2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * @(#)hash_func.c 8.2 (Berkeley) 2/21/94
37 * $DragonFly: src/lib/libc/db/hash/hash_func.c,v 1.4 2003/11/12 20:21:23 eirikn Exp $
40 #include <sys/types.h>
47 static u_int32_t hash1 (const void *, size_t);
48 static u_int32_t hash2 (const void *, size_t);
49 static u_int32_t hash3 (const void *, size_t);
50 static u_int32_t hash4 (const void *, size_t);
52 /* Global default hash function */
53 u_int32_t (*__default_hash) (const void *, size_t) = hash4;
58 * Assume that we've already split the bucket to which this key hashes,
59 * calculate that bucket, and check that in fact we did already split it.
61 * This came from ejb's hsearch.
65 #define PRIME2 1048583
72 register const u_char *key;
75 /* Convert string to integer */
76 for (key = keyarg, h = 0; len--;)
77 h = h * PRIME1 ^ (*key++ - ' ');
83 * Phong's linear congruential hash
85 #define dcharhash(h, c) ((h) = 0x63c63cd9*(h) + 0x9c39c33d + (c))
92 register const u_char *e, *key;
98 for (h = 0; key != e;) {
108 * This is INCREDIBLY ugly, but fast. We break the string up into 8 byte
109 * units. On the first time through the loop we get the "leftover bytes"
110 * (strlen % 8). On every other iteration, we perform 8 HASHC's so we handle
111 * all 8 bytes. Essentially, this saves us 7 cmp & branch instructions. If
112 * this routine is heavily used enough, it's worth the ugly coding.
114 * OZ's original sdbm hash
121 register const u_char *key;
122 register size_t loop;
123 register u_int32_t h;
125 #define HASHC h = *key++ + 65599 * h
130 loop = (len + 8 - 1) >> 3;
132 switch (len & (8 - 1)) {
163 /* Hash function from Chris Torek. */
169 register const u_char *key;
170 register size_t loop;
171 register u_int32_t h;
173 #define HASH4a h = (h << 5) - h + *key++;
174 #define HASH4b h = (h << 5) + h + *key++;
180 loop = (len + 8 - 1) >> 3;
182 switch (len & (8 - 1)) {