WebSVN – HelenOS – Blame – /branches/dd/kernel/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
1702	cejka	29	/** @addtogroup genericadt
		30	* @{
		31	*/
		32
1248	jermar	33	/**
1704	cejka	34	* @file
1248	jermar	35	* @brief Implementation of generic chained hash table.
		36	*
		37	* This file contains implementation of generic chained hash table.
790	jermar	38	*/
		39
		40	#include <adt/hash_table.h>
		41	#include <adt/list.h>
		42	#include <typedefs.h>
		43	#include <arch/types.h>
		44	#include <debug.h>
814	palkovsky	45	#include <mm/slab.h>
790	jermar	46	#include <memstr.h>
		47
		48	/** Create chained hash table.
		49	*
		50	* @param h Hash table structure. Will be initialized by this call.
		51	* @param m Number of slots in the hash table.
		52	* @param max_keys Maximal number of keys needed to identify an item.
		53	* @param op Hash table operations structure.
		54	*/
		55	void hash_table_create(hash_table_t h, count_t m, count_t max_keys, hash_table_operations_t op)
		56	{
902	jermar	57	int i;
		58
790	jermar	59	ASSERT(h);
		60	ASSERT(op && op->hash && op->compare);
		61	ASSERT(max_keys > 0);
		62
1154	jermar	63	h->entry = malloc(m * sizeof(link_t), 0);
790	jermar	64	if (!h->entry) {
		65	panic("cannot allocate memory for hash table\n");
		66	}
1154	jermar	67	memsetb((__address) h->entry, m * sizeof(link_t), 0);
790	jermar	68
902	jermar	69	for (i = 0; i < m; i++)
		70	list_initialize(&h->entry[i]);
		71
790	jermar	72	h->entries = m;
		73	h->max_keys = max_keys;
		74	h->op = op;
		75	}
		76
		77	/** Insert item into hash table.
		78	*
		79	* @param h Hash table.
1708	jermar	80	* @param key Array of all keys necessary to compute hash index.
790	jermar	81	* @param item Item to be inserted into the hash table.
		82	*/
792	jermar	83	void hash_table_insert(hash_table_t h, __native key[], link_t item)
790	jermar	84	{
		85	index_t chain;
		86
		87	ASSERT(item);
		88	ASSERT(h && h->op && h->op->hash && h->op->compare);
		89
		90	chain = h->op->hash(key);
		91	ASSERT(chain < h->entries);
		92
		93	list_append(item, &h->entry[chain]);
		94	}
		95
		96	/** Search hash table for an item matching keys.
		97	*
		98	* @param h Hash table.
		99	* @param key Array of all keys needed to compute hash index.
		100	*
		101	* @return Matching item on success, NULL if there is no such item.
		102	*/
		103	link_t hash_table_find(hash_table_t h, __native key[])
		104	{
		105	link_t *cur;
		106	index_t chain;
		107
		108	ASSERT(h && h->op && h->op->hash && h->op->compare);
		109
		110	chain = h->op->hash(key);
		111	ASSERT(chain < h->entries);
		112
		113	for (cur = h->entry[chain].next; cur != &h->entry[chain]; cur = cur->next) {
		114	if (h->op->compare(key, h->max_keys, cur)) {
		115	/*
		116	* The entry is there.
		117	*/
		118	return cur;
		119	}
		120	}
		121
		122	return NULL;
		123	}
		124
		125	/** Remove all matching items from hash table.
		126	*
		127	* For each removed item, h->remove_callback() is called.
		128	*
		129	* @param h Hash table.
		130	* @param key Array of keys that will be compared against items of the hash table.
1248	jermar	131	* @param keys Number of keys in the key array.
790	jermar	132	*/
		133	void hash_table_remove(hash_table_t *h, __native key[], count_t keys)
		134	{
		135	index_t chain;
		136	link_t *cur;
		137
		138	ASSERT(h && h->op && h->op->hash && h->op->compare && h->op->remove_callback);
		139	ASSERT(keys <= h->max_keys);
		140
		141	if (keys == h->max_keys) {
		142
		143	/*
		144	* All keys are known, hash_table_find() can be used to find the entry.
		145	*/
		146
		147	cur = hash_table_find(h, key);
		148	if (cur) {
		149	list_remove(cur);
		150	h->op->remove_callback(cur);
		151	}
		152	return;
		153	}
		154
		155	/*
		156	* Fewer keys were passed.
		157	* Any partially matching entries are to be removed.
		158	*/
		159	for (chain = 0; chain < h->entries; chain++) {
		160	for (cur = h->entry[chain].next; cur != &h->entry[chain]; cur = cur->next) {
		161	if (h->op->compare(key, keys, cur)) {
		162	link_t *hlp;
		163
		164	hlp = cur;
		165	cur = cur->prev;
		166
		167	list_remove(hlp);
		168	h->op->remove_callback(hlp);
		169
		170	continue;
		171	}
		172	}
		173	}
		174	}
1702	cejka	175
		176	/** @}
		177	*/
		178

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