WebSVN – HelenOS-historic – Blame – /kernel/trunk/generic/src/adt/hash_table.c

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	{
902	jermar	50	int i;
		51
790	jermar	52	ASSERT(h);
		53	ASSERT(op && op->hash && op->compare);
		54	ASSERT(max_keys > 0);
		55
822	palkovsky	56	h->entry = malloc(m * sizeof(link_t *), 0);
790	jermar	57	if (!h->entry) {
		58	panic("cannot allocate memory for hash table\n");
		59	}
		60	memsetb((__address) h->entry, m * sizeof(link_t *), 0);
		61
902	jermar	62	for (i = 0; i < m; i++)
		63	list_initialize(&h->entry[i]);
		64
790	jermar	65	h->entries = m;
		66	h->max_keys = max_keys;
		67	h->op = op;
		68	}
		69
		70	/** Insert item into hash table.
		71	*
		72	* @param h Hash table.
		73	* @param hey Array of all keys necessary to compute hash index.
		74	* @param item Item to be inserted into the hash table.
		75	*/
792	jermar	76	void hash_table_insert(hash_table_t h, __native key[], link_t item)
790	jermar	77	{
		78	index_t chain;
		79
		80	ASSERT(item);
		81	ASSERT(h && h->op && h->op->hash && h->op->compare);
		82
		83	chain = h->op->hash(key);
		84	ASSERT(chain < h->entries);
		85
		86	list_append(item, &h->entry[chain]);
		87	}
		88
		89	/** Search hash table for an item matching keys.
		90	*
		91	* @param h Hash table.
		92	* @param key Array of all keys needed to compute hash index.
		93	*
		94	* @return Matching item on success, NULL if there is no such item.
		95	*/
		96	link_t hash_table_find(hash_table_t h, __native key[])
		97	{
		98	link_t *cur;
		99	index_t chain;
		100
		101	ASSERT(h && h->op && h->op->hash && h->op->compare);
		102
		103	chain = h->op->hash(key);
		104	ASSERT(chain < h->entries);
		105
		106	/*
		107	* The hash table is not redundant.
		108	* Check if the keys are not in place already.
		109	*/
		110	for (cur = h->entry[chain].next; cur != &h->entry[chain]; cur = cur->next) {
		111	if (h->op->compare(key, h->max_keys, cur)) {
		112	/*
		113	* The entry is there.
		114	*/
		115	return cur;
		116	}
		117	}
		118
		119	return NULL;
		120	}
		121
		122	/** Remove all matching items from hash table.
		123	*
		124	* For each removed item, h->remove_callback() is called.
		125	*
		126	* @param h Hash table.
		127	* @param key Array of keys that will be compared against items of the hash table.
		128	* @param keys Number of keys in the 'key' array.
		129	*/
		130	void hash_table_remove(hash_table_t *h, __native key[], count_t keys)
		131	{
		132	index_t chain;
		133	link_t *cur;
		134
		135	ASSERT(h && h->op && h->op->hash && h->op->compare && h->op->remove_callback);
		136	ASSERT(keys <= h->max_keys);
		137
		138	if (keys == h->max_keys) {
		139
		140	/*
		141	* All keys are known, hash_table_find() can be used to find the entry.
		142	*/
		143
		144	cur = hash_table_find(h, key);
		145	if (cur) {
		146	list_remove(cur);
		147	h->op->remove_callback(cur);
		148	}
		149	return;
		150	}
		151
		152	/*
		153	* Fewer keys were passed.
		154	* Any partially matching entries are to be removed.
		155	*/
		156	for (chain = 0; chain < h->entries; chain++) {
		157	for (cur = h->entry[chain].next; cur != &h->entry[chain]; cur = cur->next) {
		158	if (h->op->compare(key, keys, cur)) {
		159	link_t *hlp;
		160
		161	hlp = cur;
		162	cur = cur->prev;
		163
		164	list_remove(hlp);
		165	h->op->remove_callback(hlp);
		166
		167	continue;
		168	}
		169	}
		170	}
		171	}

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(root)/kernel/trunk/generic/src/adt/hash_table.c – Rev 905