/* * 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 BSD_SYS_QUEUE_CIRCLEQ_H #define BSD_SYS_QUEUE_CIRCLEQ_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 before or 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. */ #undef _Q_INVALIDATE #ifdef QUEUE_MACRO_DEBUG #define _Q_INVALIDATE(a) (a) = ((void *)-1) #else #define _Q_INVALIDATE(a) #endif /* * 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) \ { CIRCLEQ_END(&head), CIRCLEQ_END(&head) } #define CIRCLEQ_ENTRY(type) \ struct { \ struct type *cqe_next; /* next element */ \ struct type *cqe_prev; /* previous element */ \ } /* * Circular queue access methods */ #define CIRCLEQ_FIRST(head) ((head)->cqh_first) #define CIRCLEQ_LAST(head) ((head)->cqh_last) #define CIRCLEQ_END(head) ((void *)(head)) #define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next) #define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev) #define CIRCLEQ_EMPTY(head) \ (CIRCLEQ_FIRST(head) == CIRCLEQ_END(head)) #define CIRCLEQ_FOREACH(var, head, field) \ for((var) = CIRCLEQ_FIRST(head); \ (var) != CIRCLEQ_END(head); \ (var) = CIRCLEQ_NEXT(var, field)) #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \ for((var) = CIRCLEQ_LAST(head); \ (var) != CIRCLEQ_END(head); \ (var) = CIRCLEQ_PREV(var, field)) /* * Circular queue functions. */ #define CIRCLEQ_INIT(head) do { \ (head)->cqh_first = CIRCLEQ_END(head); \ (head)->cqh_last = CIRCLEQ_END(head); \ } while (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 == CIRCLEQ_END(head)) \ (head)->cqh_last = (elm); \ else \ (listelm)->field.cqe_next->field.cqe_prev = (elm); \ (listelm)->field.cqe_next = (elm); \ } while (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 == CIRCLEQ_END(head)) \ (head)->cqh_first = (elm); \ else \ (listelm)->field.cqe_prev->field.cqe_next = (elm); \ (listelm)->field.cqe_prev = (elm); \ } while (0) #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \ (elm)->field.cqe_next = (head)->cqh_first; \ (elm)->field.cqe_prev = CIRCLEQ_END(head); \ if ((head)->cqh_last == CIRCLEQ_END(head)) \ (head)->cqh_last = (elm); \ else \ (head)->cqh_first->field.cqe_prev = (elm); \ (head)->cqh_first = (elm); \ } while (0) #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \ (elm)->field.cqe_next = CIRCLEQ_END(head); \ (elm)->field.cqe_prev = (head)->cqh_last; \ if ((head)->cqh_first == CIRCLEQ_END(head)) \ (head)->cqh_first = (elm); \ else \ (head)->cqh_last->field.cqe_next = (elm); \ (head)->cqh_last = (elm); \ } while (0) #define CIRCLEQ_REMOVE(head, elm, field) do { \ if ((elm)->field.cqe_next == CIRCLEQ_END(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 == CIRCLEQ_END(head)) \ (head)->cqh_first = (elm)->field.cqe_next; \ else \ (elm)->field.cqe_prev->field.cqe_next = \ (elm)->field.cqe_next; \ _Q_INVALIDATE((elm)->field.cqe_prev); \ _Q_INVALIDATE((elm)->field.cqe_next); \ } while (0) #define CIRCLEQ_REPLACE(head, elm, elm2, field) do { \ if (((elm2)->field.cqe_next = (elm)->field.cqe_next) == \ CIRCLEQ_END(head)) \ (head).cqh_last = (elm2); \ else \ (elm2)->field.cqe_next->field.cqe_prev = (elm2); \ if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) == \ CIRCLEQ_END(head)) \ (head).cqh_first = (elm2); \ else \ (elm2)->field.cqe_prev->field.cqe_next = (elm2); \ _Q_INVALIDATE((elm)->field.cqe_prev); \ _Q_INVALIDATE((elm)->field.cqe_next); \ } while (0) #endif /* !BSD_SYS_QUEUE_CIRCLEQ_H */