libaaruformat 1.0 Aaru Data Preservation Suite - Format Library

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hash_map.c
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1/*
2 * This file is part of the Aaru Data Preservation Suite.
3 * Copyright (c) 2019-2025 Natalia Portillo.
4 *
5 * This library is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU Lesser General Public License as
7 * published by the Free Software Foundation; either version 2.1 of the
8 * License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
17 */
18
19#include <stdbool.h>
20#include <stdint.h>
21#include <stdlib.h>
22
23#include "hash_map.h"
24
25#define INITIAL_SIZE 1024
26#define LOAD_FACTOR 0.75
27
49 hash_map_t *create_map(size_t size)
50{
51 hash_map_t *map = malloc(sizeof(hash_map_t));
52 map->table = calloc(size, sizeof(kv_pair_t));
53 map->size = size;
54 map->count = 0;
55
56 return map;
57}
58
73 void free_map(hash_map_t *map)
74{
75 free(map->table);
76 free(map);
77}
78
101 static void resize_map(hash_map_t *map, size_t new_size)
102{
103 kv_pair_t *old_table = map->table;
104 size_t old_size = map->size;
105
106 map->table = calloc(new_size, sizeof(kv_pair_t));
107 map->size = new_size;
108 map->count = 0;
109
110 for(size_t i = 0; i < old_size; i++)
111 if(old_table[i].key != 0)
112 {
113 // Re-insert
114 size_t idx = old_table[i].key % new_size;
115
116 while(map->table[idx].key != 0) idx = (idx + 1) % new_size;
117
118 map->table[idx] = old_table[i];
119 map->count++;
120 }
121
122 free(old_table);
123}
124
153 bool insert_map(hash_map_t *map, uint64_t key, uint64_t value)
154{
155 if((double)map->count / map->size > LOAD_FACTOR) resize_map(map, map->size * 2);
156
157 size_t idx = key % map->size;
158
159 while(map->table[idx].key != 0 && map->table[idx].key != key) idx = (idx + 1) % map->size;
160
161 if(map->table[idx].key == key) return false; // Already present
162
163 map->table[idx].key = key;
164 map->table[idx].value = value;
165 map->count++;
166
167 return true;
168}
169
196 bool lookup_map(const hash_map_t *map, uint64_t key, uint64_t *out_value)
197{
198 size_t idx = key % map->size;
199
200 while(map->table[idx].key != 0)
201 {
202 if(map->table[idx].key == key)
203 {
204 *out_value = map->table[idx].value;
205 return true;
206 }
207
208 idx = (idx + 1) % map->size;
209 }
210
211 return false;
212}
lookup_map
bool lookup_map(const hash_map_t *map, uint64_t key, uint64_t *out_value)
Looks up a value by key in the hash map.
Definition hash_map.c:196
create_map
hash_map_t * create_map(size_t size)
Creates a new hash map with the specified initial size.
Definition hash_map.c:49
insert_map
bool insert_map(hash_map_t *map, uint64_t key, uint64_t value)
Inserts a key-value pair into the hash map.
Definition hash_map.c:153
LOAD_FACTOR
#define LOAD_FACTOR
Definition hash_map.c:26
free_map
void free_map(hash_map_t *map)
Frees all memory associated with a hash map.
Definition hash_map.c:73
resize_map
static void resize_map(hash_map_t *map, size_t new_size)
Resizes the hash map to a new size and rehashes all entries.
Definition hash_map.c:101
hash_map.h
hash_map_t
Minimal open-addressing hash map for 64-bit key/value pairs used in deduplication lookup.
Definition hash_map.h:50
hash_map_t::count
size_t count
Number of active (filled) entries.
Definition hash_map.h:53
hash_map_t::size
size_t size
Allocated slot capacity of table.
Definition hash_map.h:52
hash_map_t::table
kv_pair_t * table
Array of key/value slots of length == size.
Definition hash_map.h:51
kv_pair_t
Single key/value slot used internally by the open-addressing hash map.
Definition hash_map.h:33
kv_pair_t::value
uint64_t value
Associated value payload (64-bit) stored alongside the key.
Definition hash_map.h:35
kv_pair_t::key
uint64_t key
Stored key (64-bit). May use a reserved sentinel to denote an empty slot.
Definition hash_map.h:34