Add 'const' where appropriate to index handling functions
[git/git.git] / hash.h
CommitLineData
9027f53c
LT
1#ifndef HASH_H
2#define HASH_H
3
4/*
5 * These are some simple generic hash table helper functions.
6 * Not necessarily suitable for all users, but good for things
7 * where you want to just keep track of a list of things, and
8 * have a good hash to use on them.
9 *
10 * It keeps the hash table at roughly 50-75% free, so the memory
11 * cost of the hash table itself is roughly
12 *
13 * 3 * 2*sizeof(void *) * nr_of_objects
14 *
15 * bytes.
16 *
17 * FIXME: on 64-bit architectures, we waste memory. It would be
18 * good to have just 32-bit pointers, requiring a special allocator
19 * for hashed entries or something.
20 */
21struct hash_table_entry {
22 unsigned int hash;
23 void *ptr;
24};
25
26struct hash_table {
27 unsigned int size, nr;
28 struct hash_table_entry *array;
29};
30
d1f128b0 31extern void *lookup_hash(unsigned int hash, const struct hash_table *table);
9027f53c 32extern void **insert_hash(unsigned int hash, void *ptr, struct hash_table *table);
d1f128b0 33extern int for_each_hash(const struct hash_table *table, int (*fn)(void *));
9027f53c
LT
34extern void free_hash(struct hash_table *table);
35
36static inline void init_hash(struct hash_table *table)
37{
38 table->size = 0;
39 table->nr = 0;
40 table->array = NULL;
41}
42
43#endif