newlib/libc/search/hcreate_r.c

   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 #include <sys/cdefs.h>
  45 #if 0
  46 #if defined(LIBC_SCCS) && !defined(lint)
  47 __RCSID("$NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $");
  48 #endif /* LIBC_SCCS and not lint */
  49 #endif
  50
  51 #include <sys/types.h>
  52 #include <sys/queue.h>
  53 #include <errno.h>
  54 #include <search.h>
  55 #include <stdlib.h>
  56 #include <string.h>
  57
  58 /*
  59  * DO NOT MAKE THIS STRUCTURE LARGER THAN 32 BYTES (4 ptrs on 64-bit
  60  * ptr machine) without adjusting MAX_BUCKETS_LG2 below.
  61  */
  62 struct internal_entry {
  63         SLIST_ENTRY(internal_entry) link;
  64         ENTRY ent;
  65 };
  66 SLIST_HEAD(internal_head, internal_entry);
  67
  68 #define MIN_BUCKETS_LG2 4
  69 #define MIN_BUCKETS     (1 << MIN_BUCKETS_LG2)
  70
  71 /*
  72  * max * sizeof internal_entry must fit into size_t.
  73  * assumes internal_entry is <= 32 (2^5) bytes.
  74  */
  75 #ifdef __MSP430X_LARGE__
  76 /* 20-bit size_t.  */
  77 #define MAX_BUCKETS_LG2 (20 - 1 - 5)
  78 #else
  79 #define MAX_BUCKETS_LG2 (sizeof (size_t) * 8 - 1 - 5)
  80 #endif
  81 #define MAX_BUCKETS     ((size_t)1 << MAX_BUCKETS_LG2)
  82
  83 /* Default hash function, from db/hash/hash_func.c */
  84 extern __uint32_t (*__default_hash)(const void *, size_t);
  85
  86 int
  87 hcreate_r(size_t nel, struct hsearch_data *htab)
  88 {
  89         size_t idx;
  90         unsigned int p2;
  91
  92         /* Make sure this this isn't called when a table already exists. */
  93         if (htab->htable != NULL) {
  94                 errno = EINVAL;
  95                 return 0;
  96         }
  97
  98         /* If nel is too small, make it min sized. */
  99         if (nel < MIN_BUCKETS)
 100                 nel = MIN_BUCKETS;
 101
 102         /* If it's too large, cap it. */
 103         if (nel > MAX_BUCKETS)
 104                 nel = MAX_BUCKETS;
 105
 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++)
 109                         nel >>= 1;
 110                 nel = 1 << p2;
 111         }
 112
 113         /* Allocate the table. */
 114         htab->htablesize = nel;
 115         htab->htable = malloc(htab->htablesize * sizeof htab->htable[0]);
 116         if (htab->htable == NULL) {
 117                 errno = ENOMEM;
 118                 return 0;
 119         }
 120
 121         /* Initialize it. */
 122         for (idx = 0; idx < htab->htablesize; idx++)
 123                 SLIST_INIT(&(htab->htable[idx]));
 124
 125         return 1;
 126 }
 127
 128 void
 129 hdestroy_r(struct hsearch_data *htab)
 130 {
 131 #if 0
 132         struct internal_entry *ie;
 133         size_t idx;
 134 #endif
 135         if (htab->htable == NULL)
 136                 return;
 137
 138 #if 0
 139         for (idx = 0; idx < htab->htablesize; idx++) {
 140                 while (!SLIST_EMPTY(&(htab->htable[idx]))) {
 141                         ie = SLIST_FIRST(&(htab->htable[idx]));
 142                         SLIST_REMOVE_HEAD(&(htab->htable[idx]), link);
 143                         free(ie->ent.key);
 144                         free(ie);
 145                 }
 146         }
 147 #endif
 148         free(htab->htable);
 149         htab->htable = NULL;
 150 }
 151
 152 int
 153 hsearch_r(ENTRY item, ACTION action, ENTRY **retval, struct hsearch_data *htab)
 154 {
 155         struct internal_head *head;
 156         struct internal_entry *ie;
 157         __uint32_t hashval;
 158         size_t len;
 159
 160         len = strlen(item.key);
 161         hashval = (*__default_hash)(item.key, len);
 162
 163         head = &(htab->htable[hashval & (htab->htablesize - 1)]);
 164         ie = SLIST_FIRST(head);
 165         while (ie != NULL) {
 166                 if (strcmp(ie->ent.key, item.key) == 0)
 167                         break;
 168                 ie = SLIST_NEXT(ie, link);
 169         }
 170
 171         if (ie != NULL)
 172           {
 173             *retval = &ie->ent;
 174             return 1;
 175           }
 176         else if (action == FIND)
 177           {
 178             *retval = NULL;
 179             return 0;
 180           }
 181
 182         ie = malloc(sizeof *ie);
 183         if (ie == NULL)
 184           {
 185             *retval = NULL;
 186             return 0;
 187           }
 188         ie->ent.key = item.key;
 189         ie->ent.data = item.data;
 190
 191         SLIST_INSERT_HEAD(head, ie, link);
 192         *retval = &ie->ent;
 193         return 1;
 194 }