crc32.c

this is aes algorithm

/*-
 * Copyright (c) 1982, 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)if_ethersubr.c	8.1 (Berkeley) 6/10/93
 * $FreeBSD: src/sys/net/if_ethersubr.c,v 1.177.2.14 2008/02/12 22:27:27 emaste Exp $
 */

#include "types.h"

/* 
 * From FreeBSD sys/net/ethernet.h
 * Ethernet CRC32 polynomials (big- and little-endian verions).
 */
#define ETHER_CRC_POLY_LE       0xedb88320
#define ETHER_CRC_POLY_BE       0x04c11db6

/* FreeBSD has a faster version but it uses more memory - we're using the reference version */
uint32_t
ether_crc32_le(const uint8_t *buf, size_t len)
{
	size_t i;
	uint32_t crc, carry;
	int bit;
	uint8_t data;

	crc = 0xffffffff;	/* initial value */

	for (i = 0; i < len; i++) {
		for (data = *buf++, bit = 0; bit < 8; bit++, data >>= 1)
			carry = (crc ^ data) & 1;
			crc >>= 1;
			if (carry)
				crc = (crc ^ ETHER_CRC_POLY_LE);
	}

	return (crc);
}