1/*-
2 * Copyright (c) 2013, Joseph Koshy
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 *    in this position and unchanged.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27/*
28 * An implementation of the Fowler-Noll-Vo hash function.
29 *
30 * References:
31 * - http://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function
32 * - http://www.isthe.com/chongo/tech/comp/fnv/
33 */
34
35#include <sys/types.h>
36
37#include <limits.h>
38
39#include "_libelftc.h"
40
41ELFTC_VCSID("$Id: libelftc_hash.c 2870 2013-01-07 10:38:43Z jkoshy $");
42
43/*
44 * Use the size of an 'int' to determine the magic numbers used by the
45 * hash function.
46 */
47
48#if	INT_MAX == 2147483647UL
49#define	FNV_PRIME		16777619UL
50#define FNV_OFFSET		2166136261UL
51#elif	INT_MAX == 18446744073709551615ULL
52#define	FNV_PRIME		1099511628211ULL
53#define	FNV_OFFSET		14695981039346656037ULL
54#else
55#error	sizeof(int) is unknown.
56#endif
57
58unsigned int
59libelftc_hash_string(const char *s)
60{
61	char c;
62	unsigned int hash;
63
64	for (hash = FNV_OFFSET; (c = *s) != '\0'; s++) {
65		hash ^= c;
66		hash *= FNV_PRIME;
67	}
68
69	return (hash);
70}
71