/* * Copyright (c) 1991, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)queue.h 8.5 (Berkeley) 8/20/94 */ #ifndef _SYS_QUEUE_H_ #define _SYS_QUEUE_H_ /* * This file defines five types of data structures: singly-linked lists, * lists, simple queues, tail queues, and circular queues. * * A singly-linked list is headed by a single forward pointer. The * elements are singly linked for minimum space and pointer manipulation * overhead at the expense of O(n) removal for arbitrary elements. New * elements can be added to the list after an existing element or at the * head of the list. Elements being removed from the head of the list * should use the explicit macro for this purpose for optimum * efficiency. A singly-linked list may only be traversed in the forward * direction. Singly-linked lists are ideal for applications with large * datasets and few or no removals or for implementing a LIFO queue. * * A list is headed by a single forward pointer (or an array of forward * pointers for a hash table header). The elements are doubly linked * so that an arbitrary element can be removed without a need to * traverse the list. New elements can be added to the list before * or after an existing element or at the head of the list. A list * may only be traversed in the forward direction. * * A simple queue is headed by a pair of pointers, one the head of the * list and the other to the tail of the list. The elements are singly * linked to save space, so elements can only be removed from the * head of the list. New elements can be added to the list after * an existing element, at the head of the list, or at the end of the * list. A simple queue may only be traversed in the forward direction. * * A tail queue is headed by a pair of pointers, one to the head of the * list and the other to the tail of the list. The elements are doubly * linked so that an arbitrary element can be removed without a need to * traverse the list. New elements can be added to the list before or * after an existing element, at the head of the list, or at the end of * the list. A tail queue may be traversed in either direction. * * A circle queue is headed by a pair of pointers, one to the head of the * list and the other to the tail of the list. The elements are doubly * linked so that an arbitrary element can be removed without a need to * traverse the list. New elements can be added to the list before or after * an existing element, at the head of the list, or at the end of the list. * A circle queue may be traversed in either direction, but has a more * complex end of list detection. * * For details on the use of these macros, see the queue(3) manual page. */ /* * Simple queue definitions. */ #define SIMPLEQ_HEAD(name, type) \ struct name { \ struct type *sqh_first; /* first element */ \ struct type **sqh_last; /* addr of last next element */ \ } #define SIMPLEQ_HEAD_INITIALIZER(head) \ { \ NULL, &(head).sqh_first \ } #define SIMPLEQ_ENTRY(type) \ struct { \ struct type *sqe_next; /* next element */ \ } /* * Simple queue functions. */ #define SIMPLEQ_INIT(head) \ do { \ (head)->sqh_first = NULL; \ (head)->sqh_last = &(head)->sqh_first; \ } while (/*CONSTCOND*/ 0) #define SIMPLEQ_INSERT_HEAD(head, elm, field) \ do { \ if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \ (head)->sqh_last = &(elm)->field.sqe_next; \ (head)->sqh_first = (elm); \ } while (/*CONSTCOND*/ 0) #define SIMPLEQ_INSERT_TAIL(head, elm, field) \ do { \ (elm)->field.sqe_next = NULL; \ *(head)->sqh_last = (elm); \ (head)->sqh_last = &(elm)->field.sqe_next; \ } while (/*CONSTCOND*/ 0) #define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) \ do { \ if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL) \ (head)->sqh_last = &(elm)->field.sqe_next; \ (listelm)->field.sqe_next = (elm); \ } while (/*CONSTCOND*/ 0) #define SIMPLEQ_REMOVE_HEAD(head, field) \ do { \ if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \ (head)->sqh_last = &(head)->sqh_first; \ } while (/*CONSTCOND*/ 0) #define SIMPLEQ_REMOVE(head, elm, type, field) \ do { \ if ((head)->sqh_first == (elm)) { \ SIMPLEQ_REMOVE_HEAD((head), field); \ } else { \ struct type *curelm = (head)->sqh_first; \ while (curelm->field.sqe_next != (elm)) \ curelm = curelm->field.sqe_next; \ if ((curelm->field.sqe_next = \ curelm->field.sqe_next->field.sqe_next) == NULL) \ (head)->sqh_last = &(curelm)->field.sqe_next; \ } \ } while (/*CONSTCOND*/ 0) #define SIMPLEQ_FOREACH(var, head, field) \ for ((var) = ((head)->sqh_first); (var); (var) = ((var)->field.sqe_next)) /* * Simple queue access methods. */ #define SIMPLEQ_EMPTY(head) ((head)->sqh_first == NULL) #define SIMPLEQ_FIRST(head) ((head)->sqh_first) #define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next) /* * Tail queue definitions. */ #define _TAILQ_HEAD(name, type, qual) \ struct name { \ qual type *tqh_first; /* first element */ \ qual type *qual *tqh_last; /* addr of last next element */ \ } #define TAILQ_HEAD(name, type) _TAILQ_HEAD(name, struct type, ) #define TAILQ_HEAD_INITIALIZER(head) \ { \ NULL, &(head).tqh_first \ } #define _TAILQ_ENTRY(type, qual) \ struct { \ qual type *tqe_next; /* next element */ \ qual type *qual *tqe_prev; /* address of previous next element */ \ } #define TAILQ_ENTRY(type) _TAILQ_ENTRY(struct type, ) /* * Tail queue functions. */ #define TAILQ_INIT(head) \ do { \ (head)->tqh_first = NULL; \ (head)->tqh_last = &(head)->tqh_first; \ } while (/*CONSTCOND*/ 0) #define TAILQ_INSERT_HEAD(head, elm, field) \ do { \ if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \ (head)->tqh_first->field.tqe_prev = &(elm)->field.tqe_next; \ else \ (head)->tqh_last = &(elm)->field.tqe_next; \ (head)->tqh_first = (elm); \ (elm)->field.tqe_prev = &(head)->tqh_first; \ } while (/*CONSTCOND*/ 0) #define TAILQ_INSERT_TAIL(head, elm, field) \ do { \ (elm)->field.tqe_next = NULL; \ (elm)->field.tqe_prev = (head)->tqh_last; \ *(head)->tqh_last = (elm); \ (head)->tqh_last = &(elm)->field.tqe_next; \ } while (/*CONSTCOND*/ 0) #define TAILQ_INSERT_AFTER(head, listelm, elm, field) \ do { \ if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL) \ (elm)->field.tqe_next->field.tqe_prev = &(elm)->field.tqe_next; \ else \ (head)->tqh_last = &(elm)->field.tqe_next; \ (listelm)->field.tqe_next = (elm); \ (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \ } while (/*CONSTCOND*/ 0) #define TAILQ_INSERT_BEFORE(listelm, elm, field) \ do { \ (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \ (elm)->field.tqe_next = (listelm); \ *(listelm)->field.tqe_prev = (elm); \ (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \ } while (/*CONSTCOND*/ 0) #define TAILQ_REMOVE(head, elm, field) \ do { \ if (((elm)->field.tqe_next) != NULL) \ (elm)->field.tqe_next->field.tqe_prev = (elm)->field.tqe_prev; \ else \ (head)->tqh_last = (elm)->field.tqe_prev; \ *(elm)->field.tqe_prev = (elm)->field.tqe_next; \ } while (/*CONSTCOND*/ 0) #define TAILQ_FOREACH(var, head, field) \ for ((var) = ((head)->tqh_first); (var); (var) = ((var)->field.tqe_next)) #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \ for ((var) = (*(((struct headname *)((head)->tqh_last))->tqh_last)); \ (var); \ (var) = (*(((struct headname *)((var)->field.tqe_prev))->tqh_last))) #define TAILQ_CONCAT(head1, head2, field) \ do { \ if (!TAILQ_EMPTY(head2)) { \ *(head1)->tqh_last = (head2)->tqh_first; \ (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \ (head1)->tqh_last = (head2)->tqh_last; \ TAILQ_INIT((head2)); \ } \ } while (/*CONSTCOND*/ 0) /* * Tail queue access methods. */ #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL) #define TAILQ_FIRST(head) ((head)->tqh_first) #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next) #define TAILQ_LAST(head, headname) \ (*(((struct headname *)((head)->tqh_last))->tqh_last)) #define TAILQ_PREV(elm, headname, field) \ (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last)) /* * Circular queue definitions. */ #define CIRCLEQ_HEAD(name, type) \ struct name { \ struct type *cqh_first; /* first element */ \ struct type *cqh_last; /* last element */ \ } #define CIRCLEQ_HEAD_INITIALIZER(head) \ { \ (void *)&head, (void *)&head \ } #define CIRCLEQ_ENTRY(type) \ struct { \ struct type *cqe_next; /* next element */ \ struct type *cqe_prev; /* previous element */ \ } /* * Circular queue functions. */ #define CIRCLEQ_INIT(head) \ do { \ (head)->cqh_first = (void *)(head); \ (head)->cqh_last = (void *)(head); \ } while (/*CONSTCOND*/ 0) #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) \ do { \ (elm)->field.cqe_next = (listelm)->field.cqe_next; \ (elm)->field.cqe_prev = (listelm); \ if ((listelm)->field.cqe_next == (void *)(head)) \ (head)->cqh_last = (elm); \ else \ (listelm)->field.cqe_next->field.cqe_prev = (elm); \ (listelm)->field.cqe_next = (elm); \ } while (/*CONSTCOND*/ 0) #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) \ do { \ (elm)->field.cqe_next = (listelm); \ (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \ if ((listelm)->field.cqe_prev == (void *)(head)) \ (head)->cqh_first = (elm); \ else \ (listelm)->field.cqe_prev->field.cqe_next = (elm); \ (listelm)->field.cqe_prev = (elm); \ } while (/*CONSTCOND*/ 0) #define CIRCLEQ_INSERT_HEAD(head, elm, field) \ do { \ (elm)->field.cqe_next = (head)->cqh_first; \ (elm)->field.cqe_prev = (void *)(head); \ if ((head)->cqh_last == (void *)(head)) \ (head)->cqh_last = (elm); \ else \ (head)->cqh_first->field.cqe_prev = (elm); \ (head)->cqh_first = (elm); \ } while (/*CONSTCOND*/ 0) #define CIRCLEQ_INSERT_TAIL(head, elm, field) \ do { \ (elm)->field.cqe_next = (void *)(head); \ (elm)->field.cqe_prev = (head)->cqh_last; \ if ((head)->cqh_first == (void *)(head)) \ (head)->cqh_first = (elm); \ else \ (head)->cqh_last->field.cqe_next = (elm); \ (head)->cqh_last = (elm); \ } while (/*CONSTCOND*/ 0) #define CIRCLEQ_REMOVE(head, elm, field) \ do { \ if ((elm)->field.cqe_next == (void *)(head)) \ (head)->cqh_last = (elm)->field.cqe_prev; \ else \ (elm)->field.cqe_next->field.cqe_prev = (elm)->field.cqe_prev; \ if ((elm)->field.cqe_prev == (void *)(head)) \ (head)->cqh_first = (elm)->field.cqe_next; \ else \ (elm)->field.cqe_prev->field.cqe_next = (elm)->field.cqe_next; \ } while (/*CONSTCOND*/ 0) #define CIRCLEQ_FOREACH(var, head, field) \ for ((var) = ((head)->cqh_first); (var) != (const void *)(head); \ (var) = ((var)->field.cqe_next)) #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \ for ((var) = ((head)->cqh_last); (var) != (const void *)(head); \ (var) = ((var)->field.cqe_prev)) /* * Circular queue access methods. */ #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head)) #define CIRCLEQ_FIRST(head) ((head)->cqh_first) #define CIRCLEQ_LAST(head) ((head)->cqh_last) #define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next) #define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev) #define CIRCLEQ_LOOP_NEXT(head, elm, field) \ (((elm)->field.cqe_next == (void *)(head)) ? ((head)->cqh_first) \ : (elm->field.cqe_next)) #define CIRCLEQ_LOOP_PREV(head, elm, field) \ (((elm)->field.cqe_prev == (void *)(head)) ? ((head)->cqh_last) \ : (elm->field.cqe_prev)) #endif /* sys/queue.h */