external/gpl2/lvm2/dist/lib/misc/crc.c

   1 /*      $NetBSD$        */
   2
   3 /*
   4  * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
   5  * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
   6  *
   7  * This file is part of LVM2.
   8  *
   9  * This copyrighted material is made available to anyone wishing to use,
  10  * modify, copy, or redistribute it subject to the terms and conditions
  11  * of the GNU Lesser General Public License v.2.1.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public License
  14  * along with this program; if not, write to the Free Software Foundation,
  15  * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  16  */
  17
  18 #include "lib.h"
  19
  20 #include "crc.h"
  21
  22 /* Calculate an endian-independent CRC of supplied buffer */
  23 uint32_t calc_crc(uint32_t initial, const void *buf, uint32_t size)
  24 {
  25         static const uint32_t crctab[] = {
  26                 0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
  27                 0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
  28                 0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
  29                 0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c
  30         };
  31         uint32_t i, crc = initial;
  32         const uint8_t *data = (const uint8_t *) buf;
  33
  34         for (i = 0; i < size; i++) {
  35                 crc ^= *data++;
  36                 crc = (crc >> 4) ^ crctab[crc & 0xf];
  37                 crc = (crc >> 4) ^ crctab[crc & 0xf];
  38         }
  39         return crc;
  40 }