base/crc.cc

   1 /* $Id$ */
   2
   3 /*
   4  * Copyright (c) 1988, 1992, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   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
  36 #include <sstream>
  37 #include <string>
  38
  39 #include "sim/host.hh"
  40 #include "base/crc.hh"
  41
  42 #define ETHER_CRC_POLY_LE 0xedb88320
  43 #define ETHER_CRC_POLY_BE 0x04c11db6
  44
  45 #if 0
  46 /*
  47  * This is for reference.  We have a table-driven version
  48  * of the little-endian crc32 generator, which is faster
  49  * than the double-loop.
  50  */
  51 uint32_t
  52 crc32le(const uint8_t *buf, size_t len)
  53 {
  54     uint32_t c, crc, carry;
  55     size_t i, j;
  56
  57     crc = 0xffffffffU;      /* initial value */
  58
  59     for (i = 0; i < len; i++) {
  60         c = buf[i];
  61         for (j = 0; j < 8; j++) {
  62             carry = ((crc & 0x01) ? 1 : 0) ^ (c & 0x01);
  63             crc >>= 1;
  64             c >>= 1;
  65             if (carry)
  66                 crc = (crc ^ ETHER_CRC_POLY_LE);
  67         }
  68     }
  69
  70     return (crc);
  71 }
  72 #else
  73 uint32_t
  74 crc32le(const uint8_t *buf, size_t len)
  75 {
  76     static const uint32_t crctab[] = {
  77         0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
  78         0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
  79         0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
  80         0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c
  81     };
  82     uint32_t crc;
  83     int i;
  84
  85     crc = 0xffffffffU;      /* initial value */
  86
  87     for (i = 0; i < len; i++) {
  88         crc ^= buf[i];
  89         crc = (crc >> 4) ^ crctab[crc & 0xf];
  90         crc = (crc >> 4) ^ crctab[crc & 0xf];
  91     }
  92
  93     return (crc);
  94 }
  95 #endif
  96
  97 uint32_t
  98 crc32be(const uint8_t *buf, size_t len)
  99 {
 100     uint32_t c, crc, carry;
 101     size_t i, j;
 102
 103     crc = 0xffffffffU;      /* initial value */
 104
 105     for (i = 0; i < len; i++) {
 106         c = buf[i];
 107         for (j = 0; j < 8; j++) {
 108             carry = ((crc & 0x80000000U) ? 1 : 0) ^ (c & 0x01);
 109             crc <<= 1;
 110             c >>= 1;
 111             if (carry)
 112                 crc = (crc ^ ETHER_CRC_POLY_BE) | carry;
 113         }
 114     }
 115
 116     return (crc);
 117 }