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/*
DeaDBeeF - ultimate music player for GNU/Linux systems with X11
Copyright (C) 2009-2011 Alexey Yakovenko <waker@users.sourceforge.net>
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <string.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
typedef struct metacache_str_s {
struct metacache_str_s *next;
uint32_t refcount;
char cmpidx; // positive means "equals", negative means "notequals"
char str[1];
} metacache_str_t;
typedef struct {
// uint32_t hash;
metacache_str_t *chain;
} metacache_hash_t;
#define HASH_SIZE 4096
static metacache_hash_t hash[HASH_SIZE];
uint32_t
metacache_get_hash_sdbm (const char *str) {
uint32_t hash = 0;
int c;
while (c = *str++)
hash = c + (hash << 6) + (hash << 16) - hash;
return hash;
}
metacache_str_t *
metacache_find_in_bucket (uint32_t h, const char *str) {
metacache_hash_t *bucket = &hash[h];
metacache_str_t *chain = bucket->chain;
while (chain) {
if (!strcmp (chain->str, str)) {
return chain;
}
chain = chain->next;
}
return NULL;
}
static int n_strings = 0;
static int n_inserts = 0;
static int n_buckets = 0;
const char *
metacache_add_string (const char *str) {
// printf ("n_strings=%d, n_inserts=%d, n_buckets=%d\n", n_strings, n_inserts, n_buckets);
uint32_t h = metacache_get_hash_sdbm (str);
metacache_str_t *data = metacache_find_in_bucket (h % HASH_SIZE, str);
n_inserts++;
if (data) {
data->refcount++;
return data->str;
}
metacache_hash_t *bucket = &hash[h % HASH_SIZE];
if (!bucket->chain) {
n_buckets++;
}
size_t len = strlen (str);
data = malloc (sizeof (metacache_str_t) + len);
memset (data, 0, sizeof (metacache_str_t) + len);
data->refcount = 1;
memcpy (data->str, str, len+1);
data->next = bucket->chain;
bucket->chain = data;
n_strings++;
return data->str;
}
void
metacache_remove_string (const char *str) {
uint32_t h = metacache_get_hash_sdbm (str);
metacache_hash_t *bucket = &hash[h % HASH_SIZE];
metacache_str_t *chain = bucket->chain;
metacache_str_t *prev = NULL;
while (chain) {
if (!strcmp (chain->str, str)) {
chain->refcount--;
if (chain->refcount == 0) {
if (prev) {
prev->next = chain->next;
}
else {
bucket->chain = chain->next;
}
free (chain);
}
break;
}
prev = chain;
chain = chain->next;
}
}
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