xref: /freebsd/sys/net/toeplitz.c (revision f126890ac5386406dadf7c4cfa9566cbb56537c5)
1 /*-
2  * Copyright (c) 2010 David Malone <dwmalone@FreeBSD.org>
3  * 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  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 
27 #include <sys/types.h>
28 
29 #include <net/rss_config.h>
30 #include <net/toeplitz.h>
31 
32 #include <sys/systm.h>
33 
34 uint32_t
35 toeplitz_hash(u_int keylen, const uint8_t *key, u_int datalen,
36     const uint8_t *data)
37 {
38 	uint32_t hash = 0, v;
39 	u_int i, b;
40 
41 	/* XXXRW: Perhaps an assertion about key length vs. data length? */
42 
43 	v = (key[0]<<24) + (key[1]<<16) + (key[2] <<8) + key[3];
44 	for (i = 0; i < datalen; i++) {
45 		for (b = 0; b < 8; b++) {
46 			if (data[i] & (1<<(7-b)))
47 				hash ^= v;
48 			v <<= 1;
49 			if ((i + 4) < RSS_KEYSIZE &&
50 			    (key[i+4] & (1<<(7-b))))
51 				v |= 1;
52 		}
53 	}
54 	return (hash);
55 }
56