#include <stddef.h>
#include <assert.h>
-/*
- * Simple doubly linked list implementation.
- *
- * 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.
- */
-
+/** A doubly-linked list entry (or list head) */
struct list_head {
+ /** Next list entry */
struct list_head *next;
+ /** Previous list entry */
struct list_head *prev;
};
-#define LIST_HEAD_INIT( name ) { &(name), &(name) }
+/**
+ * Initialise a static list head
+ *
+ * @v list List head
+ */
+#define LIST_HEAD_INIT( list ) { &(list), &(list) }
-#define LIST_HEAD( name ) \
- struct list_head name = LIST_HEAD_INIT ( name )
+/**
+ * Declare a static list head
+ *
+ * @v list List head
+ */
+#define LIST_HEAD( list ) \
+ struct list_head list = LIST_HEAD_INIT ( list )
-#define INIT_LIST_HEAD( ptr ) do { \
- (ptr)->next = (ptr); (ptr)->prev = (ptr); \
-} while ( 0 )
+/**
+ * Initialise a list head
+ *
+ * @v list List head
+ */
+#define INIT_LIST_HEAD( list ) do { \
+ (list)->next = (list); \
+ (list)->prev = (list); \
+ } while ( 0 )
-/*
- * Insert a new entry between two known consecutive entries.
+/**
+ * Check a list entry or list head is valid
*
- * This is only for internal list manipulation where we know
- * the prev/next entries already!
+ * @v list List entry or head
+ */
+#define list_check( list ) ( { \
+ assert ( (list) != NULL ); \
+ assert ( (list)->prev != NULL ); \
+ assert ( (list)->next != NULL ); \
+ assert ( (list)->next->prev == (list) ); \
+ assert ( (list)->prev->next == (list) ); \
+ } )
+
+/**
+ * Insert a list entry between two known consecutive entries
+ *
+ * @v new New list entry
+ * @v prev Previous list entry
+ * @v next Next list entry
*/
static inline void __list_add ( struct list_head *new,
struct list_head *prev,
/**
* Add a new entry to the head of a list
*
- * @v new New entry to be added
- * @v head List head to add it after
- *
- * Insert a new entry after the specified head. This is good for
- * implementing stacks.
+ * @v new New entry to be added
+ * @v head List head, or entry after which to add the new entry
*/
static inline void list_add ( struct list_head *new, struct list_head *head ) {
__list_add ( new, head, head->next );
}
#define list_add( new, head ) do { \
- assert ( (head)->next->prev == (head) ); \
- assert ( (head)->prev->next == (head) ); \
+ list_check ( (head) ); \
list_add ( (new), (head) ); \
} while ( 0 )
/**
* Add a new entry to the tail of a list
*
- * @v new New entry to be added
- * @v head List head to add it before
- *
- * Insert a new entry before the specified head. This is useful for
- * implementing queues.
+ * @v new New entry to be added
+ * @v head List head, or entry before which to add the new entry
*/
static inline void list_add_tail ( struct list_head *new,
struct list_head *head ) {
__list_add ( new, head->prev, head );
}
#define list_add_tail( new, head ) do { \
- assert ( (head)->next->prev == (head) ); \
- assert ( (head)->prev->next == (head) ); \
+ list_check ( (head) ); \
list_add_tail ( (new), (head) ); \
} while ( 0 )
-/*
- * Delete a list entry by making the prev/next entries
- * point to each other.
+/**
+ * Delete a list entry between two known consecutive entries
*
- * This is only for internal list manipulation where we know
- * the prev/next entries already!
+ * @v prev Previous list entry
+ * @v next Next list entry
*/
-static inline void __list_del ( struct list_head * prev,
- struct list_head * next ) {
+static inline void __list_del ( struct list_head *prev,
+ struct list_head *next ) {
next->prev = prev;
prev->next = next;
}
/**
* Delete an entry from a list
*
- * @v entry Element to delete from the list
+ * @v list List entry
*
* Note that list_empty() on entry does not return true after this;
* the entry is in an undefined state.
*/
-static inline void list_del ( struct list_head *entry ) {
- __list_del ( entry->prev, entry->next );
+static inline void list_del ( struct list_head *list ) {
+ __list_del ( list->prev, list->next );
}
-#define list_del( entry ) do { \
- assert ( (entry)->prev != NULL ); \
- assert ( (entry)->next != NULL ); \
- assert ( (entry)->next->prev == (entry) ); \
- assert ( (entry)->prev->next == (entry) ); \
- list_del ( (entry) ); \
+#define list_del( list ) do { \
+ list_check ( (list) ); \
+ list_del ( (list) ); \
} while ( 0 )
/**
* Test whether a list is empty
*
- * @v head List to test.
+ * @v list List head
*/
-static inline int list_empty ( const struct list_head *head ) {
- return head->next == head;
+static inline int list_empty ( const struct list_head *list ) {
+ return ( list->next == list );
}
+#define list_empty( list ) ( { \
+ list_check ( (list) ); \
+ list_empty ( (list) ); } )
/**
- * Get the containing struct for this entry
- *
- * @v ptr The struct list_head pointer
- * @v type The type of the struct this is embedded in
- * @v member The name of the list_struct within the struct
- */
-#define list_entry( ptr, type, member ) \
- container_of ( ptr, type, member )
-
-/**
- * Iterate over a list
+ * Get the container of a list entry
*
- * @v pos The &struct list_head to use as a loop counter
- * @v head The head for your list
+ * @v list List entry
+ * @v type Containing type
+ * @v member Name of list field within containing type
+ * @ret container Containing object
*/
-#define list_for_each( pos, head ) \
- for ( pos = (head)->next; pos != (head); pos = pos->next )
+#define list_entry( list, type, member ) ( { \
+ list_check ( (list) ); \
+ container_of ( list, type, member ); } )
/**
* Iterate over entries in a list
*
- * @v pos The type * to use as a loop counter
- * @v head The head for your list
- * @v member The name of the list_struct within the struct
+ * @v pos Iterator
+ * @v head List head
+ * @v member Name of list field within iterator's type
*/
#define list_for_each_entry( pos, head, member ) \
- for ( pos = list_entry ( (head)->next, typeof ( *pos ), member ); \
+ for ( list_check ( (head) ), \
+ pos = list_entry ( (head)->next, typeof ( *pos ), member ); \
&pos->member != (head); \
pos = list_entry ( pos->member.next, typeof ( *pos ), member ) )
/**
* Iterate over entries in a list in reverse order
*
- * @v pos The type * to use as a loop counter
- * @v head The head for your list
- * @v member The name of the list_struct within the struct
+ * @v pos Iterator
+ * @v head List head
+ * @v member Name of list field within iterator's type
*/
#define list_for_each_entry_reverse( pos, head, member ) \
- for ( pos = list_entry ( (head)->prev, typeof ( *pos ), member ); \
+ for ( list_check ( (head) ), \
+ pos = list_entry ( (head)->prev, typeof ( *pos ), member ); \
&pos->member != (head); \
pos = list_entry ( pos->member.prev, typeof ( *pos ), member ) )
/**
- * Iterate over entries in a list, safe against deletion of entries
+ * Iterate over entries in a list, safe against deletion of the current entry
*
- * @v pos The type * to use as a loop counter
- * @v tmp Another type * to use for temporary storage
- * @v head The head for your list
- * @v member The name of the list_struct within the struct
+ * @v pos Iterator
+ * @v tmp Temporary value (of same type as iterator)
+ * @v head List head
+ * @v member Name of list field within iterator's type
*/
#define list_for_each_entry_safe( pos, tmp, head, member ) \
- for ( pos = list_entry ( (head)->next, typeof ( *pos ), member ), \
+ for ( list_check ( (head) ), \
+ pos = list_entry ( (head)->next, typeof ( *pos ), member ), \
tmp = list_entry ( pos->member.next, typeof ( *tmp ), member ); \
&pos->member != (head); \
pos = tmp, \
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