src/base/crc.cc

   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
  34 #include <string>
  35
  36 #include "sim/host.hh"
  37 #include "base/crc.hh"
  38
  39 #define ETHER_CRC_POLY_LE 0xedb88320
  40 #define ETHER_CRC_POLY_BE 0x04c11db6
  41
  42 #if 0
  43 /*
  44  * This is for reference.  We have a table-driven version
  45  * of the little-endian crc32 generator, which is faster
  46  * than the double-loop.
  47  */
  48 uint32_t
  49 crc32le(const uint8_t *buf, size_t len)
  50 {
  51     uint32_t c, crc, carry;
  52     size_t i, j;
  53
  54     crc = 0xffffffffU;      /* initial value */
  55
  56     for (i = 0; i < len; i++) {
  57         c = buf[i];
  58         for (j = 0; j < 8; j++) {
  59             carry = ((crc & 0x01) ? 1 : 0) ^ (c & 0x01);
  60             crc >>= 1;
  61             c >>= 1;
  62             if (carry)
  63                 crc = (crc ^ ETHER_CRC_POLY_LE);
  64         }
  65     }
  66
  67     return (crc);
  68 }
  69 #else
  70 uint32_t
  71 crc32le(const uint8_t *buf, size_t len)
  72 {
  73     static const uint32_t crctab[] = {
  74         0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
  75         0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
  76         0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
  77         0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c
  78     };
  79     uint32_t crc;
  80     int i;
  81
  82     crc = 0xffffffffU;      /* initial value */
  83
  84     for (i = 0; i < len; i++) {
  85         crc ^= buf[i];
  86         crc = (crc >> 4) ^ crctab[crc & 0xf];
  87         crc = (crc >> 4) ^ crctab[crc & 0xf];
  88     }
  89
  90     return (crc);
  91 }
  92 #endif
  93
  94 uint32_t
  95 crc32be(const uint8_t *buf, size_t len)
  96 {
  97     uint32_t c, crc, carry;
  98     size_t i, j;
  99
 100     crc = 0xffffffffU;      /* initial value */
 101
 102     for (i = 0; i < len; i++) {
 103         c = buf[i];
 104         for (j = 0; j < 8; j++) {
 105             carry = ((crc & 0x80000000U) ? 1 : 0) ^ (c & 0x01);
 106             crc <<= 1;
 107             c >>= 1;
 108             if (carry)
 109                 crc = (crc ^ ETHER_CRC_POLY_BE) | carry;
 110         }
 111     }
 112
 113     return (crc);
 114 }