source: abnfparser/bap/hcreate.c @ 545

Last change on this file since 545 was 407, checked in by ylafon@…, 11 years ago

unixism

File size: 4.9 KB
Line 
1/* $NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $ */
2/* $FreeBSD: src/lib/libc/stdlib/hcreate.c,v 1.1.2.2 2001/10/02 11:22:56 ru Exp $ */
3
4/*
5 * Copyright (c) 2001 Christopher G. Demetriou
6 * All rights reserved.
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 for the
19 *          NetBSD Project.  See http://www.netbsd.org/ for
20 *          information about NetBSD.
21 * 4. The name of the author may not be used to endorse or promote products
22 *    derived from this software without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 *
35 * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>>
36 */
37
38/*
39 * hcreate() / hsearch() / hdestroy()
40 *
41 * SysV/XPG4 hash table functions.
42 *
43 * Implementation done based on NetBSD manual page and Solaris manual page,
44 * plus my own personal experience about how they're supposed to work.
45 *
46 * I tried to look at Knuth (as cited by the Solaris manual page), but
47 * nobody had a copy in the office, so...
48 */
49
50#include <sys/cdefs.h>
51#if defined(LIBC_SCCS) && !defined(lint)
52__RCSID("$NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $");
53#endif /* LIBC_SCCS and not lint */
54
55#include <sys/types.h>
56#include <sys/queue.h>
57#include <errno.h>
58#include <search.h>
59#include <stdlib.h>
60#include <string.h>
61
62/*
63 * DO NOT MAKE THIS STRUCTURE LARGER THAN 32 BYTES (4 ptrs on 64-bit
64 * ptr machine) without adjusting MAX_BUCKETS_LG2 below.
65 */
66struct internal_entry {
67        SLIST_ENTRY(internal_entry) link;
68        ENTRY ent;
69};
70SLIST_HEAD(internal_head, internal_entry);
71
72#define MIN_BUCKETS_LG2 4
73#define MIN_BUCKETS     (1 << MIN_BUCKETS_LG2)
74
75/*
76 * max * sizeof internal_entry must fit into size_t.
77 * assumes internal_entry is <= 32 (2^5) bytes.
78 */
79#define MAX_BUCKETS_LG2 (sizeof (size_t) * 8 - 1 - 5)
80#define MAX_BUCKETS     ((size_t)1 << MAX_BUCKETS_LG2)
81
82/* Default hash function, from db/hash/hash_func.c */
83extern u_int32_t (*__default_hash)(const void *, size_t);
84
85static struct internal_head *htable;
86static size_t htablesize;
87
88int
89hcreate(size_t nel)
90{
91        size_t idx;
92        unsigned int p2;
93
94        /* Make sure this this isn't called when a table already exists. */
95        if (htable != NULL) {
96                errno = EINVAL;
97                return 0;
98        }
99
100        /* If nel is too small, make it min sized. */
101        if (nel < MIN_BUCKETS)
102                nel = MIN_BUCKETS;
103
104        /* If it's too large, cap it. */
105        if (nel > MAX_BUCKETS)
106                nel = MAX_BUCKETS;
107
108        /* If it's is not a power of two in size, round up. */
109        if ((nel & (nel - 1)) != 0) {
110                for (p2 = 0; nel != 0; p2++)
111                        nel >>= 1;
112                nel = 1 << p2;
113        }
114       
115        /* Allocate the table. */
116        htablesize = nel;
117        htable = malloc(htablesize * sizeof htable[0]);
118        if (htable == NULL) {
119                errno = ENOMEM;
120                return 0;
121        }
122
123        /* Initialize it. */
124        for (idx = 0; idx < htablesize; idx++)
125                SLIST_INIT(&htable[idx]);
126
127        return 1;
128}
129
130void
131hdestroy(void)
132{
133        struct internal_entry *ie;
134        size_t idx;
135
136        if (htable == NULL)
137                return;
138
139        for (idx = 0; idx < htablesize; idx++) {
140                while (!SLIST_EMPTY(&htable[idx])) {
141                        ie = SLIST_FIRST(&htable[idx]);
142                        SLIST_REMOVE_HEAD(&htable[idx], link);
143                        free(ie->ent.key);
144                        free(ie);
145                }
146        }
147        free(htable);
148        htable = NULL;
149}
150
151ENTRY *
152hsearch(ENTRY item, ACTION action)
153{
154        struct internal_head *head;
155        struct internal_entry *ie;
156        uint32_t hashval;
157        size_t len;
158
159        len = strlen(item.key);
160        hashval = (*__default_hash)(item.key, len);
161
162        head = &htable[hashval & (htablesize - 1)];
163        ie = SLIST_FIRST(head);
164        while (ie != NULL) {
165                if (strcmp(ie->ent.key, item.key) == 0)
166                        break;
167                ie = SLIST_NEXT(ie, link);
168        }
169
170        if (ie != NULL)
171                return &ie->ent;
172        else if (action == FIND)
173                return NULL;
174
175        ie = malloc(sizeof *ie);
176        if (ie == NULL)
177                return NULL;
178        ie->ent.key = item.key;
179        ie->ent.data = item.data;
180
181        SLIST_INSERT_HEAD(head, ie, link);
182        return &ie->ent;
183}
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