1
/* $NetBSD: hash.c,v 1.19 2009/01/24 10:59:09 dsl Exp $ */
4
* Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
7
* This code is derived from software contributed to Berkeley by
10
* Redistribution and use in source and binary forms, with or without
11
* modification, are permitted provided that the following conditions
13
* 1. Redistributions of source code must retain the above copyright
14
* notice, this list of conditions and the following disclaimer.
15
* 2. Redistributions in binary form must reproduce the above copyright
16
* notice, this list of conditions and the following disclaimer in the
17
* documentation and/or other materials provided with the distribution.
18
* 3. Neither the name of the University nor the names of its contributors
19
* may be used to endorse or promote products derived from this software
20
* without specific prior written permission.
22
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36
* Copyright (c) 1988, 1989 by Adam de Boor
37
* Copyright (c) 1989 by Berkeley Softworks
38
* All rights reserved.
40
* This code is derived from software contributed to Berkeley by
43
* Redistribution and use in source and binary forms, with or without
44
* modification, are permitted provided that the following conditions
46
* 1. Redistributions of source code must retain the above copyright
47
* notice, this list of conditions and the following disclaimer.
48
* 2. Redistributions in binary form must reproduce the above copyright
49
* notice, this list of conditions and the following disclaimer in the
50
* documentation and/or other materials provided with the distribution.
51
* 3. All advertising materials mentioning features or use of this software
52
* must display the following acknowledgement:
53
* This product includes software developed by the University of
54
* California, Berkeley and its contributors.
55
* 4. Neither the name of the University nor the names of its contributors
56
* may be used to endorse or promote products derived from this software
57
* without specific prior written permission.
59
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
60
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
61
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
62
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
63
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
64
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
65
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
66
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
67
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
68
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
73
static char rcsid[] = "$NetBSD: hash.c,v 1.19 2009/01/24 10:59:09 dsl Exp $";
75
#include <sys/cdefs.h>
78
static char sccsid[] = "@(#)hash.c 8.1 (Berkeley) 6/6/93";
80
__RCSID("$NetBSD: hash.c,v 1.19 2009/01/24 10:59:09 dsl Exp $");
87
* This module contains routines to manipulate a hash table.
88
* See hash.h for a definition of the structure of the hash
89
* table. Hash tables grow automatically as the amount of
90
* information increases.
97
* Forward references to local procedures that are used before they're
101
static void RebuildTable(Hash_Table *);
104
* The following defines the ratio of # entries to # buckets
105
* at which we rebuild the table to make it larger.
108
#define rebuildLimit 3
111
*---------------------------------------------------------
115
* This routine just sets up the hash table.
118
* t Structure to to hold table.
119
* numBuckets How many buckets to create for starters. This
120
* number is rounded up to a power of two. If
121
* <= 0, a reasonable default is chosen. The
122
* table will grow in size later as needed.
128
* Memory is allocated for the initial bucket area.
130
*---------------------------------------------------------
134
Hash_InitTable(Hash_Table *t, int numBuckets)
137
struct Hash_Entry **hp;
140
* Round up the size to a power of two.
145
for (i = 2; i < numBuckets; i <<= 1)
151
t->bucketPtr = hp = bmake_malloc(sizeof(*hp) * i);
157
*---------------------------------------------------------
159
* Hash_DeleteTable --
161
* This routine removes everything from a hash table
162
* and frees up the memory space it occupied (except for
163
* the space in the Hash_Table structure).
169
* Lots of memory is freed up.
171
*---------------------------------------------------------
175
Hash_DeleteTable(Hash_Table *t)
177
struct Hash_Entry **hp, *h, *nexth = NULL;
180
for (hp = t->bucketPtr, i = t->size; --i >= 0;) {
181
for (h = *hp++; h != NULL; h = nexth) {
189
* Set up the hash table to cause memory faults on any future access
190
* attempts until re-initialization.
196
*---------------------------------------------------------
200
* Searches a hash table for an entry corresponding to key.
203
* t Hash table to search.
207
* The return value is a pointer to the entry for key,
208
* if key was present in the table. If key was not
209
* present, NULL is returned.
214
*---------------------------------------------------------
218
Hash_FindEntry(Hash_Table *t, const char *key)
224
for (h = 0, p = key; *p;)
225
h = (h << 5) - h + *p++;
227
for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next)
228
if (e->namehash == h && strcmp(e->name, p) == 0)
234
*---------------------------------------------------------
236
* Hash_CreateEntry --
238
* Searches a hash table for an entry corresponding to
239
* key. If no entry is found, then one is created.
242
* t Hash table to search.
244
* newPtr Filled in with TRUE if new entry created,
248
* The return value is a pointer to the entry. If *newPtr
249
* isn't NULL, then *newPtr is filled in with TRUE if a
250
* new entry was created, and FALSE if an entry already existed
251
* with the given key.
254
* Memory may be allocated, and the hash buckets may be modified.
255
*---------------------------------------------------------
259
Hash_CreateEntry(Hash_Table *t, const char *key, Boolean *newPtr)
265
struct Hash_Entry **hp;
268
* Hash the key. As a side effect, save the length (strlen) of the
269
* key in case we need to create the entry.
271
for (h = 0, p = key; *p;)
272
h = (h << 5) - h + *p++;
275
for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) {
276
if (e->namehash == h && strcmp(e->name, p) == 0) {
284
* The desired entry isn't there. Before allocating a new entry,
285
* expand the table if necessary (and this changes the resulting
288
if (t->numEntries >= rebuildLimit * t->size)
290
e = bmake_malloc(sizeof(*e) + keylen);
291
hp = &t->bucketPtr[h & t->mask];
294
Hash_SetValue(e, NULL);
296
(void)strcpy(e->name, p);
305
*---------------------------------------------------------
307
* Hash_DeleteEntry --
309
* Delete the given hash table entry and free memory associated with
316
* Hash chain that entry lives in is modified and memory is freed.
318
*---------------------------------------------------------
322
Hash_DeleteEntry(Hash_Table *t, Hash_Entry *e)
328
for (hp = &t->bucketPtr[e->namehash & t->mask];
329
(p = *hp) != NULL; hp = &p->next) {
337
(void)write(2, "bad call to Hash_DeleteEntry\n", 29);
342
*---------------------------------------------------------
345
* This procedure sets things up for a complete search
346
* of all entries recorded in the hash table.
349
* t Table to be searched.
350
* searchPtr Area in which to keep state about search.
353
* The return value is the address of the first entry in
354
* the hash table, or NULL if the table is empty.
357
* The information in searchPtr is initialized so that successive
358
* calls to Hash_Next will return successive HashEntry's
361
*---------------------------------------------------------
365
Hash_EnumFirst(Hash_Table *t, Hash_Search *searchPtr)
367
searchPtr->tablePtr = t;
368
searchPtr->nextIndex = 0;
369
searchPtr->hashEntryPtr = NULL;
370
return Hash_EnumNext(searchPtr);
374
*---------------------------------------------------------
377
* This procedure returns successive entries in the hash table.
380
* searchPtr Area used to keep state about search.
383
* The return value is a pointer to the next HashEntry
384
* in the table, or NULL when the end of the table is
388
* The information in searchPtr is modified to advance to the
391
*---------------------------------------------------------
395
Hash_EnumNext(Hash_Search *searchPtr)
398
Hash_Table *t = searchPtr->tablePtr;
401
* The hashEntryPtr field points to the most recently returned
402
* entry, or is nil if we are starting up. If not nil, we have
403
* to start at the next one in the chain.
405
e = searchPtr->hashEntryPtr;
409
* If the chain ran out, or if we are starting up, we need to
410
* find the next nonempty chain.
413
if (searchPtr->nextIndex >= t->size)
415
e = t->bucketPtr[searchPtr->nextIndex++];
417
searchPtr->hashEntryPtr = e;
422
*---------------------------------------------------------
425
* This local routine makes a new hash table that
426
* is larger than the old one.
432
* The entire hash table is moved, so any bucket numbers
433
* from the old table are invalid.
435
*---------------------------------------------------------
439
RebuildTable(Hash_Table *t)
441
Hash_Entry *e, *next = NULL, **hp, **xp;
446
oldhp = t->bucketPtr;
447
oldsize = i = t->size;
450
t->mask = mask = i - 1;
451
t->bucketPtr = hp = bmake_malloc(sizeof(*hp) * i);
454
for (hp = oldhp, i = oldsize; --i >= 0;) {
455
for (e = *hp++; e != NULL; e = next) {
457
xp = &t->bucketPtr[e->namehash & mask];