summaryrefslogtreecommitdiff
path: root/lib/hash.c
blob: 6db79ea77a6ba7c9d1b27702c9d755e69c766830 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
/* Hash routine.
 * Copyright (C) 1998 Kunihiro Ishiguro
 *
 * This file is part of GNU Zebra.
 *
 * GNU Zebra is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2, or (at your
 * option) any later version.
 *
 * GNU Zebra is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU Zebra; see the file COPYING.  If not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <zebra.h>

#include "hash.h"
#include "memory.h"

/* Allocate a new hash.  */
struct hash *
hash_create_size (unsigned int size, unsigned int (*hash_key) (void *),
                                     int (*hash_cmp) (const void *, const void *))
{
  struct hash *hash;

  hash = XMALLOC (MTYPE_HASH, sizeof (struct hash));
  hash->index = XCALLOC (MTYPE_HASH_INDEX,
			 sizeof (struct hash_backet *) * size);
  hash->size = size;
  hash->hash_key = hash_key;
  hash->hash_cmp = hash_cmp;
  hash->count = 0;

  return hash;
}

/* Allocate a new hash with default hash size.  */
struct hash *
hash_create (unsigned int (*hash_key) (void *), 
             int (*hash_cmp) (const void *, const void *))
{
  return hash_create_size (HASHTABSIZE, hash_key, hash_cmp);
}

/* Utility function for hash_get().  When this function is specified
   as alloc_func, return arugment as it is.  This function is used for
   intern already allocated value.  */
void *
hash_alloc_intern (void *arg)
{
  return arg;
}

/* Lookup and return hash backet in hash.  If there is no
   corresponding hash backet and alloc_func is specified, create new
   hash backet.  */
void *
hash_get (struct hash *hash, void *data, void * (*alloc_func) (void *))
{
  unsigned int key;
  unsigned int index;
  void *newdata;
  struct hash_backet *backet;

  key = (*hash->hash_key) (data);
  index = key % hash->size;

  for (backet = hash->index[index]; backet != NULL; backet = backet->next) 
    if (backet->key == key && (*hash->hash_cmp) (backet->data, data))
      return backet->data;

  if (alloc_func)
    {
      newdata = (*alloc_func) (data);
      if (newdata == NULL)
	return NULL;

      backet = XMALLOC (MTYPE_HASH_BACKET, sizeof (struct hash_backet));
      backet->data = newdata;
      backet->key = key;
      backet->next = hash->index[index];
      hash->index[index] = backet;
      hash->count++;
      return backet->data;
    }
  return NULL;
}

/* Hash lookup.  */
void *
hash_lookup (struct hash *hash, void *data)
{
  return hash_get (hash, data, NULL);
}

/* Simple Bernstein hash which is simple and fast for common case */
unsigned int string_hash_make (const char *str)
{
  unsigned int hash = 0;

  while (*str)
    hash = (hash * 33) ^ (unsigned int) *str++;

  return hash;
}

/* This function release registered value from specified hash.  When
   release is successfully finished, return the data pointer in the
   hash backet.  */
void *
hash_release (struct hash *hash, void *data)
{
  void *ret;
  unsigned int key;
  unsigned int index;
  struct hash_backet *backet;
  struct hash_backet *pp;

  key = (*hash->hash_key) (data);
  index = key % hash->size;

  for (backet = pp = hash->index[index]; backet; backet = backet->next)
    {
      if (backet->key == key && (*hash->hash_cmp) (backet->data, data)) 
	{
	  if (backet == pp) 
	    hash->index[index] = backet->next;
	  else 
	    pp->next = backet->next;

	  ret = backet->data;
	  XFREE (MTYPE_HASH_BACKET, backet);
	  hash->count--;
	  return ret;
	}
      pp = backet;
    }
  return NULL;
}

/* Iterator function for hash.  */
void
hash_iterate (struct hash *hash, 
	      void (*func) (struct hash_backet *, void *), void *arg)
{
  unsigned int i;
  struct hash_backet *hb;
  struct hash_backet *hbnext;

  for (i = 0; i < hash->size; i++)
    for (hb = hash->index[i]; hb; hb = hbnext)
      {
	/* get pointer to next hash backet here, in case (*func)
	 * decides to delete hb by calling hash_release
	 */
	hbnext = hb->next;
	(*func) (hb, arg);
      }
}

/* Clean up hash.  */
void
hash_clean (struct hash *hash, void (*free_func) (void *))
{
  unsigned int i;
  struct hash_backet *hb;
  struct hash_backet *next;

  for (i = 0; i < hash->size; i++)
    {
      for (hb = hash->index[i]; hb; hb = next)
	{
	  next = hb->next;
	      
	  if (free_func)
	    (*free_func) (hb->data);

	  XFREE (MTYPE_HASH_BACKET, hb);
	  hash->count--;
	}
      hash->index[i] = NULL;
    }
}

/* Free hash memory.  You may call hash_clean before call this
   function.  */
void
hash_free (struct hash *hash)
{
  XFREE (MTYPE_HASH_INDEX, hash->index);
  XFREE (MTYPE_HASH, hash);
}