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