1 /* $NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $ */
2
3 /*
4 * Copyright (c) 2001 Christopher G. Demetriou
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used to endorse or promote products
16 * derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * <<Id: LICENSE_GC,v 1.1 2001/10/01 23:24:05 cgd Exp>>
30 */
31
32 /*
33 * hcreate() / hsearch() / hdestroy()
34 *
35 * SysV/XPG4 hash table functions.
36 *
37 * Implementation done based on NetBSD manual page and Solaris manual page,
38 * plus my own personal experience about how they're supposed to work.
39 *
40 * I tried to look at Knuth (as cited by the Solaris manual page), but
41 * nobody had a copy in the office, so...
42 */
43
44 #define _DEFAULT_SOURCE
45 #include <sys/cdefs.h>
46 #if 0
47 #if defined(LIBC_SCCS) && !defined(lint)
48 __RCSID("$NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $");
49 #endif /* LIBC_SCCS and not lint */
50 #endif
51
52 #include <sys/types.h>
53 #include <sys/queue.h>
54 #include <errno.h>
55 #include <search.h>
56 #include <stdlib.h>
57 #include <string.h>
58 #include "db_local.h"
59 #include "hash.h"
60 #include "page.h"
61 #include "extern.h"
62
63 /*
64 * DO NOT MAKE THIS STRUCTURE LARGER THAN 32 BYTES (4 ptrs on 64-bit
65 * ptr machine) without adjusting MAX_BUCKETS_LG2 below.
66 */
67 struct internal_entry {
68 SLIST_ENTRY(internal_entry) link;
69 ENTRY ent;
70 };
71 SLIST_HEAD(internal_head, internal_entry);
72
73 #define MIN_BUCKETS_LG2 4
74 #define MIN_BUCKETS (1 << MIN_BUCKETS_LG2)
75
76 /*
77 * max * sizeof internal_entry must fit into size_t.
78 * assumes internal_entry is <= 32 (2^5) bytes.
79 */
80 #ifdef __MSP430X_LARGE__
81 /* 20-bit size_t. */
82 #define MAX_BUCKETS_LG2 (20 - 1 - 5)
83 #else
84 #define MAX_BUCKETS_LG2 (sizeof (size_t) * 8 - 1 - 5)
85 #endif
86 #define MAX_BUCKETS ((size_t)1 << MAX_BUCKETS_LG2)
87
88 int
hcreate_r(size_t nel,struct hsearch_data * htab)89 hcreate_r(size_t nel, struct hsearch_data *htab)
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 (htab->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 htab->htablesize = nel;
117 htab->htable = malloc(htab->htablesize * sizeof htab->htable[0]);
118 if (htab->htable == NULL) {
119 errno = ENOMEM;
120 return 0;
121 }
122
123 /* Initialize it. */
124 for (idx = 0; idx < htab->htablesize; idx++)
125 SLIST_INIT(&(htab->htable[idx]));
126
127 return 1;
128 }
129
130 void
hdestroy_r(struct hsearch_data * htab)131 hdestroy_r(struct hsearch_data *htab)
132 {
133 #if 0
134 struct internal_entry *ie;
135 size_t idx;
136 #endif
137 if (htab->htable == NULL)
138 return;
139
140 #if 0
141 for (idx = 0; idx < htab->htablesize; idx++) {
142 while (!SLIST_EMPTY(&(htab->htable[idx]))) {
143 ie = SLIST_FIRST(&(htab->htable[idx]));
144 SLIST_REMOVE_HEAD(&(htab->htable[idx]), link);
145 free(ie->ent.key);
146 free(ie);
147 }
148 }
149 #endif
150 free(htab->htable);
151 htab->htable = NULL;
152 }
153
154 int
hsearch_r(ENTRY item,ACTION action,ENTRY ** retval,struct hsearch_data * htab)155 hsearch_r(ENTRY item, ACTION action, ENTRY **retval, struct hsearch_data *htab)
156 {
157 struct internal_head *head;
158 struct internal_entry *ie;
159 __uint32_t hashval;
160 size_t len;
161
162 len = strlen(item.key);
163 hashval = __default_hash(item.key, len);
164
165 head = &(htab->htable[hashval & (htab->htablesize - 1)]);
166 ie = SLIST_FIRST(head);
167 while (ie != NULL) {
168 if (strcmp(ie->ent.key, item.key) == 0)
169 break;
170 ie = SLIST_NEXT(ie, link);
171 }
172
173 if (ie != NULL)
174 {
175 *retval = &ie->ent;
176 return 1;
177 }
178 else if (action == FIND)
179 {
180 *retval = NULL;
181 return 0;
182 }
183
184 ie = malloc(sizeof *ie);
185 if (ie == NULL)
186 {
187 *retval = NULL;
188 return 0;
189 }
190 ie->ent.key = item.key;
191 ie->ent.data = item.data;
192
193 SLIST_INSERT_HEAD(head, ie, link);
194 *retval = &ie->ent;
195 return 1;
196 }
197
