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/*-
 * Copyright (c) 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Margo Seltzer.
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 */
 
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)hash_func.c 8.2 (Berkeley) 2/21/94";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
#include <sys/types.h>
 
#include "db_local.h"
#include "hash.h"
#include "page.h"
#include "extern.h"
 
#if 0
static __uint32_t hash1(const void *, size_t);
static __uint32_t hash2(const void *, size_t);
static __uint32_t hash3(const void *, size_t);
#endif
static __uint32_t hash4(const void *, size_t);
 
/* Global default hash function */
__uint32_t (*__default_hash)(const void *, size_t) = hash4;
 
/*
 * HASH FUNCTIONS
 *
 * Assume that we've already split the bucket to which this key hashes,
 * calculate that bucket, and check that in fact we did already split it.
 *
 * This came from ejb's hsearch.
 */
 
#define PRIME1          37
#define PRIME2          1048583
 
#if 0
static __uint32_t
hash1(keyarg, len)
        const void *keyarg;
        size_t len;
{
        const u_char *key;
        __uint32_t h;
 
        /* Convert string to integer */
        for (key = keyarg, h = 0; len--;)
                h = h * PRIME1 ^ (*key++ - ' ');
        h %= PRIME2;
        return (h);
}
#endif
 
/*
 * Phong's linear congruential hash
 */
#define dcharhash(h, c) ((h) = 0x63c63cd9*(h) + 0x9c39c33d + (c))
 
#if 0
static __uint32_t
hash2(keyarg, len)
        const void *keyarg;
        size_t len;
{
        const u_char *e, *key;
        __uint32_t h;
        u_char c;
 
        key = keyarg;
        e = key + len;
        for (h = 0; key != e;) {
                c = *key++;
                if (!c && key > e)
                        break;
                dcharhash(h, c);
        }
        return (h);
}
#endif
 
/*
 * This is INCREDIBLY ugly, but fast.  We break the string up into 8 byte
 * units.  On the first time through the loop we get the "leftover bytes"
 * (strlen % 8).  On every other iteration, we perform 8 HASHC's so we handle
 * all 8 bytes.  Essentially, this saves us 7 cmp & branch instructions.  If
 * this routine is heavily used enough, it's worth the ugly coding.
 *
 * OZ's original sdbm hash
 */
#if 0
static __uint32_t
hash3(keyarg, len)
        const void *keyarg;
        size_t len;
{
        const u_char *key;
        size_t loop;
        __uint32_t h;
 
#define HASHC   h = *key++ + 65599 * h
 
        h = 0;
        key = keyarg;
        if (len > 0) {
                loop = (len + 8 - 1) >> 3;
 
                switch (len & (8 - 1)) {
                case 0:
                        do {
                                HASHC;
                                /* FALLTHROUGH */
                case 7:
                                HASHC;
                                /* FALLTHROUGH */
                case 6:
                                HASHC;
                                /* FALLTHROUGH */
                case 5:
                                HASHC;
                                /* FALLTHROUGH */
                case 4:
                                HASHC;
                                /* FALLTHROUGH */
                case 3:
                                HASHC;
                                /* FALLTHROUGH */
                case 2:
                                HASHC;
                                /* FALLTHROUGH */
                case 1:
                                HASHC;
                        } while (--loop);
                }
        }
        return (h);
}
#endif
 
/* Hash function from Chris Torek. */
static __uint32_t
hash4(keyarg, len)
        const void *keyarg;
        size_t len;
{
        const u_char *key;
        size_t loop;
        __uint32_t h;
 
#define HASH4a   h = (h << 5) - h + *key++;
#define HASH4b   h = (h << 5) + h + *key++;
#define HASH4 HASH4b
 
        h = 0;
        key = keyarg;
        if (len > 0) {
                loop = (len + 8 - 1) >> 3;
 
                switch (len & (8 - 1)) {
                case 0:
                        do {
                                HASH4;
                                /* FALLTHROUGH */
                case 7:
                                HASH4;
                                /* FALLTHROUGH */
                case 6:
                                HASH4;
                                /* FALLTHROUGH */
                case 5:
                                HASH4;
                                /* FALLTHROUGH */
                case 4:
                                HASH4;
                                /* FALLTHROUGH */
                case 3:
                                HASH4;
                                /* FALLTHROUGH */
                case 2:
                                HASH4;
                                /* FALLTHROUGH */
                case 1:
                                HASH4;
                        } while (--loop);
                }
        }
        return (h);
}

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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.17.0/] [newlib/] [libc/] [search/] [hash_func.c] - Blame information for rev 171

Line No.	Rev	Author	Line
1	148	jeremybenn	`/*-`
2			`* Copyright (c) 1990, 1993`
3			`* The Regents of the University of California. All rights reserved.`
4			`*`
5			`* This code is derived from software contributed to Berkeley by`
6			`* Margo Seltzer.`
7			`*`
8			`* Redistribution and use in source and binary forms, with or without`
9			`* modification, are permitted provided that the following conditions`
10			`* are met:`
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.`
23			`*`
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`
34			`* SUCH DAMAGE.`
35			`*/`
36
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 */`
40			`#include <sys/cdefs.h>`
41			`#include <sys/types.h>`
42
43			`#include "db_local.h"`
44			`#include "hash.h"`
45			`#include "page.h"`
46			`#include "extern.h"`
47
48			`#if 0`
49			`static __uint32_t hash1(const void *, size_t);`
50			`static __uint32_t hash2(const void *, size_t);`
51			`static __uint32_t hash3(const void *, size_t);`
52			`#endif`
53			`static __uint32_t hash4(const void *, size_t);`
54
55			`/* Global default hash function */`
56			`__uint32_t (__default_hash)(const void , size_t) = hash4;`
57
58			`/*`
59			`* HASH FUNCTIONS`
60			`*`
61			`* Assume that we've already split the bucket to which this key hashes,`
62			`* calculate that bucket, and check that in fact we did already split it.`
63			`*`
64			`* This came from ejb's hsearch.`
65			`*/`
66
67			`#define PRIME1 37`
68			`#define PRIME2 1048583`
69
70			`#if 0`
71			`static __uint32_t`
72			`hash1(keyarg, len)`
73			`const void *keyarg;`
74			`size_t len;`
75			`{`
76			`const u_char *key;`
77			`__uint32_t h;`
78
79			`/* Convert string to integer */`
80			`for (key = keyarg, h = 0; len--;)`
81			`h = h * PRIME1 ^ (*key++ - ' ');`
82			`h %= PRIME2;`
83			`return (h);`
84			`}`
85			`#endif`
86
87			`/*`
88			`* Phong's linear congruential hash`
89			`*/`
90			`#define dcharhash(h, c) ((h) = 0x63c63cd9*(h) + 0x9c39c33d + (c))`
91
92			`#if 0`
93			`static __uint32_t`
94			`hash2(keyarg, len)`
95			`const void *keyarg;`
96			`size_t len;`
97			`{`
98			`const u_char e, key;`
99			`__uint32_t h;`
100			`u_char c;`
101
102			`key = keyarg;`
103			`e = key + len;`
104			`for (h = 0; key != e;) {`
105			`c = *key++;`
106			`if (!c && key > e)`
107			`break;`
108			`dcharhash(h, c);`
109			`}`
110			`return (h);`
111			`}`
112			`#endif`
113
114			`/*`
115			`* This is INCREDIBLY ugly, but fast. We break the string up into 8 byte`
116			`* units. On the first time through the loop we get the "leftover bytes"`
117			`* (strlen % 8). On every other iteration, we perform 8 HASHC's so we handle`
118			`* all 8 bytes. Essentially, this saves us 7 cmp & branch instructions. If`
119			`* this routine is heavily used enough, it's worth the ugly coding.`
120			`*`
121			`* OZ's original sdbm hash`
122			`*/`
123			`#if 0`
124			`static __uint32_t`
125			`hash3(keyarg, len)`
126			`const void *keyarg;`
127			`size_t len;`
128			`{`
129			`const u_char *key;`
130			`size_t loop;`
131			`__uint32_t h;`
132
133			`#define HASHC h = key++ + 65599 h`
134
135			`h = 0;`
136			`key = keyarg;`
137			`if (len > 0) {`
138			`loop = (len + 8 - 1) >> 3;`
139
140			`switch (len & (8 - 1)) {`
141			`case 0:`
142			`do {`
143			`HASHC;`
144			`/* FALLTHROUGH */`
145			`case 7:`
146			`HASHC;`
147			`/* FALLTHROUGH */`
148			`case 6:`
149			`HASHC;`
150			`/* FALLTHROUGH */`
151			`case 5:`
152			`HASHC;`
153			`/* FALLTHROUGH */`
154			`case 4:`
155			`HASHC;`
156			`/* FALLTHROUGH */`
157			`case 3:`
158			`HASHC;`
159			`/* FALLTHROUGH */`
160			`case 2:`
161			`HASHC;`
162			`/* FALLTHROUGH */`
163			`case 1:`
164			`HASHC;`
165			`} while (--loop);`
166			`}`
167			`}`
168			`return (h);`
169			`}`
170			`#endif`
171
172			`/* Hash function from Chris Torek. */`
173			`static __uint32_t`
174			`hash4(keyarg, len)`
175			`const void *keyarg;`
176			`size_t len;`
177			`{`
178			`const u_char *key;`
179			`size_t loop;`
180			`__uint32_t h;`
181
182			`#define HASH4a h = (h << 5) - h + *key++;`
183			`#define HASH4b h = (h << 5) + h + *key++;`
184			`#define HASH4 HASH4b`
185
186			`h = 0;`
187			`key = keyarg;`
188			`if (len > 0) {`
189			`loop = (len + 8 - 1) >> 3;`
190
191			`switch (len & (8 - 1)) {`
192			`case 0:`
193			`do {`
194			`HASH4;`
195			`/* FALLTHROUGH */`
196			`case 7:`
197			`HASH4;`
198			`/* FALLTHROUGH */`
199			`case 6:`
200			`HASH4;`
201			`/* FALLTHROUGH */`
202			`case 5:`
203			`HASH4;`
204			`/* FALLTHROUGH */`
205			`case 4:`
206			`HASH4;`
207			`/* FALLTHROUGH */`
208			`case 3:`
209			`HASH4;`
210			`/* FALLTHROUGH */`
211			`case 2:`
212			`HASH4;`
213			`/* FALLTHROUGH */`
214			`case 1:`
215			`HASH4;`
216			`} while (--loop);`
217			`}`
218			`}`
219			`return (h);`
220			`}`