hcreate.c revision 92986
11590Srgrimes/* $NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $ */ 21590Srgrimes 31590Srgrimes/* 41590Srgrimes * Copyright (c) 2001 Christopher G. Demetriou 51590Srgrimes * All rights reserved. 61590Srgrimes * 71590Srgrimes * Redistribution and use in source and binary forms, with or without 81590Srgrimes * modification, are permitted provided that the following conditions 91590Srgrimes * are met: 101590Srgrimes * 1. Redistributions of source code must retain the above copyright 111590Srgrimes * notice, this list of conditions and the following disclaimer. 121590Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 131590Srgrimes * notice, this list of conditions and the following disclaimer in the 141590Srgrimes * documentation and/or other materials provided with the distribution. 151590Srgrimes * 3. All advertising materials mentioning features or use of this software 161590Srgrimes * must display the following acknowledgement: 171590Srgrimes * This product includes software developed for the 181590Srgrimes * NetBSD Project. See http://www.netbsd.org/ for 191590Srgrimes * information about NetBSD. 201590Srgrimes * 4. The name of the author may not be used to endorse or promote products 211590Srgrimes * derived from this software without specific prior written permission. 221590Srgrimes * 231590Srgrimes * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 241590Srgrimes * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 251590Srgrimes * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 261590Srgrimes * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 271590Srgrimes * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 281590Srgrimes * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 291590Srgrimes * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 301590Srgrimes * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 311590Srgrimes * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 321590Srgrimes * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 331590Srgrimes * 3487674Smarkm * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>> 3587674Smarkm */ 3687674Smarkm 3787674Smarkm/* 381590Srgrimes * hcreate() / hsearch() / hdestroy() 3987674Smarkm * 4028694Scharnier * SysV/XPG4 hash table functions. 411590Srgrimes * 421590Srgrimes * Implementation done based on NetBSD manual page and Solaris manual page, 431590Srgrimes * plus my own personal experience about how they're supposed to work. 441590Srgrimes * 451590Srgrimes * I tried to look at Knuth (as cited by the Solaris manual page), but 461590Srgrimes * nobody had a copy in the office, so... 47181922Sache */ 481590Srgrimes 491590Srgrimes#include <sys/cdefs.h> 501590Srgrimes#if 0 511590Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 521590Srgrimes__RCSID("$NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $"); 538874Srgrimes#endif /* LIBC_SCCS and not lint */ 541590Srgrimes#endif 551590Srgrimes__FBSDID("$FreeBSD: head/lib/libc/stdlib/hcreate.c 92986 2002-03-22 21:53:29Z obrien $"); 5697981Sjmallett 571590Srgrimes#include <sys/types.h> 581590Srgrimes#include <sys/queue.h> 5953073Sdavidn#include <errno.h> 601590Srgrimes#include <search.h> 611590Srgrimes#include <stdlib.h> 621590Srgrimes#include <string.h> 6353073Sdavidn#include "namespace.h" 6453073Sdavidn 651590Srgrimes/* 661590Srgrimes * DO NOT MAKE THIS STRUCTURE LARGER THAN 32 BYTES (4 ptrs on 64-bit 671590Srgrimes * ptr machine) without adjusting MAX_BUCKETS_LG2 below. 689987Swollman */ 691590Srgrimesstruct internal_entry { 701590Srgrimes SLIST_ENTRY(internal_entry) link; 711590Srgrimes ENTRY ent; 7253073Sdavidn}; 7353073SdavidnSLIST_HEAD(internal_head, internal_entry); 7453073Sdavidn 7553073Sdavidn#define MIN_BUCKETS_LG2 4 7653073Sdavidn#define MIN_BUCKETS (1 << MIN_BUCKETS_LG2) 7774603Sache 781590Srgrimes/* 791590Srgrimes * max * sizeof internal_entry must fit into size_t. 801590Srgrimes * assumes internal_entry is <= 32 (2^5) bytes. 811590Srgrimes */ 8274603Sache#define MAX_BUCKETS_LG2 (sizeof (size_t) * 8 - 1 - 5) 831590Srgrimes#define MAX_BUCKETS ((size_t)1 << MAX_BUCKETS_LG2) 841590Srgrimes 8574603Sache/* Default hash function, from db/hash/hash_func.c */ 86181922Sacheextern u_int32_t (*__default_hash)(const void *, size_t); 871590Srgrimes 881590Srgrimesstatic struct internal_head *htable; 891590Srgrimesstatic size_t htablesize; 901590Srgrimes 911590Srgrimesint 9242481Speterhcreate(size_t nel) 931590Srgrimes{ 9422558Sdanny size_t idx; 9597981Sjmallett unsigned int p2; 961590Srgrimes 971590Srgrimes /* Make sure this this isn't called when a table already exists. */ 9810948Sdima if (htable != NULL) { 9910948Sdima errno = EINVAL; 10011339Sache return 0; 10142481Speter } 10242481Speter 10322558Sdanny /* If nel is too small, make it min sized. */ 10442481Speter if (nel < MIN_BUCKETS) 10510948Sdima nel = MIN_BUCKETS; 1061590Srgrimes 1071590Srgrimes /* If it's too large, cap it. */ 1089987Swollman if (nel > MAX_BUCKETS) 1091590Srgrimes nel = MAX_BUCKETS; 11032055Salex 1111590Srgrimes /* If it's is not a power of two in size, round up. */ 1129987Swollman if ((nel & (nel - 1)) != 0) { 1133138Sache for (p2 = 0; nel != 0; p2++) 1143138Sache nel >>= 1; 1151590Srgrimes nel = 1 << p2; 1161590Srgrimes } 11732055Salex 11822558Sdanny /* Allocate the table. */ 11942481Speter htablesize = nel; 1201590Srgrimes htable = malloc(htablesize * sizeof htable[0]); 121 if (htable == NULL) { 122 errno = ENOMEM; 123 return 0; 124 } 125 126 /* Initialize it. */ 127 for (idx = 0; idx < htablesize; idx++) 128 SLIST_INIT(&htable[idx]); 129 130 return 1; 131} 132 133void 134hdestroy(void) 135{ 136 struct internal_entry *ie; 137 size_t idx; 138 139 if (htable == NULL) 140 return; 141 142 for (idx = 0; idx < htablesize; idx++) { 143 while (!SLIST_EMPTY(&htable[idx])) { 144 ie = SLIST_FIRST(&htable[idx]); 145 SLIST_REMOVE_HEAD(&htable[idx], link); 146 free(ie->ent.key); 147 free(ie); 148 } 149 } 150 free(htable); 151 htable = NULL; 152} 153 154ENTRY * 155hsearch(ENTRY item, ACTION action) 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 = &htable[hashval & (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 return &ie->ent; 175 else if (action == FIND) 176 return NULL; 177 178 ie = malloc(sizeof *ie); 179 if (ie == NULL) 180 return NULL; 181 ie->ent.key = item.key; 182 ie->ent.data = item.data; 183 184 SLIST_INSERT_HEAD(head, ie, link); 185 return &ie->ent; 186} 187