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
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9 * modification, are permitted provided that the following conditions
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12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
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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
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24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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37 #if defined(LIBC_SCCS) && !defined(lint)
38 static char sccsid
[] = "@(#)hash_func.c 8.2 (Berkeley) 2/21/94";
39 #endif /* LIBC_SCCS and not lint */
41 #include <sys/types.h>
48 static u_int32_t hash1
__P((const void *, size_t));
49 static u_int32_t hash2
__P((const void *, size_t));
50 static u_int32_t hash3
__P((const void *, size_t));
51 static u_int32_t hash4
__P((const void *, size_t));
53 /* Global default hash function */
54 u_int32_t (*__default_hash
) __P((const void *, size_t)) = hash4
;
59 * Assume that we've already split the bucket to which this key hashes,
60 * calculate that bucket, and check that in fact we did already split it.
62 * This came from ejb's hsearch.
66 #define PRIME2 1048583
73 register const u_char
*key
;
76 /* Convert string to integer */
77 for (key
= keyarg
, h
= 0; len
--;)
78 h
= h
* PRIME1
^ (*key
++ - ' ');
84 * Phong's linear congruential hash
86 #define dcharhash(h, c) ((h) = 0x63c63cd9*(h) + 0x9c39c33d + (c))
93 register const u_char
*e
, *key
;
99 for (h
= 0; key
!= e
;) {
109 * This is INCREDIBLY ugly, but fast. We break the string up into 8 byte
110 * units. On the first time through the loop we get the "leftover bytes"
111 * (strlen % 8). On every other iteration, we perform 8 HASHC's so we handle
112 * all 8 bytes. Essentially, this saves us 7 cmp & branch instructions. If
113 * this routine is heavily used enough, it's worth the ugly coding.
115 * OZ's original sdbm hash
122 register const u_char
*key
;
123 register size_t loop
;
124 register u_int32_t h
;
126 #define HASHC h = *key++ + 65599 * h
131 loop
= (len
+ 8 - 1) >> 3;
133 switch (len
& (8 - 1)) {
164 /* Hash function from Chris Torek. */
170 register const u_char
*key
;
171 register size_t loop
;
172 register u_int32_t h
;
174 #define HASH4a h = (h << 5) - h + *key++;
175 #define HASH4b h = (h << 5) + h + *key++;
181 loop
= (len
+ 8 - 1) >> 3;
183 switch (len
& (8 - 1)) {