Subversion Repositories HelenOS

Rev

Rev 792 | Rev 822 | Go to most recent revision | Details | Compare with Previous | Last modification | View Log | RSS feed

Rev Author Line No. Line
790 jermar 1
/*
2
 * Copyright (C) 2006 Jakub Jermar
3
 * All rights reserved.
4
 *
5
 * Redistribution and use in source and binary forms, with or without
6
 * modification, are permitted provided that the following conditions
7
 * are met:
8
 *
9
 * - Redistributions of source code must retain the above copyright
10
 *   notice, this list of conditions and the following disclaimer.
11
 * - Redistributions in binary form must reproduce the above copyright
12
 *   notice, this list of conditions and the following disclaimer in the
13
 *   documentation and/or other materials provided with the distribution.
14
 * - The name of the author may not be used to endorse or promote products
15
 *   derived from this software without specific prior written permission.
16
 *
17
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27
 */
28
 
29
/*
30
 * This is an implementation of generic chained hash table.
31
 */
32
 
33
#include <adt/hash_table.h>
34
#include <adt/list.h>
35
#include <typedefs.h>
36
#include <arch/types.h>
37
#include <debug.h>
814 palkovsky 38
#include <mm/slab.h>
790 jermar 39
#include <memstr.h>
40
 
41
/** Create chained hash table.
42
 *
43
 * @param h Hash table structure. Will be initialized by this call.
44
 * @param m Number of slots in the hash table.
45
 * @param max_keys Maximal number of keys needed to identify an item.
46
 * @param op Hash table operations structure.
47
 */
48
void hash_table_create(hash_table_t *h, count_t m, count_t max_keys, hash_table_operations_t *op)
49
{
50
    ASSERT(h);
51
    ASSERT(op && op->hash && op->compare);
52
    ASSERT(max_keys > 0);
53
 
54
    h->entry = malloc(m * sizeof(link_t *));
55
    if (!h->entry) {
56
        panic("cannot allocate memory for hash table\n");
57
    }
58
    memsetb((__address) h->entry, m * sizeof(link_t *), 0);
59
 
60
    h->entries = m;
61
    h->max_keys = max_keys;
62
    h->op = op;
63
}
64
 
65
/** Insert item into hash table.
66
 *
67
 * @param h Hash table.
68
 * @param hey Array of all keys necessary to compute hash index.
69
 * @param item Item to be inserted into the hash table.
70
 */
792 jermar 71
void hash_table_insert(hash_table_t *h, __native key[], link_t *item)
790 jermar 72
{
73
    index_t chain;
74
 
75
    ASSERT(item);
76
    ASSERT(h && h->op && h->op->hash && h->op->compare);
77
 
78
    chain = h->op->hash(key);
79
    ASSERT(chain < h->entries);
80
 
81
    list_append(item, &h->entry[chain]);
82
}
83
 
84
/** Search hash table for an item matching keys.
85
 *
86
 * @param h Hash table.
87
 * @param key Array of all keys needed to compute hash index.
88
 *
89
 * @return Matching item on success, NULL if there is no such item.
90
 */
91
link_t *hash_table_find(hash_table_t *h, __native key[])
92
{
93
    link_t *cur;
94
    index_t chain;
95
 
96
    ASSERT(h && h->op && h->op->hash && h->op->compare);
97
 
98
    chain = h->op->hash(key);
99
    ASSERT(chain < h->entries);
100
 
101
    /*
102
     * The hash table is not redundant.
103
     * Check if the keys are not in place already.
104
     */
105
    for (cur = h->entry[chain].next; cur != &h->entry[chain]; cur = cur->next) {
106
        if (h->op->compare(key, h->max_keys, cur)) {
107
            /*
108
             * The entry is there.
109
             */
110
            return cur;
111
        }
112
    }
113
 
114
    return NULL;
115
}
116
 
117
/** Remove all matching items from hash table.
118
 *
119
 * For each removed item, h->remove_callback() is called.
120
 *
121
 * @param h Hash table.
122
 * @param key Array of keys that will be compared against items of the hash table.
123
 * @param keys Number of keys in the 'key' array.
124
 */
125
void hash_table_remove(hash_table_t *h, __native key[], count_t keys)
126
{
127
    index_t chain;
128
    link_t *cur;
129
 
130
    ASSERT(h && h->op && h->op->hash && h->op->compare && h->op->remove_callback);
131
    ASSERT(keys <= h->max_keys);
132
 
133
    if (keys == h->max_keys) {
134
 
135
        /*
136
         * All keys are known, hash_table_find() can be used to find the entry.
137
         */
138
 
139
        cur = hash_table_find(h, key);
140
        if (cur) {
141
            list_remove(cur);
142
            h->op->remove_callback(cur);
143
        }
144
        return;
145
    }
146
 
147
    /*
148
     * Fewer keys were passed.
149
     * Any partially matching entries are to be removed.
150
     */
151
    for (chain = 0; chain < h->entries; chain++) {
152
        for (cur = h->entry[chain].next; cur != &h->entry[chain]; cur = cur->next) {
153
            if (h->op->compare(key, keys, cur)) {
154
                link_t *hlp;
155
 
156
                hlp = cur;
157
                cur = cur->prev;
158
 
159
                list_remove(hlp);
160
                h->op->remove_callback(hlp);
161
 
162
                continue;
163
            }
164
        }
165
    }
166
}