4 * This file is part of BeRTOS.
6 * Bertos is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 * As a special exception, you may use this file as part of a free software
21 * library without restriction. Specifically, if other files instantiate
22 * templates or use macros or inline functions from this file, or you compile
23 * this file and link it with other files to produce an executable, this
24 * file does not by itself cause the resulting executable to be covered by
25 * the GNU General Public License. This exception does not however
26 * invalidate any other reasons why the executable file might be covered by
27 * the GNU General Public License.
29 * Copyright 2004, 2006 Develer S.r.l. (http://www.develer.com/)
30 * Copyright 2004 Giovanni Bajo
31 * All Rights Reserved.
34 * \brief Portable hash table
36 * This file implements a portable hash table, with the following features:
38 * \li Open double-hashing. The maximum number of elements is fixed. The double hashing
39 * function improves recovery in case of collisions.
40 * \li Configurable size (which is clamped to a power of two)
41 * \li Visiting interface through iterator (returns the element in random order).
42 * \li The key is stored within the data and a hook is used to extract it. Optionally, it
43 * is possible to store a copy of the key within the hash table.
45 * Since the hashing is open, there is no way to remove elements from the table. Instead, a
46 * function is provided to clear the table completely.
48 * The data stored within the table must be a pointer. The NULL pointer is used as
49 * a marker for a free node, so it is invalid to store a NULL pointer in the table
50 * with \c ht_insert().
54 * \author Giovanni Bajo <rasky@develer.com>
59 *#* Revision 1.8 2006/07/19 12:56:27 bernie
60 *#* Convert to new Doxygen style.
62 *#* Revision 1.7 2006/06/01 12:27:39 marco
63 *#* Added utilities for protocols
67 #ifndef MWARE_HASHTABLE_H
68 #define MWARE_HASHTABLE_H
70 #include <cfg/compiler.h>
71 #include <cfg/macros.h>
72 #include <cfg/debug.h>
75 * Enable/disable support to declare special hash tables which maintain a copy of
76 * the key internally instead of relying on the hook to extract it from the data.
78 #define CONFIG_HT_OPTIONAL_INTERNAL_KEY 1
80 /// Maximum length of the internal key (use (2^n)-1 for slight speedup)
81 #define INTERNAL_KEY_MAX_LENGTH 15
84 * Hook to get the key from \a data, which is an element of the hash table. The
85 * key must be returned together with \a key_length (in words).
87 typedef const void *(*hook_get_key)(const void *data, uint8_t *key_length);
91 * Hash table description
93 * \note This structures MUST NOT be accessed directly. Its definition is
94 * provided in the header file only for optimization purposes (see the rationale
97 * \note If new elements must be added to this list, please double check
98 * \c DECLARE_HASHTABLE, which requires the existing elements to be at the top.
102 const void **mem; ///< Buckets of data
103 uint16_t max_elts_log2; ///< Log2 of the size of the table
105 bool key_internal : 1; ///< true if the key is copied internally
108 hook_get_key hook; ///< Hook to get the key
109 uint8_t *mem; ///< Pointer to the key memory
114 /// Iterator to walk the hash table
123 * Declare a hash table in the current scope
125 * \param name Variable name
126 * \param size Number of elements
127 * \param hook_gk Hook to be used to extract the key from the node
129 * \note The number of elements will be rounded down to the nearest
133 #define DECLARE_HASHTABLE(name, size, hook_gk) \
134 static const void* name##_nodes[1 << UINT32_LOG2(size)]; \
135 struct HashTable name = { name##_nodes, UINT32_LOG2(size), { false }, hook_gk }
137 /** Exactly like \c DECLARE_HASHTABLE, but the variable will be declared as static. */
138 #define DECLARE_HASHTABLE_STATIC(name, size, hook_gk) \
139 static const void* name##_nodes[1 << UINT32_LOG2(size)]; \
140 static struct HashTable name = { name##_nodes, UINT32_LOG2(size), { false }, { hook_gk } }
142 #if CONFIG_HT_OPTIONAL_INTERNAL_KEY
143 /** Declare a hash table with internal copies of the keys. This version does not
144 * require a hook, nor it requires the user to allocate static memory for the keys.
145 * It is mostly suggested for tables whose keys are computed on the fly and need
146 * to be stored somewhere.
148 #define DECLARE_HASHTABLE_INTERNALKEY(name, size) \
149 static uint8_t name##_keys[(1 << UINT32_LOG2(size)) * (INTERNAL_KEY_MAX_LENGTH + 1)]; \
150 static const void* name##_nodes[1 << UINT32_LOG2(size)]; \
151 struct HashTable name = { name##_nodes, UINT32_LOG2(size), { true }, name##_keys }
153 /** Exactly like \c DECLARE_HASHTABLE_INTERNALKEY, but the variable will be declared as static. */
154 #define DECLARE_HASHTABLE_INTERNALKEY_STATIC(name, size) \
155 static uint8_t name##_keys[(1 << UINT32_LOG2(size)) * (INTERNAL_KEY_MAX_LENGTH + 1)]; \
156 static const void* name##_nodes[1 << UINT32_LOG2(size)]; \
157 static struct HashTable name = { name##_nodes, UINT32_LOG2(size), { true }, name##_keys }
161 * Initialize (and clear) a hash table in a memory buffer.
163 * \param ht Hash table declared with \c DECLARE_HASHTABLE
165 * \note This function must be called before using the hash table. Optionally,
166 * it can be called later in the program to clear the hash table,
167 * removing all its elements.
169 void ht_init(struct HashTable* ht);
172 * Insert an element into the hash table
174 * \param ht Handle of the hash table
175 * \param data Data to be inserted into the table
176 * \return true if insertion was successful, false otherwise (table is full)
178 * \note The key for the element to insert is extract from the data with
179 * the hook. This means that this function cannot be called for hashtables
180 * with internal keys.
182 * \note If an element with the same key already exists in the table,
183 * it will be overwritten.
185 * \note It is not allowed to store NULL in the table. If you pass NULL as data,
186 * the function call will fail.
188 bool ht_insert(struct HashTable* ht, const void* data);
191 * Insert an element into the hash table
193 * \param ht Handle of the hash table
194 * \param key Key of the element
195 * \param key_length Length of the key in characters
196 * \param data Data to be inserted into the table
197 * \return true if insertion was successful, false otherwise (table is full)
199 * \note If this function is called for hash table with external keys,
200 * the key provided must be match the key that would be extracted with the
201 * hook, otherwise the function will fail.
203 * \note If an element with the same key already exists in the table,
204 * it will be overwritten.
206 * \note It is not allowed to store NULL in the table. If you pass NULL as data,
207 * the function call will fail.
209 bool ht_insert_with_key(struct HashTable* ht, const void* key, uint8_t key_length, const void* data);
212 * Find an element in the hash table
214 * \param ht Handle of the hash table
215 * \param key Key of the element
216 * \param key_length Length of the key in characters
217 * \return Data of the element, or NULL if no element was found for the given key.
219 const void* ht_find(struct HashTable* ht, const void* key, uint8_t key_length);
221 /** Similar to \c ht_insert_with_key() but \a key is an ASCIIZ string */
222 #define ht_insert_str(ht, key, data) ht_insert_with_key(ht, key, strlen(key), data)
224 /** Similar to \c ht_find() but \a key is an ASCIIZ string */
225 #define ht_find_str(ht, key) ht_find(ht, key, strlen(key))
227 /// Get an iterator to the begin of the hash table \a ht
228 INLINE HashIterator ht_iter_begin(struct HashTable* ht)
233 h.end = &ht->mem[1 << ht->max_elts_log2];
235 while (h.pos != h.end && !*h.pos)
242 * Get an iterator to the (exclusive) end of the hash table \a ht
244 * \note Like in STL, the end iterator is not a valid iterator (you
245 * cannot call \c ht_iter_get() on it), and it must be used only to
246 * detect if we reached the end of the iteration (through \c ht_iter_cmp()).
248 INLINE HashIterator ht_iter_end(struct HashTable* ht)
252 h.pos = h.end = &ht->mem[1 << ht->max_elts_log2];
257 /// Compare \a it1 and \a it2 for equality
258 INLINE bool ht_iter_cmp(HashIterator it1, HashIterator it2)
260 ASSERT(it1.end == it2.end);
261 return it1.pos == it2.pos;
264 /// Get the element within the hash table \a ht pointed by the iterator \a iter
265 INLINE const void* ht_iter_get(HashIterator iter)
266 { return *iter.pos; }
268 /** Return an iterator pointing to the element following \a h
270 * \note The order of the elements visited during the iteration is casual,
271 * and depends on the implementation.
274 INLINE HashIterator ht_iter_next(HashIterator h)
277 while (h.pos != h.end && !(*h.pos))
283 #endif /* MWARE_HASHTABLE_H */