freebsd-skq/sys/net/toeplitz.c

/*-
 * Copyright (c) 2010 David Malone <dwmalone@FreeBSD.org>
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/types.h>

#include <net/rss_config.h>
#include <net/toeplitz.h>

#include <sys/systm.h>

uint32_t
toeplitz_hash(u_int keylen, const uint8_t *key, u_int datalen,
    const uint8_t *data)
{
	uint32_t hash = 0, v;
	u_int i, b;

	/* XXXRW: Perhaps an assertion about key length vs. data length? */

	v = (key[0]<<24) + (key[1]<<16) + (key[2] <<8) + key[3];
	for (i = 0; i < datalen; i++) {
		for (b = 0; b < 8; b++) {
			if (data[i] & (1<<(7-b)))
				hash ^= v;
			v <<= 1;
			if ((i + 4) < RSS_KEYSIZE &&
			    (key[i+4] & (1<<(7-b))))
				v |= 1;
		}
	}
	return (hash);
}