Merged in sandervrijders/ouroboros/be-pff (pull request #324)

lib, ipcpd: Add hashtable and PDU Forwarding Function

1 files changed, 188 insertions, 0 deletions

diff --git a/src/lib/hashtable.c b/src/lib/hashtable.c
new file mode 100644
index 00000000..cc73d6a0
--- /dev/null
+++ b/src/lib/hashtable.c
@@ -0,0 +1,188 @@
+/*
+ * Ouroboros - Copyright (C) 2016
+ *
+ * Hash table with separate chaining on collisions
+ *
+ *    Sander Vrijders <[email protected]>
+ *
+ * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <ouroboros/config.h>
+#include <ouroboros/hashtable.h>
+#include <ouroboros/list.h>
+#include <ouroboros/errno.h>
+
+#include <assert.h>
+
+struct htable_entry {
+        struct list_head next;
+        uint64_t         key;
+        void *           val;
+};
+
+struct htable {
+        struct list_head * buckets;
+        bool               hash_key;
+        uint64_t           buckets_size;
+};
+
+struct htable * htable_create(uint64_t buckets, bool hash_key)
+{
+        struct htable * tmp;
+        unsigned int i;
+
+        if (buckets == 0)
+                return NULL;
+
+        buckets--;
+        buckets |= buckets >> 1;
+        buckets |= buckets >> 2;
+        buckets |= buckets >> 4;
+        buckets |= buckets >> 8;
+        buckets |= buckets >> 16;
+        buckets |= buckets >> 32;
+        buckets++;
+
+        tmp = malloc(sizeof(*tmp));
+        if (tmp == NULL)
+                return NULL;
+
+        tmp->hash_key = hash_key;
+        tmp->buckets_size = buckets;
+
+        tmp->buckets = malloc(buckets * sizeof(*tmp->buckets));
+        if (tmp->buckets == NULL) {
+                free(tmp);
+                return NULL;
+        }
+
+        for (i = 0; i < buckets; i++)
+                INIT_LIST_HEAD(&(tmp->buckets[i]));
+
+        return tmp;
+}
+
+int htable_destroy(struct htable * table)
+{
+        unsigned int          i;
+        struct list_head *    pos = NULL;
+        struct list_head *    n = NULL;
+        struct htable_entry * entry;
+
+        assert(table);
+
+        for (i = 0; i < table->buckets_size; i++) {
+                list_for_each_safe(pos, n, &(table->buckets[i])) {
+                        entry = list_entry(pos, struct htable_entry, next);
+                        free(entry->val);
+                        free(entry);
+                }
+        }
+
+        free(table->buckets);
+        free(table);
+
+        return 0;
+}
+
+static uint64_t hash(uint64_t x)
+{
+        x = (x ^ (x >> 30)) * UINT64_C(0xbf58476d1ce4e5b9);
+        x = (x ^ (x >> 27)) * UINT64_C(0x94d049bb133111eb);
+        x = x ^ (x >> 31);
+
+        return x;
+}
+
+static uint64_t calc_key(struct htable * table, uint64_t key)
+{
+        if (table->hash_key == true)
+                key = hash(key);
+
+        return (key & (table->buckets_size - 1));
+}
+
+int htable_insert(struct htable * table, uint64_t key, void * val)
+{
+        struct htable_entry * entry;
+        uint64_t              lookup_key;
+        struct list_head *    pos = NULL;
+
+        assert(table);
+
+        lookup_key = calc_key(table, key);
+
+        list_for_each(pos, &(table->buckets[lookup_key])) {
+                entry = list_entry(pos, struct htable_entry, next);
+                if (entry->key == key)
+                        return -1;
+        }
+
+        entry = malloc(sizeof(*entry));
+        if (entry == NULL)
+                return -ENOMEM;
+
+        entry->key = key;
+        entry->val = val;
+        INIT_LIST_HEAD(&entry->next);
+
+        list_add(&entry->next, &(table->buckets[lookup_key]));
+
+        return 0;
+}
+
+void * htable_lookup(struct htable * table, uint64_t key)
+{
+        struct htable_entry * entry;
+        struct list_head *    pos = NULL;
+        uint64_t              lookup_key;
+
+        assert(table);
+
+        lookup_key = calc_key(table, key);
+
+        list_for_each(pos, &(table->buckets[lookup_key])) {
+                entry = list_entry(pos, struct htable_entry, next);
+                if (entry->key == key)
+                        return entry->val;
+        }
+
+        return NULL;
+}
+
+int htable_delete(struct htable * table, uint64_t key)
+{
+        struct htable_entry * entry;
+        uint64_t              lookup_key;
+        struct list_head *    pos = NULL;
+        struct list_head *    n = NULL;
+
+        assert(table);
+
+        lookup_key = calc_key(table, key);
+
+        list_for_each_safe(pos, n, &(table->buckets[lookup_key])) {
+                entry = list_entry(pos, struct htable_entry, next);
+                if (entry->key == key) {
+                        list_del(&entry->next);
+                        free(entry->val);
+                        free(entry);
+                        return 0;
+                }
+        }
+
+        return -1;
+}