src/mesa/shader/hash_table.c

   1 /*
   2  * Copyright © 2008 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 /**
  25  * \file hash_table.c
  26  * \brief Implementation of a generic, opaque hash table data type.
  27  *
  28  * \author Ian Romanick <ian.d.romanick@intel.com>
  29  */
  30 #include <stdlib.h>
  31 #include <string.h>
  32
  33 #include <assert.h>
  34
  35 #include "main/imports.h"
  36 #include "main/simple_list.h"
  37 #include "hash_table.h"
  38
  39 struct node {
  40    struct node *next;
  41    struct node *prev;
  42 };
  43
  44 struct hash_table {
  45     hash_func_t    hash;
  46     hash_compare_func_t  compare;
  47
  48     unsigned num_buckets;
  49     struct node buckets[1];
  50 };
  51
  52
  53 struct hash_node {
  54     struct node link;
  55     const void *key;
  56     void *data;
  57 };
  58
  59
  60 struct hash_table *
  61 hash_table_ctor(unsigned num_buckets, hash_func_t hash,
  62                 hash_compare_func_t compare)
  63 {
  64     struct hash_table *ht;
  65     unsigned i;
  66
  67
  68     if (num_buckets < 16) {
  69         num_buckets = 16;
  70     }
  71
  72     ht = _mesa_malloc(sizeof(*ht) + ((num_buckets - 1)
  73                                      * sizeof(ht->buckets[0])));
  74     if (ht != NULL) {
  75         ht->hash = hash;
  76         ht->compare = compare;
  77         ht->num_buckets = num_buckets;
  78
  79         for (i = 0; i < num_buckets; i++) {
  80             make_empty_list(& ht->buckets[i]);
  81         }
  82     }
  83
  84     return ht;
  85 }
  86
  87
  88 void
  89 hash_table_dtor(struct hash_table *ht)
  90 {
  91    hash_table_clear(ht);
  92    _mesa_free(ht);
  93 }
  94
  95
  96 void
  97 hash_table_clear(struct hash_table *ht)
  98 {
  99    struct node *node;
 100    struct node *temp;
 101    unsigned i;
 102
 103
 104    for (i = 0; i < ht->num_buckets; i++) {
 105       foreach_s(node, temp, & ht->buckets[i]) {
 106          remove_from_list(node);
 107          _mesa_free(node);
 108       }
 109
 110       assert(is_empty_list(& ht->buckets[i]));
 111    }
 112 }
 113
 114
 115 void *
 116 hash_table_find(struct hash_table *ht, const void *key)
 117 {
 118     const unsigned hash_value = (*ht->hash)(key);
 119     const unsigned bucket = hash_value % ht->num_buckets;
 120     struct node *node;
 121
 122     foreach(node, & ht->buckets[bucket]) {
 123        struct hash_node *hn = (struct hash_node *) node;
 124
 125        if ((*ht->compare)(hn->key, key) == 0) {
 126           return hn->data;
 127        }
 128     }
 129
 130     return NULL;
 131 }
 132
 133
 134 void
 135 hash_table_insert(struct hash_table *ht, void *data, const void *key)
 136 {
 137     const unsigned hash_value = (*ht->hash)(key);
 138     const unsigned bucket = hash_value % ht->num_buckets;
 139     struct hash_node *node;
 140
 141     node = _mesa_calloc(sizeof(*node));
 142
 143     node->data = data;
 144     node->key = key;
 145
 146     insert_at_head(& ht->buckets[bucket], & node->link);
 147 }
 148
 149
 150 unsigned
 151 hash_table_string_hash(const void *key)
 152 {
 153     const char *str = (const char *) key;
 154     unsigned hash = 5381;
 155
 156
 157     while (*str != '\0') {
 158         hash = (hash * 33) + *str;
 159         str++;
 160     }
 161
 162     return hash;
 163 }