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#ifndef HASHMAP_H
#define HASHMAP_H
/*
* Generic implementation of hash-based key-value mappings.
* See Documentation/technical/api-hashmap.txt.
*/
/* FNV-1 functions */
extern unsigned int strhash(const char *buf);
extern unsigned int strihash(const char *buf);
extern unsigned int memhash(const void *buf, size_t len);
extern unsigned int memihash(const void *buf, size_t len);
extern unsigned int memihash_cont(unsigned int hash_seed, const void *buf, size_t len);
static inline unsigned int sha1hash(const unsigned char *sha1)
{
/*
* Equivalent to 'return *(unsigned int *)sha1;', but safe on
* platforms that don't support unaligned reads.
*/
unsigned int hash;
memcpy(&hash, sha1, sizeof(hash));
return hash;
}
/* data structures */
struct hashmap_entry {
struct hashmap_entry *next;
unsigned int hash;
};
typedef int (*hashmap_cmp_fn)(const void *entry, const void *entry_or_key,
const void *keydata);
struct hashmap {
struct hashmap_entry **table;
hashmap_cmp_fn cmpfn;
unsigned int size, tablesize, grow_at, shrink_at;
unsigned disallow_rehash : 1;
};
struct hashmap_iter {
struct hashmap *map;
struct hashmap_entry *next;
unsigned int tablepos;
};
/* hashmap functions */
extern void hashmap_init(struct hashmap *map, hashmap_cmp_fn equals_function,
size_t initial_size);
extern void hashmap_free(struct hashmap *map, int free_entries);
/* hashmap_entry functions */
static inline void hashmap_entry_init(void *entry, unsigned int hash)
{
struct hashmap_entry *e = entry;
e->hash = hash;
e->next = NULL;
}
extern void *hashmap_get(const struct hashmap *map, const void *key,
const void *keydata);
extern void *hashmap_get_next(const struct hashmap *map, const void *entry);
extern void hashmap_add(struct hashmap *map, void *entry);
extern void *hashmap_put(struct hashmap *map, void *entry);
extern void *hashmap_remove(struct hashmap *map, const void *key,
const void *keydata);
static inline void *hashmap_get_from_hash(const struct hashmap *map,
unsigned int hash, const void *keydata)
{
struct hashmap_entry key;
hashmap_entry_init(&key, hash);
return hashmap_get(map, &key, keydata);
}
int hashmap_bucket(const struct hashmap *map, unsigned int hash);
/*
* Disallow/allow rehashing of the hashmap.
* This is useful if the caller knows that the hashmap
* needs multi-threaded access. The caller is still
* required to guard/lock searches and inserts in a
* manner appropriate to their usage. This simply
* prevents the table from being unexpectedly re-mapped.
*
* If is up to the caller to ensure that the hashmap is
* initialized to a reasonable size to prevent poor
* performance.
*
* When value=1, prevent future rehashes on adds and deleted.
* When value=0, allow future rehahses. This DOES NOT force
* a rehash now.
*/
static inline void hashmap_disallow_rehash(struct hashmap *map, unsigned value)
{
map->disallow_rehash = value;
}
/* hashmap_iter functions */
extern void hashmap_iter_init(struct hashmap *map, struct hashmap_iter *iter);
extern void *hashmap_iter_next(struct hashmap_iter *iter);
static inline void *hashmap_iter_first(struct hashmap *map,
struct hashmap_iter *iter)
{
hashmap_iter_init(map, iter);
return hashmap_iter_next(iter);
}
/* string interning */
extern const void *memintern(const void *data, size_t len);
static inline const char *strintern(const char *string)
{
return memintern(string, strlen(string));
}
#endif
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