1 files changed, 108 insertions, 0 deletions
diff --git a/src/tag_pool.c b/src/tag_pool.c
new file mode 100644
index 000000000..744a82fdb
--- /dev/null
+++ b/src/tag_pool.c
@@ -0,0 +1,108 @@
+/* the Music Player Daemon (MPD)
+ * Copyright (C) 2008 Max Kellermann <max@duempel.org>
+ * This project's homepage is: http://www.musicpd.org
+ *
+ * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include "tag_pool.h"
+#include "utils.h"
+
+#define NUM_SLOTS 4096
+
+struct slot {
+	struct slot *next;
+	unsigned char ref;
+	struct tag_item item;
+} mpd_packed;
+
+struct slot *slots[NUM_SLOTS];
+
+static inline unsigned
+calc_hash_n(enum tag_type type, const char *p, size_t length)
+{
+	unsigned hash = 5381;
+
+	assert(p != NULL);
+
+	while (length-- > 0)
+		hash = (hash << 5) + hash + *p++;
+
+	return hash ^ type;
+}
+
+static inline unsigned
+calc_hash(enum tag_type type, const char *p)
+{
+	unsigned hash = 5381;
+
+	assert(p != NULL);
+
+	while (*p != 0)
+		hash = (hash << 5) + hash + *p++;
+
+	return hash ^ type;
+}
+
+static inline struct slot *
+tag_item_to_slot(struct tag_item *item)
+{
+	return (struct slot*)(((char*)item) - offsetof(struct slot, item));
+}
+
+struct tag_item *tag_pool_get_item(enum tag_type type,
+				   const char *value, int length)
+{
+	struct slot **slot_p, *slot;
+
+	slot_p = &slots[calc_hash_n(type, value, length) % NUM_SLOTS];
+	for (slot = *slot_p; slot != NULL; slot = slot->next) {
+		if (slot->item.type == type &&
+		    strcmp(value, slot->item.value) == 0 && slot->ref < 0xff) {
+			assert(slot->ref > 0);
+			++slot->ref;
+			return &slot->item;
+		}
+	}
+
+	slot = xmalloc(sizeof(*slot) + length);
+	slot->next = *slot_p;
+	slot->ref = 1;
+	slot->item.type = type;
+	memcpy(slot->item.value, value, length);
+	slot->item.value[length] = 0;
+	*slot_p = slot;
+	return &slot->item;
+}
+
+void tag_pool_put_item(struct tag_item *item)
+{
+	struct slot **slot_p, *slot;
+
+	slot = tag_item_to_slot(item);
+	assert(slot->ref > 0);
+	--slot->ref;
+
+	if (slot->ref > 0)
+		return;
+
+	for (slot_p = &slots[calc_hash(item->type, item->value) % NUM_SLOTS];
+	     *slot_p != slot;
+	     slot_p = &(*slot_p)->next) {
+		assert(*slot_p != NULL);
+	}
+
+	*slot_p = slot->next;
+	free(slot);
+}