X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=list.h;h=e4b5a1f67b066b73d2a89e0b2e9a7cd6eac00a66;hp=ba6211ba191395e40fd63d526ab9ddacc2b7f697;hb=11ef83c4abb2ccbdf3f99a8adf98749b2b0656c2;hpb=c79899fe6a1e8eb3086749f46c599d9790d99921;ds=sidebyside

diff --git a/list.h b/list.h
index ba6211ba..e4b5a1f6 100644
--- a/list.h
+++ b/list.h
@@ -9,6 +9,7 @@
 
 #include <stddef.h> /* offsetof */
 
+/** get the struct this entry is embedded in */
 #define container_of(ptr, type, member) ({                      \
 	const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 	(type *)( (char *)__mptr - offsetof(type,member) );})
@@ -24,22 +25,32 @@
  */
 #define LIST_POISON2  ((void *) 0x00200200)
 
-/**
- * Simple doubly linked list implementation.
- *
+/** Simple doubly linked list implementation. */
+struct list_head {
+	/** pointer to the next list entry */
+	struct list_head *next;
+	/** pointer to the previous list entry */
+	struct list_head *prev;
+};
+
+/** Define an initialized list head. */
+#define INITIALIZED_LIST_HEAD(name) struct list_head name = { &(name), &(name) }
+
+
+/** must be called before using any other list functions */
+#define INIT_LIST_HEAD(ptr) do { \
+	(ptr)->next = (ptr); (ptr)->prev = (ptr); \
+} while (0)
+
+
+/*
  * Some of the internal functions ("__xxx") are useful when
  * manipulating whole lists rather than single entries, as
  * sometimes we already know the next/prev entries and we can
  * generate better code by using them directly rather than
  * using the generic single-entry routines.
  */
-struct list_head {
-	struct list_head *next, *prev;
-};
 
-#define INIT_LIST_HEAD(ptr) do { \
-	(ptr)->next = (ptr); (ptr)->prev = (ptr); \
-} while (0)
 
 /*
  * Insert a new entry between two known consecutive entries.
@@ -193,3 +204,25 @@ static inline int list_empty(const struct list_head *head)
 		n = list_entry(pos->member.prev, typeof(*pos), member);	\
 	     &pos->member != (head); 					\
 	     pos = n, n = list_entry(n->member.prev, typeof(*n), member))
+
+/**
+ * Get the first element from a list
+ * \param ptr the list head to take the element from.
+ * \param type The type of the struct this is embedded in.
+ * \param member The name of the list_struct within the struct.
+ *
+ * Note that list is expected to be not empty.
+ */
+#define list_first_entry(ptr, type, member) \
+        list_entry((ptr)->next, type, member)
+
+/**
+ * Test whether a list has just one entry.
+ *
+ * \param head The list to test.
+ */
+static inline int list_is_singular(const struct list_head *head)
+{
+	return !list_empty(head) && (head->next == head->prev);
+}
+