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hash_table.c
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hash_table.c
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//
// Lightweight static hash table source file
//
#include "hash_table.h"
#include "misc.h"
/**
* Hash function : Robert Jenkins' 32 bit integer hash
*/
static UINT32 hash_function(UINT32 const key)
{
UINT32 hash = key;
hash = (hash + 0x7ed55d16) + (hash << 12);
hash = (hash ^ 0xc761c23c) ^ (hash >> 19);
hash = (hash + 0x165667b1) + (hash << 5);
hash = (hash + 0xd3a2646c) ^ (hash << 9);
hash = (hash + 0xfd7046c5) + (hash << 3);
hash = (hash ^ 0xb55a4f09) ^ (hash >> 16);
return hash;
}
void hash_table_init(hash_table* ht, UINT32 const capacity,
UINT8 node_size, /* user may use custom data structure
that includes hash_node */
UINT8* node_buffer, UINT32 const buffer_size,
hash_node** buckets, UINT32 const num_buckets)
{
BUG_ON("null pointer", ht == NULL ||
buckets == NULL ||
node_buffer == NULL);
BUG_ON("invalid argument", capacity <= 0 ||
capacity > num_buckets ||
capacity * node_size > buffer_size ||
node_size < sizeof(hash_node) );
ht->size = 0;
ht->capacity = capacity;
ht->node_size = node_size;
ht->buckets = buckets;
ht->num_buckets = num_buckets;
ht->node_buffer = node_buffer;
ht->buffer_size = buffer_size;
ht->free_nodes = NULL;
ht->last_used_node = NULL;
}
hash_node* hash_table_get_node(hash_table* ht, UINT32 const key)
{
hash_node* node;
UINT32 hash_val;
BUG_ON("null pointer", ht == NULL);
if (ht->last_used_node && ht->last_used_node->key == key)
return ht->last_used_node;
hash_val = hash_function(key) % ht->num_buckets;
node = ht->buckets[hash_val];
while (node) {
if (node->key == key) {
ht->last_used_node = node;
return node;
}
node = node->next;
}
return NULL;
}
BOOL32 hash_table_get(hash_table* ht, UINT32 const key, UINT32 *val)
{
hash_node* node = hash_table_get_node(ht, key);
if(!node) return 1;
*val = node->val;
return 0;
}
BOOL32 hash_table_insert(hash_table* ht, UINT32 const key, UINT32 const val)
{
hash_node* new_node;
UINT32 hash_val;
BUG_ON("null pointer", ht == NULL);
if (hash_table_is_full(ht))
return 1;
if (ht->free_nodes) {
new_node = ht->free_nodes;
ht->free_nodes = new_node->next;
new_node->next = NULL;
}
else {
new_node = (hash_node*)(& ht->node_buffer[ht->size * ht->node_size]);
}
new_node->key = key;
new_node->val = val;
hash_val = hash_function(key) % ht->num_buckets;
new_node->next = ht->buckets[hash_val];
ht->buckets[hash_val] = ht->last_used_node = new_node;
ht->size += 1;
return 0;
}
BOOL32 hash_table_update(hash_table* ht, UINT32 const key, UINT32 const newval)
{
hash_node* node = hash_table_get_node(ht, key);
if(!node) return 1;
node->val = newval;
return 0;
}
BOOL32 hash_table_remove(hash_table* ht, UINT32 const key)
{
hash_node *node, *pre_node = NULL;
UINT32 hash_val;
BUG_ON("null pointer", ht == NULL);
hash_val = hash_function(key) % ht->num_buckets;
node = ht->buckets[hash_val];
while (node) {
if (node->key == key) {
if (pre_node)
pre_node->next = node->next;
else
ht->buckets[hash_val] = node->next;
node->next = ht->free_nodes;
ht->free_nodes = node;
ht->size -= 1;
return 0;
}
pre_node = node;
node = node->next;
}
return 1;
}