2 * Copyright (c) 2001 Christopher G. Demetriou
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed for the
16 * NetBSD Project. See http://www.netbsd.org/ for
17 * information about NetBSD.
18 * 4. The name of the author may not be used to endorse or promote products
19 * derived from this software without specific prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>>
34 * $NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $
35 * $FreeBSD: src/lib/libc/stdlib/hcreate.c,v 1.1.2.2 2001/10/02 11:22:56 ru Exp $
36 * $DragonFly: src/lib/libc/stdlib/hcreate.c,v 1.2 2003/06/17 04:26:46 dillon Exp $
40 * hcreate() / hsearch() / hdestroy()
42 * SysV/XPG4 hash table functions.
44 * Implementation done based on NetBSD manual page and Solaris manual page,
45 * plus my own personal experience about how they're supposed to work.
47 * I tried to look at Knuth (as cited by the Solaris manual page), but
48 * nobody had a copy in the office, so...
51 #include <sys/cdefs.h>
53 #include <sys/types.h>
54 #include <sys/queue.h>
61 * DO NOT MAKE THIS STRUCTURE LARGER THAN 32 BYTES (4 ptrs on 64-bit
62 * ptr machine) without adjusting MAX_BUCKETS_LG2 below.
64 struct internal_entry {
65 SLIST_ENTRY(internal_entry) link;
68 SLIST_HEAD(internal_head, internal_entry);
70 #define MIN_BUCKETS_LG2 4
71 #define MIN_BUCKETS (1 << MIN_BUCKETS_LG2)
74 * max * sizeof internal_entry must fit into size_t.
75 * assumes internal_entry is <= 32 (2^5) bytes.
77 #define MAX_BUCKETS_LG2 (sizeof (size_t) * 8 - 1 - 5)
78 #define MAX_BUCKETS ((size_t)1 << MAX_BUCKETS_LG2)
80 /* Default hash function, from db/hash/hash_func.c */
81 extern u_int32_t (*__default_hash)(const void *, size_t);
83 static struct internal_head *htable;
84 static size_t htablesize;
92 /* Make sure this this isn't called when a table already exists. */
98 /* If nel is too small, make it min sized. */
99 if (nel < MIN_BUCKETS)
102 /* If it's too large, cap it. */
103 if (nel > MAX_BUCKETS)
106 /* If it's is not a power of two in size, round up. */
107 if ((nel & (nel - 1)) != 0) {
108 for (p2 = 0; nel != 0; p2++)
113 /* Allocate the table. */
115 htable = malloc(htablesize * sizeof htable[0]);
116 if (htable == NULL) {
122 for (idx = 0; idx < htablesize; idx++)
123 SLIST_INIT(&htable[idx]);
131 struct internal_entry *ie;
137 for (idx = 0; idx < htablesize; idx++) {
138 while (!SLIST_EMPTY(&htable[idx])) {
139 ie = SLIST_FIRST(&htable[idx]);
140 SLIST_REMOVE_HEAD(&htable[idx], link);
150 hsearch(ENTRY item, ACTION action)
152 struct internal_head *head;
153 struct internal_entry *ie;
157 len = strlen(item.key);
158 hashval = (*__default_hash)(item.key, len);
160 head = &htable[hashval & (htablesize - 1)];
161 ie = SLIST_FIRST(head);
163 if (strcmp(ie->ent.key, item.key) == 0)
165 ie = SLIST_NEXT(ie, link);
170 else if (action == FIND)
173 ie = malloc(sizeof *ie);
176 ie->ent.key = item.key;
177 ie->ent.data = item.data;
179 SLIST_INSERT_HEAD(head, ie, link);