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/*      $NetBSD: queue.h,v 1.52 2009/04/20 09:56:08 mschuett Exp $ */
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/*
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 * QEMU version: Copy from netbsd, removed debug code, removed some of
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 * the implementations.  Left in singly-linked lists, lists, simple
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 * queues, and tail queues.
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 */
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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 QEMU_SYS_QUEUE_H_
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#define QEMU_SYS_QUEUE_H_
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/*
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 * This file defines four types of data structures: singly-linked lists,
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 * lists, simple queues, and tail queues.
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 *
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 * A singly-linked list is headed by a single forward pointer. The
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 * elements are singly linked for minimum space and pointer manipulation
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 * overhead at the expense of O(n) removal for arbitrary elements. New
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 * elements can be added to the list after an existing element or at the
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 * head of the list.  Elements being removed from the head of the list
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 * should use the explicit macro for this purpose for optimum
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 * efficiency. A singly-linked list may only be traversed in the forward
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 * direction.  Singly-linked lists are ideal for applications with large
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 * datasets and few or no removals or for 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 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 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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 * For details on the use of these macros, see the queue(3) manual page.
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 */
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#include "qemu/atomic.h" /* for smp_wmb() */
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/*
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 * List definitions.
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 */
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#define QLIST_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 QLIST_HEAD_INITIALIZER(head)                                    \
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        { NULL }
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#define QLIST_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 functions.
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 */
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#define QLIST_INIT(head) do {                                           \
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        (head)->lh_first = NULL;                                        \
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} while (/*CONSTCOND*/0)
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#define QLIST_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 (/*CONSTCOND*/0)
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#define QLIST_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 (/*CONSTCOND*/0)
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#define QLIST_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 (/*CONSTCOND*/0)
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#define QLIST_INSERT_HEAD_RCU(head, elm, field) do {                    \
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        (elm)->field.le_prev = &(head)->lh_first;                       \
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        (elm)->field.le_next = (head)->lh_first;                        \
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        smp_wmb(); /* fill elm before linking it */                     \
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        if ((head)->lh_first != NULL)  {                                \
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            (head)->lh_first->field.le_prev = &(elm)->field.le_next;    \
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        }                                                               \
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        (head)->lh_first = (elm);                                       \
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        smp_wmb();                                                      \
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} while (/* CONSTCOND*/0)
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#define QLIST_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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} while (/*CONSTCOND*/0)
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#define QLIST_FOREACH(var, head, field)                                 \
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        for ((var) = ((head)->lh_first);                                \
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                (var);                                                  \
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                (var) = ((var)->field.le_next))
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#define QLIST_FOREACH_SAFE(var, head, field, next_var)                  \
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        for ((var) = ((head)->lh_first);                                \
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                (var) && ((next_var) = ((var)->field.le_next), 1);      \
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                (var) = (next_var))
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/*
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 * List access methods.
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 */
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#define QLIST_EMPTY(head)                ((head)->lh_first == NULL)
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#define QLIST_FIRST(head)                ((head)->lh_first)
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#define QLIST_NEXT(elm, field)           ((elm)->field.le_next)
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/*
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 * Singly-linked List definitions.
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 */
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#define QSLIST_HEAD(name, type)                                          \
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struct name {                                                           \
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        struct type *slh_first; /* first element */                     \
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}
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#define QSLIST_HEAD_INITIALIZER(head)                                    \
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        { NULL }
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#define QSLIST_ENTRY(type)                                               \
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struct {                                                                \
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        struct type *sle_next;  /* next element */                      \
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}
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/*
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 * Singly-linked List functions.
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 */
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#define QSLIST_INIT(head) do {                                           \
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        (head)->slh_first = NULL;                                       \
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} while (/*CONSTCOND*/0)
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#define QSLIST_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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} while (/*CONSTCOND*/0)
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#define QSLIST_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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} while (/*CONSTCOND*/0)
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#define QSLIST_REMOVE_HEAD(head, field) do {                             \
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        (head)->slh_first = (head)->slh_first->field.sle_next;          \
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} while (/*CONSTCOND*/0)
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#define QSLIST_REMOVE_AFTER(slistelm, field) do {                        \
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        (slistelm)->field.sle_next =                                    \
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            QSLIST_NEXT(QSLIST_NEXT((slistelm), field), field);           \
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} while (/*CONSTCOND*/0)
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#define QSLIST_FOREACH(var, head, field)                                 \
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        for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
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#define QSLIST_FOREACH_SAFE(var, head, field, tvar)                      \
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        for ((var) = QSLIST_FIRST((head));                               \
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            (var) && ((tvar) = QSLIST_NEXT((var), field), 1);            \
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            (var) = (tvar))
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/*
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 * Singly-linked List access methods.
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 */
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#define QSLIST_EMPTY(head)       ((head)->slh_first == NULL)
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#define QSLIST_FIRST(head)       ((head)->slh_first)
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#define QSLIST_NEXT(elm, field)  ((elm)->field.sle_next)
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/*
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 * Simple queue definitions.
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 */
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#define QSIMPLEQ_HEAD(name, type)                                       \
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struct name {                                                           \
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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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}
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#define QSIMPLEQ_HEAD_INITIALIZER(head)                                 \
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    { NULL, &(head).sqh_first }
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#define QSIMPLEQ_ENTRY(type)                                            \
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struct {                                                                \
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    struct type *sqe_next;    /* next element */                        \
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}
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/*
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 * Simple queue functions.
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 */
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#define QSIMPLEQ_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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} while (/*CONSTCOND*/0)
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#define QSIMPLEQ_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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} while (/*CONSTCOND*/0)
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#define QSIMPLEQ_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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} while (/*CONSTCOND*/0)
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#define QSIMPLEQ_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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} while (/*CONSTCOND*/0)
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#define QSIMPLEQ_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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} while (/*CONSTCOND*/0)
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#define QSIMPLEQ_REMOVE(head, elm, type, field) do {                    \
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    if ((head)->sqh_first == (elm)) {                                   \
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        QSIMPLEQ_REMOVE_HEAD((head), field);                            \
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    } else {                                                            \
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        struct type *curelm = (head)->sqh_first;                        \
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        while (curelm->field.sqe_next != (elm))                         \
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            curelm = curelm->field.sqe_next;                            \
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        if ((curelm->field.sqe_next =                                   \
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            curelm->field.sqe_next->field.sqe_next) == NULL)            \
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                (head)->sqh_last = &(curelm)->field.sqe_next;           \
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    }                                                                   \
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} while (/*CONSTCOND*/0)
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#define QSIMPLEQ_FOREACH(var, head, field)                              \
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    for ((var) = ((head)->sqh_first);                                   \
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        (var);                                                          \
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        (var) = ((var)->field.sqe_next))
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#define QSIMPLEQ_FOREACH_SAFE(var, head, field, next)                   \
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    for ((var) = ((head)->sqh_first);                                   \
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        (var) && ((next = ((var)->field.sqe_next)), 1);                 \
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        (var) = (next))
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#define QSIMPLEQ_CONCAT(head1, head2) do {                              \
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    if (!QSIMPLEQ_EMPTY((head2))) {                                     \
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        *(head1)->sqh_last = (head2)->sqh_first;                        \
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        (head1)->sqh_last = (head2)->sqh_last;                          \
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        QSIMPLEQ_INIT((head2));                                         \
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    }                                                                   \
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} while (/*CONSTCOND*/0)
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#define QSIMPLEQ_LAST(head, type, field)                                \
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    (QSIMPLEQ_EMPTY((head)) ?                                           \
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        NULL :                                                          \
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            ((struct type *)(void *)                                    \
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        ((char *)((head)->sqh_last) - offsetof(struct type, field))))
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/*
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 * Simple queue access methods.
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 */
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#define QSIMPLEQ_EMPTY(head)        ((head)->sqh_first == NULL)
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#define QSIMPLEQ_FIRST(head)        ((head)->sqh_first)
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#define QSIMPLEQ_NEXT(elm, field)   ((elm)->field.sqe_next)
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/*
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 * Tail queue definitions.
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 */
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#define Q_TAILQ_HEAD(name, type, qual)                                  \
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struct name {                                                           \
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        qual type *tqh_first;           /* first element */             \
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        qual type *qual *tqh_last;      /* addr of last next element */ \
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}
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#define QTAILQ_HEAD(name, type)  Q_TAILQ_HEAD(name, struct type,)
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#define QTAILQ_HEAD_INITIALIZER(head)                                   \
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        { NULL, &(head).tqh_first }
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#define Q_TAILQ_ENTRY(type, qual)                                       \
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struct {                                                                \
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        qual type *tqe_next;            /* next element */              \
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        qual type *qual *tqe_prev;      /* address of previous next element */\
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}
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#define QTAILQ_ENTRY(type)       Q_TAILQ_ENTRY(struct type,)
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/*
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 * Tail queue functions.
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 */
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#define QTAILQ_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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} while (/*CONSTCOND*/0)
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#define QTAILQ_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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        else                                                            \
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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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} while (/*CONSTCOND*/0)
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#define QTAILQ_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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} while (/*CONSTCOND*/0)
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#define QTAILQ_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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        else                                                            \
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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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} while (/*CONSTCOND*/0)
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#define QTAILQ_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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} while (/*CONSTCOND*/0)
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#define QTAILQ_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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        else                                                            \
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                (head)->tqh_last = (elm)->field.tqe_prev;               \
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        *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
385
} while (/*CONSTCOND*/0)
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#define QTAILQ_FOREACH(var, head, field)                                \
388
        for ((var) = ((head)->tqh_first);                               \
389
                (var);                                                  \
390
                (var) = ((var)->field.tqe_next))
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#define QTAILQ_FOREACH_SAFE(var, head, field, next_var)                 \
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        for ((var) = ((head)->tqh_first);                               \
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                (var) && ((next_var) = ((var)->field.tqe_next), 1);     \
395
                (var) = (next_var))
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#define QTAILQ_FOREACH_REVERSE(var, head, headname, field)              \
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        for ((var) = (*(((struct headname *)((head)->tqh_last))->tqh_last));    \
399
                (var);                                                  \
400
                (var) = (*(((struct headname *)((var)->field.tqe_prev))->tqh_last)))
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/*
403
 * Tail queue access methods.
404
 */
405
#define QTAILQ_EMPTY(head)               ((head)->tqh_first == NULL)
406
#define QTAILQ_FIRST(head)               ((head)->tqh_first)
407
#define QTAILQ_NEXT(elm, field)          ((elm)->field.tqe_next)
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#define QTAILQ_LAST(head, headname) \
410
        (*(((struct headname *)((head)->tqh_last))->tqh_last))
411
#define QTAILQ_PREV(elm, headname, field) \
412
        (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
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414
#endif  /* !QEMU_SYS_QUEUE_H_ */