1 files changed, 176 insertions, 0 deletions
diff --git a/net/batman-adv/hash.h b/net/batman-adv/hash.h
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+/*
+ * Copyright (C) 2006-2010 B.A.T.M.A.N. contributors:
+ *
+ * Simon Wunderlich, Marek Lindner
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * 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
+ *
+ */
+
+#ifndef _NET_BATMAN_ADV_HASH_H_
+#define _NET_BATMAN_ADV_HASH_H_
+
+#include <linux/list.h>
+
+/* callback to a compare function.  should
+ * compare 2 element datas for their keys,
+ * return 0 if same and not 0 if not
+ * same */
+typedef int (*hashdata_compare_cb)(void *, void *);
+
+/* the hashfunction, should return an index
+ * based on the key in the data of the first
+ * argument and the size the second */
+typedef int (*hashdata_choose_cb)(void *, int);
+typedef void (*hashdata_free_cb)(void *, void *);
+
+struct element_t {
+	void *data;		/* pointer to the data */
+	struct hlist_node hlist;	/* bucket list pointer */
+};
+
+struct hashtable_t {
+	struct hlist_head *table;   /* the hashtable itself, with the buckets */
+	int size;		    /* size of hashtable */
+};
+
+/* allocates and clears the hash */
+struct hashtable_t *hash_new(int size);
+
+/* remove element if you already found the element you want to delete and don't
+ * need the overhead to find it again with hash_remove().  But usually, you
+ * don't want to use this function, as it fiddles with hash-internals. */
+void *hash_remove_element(struct hashtable_t *hash, struct element_t *elem);
+
+/* free only the hashtable and the hash itself. */
+void hash_destroy(struct hashtable_t *hash);
+
+/* remove the hash structure. if hashdata_free_cb != NULL, this function will be
+ * called to remove the elements inside of the hash.  if you don't remove the
+ * elements, memory might be leaked. */
+static inline void hash_delete(struct hashtable_t *hash,
+			       hashdata_free_cb free_cb, void *arg)
+{
+	struct hlist_head *head;
+	struct hlist_node *walk, *safe;
+	struct element_t *bucket;
+	int i;
+
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+
+		hlist_for_each_safe(walk, safe, head) {
+			bucket = hlist_entry(walk, struct element_t, hlist);
+			if (free_cb)
+				free_cb(bucket->data, arg);
+
+			hlist_del(walk);
+			kfree(bucket);
+		}
+	}
+
+	hash_destroy(hash);
+}
+
+/* adds data to the hashtable. returns 0 on success, -1 on error */
+static inline int hash_add(struct hashtable_t *hash,
+			   hashdata_compare_cb compare,
+			   hashdata_choose_cb choose, void *data)
+{
+	int index;
+	struct hlist_head *head;
+	struct hlist_node *walk, *safe;
+	struct element_t *bucket;
+
+	if (!hash)
+		return -1;
+
+	index = choose(data, hash->size);
+	head = &hash->table[index];
+
+	hlist_for_each_safe(walk, safe, head) {
+		bucket = hlist_entry(walk, struct element_t, hlist);
+		if (compare(bucket->data, data))
+			return -1;
+	}
+
+	/* no duplicate found in list, add new element */
+	bucket = kmalloc(sizeof(struct element_t), GFP_ATOMIC);
+
+	if (!bucket)
+		return -1;
+
+	bucket->data = data;
+	hlist_add_head(&bucket->hlist, head);
+
+	return 0;
+}
+
+/* removes data from hash, if found. returns pointer do data on success, so you
+ * can remove the used structure yourself, or NULL on error .  data could be the
+ * structure you use with just the key filled, we just need the key for
+ * comparing. */
+static inline void *hash_remove(struct hashtable_t *hash,
+				hashdata_compare_cb compare,
+				hashdata_choose_cb choose, void *data)
+{
+	size_t index;
+	struct hlist_node *walk;
+	struct element_t *bucket;
+	struct hlist_head *head;
+	void *data_save;
+
+	index = choose(data, hash->size);
+	head = &hash->table[index];
+
+	hlist_for_each_entry(bucket, walk, head, hlist) {
+		if (compare(bucket->data, data)) {
+			data_save = bucket->data;
+			hlist_del(walk);
+			kfree(bucket);
+			return data_save;
+		}
+	}
+
+	return NULL;
+}
+
+/* finds data, based on the key in keydata. returns the found data on success,
+ * or NULL on error */
+static inline void *hash_find(struct hashtable_t *hash,
+			      hashdata_compare_cb compare,
+			      hashdata_choose_cb choose, void *keydata)
+{
+	int index;
+	struct hlist_head *head;
+	struct hlist_node *walk;
+	struct element_t *bucket;
+
+	if (!hash)
+		return NULL;
+
+	index = choose(keydata , hash->size);
+	head = &hash->table[index];
+
+	hlist_for_each(walk, head) {
+		bucket = hlist_entry(walk, struct element_t, hlist);
+		if (compare(bucket->data, keydata))
+			return bucket->data;
+	}
+
+	return NULL;
+}
+
+#endif /* _NET_BATMAN_ADV_HASH_H_ */