*/įor (np = head.lh_first np != NULL np = np->entries.le_next) N2 = malloc(sizeof(struct entry)) /* Insert after. N1 = malloc(sizeof(struct entry)) /* Insert at the head. List example LIST_HEAD(listhead, entry) head The macro LIST_REMOVE removes the element elm from the list. The macro LIST_INSERT_AFTER inserts the new element elm after the element listelm. The macro LIST_INSERT_HEAD inserts the new element elm at the head of the list. The macro LIST_INIT initializes the list referenced by head. The macro LIST_ENTRY declares a structure that connects the elements in the list. Struct HEADNAME *headp (The names head and headp are user selectable.) Head of the list can later be declared as: LIST_HEAD(HEADNAME, TYPE) head where HEADNAME is the name of the structure to be defined, and TYPE is the type of the elements to be linked into the list.

A LIST_HEAD structure is declared as follows: New elements can be added to the list after an existingĮlement or at the head of the list. TheĮlements are doubly linked so that an arbitrary element can be removed without traversing the list.

This structure contains a single pointer to the first element on the list. Lists A list is headed by a structure defined by the LIST_HEAD macro. See the examples below for further explanation of how these macros are used. The argument HEADNAME is the name of a user-defined structure that must be declared using the macros In the macro definitions, TYPE is the name of a user-defined structure, that must contain a field of type LIST_ENTRY, TAILQ_ENTRY, orĬIRCLEQ_ENTRY, named NAME. The termination condition for traversal is more complex.Ĭode size is about 40% greater and operations run about 45% slower than lists. They may be traversed backward, from tail to head. Tail queues add the following functionality:Įntries can be added at the end of a list.Īll list insertions and removals must specify the head of the list.Įach head entry requires two pointers rather than one.Ĭode size is about 15% greater and operations run about 20% slower than lists.Ĭircular queues add the following functionality:Įntries can be added before another entry. Lists are the simplest of the three data structures and support only the above functionality. Insertion of a new entry after any element in the list. Insertion of a new entry at the head of the list. All three structures support the following These macros define and operate on three types of data structures: lists, tail queues, and circular queues. TAILQ_REMOVE(TAILQ_HEAD * head, TYPE * elm, TAILQ_ENTRY NAME ) ĬIRCLEQ_INSERT_AFTER(CIRCLEQ_HEAD * head, TYPE * listelm ,ĬIRCLEQ_INSERT_BEFORE(CIRCLEQ_HEAD * head, TYPE * listelm ,ĬIRCLEQ_INSERT_HEAD(CIRCLEQ_HEAD * head ,ĬIRCLEQ_INSERT_TAIL(CIRCLEQ_HEAD * head , TAILQ_INSERT_AFTER(TAILQ_HEAD * head, TYPE * listelm ,

LIST_REMOVE(TYPE * elm, LIST_ENTRY NAME ) TAILQ_INSERT_HEAD, TAILQ_INSERT_TAIL, TAILQ_REMOVE, CIRCLEQ_ENTRY, CIRCLEQ_HEAD, CIRCLEQ_INIT, CIRCLEQ_INSERT_AFTER, CIRCLEQ_INSERT_BEFORE,ĬIRCLEQ_INSERT_HEAD, CIRCLEQ_INSERT_TAIL, CIRCLEQ_REMOVE - implementations of lists, tail queues, and circular queues LIST_ENTRY, LIST_HEAD, LIST_INIT, LIST_INSERT_AFTER, LIST_INSERT_HEAD, LIST_REMOVE, TAILQ_ENTRY, TAILQ_HEAD, TAILQ_INIT, TAILQ_INSERT_AFTER,

Listhead linux kernel example