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#ifndef HASH_H
#define HASH_H
/*
* These are some simple generic hash table helper functions.
* Not necessarily suitable for all users, but good for things
* where you want to just keep track of a list of things, and
* have a good hash to use on them.
*
* It keeps the hash table at roughly 50-75% free, so the memory
* cost of the hash table itself is roughly
*
* 3 * 2*sizeof(void *) * nr_of_objects
*
* bytes.
*
* FIXME: on 64-bit architectures, we waste memory. It would be
* good to have just 32-bit pointers, requiring a special allocator
* for hashed entries or something.
*/
struct hash_table_entry {
unsigned int hash;
void *ptr;
};
struct hash_table {
unsigned int size, nr;
struct hash_table_entry *array;
};
extern void *lookup_hash(unsigned int hash, const struct hash_table *table);
extern void **insert_hash(unsigned int hash, void *ptr, struct hash_table *table);
extern int for_each_hash(const struct hash_table *table, int (*fn)(void *, void *), void *data);
extern void free_hash(struct hash_table *table);
static inline void init_hash(struct hash_table *table)
{
table->size = 0;
table->nr = 0;
table->array = NULL;
}
static inline void preallocate_hash(struct hash_table *table, unsigned int elts)
{
assert(table->size == 0 && table->nr == 0 && table->array == NULL);
table->size = elts * 2;
table->array = xcalloc(sizeof(struct hash_table_entry), table->size);
}
#endif
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