QUEUE(3) | Library Functions Manual | QUEUE(3) |
SLIST_HEAD_INITIALIZER(head);
SLIST_ENTRY(TYPE);
SLIST_INIT(SLIST_HEAD *head);
SLIST_INSERT_AFTER(TYPE *listelm, TYPE *elm, SLIST_ENTRY NAME);
SLIST_INSERT_HEAD(SLIST_HEAD *head, TYPE *elm, SLIST_ENTRY NAME);
SLIST_REMOVE_HEAD(SLIST_HEAD *head, SLIST_ENTRY NAME);
SLIST_REMOVE(SLIST_HEAD *head, TYPE *elm, TYPE, SLIST_ENTRY NAME);
SLIST_FOREACH(TYPE *var, SLIST_HEAD *head, SLIST_ENTRY NAME);
SLIST_FOREACH_SAFE(TYPE *var, SLIST_HEAD *head, SLIST_ENTRY NAME, TYPE *tmp);
int
SLIST_EMPTY(SLIST_HEAD *head);
TYPE *
SLIST_FIRST(SLIST_HEAD *head);
TYPE *
SLIST_NEXT(TYPE *elm, SLIST_ENTRY NAME);
SIMPLEQ_HEAD_INITIALIZER(head);
SIMPLEQ_ENTRY(TYPE);
SIMPLEQ_INIT(SIMPLEQ_HEAD *head);
SIMPLEQ_INSERT_HEAD(SIMPLEQ_HEAD *head, TYPE *elm, SIMPLEQ_ENTRY NAME);
SIMPLEQ_INSERT_TAIL(SIMPLEQ_HEAD *head, TYPE *elm, SIMPLEQ_ENTRY NAME);
SIMPLEQ_INSERT_AFTER(SIMPLEQ_HEAD *head, TYPE *listelm, TYPE *elm, SIMPLEQ_ENTRY NAME);
SIMPLEQ_REMOVE_HEAD(SIMPLEQ_HEAD *head, SIMPLEQ_ENTRY NAME);
SIMPLEQ_REMOVE(SIMPLEQ_HEAD *head, TYPE *elm, TYPE, SIMPLEQ_ENTRY NAME);
SIMPLEQ_FOREACH(TYPE *var, SIMPLEQ_HEAD *head, SIMPLEQ_ENTRY NAME);
SIMPLEQ_FOREACH_SAFE(TYPE *var, SIMPLEQ_HEAD *head, SIMPLEQ_ENTRY NAME, TYPE *tmp);
int
SIMPLEQ_EMPTY(SIMPLEQ_HEAD *head);
TYPE *
SIMPLEQ_FIRST(SIMPLEQ_HEAD *head);
TYPE *
SIMPLEQ_NEXT(TYPE *elm, SIMPLEQ_ENTRY NAME);
TYPE *
SIMPLEQ_LAST(SIMPLEQ_HEAD *head, TYPE *elm, SIMPLEQ_ENTRY NAME);
SIMPLEQ_CONCAT(SIMPLEQ_HEAD *head1, SIMPLEQ_HEAD *head2);
STAILQ_HEAD_INITIALIZER(head);
STAILQ_ENTRY(TYPE);
STAILQ_INIT(STAILQ_HEAD *head);
STAILQ_INSERT_HEAD(STAILQ_HEAD *head, TYPE *elm, STAILQ_ENTRY NAME);
STAILQ_INSERT_TAIL(STAILQ_HEAD *head, TYPE *elm, STAILQ_ENTRY NAME);
STAILQ_INSERT_AFTER(STAILQ_HEAD *head, TYPE *listelm, TYPE *elm, STAILQ_ENTRY NAME);
STAILQ_REMOVE_HEAD(STAILQ_HEAD *head, STAILQ_ENTRY NAME);
STAILQ_REMOVE(STAILQ_HEAD *head, TYPE *elm, TYPE, STAILQ_ENTRY NAME);
STAILQ_FOREACH(TYPE *var, STAILQ_HEAD *head, STAILQ_ENTRY NAME);
STAILQ_FOREACH_SAFE(TYPE *var, STAILQ_HEAD *head, STAILQ_ENTRY NAME, TYPE *tmp);
int
STAILQ_EMPTY(STAILQ_HEAD *head);
TYPE *
STAILQ_FIRST(STAILQ_HEAD *head);
TYPE *
STAILQ_NEXT(TYPE *elm, STAILQ_ENTRY NAME);
TYPE *
STAILQ_LAST(STAILQ_HEAD *head, TYPE *elm, STAILQ_ENTRY NAME);
STAILQ_CONCAT(STAILQ_HEAD *head1, STAILQ_HEAD *head2);
LIST_HEAD_INITIALIZER(head);
LIST_ENTRY(TYPE);
LIST_INIT(LIST_HEAD *head);
LIST_INSERT_AFTER(TYPE *listelm, TYPE *elm, LIST_ENTRY NAME);
LIST_INSERT_BEFORE(TYPE *listelm, TYPE *elm, LIST_ENTRY NAME);
LIST_INSERT_HEAD(LIST_HEAD *head, TYPE *elm, LIST_ENTRY NAME);
LIST_REMOVE(TYPE *elm, LIST_ENTRY NAME);
LIST_FOREACH(TYPE *var, LIST_HEAD *head, LIST_ENTRY NAME);
int
LIST_EMPTY(LIST_HEAD *head);
TYPE *
LIST_FIRST(LIST_HEAD *head);
TYPE *
LIST_NEXT(TYPE *elm, LIST_ENTRY NAME);
TAILQ_HEAD_INITIALIZER(head);
TAILQ_ENTRY(TYPE);
TAILQ_INIT(TAILQ_HEAD *head);
TAILQ_INSERT_HEAD(TAILQ_HEAD *head, TYPE *elm, TAILQ_ENTRY NAME);
TAILQ_INSERT_TAIL(TAILQ_HEAD *head, TYPE *elm, TAILQ_ENTRY NAME);
TAILQ_INSERT_AFTER(TAILQ_HEAD *head, TYPE *listelm, TYPE *elm, TAILQ_ENTRY NAME);
TAILQ_INSERT_BEFORE(TYPE *listelm, TYPE *elm, TAILQ_ENTRY NAME);
TAILQ_REMOVE(TAILQ_HEAD *head, TYPE *elm, TAILQ_ENTRY NAME);
TAILQ_FOREACH(TYPE *var, TAILQ_HEAD *head, TAILQ_ENTRY NAME);
TAILQ_FOREACH_SAFE(TYPE *var, TAILQ_HEAD *head, TAILQ_ENTRY NAME, TYPE *tmp);
TAILQ_FOREACH_REVERSE(TYPE *var, TAILQ_HEAD *head, HEADNAME, TAILQ_ENTRY NAME);
TAILQ_FOREACH_REVERSE_SAFE(TYPE *var, TAILQ_HEAD *head, HEADNAME, TAILQ_ENTRY NAME, TYPE *tmp);
int
TAILQ_EMPTY(TAILQ_HEAD *head);
TYPE *
TAILQ_FIRST(TAILQ_HEAD *head);
TYPE *
TAILQ_NEXT(TYPE *elm, TAILQ_ENTRY NAME);
TYPE *
TAILQ_LAST(TAILQ_HEAD *head, HEADNAME);
TYPE *
TAILQ_PREV(TYPE *elm, HEADNAME, TAILQ_ENTRY NAME);
TAILQ_CONCAT(TAILQ_HEAD *head1, TAILQ_HEAD *head2, TAILQ_ENTRY NAME);
CIRCLEQ_HEAD_INITIALIZER(head);
CIRCLEQ_ENTRY(TYPE);
CIRCLEQ_INIT(CIRCLEQ_HEAD *head);
CIRCLEQ_INSERT_AFTER(CIRCLEQ_HEAD *head, TYPE *listelm, TYPE *elm, CIRCLEQ_ENTRY NAME);
CIRCLEQ_INSERT_BEFORE(CIRCLEQ_HEAD *head, TYPE *listelm, TYPE *elm, CIRCLEQ_ENTRY NAME);
CIRCLEQ_INSERT_HEAD(CIRCLEQ_HEAD *head, TYPE *elm, CIRCLEQ_ENTRY NAME);
CIRCLEQ_INSERT_TAIL(CIRCLEQ_HEAD *head, TYPE *elm, CIRCLEQ_ENTRY NAME);
CIRCLEQ_REMOVE(CIRCLEQ_HEAD *head, TYPE *elm, CIRCLEQ_ENTRY NAME);
CIRCLEQ_FOREACH(TYPE *var, CIRCLEQ_HEAD *head, CIRCLEQ_ENTRY NAME);
CIRCLEQ_FOREACH_REVERSE(TYPE *var, CIRCLEQ_HEAD *head, CIRCLEQ_ENTRY NAME);
int
CIRCLEQ_EMPTY(CIRCLEQ_HEAD *head);
TYPE *
CIRCLEQ_FIRST(CIRCLEQ_HEAD *head);
TYPE *
CIRCLEQ_LAST(CIRCLEQ_HEAD *head);
TYPE *
CIRCLEQ_NEXT(TYPE *elm, CIRCLEQ_ENTRY NAME);
TYPE *
CIRCLEQ_PREV(TYPE *elm, CIRCLEQ_ENTRY NAME);
TYPE *
CIRCLEQ_LOOP_NEXT(CIRCLEQ_HEAD *head, TYPE *elm, CIRCLEQ_ENTRY NAME);
TYPE *
CIRCLEQ_LOOP_PREV(CIRCLEQ_HEAD *head, TYPE *elm, CIRCLEQ_ENTRY NAME);
Singly-linked lists are the simplest of the five data structures and support only the above functionality. Singly-linked lists are ideal for applications with large datasets and few or no removals, or for implementing a LIFO queue.
Simple queues add the following functionality:
Simple queues are ideal for applications with large datasets and few or no removals, or for implementing a FIFO queue.
All doubly linked types of data structures (lists, tail queues, and circle queues) additionally allow:
Linked lists are the simplest of the doubly linked data structures and support only the above functionality over singly-linked lists.
Tail queues add the following functionality:
Circular queues add the following functionality:
In the macro definitions, TYPE is the name of a user defined structure, that must contain a field of type LIST_ENTRY
, SIMPLEQ_ENTRY
, SLIST_ENTRY
, TAILQ_ENTRY
, or CIRCLEQ_ENTRY
, named NAME. The argument HEADNAME is the name of a user defined structure that must be declared using the macros LIST_HEAD
, SIMPLEQ_HEAD
, SLIST_HEAD
, TAILQ_HEAD
, or CIRCLEQ_HEAD
. See the examples below for further explanation of how these macros are used.
SLIST | LIST | SIMPLEQ | STAILQ | TAILQ | CIRCLEQ | |||||||
_EMPTY | + | + | + | + | + | + | ||||||
_FIRST | + | + | + | + | + | + | ||||||
_FOREACH | + | + | + | + | + | + | ||||||
_FOREACH_REVERSE | - | - | - | - | + | + | ||||||
_INSERT_AFTER | + | + | + | + | + | + | ||||||
_INSERT_BEFORE | - | + | - | - | + | + | ||||||
_INSERT_HEAD | + | + | + | + | + | + | ||||||
_INSERT_TAIL | - | - | + | + | + | + | ||||||
_LAST | - | - | - | + | + | + | ||||||
_LOOP_NEXT | - | - | - | - | - | + | ||||||
_LOOP_PREV | - | - | - | - | - | + | ||||||
_NEXT | + | + | + | + | + | + | ||||||
_PREV | - | - | - | - | + | + | ||||||
_REMOVE | + | + | + | + | + | + | ||||||
_REMOVE_HEAD | + | - | + | + | - | - | ||||||
_CONCAT | - | - | + | + | + | - |
SLIST_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 pointer to the head of the list can later be declared as:
struct HEADNAME *headp;
(The names head
and headp
are user selectable.)
The macro SLIST_HEAD_INITIALIZER evaluates to an initializer for the list head.
The macro SLIST_EMPTY evaluates to true if there are no elements in the list.
The macro SLIST_ENTRY declares a structure that connects the elements in the list.
The macro SLIST_FIRST returns the first element in the list or NULL if the list is empty.
The macro SLIST_FOREACH traverses the list referenced by head in the forward direction, assigning each element in turn to var.
The SAFE versions uses tmp to hold the next element, so var may be freed or removed from the list.
The macro SLIST_INIT initializes the list referenced by head.
The macro SLIST_INSERT_HEAD inserts the new element elm at the head of the list.
The macro SLIST_INSERT_AFTER inserts the new element elm after the element listelm.
The macro SLIST_NEXT returns the next element in the list.
The macro SLIST_REMOVE removes the element elm from the list.
The macro SLIST_REMOVE_HEAD removes the first element from the head of the list. For optimum efficiency, elements being removed from the head of the list should explicitly use this macro instead of the generic SLIST_REMOVE macro.
SLIST_HEAD(slisthead, entry) head = SLIST_HEAD_INITIALIZER(head); struct slisthead *headp; /* Singly-linked List head. */ struct entry { ... SLIST_ENTRY(entry) entries; /* Singly-linked List. */ ... } *n1, *n2, *n3, *np; SLIST_INIT(&head); /* Initialize the list. */ n1 = malloc(sizeof(struct entry)); /* Insert at the head. */ SLIST_INSERT_HEAD(&head, n1, entries); n2 = malloc(sizeof(struct entry)); /* Insert after. */ SLIST_INSERT_AFTER(n1, n2, entries); SLIST_REMOVE(&head, n2, entry, entries);/* Deletion. */ free(n2); n3 = SLIST_FIRST(&head); SLIST_REMOVE_HEAD(&head, entries); /* Deletion from the head. */ free(n3); /* Forward traversal. */ SLIST_FOREACH(np, &head, entries) np-> ... while (!SLIST_EMPTY(&head)) { /* List Deletion. */ n1 = SLIST_FIRST(&head); SLIST_REMOVE_HEAD(&head, entries); free(n1); }
SIMPLEQ_HEAD(HEADNAME, TYPE) head;
HEADNAME
is the name of the structure to be defined, and TYPE
is the type of the elements to be linked into the simple queue. A pointer to the head of the simple queue can later be declared as:
struct HEADNAME *headp;
head
and headp
are user selectable.)The macro SIMPLEQ_ENTRY declares a structure that connects the elements in the simple queue.
The macro SIMPLEQ_HEAD_INITIALIZER provides a value which can be used to initialize a simple queue head at compile time, and is used at the point that the simple queue head variable is declared, like:
struct HEADNAME head = SIMPLEQ_HEAD_INITIALIZER(head);
The macro SIMPLEQ_INIT initializes the simple queue referenced by head.
The macro SIMPLEQ_INSERT_HEAD inserts the new element elm at the head of the simple queue.
The macro SIMPLEQ_INSERT_TAIL inserts the new element elm at the end of the simple queue.
The macro SIMPLEQ_INSERT_AFTER inserts the new element elm after the element listelm.
The macro SIMPLEQ_REMOVE removes elm from the simple queue.
The macro SIMPLEQ_REMOVE_HEAD removes the first element from the head of the simple queue. For optimum efficiency, elements being removed from the head of the queue should explicitly use this macro instead of the generic SIMPLQ_REMOVE macro.
The macro SIMPLEQ_EMPTY return true if the simple queue head has no elements.
The macro SIMPLEQ_FIRST returns the first element of the simple queue head.
The macros SIMPLEQ_FOREACH and SIMPLEQ_FOREACH_SAFE traverse the tail queue referenced by head in the forward direction, assigning each element in turn to var.
The SAFE versions uses tmp to hold the next element, so var may be freed or removed from the list.
The macro SIMPLEQ_NEXT returns the element after the element elm.
The macro SIMPLEQ_LAST returns the last item on the tail queue. If the tail queue is empty the return value is NULL.
The macro SIMPLEQ_CONCAT concatenates the tail queue headed by head2 onto the end of the one headed by head1 removing all entries from the former.
The macros prefixed with “STAILQ_” (STAILQ_HEAD, STAILQ_HEAD_INITIALIZER, STAILQ_ENTRY, STAILQ_INIT, STAILQ_INSERT_HEAD, STAILQ_INSERT_TAIL, STAILQ_INSERT_AFTER, STAILQ_REMOVE_HEAD, STAILQ_REMOVE, STAILQ_FOREACH, STAILQ_FOREACH_SAFE, STAILQ_EMPTY, STAILQ_FIRST, STAILQ_NEXT, STAILQ_LAST, and STAILQ_CONCAT) are functionally identical to these simple queue functions, and are provided for compatibility with FreeBSD.
SIMPLEQ_HEAD(simplehead, entry) head; struct simplehead *headp; /* Simple queue head. */ struct entry { ... SIMPLEQ_ENTRY(entry) entries; /* Simple queue. */ ... } *n1, *n2, *np; SIMPLEQ_INIT(&head); /* Initialize the queue. */ n1 = malloc(sizeof(struct entry)); /* Insert at the head. */ SIMPLEQ_INSERT_HEAD(&head, n1, entries); n1 = malloc(sizeof(struct entry)); /* Insert at the tail. */ SIMPLEQ_INSERT_TAIL(&head, n1, entries); n2 = malloc(sizeof(struct entry)); /* Insert after. */ SIMPLEQ_INSERT_AFTER(&head, n1, n2, entries); /* Forward traversal. */ SIMPLEQ_FOREACH(np, &head, entries) np-> ... /* Delete. */ while (SIMPLEQ_FIRST(&head) != NULL) SIMPLEQ_REMOVE_HEAD(&head, entries); if (SIMPLEQ_EMPTY(&head)) /* Test for emptiness. */ printf("nothing to do\n");
LIST_HEAD(HEADNAME, TYPE) head;
struct HEADNAME *headp;
head
and headp
are user selectable.)The macro LIST_ENTRY declares a structure that connects the elements in the list.
The macro LIST_HEAD_INITIALIZER provides a value which can be used to initialize a list head at compile time, and is used at the point that the list head variable is declared, like:
struct HEADNAME head = LIST_HEAD_INITIALIZER(head);
The macro LIST_INIT initializes the list referenced by head.
The macro LIST_INSERT_HEAD inserts the new element elm at the head of the list.
The macro LIST_INSERT_AFTER inserts the new element elm after the element listelm.
The macro LIST_INSERT_BEFORE inserts the new element elm before the element listelm.
The macro LIST_REMOVE removes the element elm from the list.
The macro LIST_EMPTY return true if the list head has no elements.
The macro LIST_FIRST returns the first element of the list head.
The macro LIST_FOREACH traverses the list referenced by head in the forward direction, assigning each element in turn to var.
The macro LIST_NEXT returns the element after the element elm.
LIST_HEAD(listhead, entry) head; struct listhead *headp; /* List head. */ struct entry { ... LIST_ENTRY(entry) entries; /* List. */ ... } *n1, *n2, *np; LIST_INIT(&head); /* Initialize the list. */ n1 = malloc(sizeof(struct entry)); /* Insert at the head. */ LIST_INSERT_HEAD(&head, n1, entries); n2 = malloc(sizeof(struct entry)); /* Insert after. */ LIST_INSERT_AFTER(n1, n2, entries); n2 = malloc(sizeof(struct entry)); /* Insert before. */ LIST_INSERT_BEFORE(n1, n2, entries); /* Forward traversal. */ LIST_FOREACH(np, &head, entries) np-> ... /* Delete. */ while (LIST_FIRST(&head) != NULL) LIST_REMOVE(LIST_FIRST(&head), entries); if (LIST_EMPTY(&head)) /* Test for emptiness. */ printf("nothing to do\n");
TAILQ_HEAD(HEADNAME, TYPE) head;
HEADNAME
is the name of the structure to be defined, and TYPE
is the type of the elements to be linked into the tail queue. A pointer to the head of the tail queue can later be declared as:
struct HEADNAME *headp;
head
and headp
are user selectable.)The macro TAILQ_ENTRY declares a structure that connects the elements in the tail queue.
The macro TAILQ_HEAD_INITIALIZER provides a value which can be used to initialize a tail queue head at compile time, and is used at the point that the tail queue head variable is declared, like:
struct HEADNAME head = TAILQ_HEAD_INITIALIZER(head);
The macro TAILQ_INIT initializes the tail queue referenced by head.
The macro TAILQ_INSERT_HEAD inserts the new element elm at the head of the tail queue.
The macro TAILQ_INSERT_TAIL inserts the new element elm at the end of the tail queue.
The macro TAILQ_INSERT_AFTER inserts the new element elm after the element listelm.
The macro TAILQ_INSERT_BEFORE inserts the new element elm before the element listelm.
The macro TAILQ_REMOVE removes the element elm from the tail queue.
The macro TAILQ_EMPTY return true if the tail queue head has no elements.
The macro TAILQ_FIRST returns the first element of the tail queue head.
The macros TAILQ_FOREACH, TAILQ_FOREACH_REVERSE, TAILQ_FOREACH_SAFE, and TAILQ_FOREACH_REVERSE_SAFE traverse the tail queue referenced by head in the forward or reverse direction direction, assigning each element in turn to var.
The SAFE versions uses tmp to hold the next element, so var may be freed or removed from the list.
The macro TAILQ_NEXT returns the element after the element elm.
The macro TAILQ_CONCAT concatenates the tail queue headed by head2 onto the end of the one headed by head1 removing all entries from the former.
TAILQ_HEAD(tailhead, entry) head; struct tailhead *headp; /* Tail queue head. */ struct entry { ... TAILQ_ENTRY(entry) entries; /* Tail queue. */ ... } *n1, *n2, *np; TAILQ_INIT(&head); /* Initialize the queue. */ n1 = malloc(sizeof(struct entry)); /* Insert at the head. */ TAILQ_INSERT_HEAD(&head, n1, entries); n1 = malloc(sizeof(struct entry)); /* Insert at the tail. */ TAILQ_INSERT_TAIL(&head, n1, entries); n2 = malloc(sizeof(struct entry)); /* Insert after. */ TAILQ_INSERT_AFTER(&head, n1, n2, entries); n2 = malloc(sizeof(struct entry)); /* Insert before. */ TAILQ_INSERT_BEFORE(n1, n2, entries); /* Forward traversal. */ TAILQ_FOREACH(np, &head, entries) np-> ... /* Reverse traversal. */ TAILQ_FOREACH_REVERSE(np, &head, tailhead, entries) np-> ... /* Delete. */ while (TAILQ_FIRST(&head) != NULL) TAILQ_REMOVE(&head, TAILQ_FIRST(&head), entries); if (TAILQ_EMPTY(&head)) /* Test for emptiness. */ printf("nothing to do\n");
CIRCLEQ_HEAD(HEADNAME, TYPE) head;
HEADNAME
is the name of the structure to be defined, and TYPE
is the type of the elements to be linked into the circular queue. A pointer to the head of the circular queue can later be declared as:
struct HEADNAME *headp;
head
and headp
are user selectable.)The macro CIRCLEQ_ENTRY declares a structure that connects the elements in the circular queue.
The macro CIRCLEQ_HEAD_INITIALIZER provides a value which can be used to initialize a circular queue head at compile time, and is used at the point that the circular queue head variable is declared, like:
struct HEADNAME head = CIRCLEQ_HEAD_INITIALIZER(head);
The macro CIRCLEQ_INIT initializes the circular queue referenced by head.
The macro CIRCLEQ_INSERT_HEAD inserts the new element elm at the head of the circular queue.
The macro CIRCLEQ_INSERT_TAIL inserts the new element elm at the end of the circular queue.
The macro CIRCLEQ_INSERT_AFTER inserts the new element elm after the element listelm.
The macro CIRCLEQ_INSERT_BEFORE inserts the new element elm before the element listelm.
The macro CIRCLEQ_REMOVE removes the element elm from the circular queue.
The macro CIRCLEQ_EMPTY return true if the circular queue head has no elements.
The macro CIRCLEQ_FIRST returns the first element of the circular queue head.
The macro CIRCLEQ_FOREACH traverses the circle queue referenced by head in the forward direction, assigning each element in turn to var. Each element is assigned exactly once.
The macro CIRCLEQ_FOREACH_REVERSE traverses the circle queue referenced by head in the reverse direction, assigning each element in turn to var. Each element is assigned exactly once.
The macro CIRCLEQ_LAST returns the last element of the circular queue head.
The macro CIRCLEQ_NEXT returns the element after the element elm.
The macro CIRCLEQ_PREV returns the element before the element elm.
The macro CIRCLEQ_LOOP_NEXT returns the element after the element elm. If elm was the last element in the queue, the first element is returned.
The macro CIRCLEQ_LOOP_PREV returns the element before the element elm. If elm was the first element in the queue, the last element is returned.
CIRCLEQ_HEAD(circleq, entry) head; struct circleq *headp; /* Circular queue head. */ struct entry { ... CIRCLEQ_ENTRY(entry) entries; /* Circular queue. */ ... } *n1, *n2, *np; CIRCLEQ_INIT(&head); /* Initialize the circular queue. */ n1 = malloc(sizeof(struct entry)); /* Insert at the head. */ CIRCLEQ_INSERT_HEAD(&head, n1, entries); n1 = malloc(sizeof(struct entry)); /* Insert at the tail. */ CIRCLEQ_INSERT_TAIL(&head, n1, entries); n2 = malloc(sizeof(struct entry)); /* Insert after. */ CIRCLEQ_INSERT_AFTER(&head, n1, n2, entries); n2 = malloc(sizeof(struct entry)); /* Insert before. */ CIRCLEQ_INSERT_BEFORE(&head, n1, n2, entries); /* Forward traversal. */ CIRCLEQ_FOREACH(np, &head, entries) np-> ... /* Reverse traversal. */ CIRCLEQ_FOREACH_REVERSE(np, &head, entries) np-> ... /* Delete. */ while (CIRCLEQ_FIRST(&head) != (void *)&head) CIRCLEQ_REMOVE(&head, CIRCLEQ_FIRST(&head), entries); if (CIRCLEQ_EMPTY(&head)) /* Test for emptiness. */ printf("nothing to do\n");
March 11, 2009 | NetBSD 6.1 |