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  * SPDX-License-Identifier: BSD-4-Clause
    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>
   41 __FBSDID("$FreeBSD: stable/12/sys/mips/mips/in_cksum.c 325966 2017-11-18 14:26:50Z pfg $");
   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 static const u_int32_t in_masks[] = {
   74 #if _BYTE_ORDER == _LITTLE_ENDIAN
   75         /*0 bytes*/ /*1 byte*/  /*2 bytes*/ /*3 bytes*/
   76         0x00000000, 0x000000FF, 0x0000FFFF, 0x00FFFFFF, /* offset 0 */
   77         0x00000000, 0x0000FF00, 0x00FFFF00, 0xFFFFFF00, /* offset 1 */
   78         0x00000000, 0x00FF0000, 0xFFFF0000, 0xFFFF0000, /* offset 2 */
   79         0x00000000, 0xFF000000, 0xFF000000, 0xFF000000, /* offset 3 */
   80 #else
   81         /*0 bytes*/ /*1 byte*/  /*2 bytes*/ /*3 bytes*/
   82         0x00000000, 0xFF000000, 0xFFFF0000, 0xFFFFFF00, /* offset 0 */
   83         0x00000000, 0x00FF0000, 0x00FFFF00, 0x00FFFFFF, /* offset 1 */
   84         0x00000000, 0x0000FF00, 0x0000FFFF, 0x0000FFFF, /* offset 2 */
   85         0x00000000, 0x000000FF, 0x000000FF, 0x000000FF, /* offset 3 */
   86 #endif
   87 };
   88 
   89 union l_util {
   90         u_int16_t s[2];
   91         u_int32_t l;
   92 };
   93 union q_util {
   94         u_int16_t s[4];
   95         u_int32_t l[2];
   96         u_int64_t q;
   97 };
   98 
   99 static u_int64_t
  100 in_cksumdata(const void *buf, int len)
  101 {
  102         const u_int32_t *lw = (const u_int32_t *) buf;
  103         u_int64_t sum = 0;
  104         u_int64_t prefilled;
  105         int offset;
  106         union q_util q_util;
  107 
  108         if ((3 & (long) lw) == 0 && len == 20) {
  109                 sum = (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3] + lw[4];
  110                 REDUCE32;
  111                 return sum;
  112         }
  113 
  114         if ((offset = 3 & (long) lw) != 0) {
  115                 const u_int32_t *masks = in_masks + (offset << 2);
  116                 lw = (u_int32_t *) (((long) lw) - offset);
  117                 sum = *lw++ & masks[len >= 3 ? 3 : len];
  118                 len -= 4 - offset;
  119                 if (len <= 0) {
  120                         REDUCE32;
  121                         return sum;
  122                 }
  123         }
  124 #if 0
  125         /*
  126          * Force to cache line boundary.
  127          */
  128         offset = 32 - (0x1f & (long) lw);
  129         if (offset < 32 && len > offset) {
  130                 len -= offset;
  131                 if (4 & offset) {
  132                         sum += (u_int64_t) lw[0];
  133                         lw += 1;
  134                 }
  135                 if (8 & offset) {
  136                         sum += (u_int64_t) lw[0] + lw[1];
  137                         lw += 2;
  138                 }
  139                 if (16 & offset) {
  140                         sum += (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3];
  141                         lw += 4;
  142                 }
  143         }
  144 #endif
  145         /*
  146          * access prefilling to start load of next cache line.
  147          * then add current cache line
  148          * save result of prefilling for loop iteration.
  149          */
  150         prefilled = lw[0];
  151         while ((len -= 32) >= 4) {
  152                 u_int64_t prefilling = lw[8];
  153                 sum += prefilled + lw[1] + lw[2] + lw[3]
  154                         + lw[4] + lw[5] + lw[6] + lw[7];
  155                 lw += 8;
  156                 prefilled = prefilling;
  157         }
  158         if (len >= 0) {
  159                 sum += prefilled + lw[1] + lw[2] + lw[3]
  160                         + lw[4] + lw[5] + lw[6] + lw[7];
  161                 lw += 8;
  162         } else {
  163                 len += 32;
  164         }
  165         while ((len -= 16) >= 0) {
  166                 sum += (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3];
  167                 lw += 4;
  168         }
  169         len += 16;
  170         while ((len -= 4) >= 0) {
  171                 sum += (u_int64_t) *lw++;
  172         }
  173         len += 4;
  174         if (len > 0)
  175                 sum += (u_int64_t) (in_masks[len] & *lw);
  176         REDUCE32;
  177         return sum;
  178 }
  179 
  180 u_short
  181 in_addword(u_short a, u_short b)
  182 {
  183         u_int64_t sum = a + b;
  184 
  185         ADDCARRY(sum);
  186         return (sum);
  187 }
  188 
  189 u_short
  190 in_pseudo(u_int32_t a, u_int32_t b, u_int32_t c)
  191 {
  192         u_int64_t sum;
  193         union q_util q_util;
  194         union l_util l_util;
  195 
  196         sum = (u_int64_t) a + b + c;
  197         REDUCE16;
  198         return (sum);
  199 }
  200 
  201 u_short
  202 in_cksum_skip(struct mbuf *m, int len, int skip)
  203 {
  204         u_int64_t sum = 0;
  205         int mlen = 0;
  206         int clen = 0;
  207         caddr_t addr;
  208         union q_util q_util;
  209         union l_util l_util;
  210 
  211         len -= skip;
  212         for (; skip && m; m = m->m_next) {
  213                 if (m->m_len > skip) {
  214                         mlen = m->m_len - skip;
  215                         addr = mtod(m, caddr_t) + skip;
  216                         goto skip_start;
  217                 } else {
  218                         skip -= m->m_len;
  219                 }
  220         }
  221 
  222         for (; m && len; m = m->m_next) {
  223                 if (m->m_len == 0)
  224                         continue;
  225                 mlen = m->m_len;
  226                 addr = mtod(m, caddr_t);
  227 skip_start:
  228                 if (len < mlen)
  229                         mlen = len;
  230 
  231                 if ((clen ^ (uintptr_t) addr) & 1)
  232                         sum += in_cksumdata(addr, mlen) << 8;
  233                 else
  234                         sum += in_cksumdata(addr, mlen);
  235 
  236                 clen += mlen;
  237                 len -= mlen;
  238         }
  239         REDUCE16;
  240         return (~sum & 0xffff);
  241 }
  242 
  243 u_int in_cksum_hdr(const struct ip *ip)
  244 {
  245         u_int64_t sum = in_cksumdata(ip, sizeof(struct ip));
  246         union q_util q_util;
  247         union l_util l_util;
  248         REDUCE16;
  249         return (~sum & 0xffff);
  250 }

Cache object: 8c0e161183bfb2b146ab7a008a7363d3


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