167         len += 16;
  168         while ((len -= 4) >= 0) {
  169                 sum += (u_int64_t) *lw++;
  170         }
  171         len += 4;
  172         if (len > 0)
  173                 sum += (u_int64_t) (in_masks[len] & *lw);
  174         REDUCE32;
  175         return sum;
  176 }
  177 
  178 u_short
  179 in_addword(u_short a, u_short b)
  180 {
  181         u_int64_t sum = a + b;
  182 
  183         ADDCARRY(sum);
  184         return (sum);
  185 }
  186 
  187 u_short
  188 in_pseudo(u_int32_t a, u_int32_t b, u_int32_t c)
  189 {
  190         u_int64_t sum;
  191         union q_util q_util;
  192         union l_util l_util;
  193 
  194         sum = (u_int64_t) a + b + c;
  195         REDUCE16;
  196         return (sum);
  197 }
  198 
  199 u_short
  200 in_cksum_skip(struct mbuf *m, int len, int skip)
  201 {
  202         u_int64_t sum = 0;
  203         int mlen = 0;
  204         int clen = 0;
  205         caddr_t addr;
  206         union q_util q_util;
  207         union l_util l_util;
  208 
  209         len -= skip;
  210         for (; skip && m; m = m->m_next) {
  211                 if (m->m_len > skip) {
  212                         mlen = m->m_len - skip;
  213                         addr = mtod(m, caddr_t) + skip;
  214                         goto skip_start;
  215                 } else {
  216                         skip -= m->m_len;
  217                 }
  218         }
  219 
  220         for (; m && len; m = m->m_next) {
  221                 if (m->m_len == 0)
  222                         continue;
  223                 mlen = m->m_len;
  224                 addr = mtod(m, caddr_t);
  225 skip_start:
  226                 if (len < mlen)
  227                         mlen = len;
  228 
  229                 if ((clen ^ (uintptr_t) addr) & 1)
  230                         sum += in_cksumdata(addr, mlen) << 8;
  231                 else
  232                         sum += in_cksumdata(addr, mlen);
  233 
  234                 clen += mlen;
  235                 len -= mlen;
  236         }
  237         REDUCE16;
  238         return (~sum & 0xffff);
  239 }
  240 
  241 u_int in_cksum_hdr(const struct ip *ip)
  242 {
  243         u_int64_t sum = in_cksumdata(ip, sizeof(struct ip));
  244         union q_util q_util;
  245         union l_util l_util;
  246         REDUCE16;
  247         return (~sum & 0xffff);
  248 }

Cache object: 880c9d0b84c89dff380a00e6117a7603


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