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/* $OpenBSD: queue.h,v 1.31 2005/11/25 08:06:25 otto Exp $ */
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/* $NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $ */
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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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* 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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* 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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* 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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* @(#)queue.h 8.5 (Berkeley) 8/20/94
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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 circular queues.
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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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* 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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* A simple queue is headed by a pair of pointers, one 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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* 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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* A circle 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 after
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* an existing element, at the head of the list, or at the end of the list.
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* A circle queue may be traversed in either direction, but has a more
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* complex end of list detection.
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* For details on the use of these macros, see the queue(3) manual page.
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#ifdef QUEUE_MACRO_DEBUG
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#define _Q_INVALIDATE(a) (a) = ((void *)-1)
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#define _Q_INVALIDATE(a)
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* Singly-linked List definitions.
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#define SLIST_HEAD(name, type) \
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struct type *slh_first; /* first element */ \
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#define SLIST_HEAD_INITIALIZER(head) \
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#define SLIST_ENTRY(type) \
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struct type *sle_next; /* next element */ \
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* Singly-linked List access methods.
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#define SLIST_FIRST(head) ((head)->slh_first)
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#define SLIST_END(head) NULL
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#define SLIST_EMPTY(head) (SLIST_FIRST(head) == SLIST_END(head))
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#define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
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#define SLIST_FOREACH(var, head, field) \
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for((var) = SLIST_FIRST(head); \
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(var) != SLIST_END(head); \
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(var) = SLIST_NEXT(var, field))
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#define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
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for ((varp) = &SLIST_FIRST((head)); \
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((var) = *(varp)) != SLIST_END(head); \
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(varp) = &SLIST_NEXT((var), field))
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* Singly-linked List functions.
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#define SLIST_INIT(head) { \
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SLIST_FIRST(head) = SLIST_END(head); \
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#define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
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(elm)->field.sle_next = (slistelm)->field.sle_next; \
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(slistelm)->field.sle_next = (elm); \
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#define SLIST_INSERT_HEAD(head, elm, field) do { \
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(elm)->field.sle_next = (head)->slh_first; \
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(head)->slh_first = (elm); \
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#define SLIST_REMOVE_NEXT(head, elm, field) do { \
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(elm)->field.sle_next = (elm)->field.sle_next->field.sle_next; \
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#define SLIST_REMOVE_HEAD(head, field) do { \
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(head)->slh_first = (head)->slh_first->field.sle_next; \
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#define SLIST_REMOVE(head, elm, type, field) do { \
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if ((head)->slh_first == (elm)) { \
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SLIST_REMOVE_HEAD((head), field); \
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struct type *curelm = (head)->slh_first; \
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while (curelm->field.sle_next != (elm)) \
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curelm = curelm->field.sle_next; \
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curelm->field.sle_next = \
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curelm->field.sle_next->field.sle_next; \
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_Q_INVALIDATE((elm)->field.sle_next); \
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#define LIST_HEAD(name, type) \
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struct type *lh_first; /* first element */ \
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#define LIST_HEAD_INITIALIZER(head) \
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#define LIST_ENTRY(type) \
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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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* List access methods
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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_INIT(head) do { \
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LIST_FIRST(head) = LIST_END(head); \
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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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#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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#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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#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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#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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* Simple queue definitions.
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#define SIMPLEQ_HEAD(name, type) \
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struct type *sqh_first; /* first element */ \
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struct type **sqh_last; /* addr of last next element */ \
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#define SIMPLEQ_HEAD_INITIALIZER(head) \
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{ NULL, &(head).sqh_first }
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#define SIMPLEQ_ENTRY(type) \
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struct type *sqe_next; /* next element */ \
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* Simple queue access methods.
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#define SIMPLEQ_FIRST(head) ((head)->sqh_first)
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#define SIMPLEQ_END(head) NULL
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#define SIMPLEQ_EMPTY(head) (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
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#define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
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#define SIMPLEQ_FOREACH(var, head, field) \
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for((var) = SIMPLEQ_FIRST(head); \
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(var) != SIMPLEQ_END(head); \
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(var) = SIMPLEQ_NEXT(var, field))
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* Simple queue functions.
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#define SIMPLEQ_INIT(head) do { \
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(head)->sqh_first = NULL; \
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(head)->sqh_last = &(head)->sqh_first; \
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#define SIMPLEQ_INSERT_HEAD(head, elm, field) do { \
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if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
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(head)->sqh_last = &(elm)->field.sqe_next; \
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(head)->sqh_first = (elm); \
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#define SIMPLEQ_INSERT_TAIL(head, elm, field) do { \
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(elm)->field.sqe_next = NULL; \
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*(head)->sqh_last = (elm); \
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(head)->sqh_last = &(elm)->field.sqe_next; \
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#define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
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if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
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(head)->sqh_last = &(elm)->field.sqe_next; \
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(listelm)->field.sqe_next = (elm); \
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#define SIMPLEQ_REMOVE_HEAD(head, field) do { \
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if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
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(head)->sqh_last = &(head)->sqh_first; \
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* Tail queue definitions.
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#define TAILQ_HEAD(name, type) \
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struct type *tqh_first; /* first element */ \
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struct type **tqh_last; /* addr of last next element */ \
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#define TAILQ_HEAD_INITIALIZER(head) \
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{ NULL, &(head).tqh_first }
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#define TAILQ_ENTRY(type) \
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struct type *tqe_next; /* next element */ \
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struct type **tqe_prev; /* address of previous next element */ \
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* tail queue access methods
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#define TAILQ_FIRST(head) ((head)->tqh_first)
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#define TAILQ_END(head) NULL
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#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
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#define TAILQ_LAST(head, headname) \
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(*(((struct headname *)((head)->tqh_last))->tqh_last))
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#define TAILQ_PREV(elm, headname, field) \
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(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
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#define TAILQ_EMPTY(head) \
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(TAILQ_FIRST(head) == TAILQ_END(head))
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#define TAILQ_FOREACH(var, head, field) \
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for((var) = TAILQ_FIRST(head); \
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(var) != TAILQ_END(head); \
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(var) = TAILQ_NEXT(var, field))
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#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
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for((var) = TAILQ_LAST(head, headname); \
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(var) != TAILQ_END(head); \
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(var) = TAILQ_PREV(var, headname, field))
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* Tail queue functions.
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#define TAILQ_INIT(head) do { \
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(head)->tqh_first = NULL; \
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(head)->tqh_last = &(head)->tqh_first; \
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#define TAILQ_INSERT_HEAD(head, elm, field) do { \
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if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
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(head)->tqh_first->field.tqe_prev = \
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&(elm)->field.tqe_next; \
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(head)->tqh_last = &(elm)->field.tqe_next; \
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(head)->tqh_first = (elm); \
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(elm)->field.tqe_prev = &(head)->tqh_first; \
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#define TAILQ_INSERT_TAIL(head, elm, field) do { \
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(elm)->field.tqe_next = NULL; \
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(elm)->field.tqe_prev = (head)->tqh_last; \
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*(head)->tqh_last = (elm); \
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(head)->tqh_last = &(elm)->field.tqe_next; \
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#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
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if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
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(elm)->field.tqe_next->field.tqe_prev = \
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&(elm)->field.tqe_next; \
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(head)->tqh_last = &(elm)->field.tqe_next; \
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(listelm)->field.tqe_next = (elm); \
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(elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
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#define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
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(elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
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(elm)->field.tqe_next = (listelm); \
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*(listelm)->field.tqe_prev = (elm); \
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(listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
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#define TAILQ_REMOVE(head, elm, field) do { \
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if (((elm)->field.tqe_next) != NULL) \
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(elm)->field.tqe_next->field.tqe_prev = \
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(elm)->field.tqe_prev; \
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(head)->tqh_last = (elm)->field.tqe_prev; \
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*(elm)->field.tqe_prev = (elm)->field.tqe_next; \
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_Q_INVALIDATE((elm)->field.tqe_prev); \
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_Q_INVALIDATE((elm)->field.tqe_next); \
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#define TAILQ_REPLACE(head, elm, elm2, field) do { \
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if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
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(elm2)->field.tqe_next->field.tqe_prev = \
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&(elm2)->field.tqe_next; \
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(head)->tqh_last = &(elm2)->field.tqe_next; \
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(elm2)->field.tqe_prev = (elm)->field.tqe_prev; \
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*(elm2)->field.tqe_prev = (elm2); \
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_Q_INVALIDATE((elm)->field.tqe_prev); \
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_Q_INVALIDATE((elm)->field.tqe_next); \
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* Circular queue definitions.
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#define CIRCLEQ_HEAD(name, type) \
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struct type *cqh_first; /* first element */ \
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struct type *cqh_last; /* last element */ \
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#define CIRCLEQ_HEAD_INITIALIZER(head) \
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{ CIRCLEQ_END(&head), CIRCLEQ_END(&head) }
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#define CIRCLEQ_ENTRY(type) \
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struct type *cqe_next; /* next element */ \
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struct type *cqe_prev; /* previous element */ \
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* Circular queue access methods
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#define CIRCLEQ_FIRST(head) ((head)->cqh_first)
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#define CIRCLEQ_LAST(head) ((head)->cqh_last)
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#define CIRCLEQ_END(head) ((void *)(head))
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#define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next)
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#define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev)
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#define CIRCLEQ_EMPTY(head) \
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(CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
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#define CIRCLEQ_FOREACH(var, head, field) \
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for((var) = CIRCLEQ_FIRST(head); \
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(var) != CIRCLEQ_END(head); \
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(var) = CIRCLEQ_NEXT(var, field))
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#define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
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for((var) = CIRCLEQ_LAST(head); \
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(var) != CIRCLEQ_END(head); \
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(var) = CIRCLEQ_PREV(var, field))
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* Circular queue functions.
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#define CIRCLEQ_INIT(head) do { \
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(head)->cqh_first = CIRCLEQ_END(head); \
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(head)->cqh_last = CIRCLEQ_END(head); \
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#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
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(elm)->field.cqe_next = (listelm)->field.cqe_next; \
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(elm)->field.cqe_prev = (listelm); \
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if ((listelm)->field.cqe_next == CIRCLEQ_END(head)) \
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(head)->cqh_last = (elm); \
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(listelm)->field.cqe_next->field.cqe_prev = (elm); \
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(listelm)->field.cqe_next = (elm); \
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#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
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(elm)->field.cqe_next = (listelm); \
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(elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
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if ((listelm)->field.cqe_prev == CIRCLEQ_END(head)) \
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(head)->cqh_first = (elm); \
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(listelm)->field.cqe_prev->field.cqe_next = (elm); \
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(listelm)->field.cqe_prev = (elm); \
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#define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
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(elm)->field.cqe_next = (head)->cqh_first; \
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(elm)->field.cqe_prev = CIRCLEQ_END(head); \
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if ((head)->cqh_last == CIRCLEQ_END(head)) \
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(head)->cqh_last = (elm); \
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(head)->cqh_first->field.cqe_prev = (elm); \
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(head)->cqh_first = (elm); \
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#define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
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(elm)->field.cqe_next = CIRCLEQ_END(head); \
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(elm)->field.cqe_prev = (head)->cqh_last; \
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if ((head)->cqh_first == CIRCLEQ_END(head)) \
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(head)->cqh_first = (elm); \
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(head)->cqh_last->field.cqe_next = (elm); \
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(head)->cqh_last = (elm); \
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#define CIRCLEQ_REMOVE(head, elm, field) do { \
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if ((elm)->field.cqe_next == CIRCLEQ_END(head)) \
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(head)->cqh_last = (elm)->field.cqe_prev; \
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(elm)->field.cqe_next->field.cqe_prev = \
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(elm)->field.cqe_prev; \
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if ((elm)->field.cqe_prev == CIRCLEQ_END(head)) \
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(head)->cqh_first = (elm)->field.cqe_next; \
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(elm)->field.cqe_prev->field.cqe_next = \
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(elm)->field.cqe_next; \
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_Q_INVALIDATE((elm)->field.cqe_prev); \
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_Q_INVALIDATE((elm)->field.cqe_next); \
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#define CIRCLEQ_REPLACE(head, elm, elm2, field) do { \
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if (((elm2)->field.cqe_next = (elm)->field.cqe_next) == \
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(head).cqh_last = (elm2); \
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(elm2)->field.cqe_next->field.cqe_prev = (elm2); \
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if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) == \
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(head).cqh_first = (elm2); \
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(elm2)->field.cqe_prev->field.cqe_next = (elm2); \
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_Q_INVALIDATE((elm)->field.cqe_prev); \
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_Q_INVALIDATE((elm)->field.cqe_next); \
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#endif /* !_SYS_QUEUE_H_ */