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  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.  /** @addtogroup genericadt
  30.  * @{
  31.  */
  32.  
  33. /**
  34.  * @file    hash_table.c
  35.  * @brief   Implementation of generic chained hash table.
  36.  *
  37.  * This file contains implementation of generic chained hash table.
  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>
  45. #include <mm/slab.h>
  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. {
  57.     int i;
  58.  
  59.     ASSERT(h);
  60.     ASSERT(op && op->hash && op->compare);
  61.     ASSERT(max_keys > 0);
  62.    
  63.     h->entry = malloc(m * sizeof(link_t), 0);
  64.     if (!h->entry) {
  65.         panic("cannot allocate memory for hash table\n");
  66.     }
  67.     memsetb((__address) h->entry, m * sizeof(link_t), 0);
  68.    
  69.     for (i = 0; i < m; i++)
  70.         list_initialize(&h->entry[i]);
  71.    
  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.
  80.  * @param hey Array of all keys necessary to compute hash index.
  81.  * @param item Item to be inserted into the hash table.
  82.  */
  83. void hash_table_insert(hash_table_t *h, __native key[], link_t *item)
  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.
  131.  * @param keys Number of keys in the key array.
  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. }
  175.  
  176.  /** @}
  177.  */
  178.  
  179.