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#include <hashtbl.h>
#include <kmalloc.h>
#include <string.h>
#define DEFAULT_INIT_SIZE 16
#define SLOT_OF_HASH(k, nslots) (((size_t)(k)*21179)%(size_t)(nslots))
typedef struct hashtbl_item {
void* key;
void* val;
struct hashtbl_item *next;
} hashtbl_item_t;
// When nitems > size * 3/4, size is multiplied by two
// When nitems < size * 1/4, size is divided by two
struct hashtbl {
key_eq_fun_t ef;
hash_fun_t hf;
size_t size, nitems;
hashtbl_item_t **items;
};
hashtbl_t *create_hashtbl(key_eq_fun_t ef, hash_fun_t hf, size_t initial_size) {
hashtbl_t *ht = (hashtbl_t*)kmalloc(sizeof(hashtbl_t));
if (ht == 0) return 0;
ht->ef = ef;
ht->hf = hf;
ht->size = (initial_size == 0 ? DEFAULT_INIT_SIZE : initial_size);
ht->nitems = 0;
ht->items = (hashtbl_item_t**)kmalloc(ht->size * sizeof(hashtbl_item_t*));
if (ht->items == 0) {
kfree(ht);
return 0;
}
for (size_t i = 0; i < ht->size; i++) ht->items[i] = 0;
return ht;
}
void delete_hashtbl(hashtbl_t *ht) {
// Free items
for (size_t i = 0; i < ht->size; i++) {
while (ht->items[i] != 0) {
hashtbl_item_t *n = ht->items[i]->next;
kfree(ht->items[i]);
ht->items[i] = n;
}
}
// Free table
kfree(ht->items);
kfree(ht);
}
static void hashtbl_check_size(hashtbl_t *ht) {
size_t nsize = 0;
if (4 * ht->nitems < ht->size) nsize = ht->size / 2;
if (4 * ht->nitems > 3 * ht->size) nsize = ht->size * 2;
if (nsize != 0) {
hashtbl_item_t **nitems = (hashtbl_item_t**)kmalloc(nsize * sizeof(hashtbl_item_t*));
if (nitems == 0) return; // if we can't realloc, too bad, we just lose space
for (size_t i = 0; i < nsize; i++) nitems[i] = 0;
// rehash
for (size_t i = 0; i < ht->size; i++) {
while (ht->items[i] != 0) {
hashtbl_item_t *x = ht->items[i];
ht->items[i] = x->next;
size_t slot = SLOT_OF_HASH(ht->hf(x->key), nsize);
x->next = nitems[slot];
nitems[slot] = x;
}
}
kfree(ht->items);
ht->size = nsize;
ht->items = nitems;
}
}
int hashtbl_add(hashtbl_t *ht, void* key, void* v) {
size_t slot = SLOT_OF_HASH(ht->hf(key), ht->size);
hashtbl_item_t *i = (hashtbl_item_t*)kmalloc(sizeof(hashtbl_item_t));
if (i == 0) return 1; // OOM
// make sure item is not already present
hashtbl_remove(ht, key);
i->key = key;
i->val = v;
i->next = ht->items[slot];
ht->items[slot] = i;
ht->nitems++;
hashtbl_check_size(ht);
return 0;
}
void* hashtbl_find(hashtbl_t* ht, void* key) {
size_t slot = SLOT_OF_HASH(ht->hf(key), ht->size);
for (hashtbl_item_t *i = ht->items[slot]; i != 0; i = i->next) {
if (ht->ef(i->key, key)) return i->val;
}
return 0;
}
void hashtbl_remove(hashtbl_t* ht, void* key) {
size_t slot = SLOT_OF_HASH(ht->hf(key), ht->size);
if (ht->items[slot] == 0) return;
if (ht->ef(ht->items[slot]->key, key)) {
hashtbl_item_t *x = ht->items[slot];
ht->items[slot] = x->next;
kfree(x);
ht->nitems--;
} else {
for (hashtbl_item_t *i = ht->items[slot]; i->next != 0; i = i->next) {
if (ht->ef(i->next->key, key)) {
hashtbl_item_t *x = i->next;
i->next = x->next;
kfree(x);
ht->nitems--;
break;
}
}
}
hashtbl_check_size(ht);
}
size_t hashtbl_count(hashtbl_t* ht) {
return ht->nitems;
}
hash_t id_hash_fun(const void* v) {
return (hash_t)v;
}
hash_t str_hash_fun(const void* v) {
hash_t h = 712;
for (char* s = (char*)v; *s != 0; s++) {
h = h * 101 + *s;
}
return h;
}
bool id_key_eq_fun(const void* a, const void* b) {
return a == b;
}
bool str_key_eq_fun(const void* a, const void* b) {
return strcmp((const char*)a, (const char*)b) == 0;
}
/* vim: set ts=4 sw=4 tw=0 noet :*/
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