Added new doubly-linked list implementation.

git-svn-id: file:///srv/svn/repos/haiku/trunk/current@2484 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/kernel/core/list.c

@@ -0,0 +1,172 @@
+/* 
+** Copyright 2003, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
+** Distributed under the terms of the OpenBeOS License.
+*/
+
+
+#include <list.h>
+
+
+#define GET_ITEM(list, item) ((void *)((uint8 *)item - list->offset))
+#define GET_LINK(list, item) ((list_link *)((uint8 *)item + list->offset))
+
+
+/** Initializes the list with a specified offset to the link
+ *	structure in the items that will be part of the list.
+ */
+
+void
+list_init_etc(struct list *list, int32 offset)
+{
+	list->link.next = list->link.prev = (list_link *)list;
+	list->offset = offset;
+}
+
+
+void
+list_init(struct list *list)
+{
+	list_init_etc(list, 0);
+}
+
+
+/** Adds a link to the head of the list
+ */
+
+void
+list_add_link_to_head(struct list *list, void *_link)
+{
+	list_link *link = (list_link *)_link;
+
+	link->next = list->link.next;
+	link->prev = (list_link *)list;
+	link->next->prev = link;
+
+	if (list->link.prev == (list_link *)list)
+		list->link.prev = link;
+	list->link.next = link;
+}
+
+
+/** Adds a link to the tail of the list
+ */
+
+void
+list_add_link_to_tail(struct list *list, void *_link)
+{
+	list_link *link = (list_link *)_link;
+
+	link->next = (list_link *)list;
+	link->prev = list->link.prev;
+
+	if (list->link.next == (list_link *)list)
+		list->link.next = link;
+	list->link.prev = link;
+}
+
+
+/** Removes a link from the list it's currently in.
+ *	Note: the link has to be in a list when you call this function.
+ */
+
+void
+list_remove_link(void *_link)
+{
+	list_link *link = (list_link *)_link;
+	
+	link->next->prev = link->prev;
+	link->prev->next = link->next;
+}
+
+
+static inline list_link *
+get_next_link(struct list *list, list_link *link)
+{
+	if (link->next == (list_link *)list)
+		return NULL;
+
+	return link->next;
+}
+
+
+static inline list_link *
+get_prev_link(struct list *list, list_link *link)
+{
+	if (link->prev == (list_link *)list)
+		return NULL;
+
+	return link->prev;
+}
+
+
+/** Gets the successor for the current item. If the passed
+ *	item is NULL, it returns the first entry in the list,
+ *	if there is one.
+ *	Returns NULL if there aren't any more items in this list.
+ */
+
+void *
+list_get_next_item(struct list *list, void *item)
+{
+	list_link *link;
+
+	if (item == NULL)
+		return list_is_empty(list) ? NULL : GET_ITEM(list, list->link.next);
+
+	link = get_next_link(list, GET_LINK(list, item));
+	return link != NULL ? GET_ITEM(list, link) : NULL;
+}
+
+
+/** Gets the predecessor for the current item. If the passed
+ *	item is NULL, it returns the last entry in the list,
+ *	if there is one.
+ *	Returns NULL if there aren't any previous items in this list.
+ */
+
+void *
+list_get_prev_item(struct list *list, void *item)
+{
+	list_link *link;
+
+	if (item == NULL)
+		return list_is_empty(list) ? NULL : GET_ITEM(list, list->link.prev);
+
+	link = get_prev_link(list, GET_LINK(list, item));
+	return link != NULL ? GET_ITEM(list, link) : NULL;
+}
+
+
+/** Removes the first item in the list and returns it.
+ *	Returns NULL if the list is empty.
+ */
+
+void *
+list_remove_head_item(struct list *list)
+{
+	list_link *link;
+
+	if (list_is_empty(list))
+		return NULL;
+
+	list_remove_link(link = list->link.next);
+	return GET_ITEM(list, link);
+}
+
+
+/** Removes the last item in the list and returns it.
+ *	Returns NULL if the list is empty.
+ */
+
+void *
+list_remove_tail_item(struct list *list)
+{
+	list_link *link;
+
+	if (list_is_empty(list))
+		return NULL;
+
+	list_remove_link(link = list->link.prev);
+	return GET_ITEM(list, link);
+}
+