172 lines
6.7 KiB
C
172 lines
6.7 KiB
C
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/* $OpenBSD: queue.h,v 1.43 2015/12/28 19:38:40 millert Exp $ */
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/* $NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $ */
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/*
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)queue.h 8.5 (Berkeley) 8/20/94
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*/
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#ifndef _SYS_QUEUE_H_
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#define _SYS_QUEUE_H_
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/*
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* This file defines five types of data structures: singly-linked lists,
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* lists, simple queues, tail queues and XOR simple queues.
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*
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*
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* A singly-linked list is headed by a single forward pointer. The elements
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* are singly linked for minimum space and pointer manipulation overhead at
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* the expense of O(n) removal for arbitrary elements. New elements can be
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* added to the list after an existing element or at the head of the list.
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* Elements being removed from the head of the list should use the explicit
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* macro for this purpose for optimum efficiency. A singly-linked list may
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* only be traversed in the forward direction. Singly-linked lists are ideal
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* for applications with large datasets and few or no removals or for
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* implementing a LIFO queue.
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*
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* A list is headed by a single forward pointer (or an array of forward
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* pointers for a hash table header). The elements are doubly linked
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* so that an arbitrary element can be removed without a need to
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* traverse the list. New elements can be added to the list before
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* or after an existing element or at the head of the list. A list
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* may only be traversed in the forward direction.
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*
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* A simple queue is headed by a pair of pointers, one to the head of the
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* list and the other to the tail of the list. The elements are singly
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* linked to save space, so elements can only be removed from the
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* head of the list. New elements can be added to the list before or after
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* an existing element, at the head of the list, or at the end of the
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* list. A simple queue may only be traversed in the forward direction.
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*
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* A tail queue is headed by a pair of pointers, one to the head of the
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* list and the other to the tail of the list. The elements are doubly
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* linked so that an arbitrary element can be removed without a need to
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* traverse the list. New elements can be added to the list before or
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* after an existing element, at the head of the list, or at the end of
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* the list. A tail queue may be traversed in either direction.
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*
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* An XOR simple queue is used in the same way as a regular simple queue.
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* The difference is that the head structure also includes a "cookie" that
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* is XOR'd with the queue pointer (first, last or next) to generate the
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* real pointer value.
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*
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* For details on the use of these macros, see the queue(3) manual page.
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*/
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#if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
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#define _Q_INVALIDATE(a) (a) = ((void *)-1)
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#else
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#define _Q_INVALIDATE(a)
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#endif
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/*
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* List definitions.
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*/
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#define LIST_HEAD(name, type) \
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struct name { \
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struct type *lh_first; /* first element */ \
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}
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#define LIST_HEAD_INITIALIZER(head) \
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{ NULL }
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#define LIST_ENTRY(type) \
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struct { \
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struct type *le_next; /* next element */ \
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struct type **le_prev; /* address of previous next element */ \
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}
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/*
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* List access methods.
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*/
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#define LIST_FIRST(head) ((head)->lh_first)
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#define LIST_END(head) NULL
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#define LIST_EMPTY(head) (LIST_FIRST(head) == LIST_END(head))
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#define LIST_NEXT(elm, field) ((elm)->field.le_next)
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#define LIST_FOREACH(var, head, field) \
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for((var) = LIST_FIRST(head); \
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(var)!= LIST_END(head); \
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(var) = LIST_NEXT(var, field))
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#define LIST_FOREACH_SAFE(var, head, field, tvar) \
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for ((var) = LIST_FIRST(head); \
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(var) && ((tvar) = LIST_NEXT(var, field), 1); \
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(var) = (tvar))
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/*
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* List functions.
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*/
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#define LIST_INIT(head) do { \
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LIST_FIRST(head) = LIST_END(head); \
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} while (0)
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#define LIST_INSERT_AFTER(listelm, elm, field) do { \
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if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
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(listelm)->field.le_next->field.le_prev = \
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&(elm)->field.le_next; \
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(listelm)->field.le_next = (elm); \
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(elm)->field.le_prev = &(listelm)->field.le_next; \
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} while (0)
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#define LIST_INSERT_BEFORE(listelm, elm, field) do { \
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(elm)->field.le_prev = (listelm)->field.le_prev; \
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(elm)->field.le_next = (listelm); \
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*(listelm)->field.le_prev = (elm); \
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(listelm)->field.le_prev = &(elm)->field.le_next; \
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} while (0)
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#define LIST_INSERT_HEAD(head, elm, field) do { \
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if (((elm)->field.le_next = (head)->lh_first) != NULL) \
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(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
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(head)->lh_first = (elm); \
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(elm)->field.le_prev = &(head)->lh_first; \
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} while (0)
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#define LIST_REMOVE(elm, field) do { \
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if ((elm)->field.le_next != NULL) \
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(elm)->field.le_next->field.le_prev = \
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(elm)->field.le_prev; \
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*(elm)->field.le_prev = (elm)->field.le_next; \
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_Q_INVALIDATE((elm)->field.le_prev); \
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_Q_INVALIDATE((elm)->field.le_next); \
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} while (0)
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#define LIST_REPLACE(elm, elm2, field) do { \
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if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
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(elm2)->field.le_next->field.le_prev = \
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&(elm2)->field.le_next; \
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(elm2)->field.le_prev = (elm)->field.le_prev; \
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*(elm2)->field.le_prev = (elm2); \
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_Q_INVALIDATE((elm)->field.le_prev); \
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_Q_INVALIDATE((elm)->field.le_next); \
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} while (0)
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#endif /* _SYS_QUEUE_H_ */
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