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>
		38	#include <mm/heap.h>
		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	}

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