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/*
* hashtbl.c
*
* Efficient dictionary hash table class.
*/
#include "compiler.h"
#include <inttypes.h>
#include <string.h>
#include "nasm.h"
#include "hashtbl.h"
#define HASH_INITIAL_SIZE 64
#define HASH_MAX_LOAD 2 /* Higher = more memory-efficient, slower */
static struct hash_tbl_node *alloc_table(size_t newsize)
{
size_t bytes = newsize*sizeof(struct hash_tbl_node);
struct hash_tbl_node *newtbl = nasm_zalloc(bytes);
return newtbl;
}
struct hash_table *hash_init(void)
{
struct hash_table *head = nasm_malloc(sizeof(struct hash_table));
head->table = alloc_table(HASH_INITIAL_SIZE);
head->load = 0;
head->size = HASH_INITIAL_SIZE;
head->max_load = HASH_INITIAL_SIZE*(HASH_MAX_LOAD-1)/HASH_MAX_LOAD;
return head;
}
/*
* Find an entry in a hash table.
*
* On failure, if "insert" is non-NULL, store data in that structure
* which can be used to insert that node using hash_add().
*
* WARNING: this data is only valid until the very next call of
* hash_add(); it cannot be "saved" to a later date.
*
* On success, return a pointer to the "data" element of the hash
* structure.
*/
void **hash_find(struct hash_table *head, const char *key,
struct hash_insert *insert)
{
struct hash_tbl_node *np;
uint64_t hash = crc64(CRC64_INIT, key);
struct hash_tbl_node *tbl = head->table;
size_t mask = head->size-1;
size_t pos = hash & mask;
size_t inc = ((hash >> 32) & mask) | 1; /* Always odd */
while ((np = &tbl[pos])->key) {
if (hash == np->hash && !strcmp(key, np->key))
return &np->data;
pos = (pos+inc) & mask;
}
/* Not found. Store info for insert if requested. */
if (insert) {
insert->head = head;
insert->hash = hash;
insert->where = np;
}
return NULL;
}
/*
* Same as hash_find, but for case-insensitive hashing.
*/
void **hash_findi(struct hash_table *head, const char *key,
struct hash_insert *insert)
{
struct hash_tbl_node *np;
uint64_t hash = crc64i(CRC64_INIT, key);
struct hash_tbl_node *tbl = head->table;
size_t mask = head->size-1;
size_t pos = hash & mask;
size_t inc = ((hash >> 32) & mask) | 1; /* Always odd */
while ((np = &tbl[pos])->key) {
if (hash == np->hash && !nasm_stricmp(key, np->key))
return &np->data;
pos = (pos+inc) & mask;
}
/* Not found. Store info for insert if requested. */
if (insert) {
insert->head = head;
insert->hash = hash;
insert->where = np;
}
return NULL;
}
/*
* Insert node. Return a pointer to the "data" element of the newly
* created hash node.
*/
void **hash_add(struct hash_insert *insert, const char *key, void *data)
{
struct hash_table *head = insert->head;
struct hash_tbl_node *np = insert->where;
/* Insert node. We can always do this, even if we need to
rebalance immediately after. */
np->hash = insert->hash;
np->key = key;
np->data = data;
if (++head->load > head->max_load) {
/* Need to expand the table */
size_t newsize = head->size << 1;
struct hash_tbl_node *newtbl = alloc_table(newsize);
size_t mask = newsize-1;
if (head->table) {
struct hash_tbl_node *op, *xp;
size_t i;
/* Rebalance all the entries */
for (i = 0, op = head->table; i < head->size; i++, op++) {
if (op->key) {
size_t pos = op->hash & mask;
size_t inc = ((op->hash >> 32) & mask) | 1;
while ((xp = &newtbl[pos])->key)
pos = (pos+inc) & mask;
*xp = *op;
if (op == np)
np = xp;
}
}
nasm_free(head->table);
}
head->table = newtbl;
head->size = newsize;
head->max_load = newsize*(HASH_MAX_LOAD-1)/HASH_MAX_LOAD;
}
return &np->data;
}
/*
* Iterate over all members of a hash set. For the first call,
* iterator should be initialized to NULL. Returns the data pointer,
* or NULL on failure.
*/
void *hash_iterate(const struct hash_table *head,
struct hash_tbl_node **iterator,
const char **key)
{
struct hash_tbl_node *np = *iterator;
struct hash_tbl_node *ep = head->table + head->size;
if (!np)
np = head->table;
while (np < ep) {
if (np->key) {
*iterator = np+1;
if (key)
*key = np->key;
return np->data;
}
np++;
}
*iterator = NULL;
if (key)
*key = NULL;
return NULL;
}
/*
* Free the hash itself. Doesn't free the data elements; use
* hash_iterate() to do that first, if needed.
*/
void hash_free(struct hash_table *head)
{
nasm_free(head->table);
nasm_free(head);
}
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