Program Listing for File queue.h¶
↰ Return to documentation for file (lib/queue.h)
/* $OpenBSD: queue.h,v 1.46 2020/12/30 13:33:12 millert Exp $ */
/* $NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $ */
/*
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)queue.h 8.5 (Berkeley) 8/20/94
*/
#ifndef _SYS_QUEUE_H_
#define _SYS_QUEUE_H_
/*
* This file defines five types of data structures: singly-linked lists,
* lists, simple queues, tail queues and XOR simple 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 to 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.
*
* An XOR simple queue is used in the same way as a regular simple queue.
* The difference is that the head structure also includes a "cookie" that
* is XOR'd with the queue pointer (first, last or next) to generate the
* real pointer value.
*
* For details on the use of these macros, see the queue(3) manual page.
*/
#if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
#define _Q_INVALID ((void *)-1)
#define _Q_INVALIDATE(a) (a) = _Q_INVALID
#else
#define _Q_INVALIDATE(a)
#endif
/*
* Singly-linked List definitions.
*/
#define SLIST_HEAD(name, type) \
struct name { \
struct type *slh_first; /* first element */ \
}
#define SLIST_HEAD_INITIALIZER(head) \
{ NULL }
#define SLIST_ENTRY(type) \
struct { \
struct type *sle_next; /* next element */ \
}
/*
* Singly-linked List access methods.
*/
#define SLIST_FIRST(head) ((head)->slh_first)
#define SLIST_END(head) NULL
#define SLIST_EMPTY(head) (SLIST_FIRST(head) == SLIST_END(head))
#define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
#define SLIST_FOREACH(var, head, field) \
for ((var) = SLIST_FIRST(head); (var) != SLIST_END(head); \
(var) = SLIST_NEXT(var, field))
#define SLIST_FOREACH_SAFE(var, head, field, tvar) \
for ((var) = SLIST_FIRST(head); \
(var) && ((tvar) = SLIST_NEXT(var, field), 1); (var) = (tvar))
/*
* Singly-linked List functions.
*/
#define SLIST_INIT(head) \
{ SLIST_FIRST(head) = SLIST_END(head); }
#define SLIST_INSERT_AFTER(slistelm, elm, field) \
do { \
(elm)->field.sle_next = (slistelm)->field.sle_next; \
(slistelm)->field.sle_next = (elm); \
} while (0)
#define SLIST_INSERT_HEAD(head, elm, field) \
do { \
(elm)->field.sle_next = (head)->slh_first; \
(head)->slh_first = (elm); \
} while (0)
#define SLIST_REMOVE_AFTER(elm, field) \
do { \
(elm)->field.sle_next = (elm)->field.sle_next->field.sle_next; \
} while (0)
#define SLIST_REMOVE_HEAD(head, field) \
do { \
(head)->slh_first = (head)->slh_first->field.sle_next; \
} while (0)
#define SLIST_REMOVE(head, elm, type, field) \
do { \
if ((head)->slh_first == (elm)) { \
SLIST_REMOVE_HEAD((head), field); \
} else { \
struct type *curelm = (head)->slh_first; \
\
while (curelm->field.sle_next != (elm)) \
curelm = curelm->field.sle_next; \
curelm->field.sle_next = curelm->field.sle_next->field.sle_next; \
} \
_Q_INVALIDATE((elm)->field.sle_next); \
} while (0)
/*
* List definitions.
*/
#define LIST_HEAD(name, type) \
struct name { \
struct type *lh_first; /* first element */ \
}
#define LIST_HEAD_INITIALIZER(head) \
{ NULL }
#define LIST_ENTRY(type) \
struct { \
struct type *le_next; /* next element */ \
struct type **le_prev; /* address of previous next element */ \
}
/*
* List access methods.
*/
#define LIST_FIRST(head) ((head)->lh_first)
#define LIST_END(head) NULL
#define LIST_EMPTY(head) (LIST_FIRST(head) == LIST_END(head))
#define LIST_NEXT(elm, field) ((elm)->field.le_next)
#define LIST_FOREACH(var, head, field) \
for ((var) = LIST_FIRST(head); (var) != LIST_END(head); \
(var) = LIST_NEXT(var, field))
#define LIST_FOREACH_SAFE(var, head, field, tvar) \
for ((var) = LIST_FIRST(head); (var) && ((tvar) = LIST_NEXT(var, field), 1); \
(var) = (tvar))
/*
* List functions.
*/
#define LIST_INIT(head) \
do { \
LIST_FIRST(head) = LIST_END(head); \
} while (0)
#define LIST_INSERT_AFTER(listelm, elm, field) \
do { \
if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
(listelm)->field.le_next->field.le_prev = &(elm)->field.le_next; \
(listelm)->field.le_next = (elm); \
(elm)->field.le_prev = &(listelm)->field.le_next; \
} while (0)
#define LIST_INSERT_BEFORE(listelm, elm, field) \
do { \
(elm)->field.le_prev = (listelm)->field.le_prev; \
(elm)->field.le_next = (listelm); \
*(listelm)->field.le_prev = (elm); \
(listelm)->field.le_prev = &(elm)->field.le_next; \
} while (0)
#define LIST_INSERT_HEAD(head, elm, field) \
do { \
if (((elm)->field.le_next = (head)->lh_first) != NULL) \
(head)->lh_first->field.le_prev = &(elm)->field.le_next; \
(head)->lh_first = (elm); \
(elm)->field.le_prev = &(head)->lh_first; \
} while (0)
#define LIST_REMOVE(elm, field) \
do { \
if ((elm)->field.le_next != NULL) \
(elm)->field.le_next->field.le_prev = (elm)->field.le_prev; \
*(elm)->field.le_prev = (elm)->field.le_next; \
_Q_INVALIDATE((elm)->field.le_prev); \
_Q_INVALIDATE((elm)->field.le_next); \
} while (0)
#define LIST_REPLACE(elm, elm2, field) \
do { \
if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
(elm2)->field.le_next->field.le_prev = &(elm2)->field.le_next; \
(elm2)->field.le_prev = (elm)->field.le_prev; \
*(elm2)->field.le_prev = (elm2); \
_Q_INVALIDATE((elm)->field.le_prev); \
_Q_INVALIDATE((elm)->field.le_next); \
} while (0)
/*
* Simple queue definitions.
*/
#define SIMPLEQ_HEAD(name, type) \
struct name { \
struct type *sqh_first; /* first element */ \
struct type **sqh_last; /* addr of last next element */ \
}
#define SIMPLEQ_HEAD_INITIALIZER(head) \
{ NULL, &(head).sqh_first }
#define SIMPLEQ_ENTRY(type) \
struct { \
struct type *sqe_next; /* next element */ \
}
/*
* Simple queue access methods.
*/
#define SIMPLEQ_FIRST(head) ((head)->sqh_first)
#define SIMPLEQ_END(head) NULL
#define SIMPLEQ_EMPTY(head) (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
#define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
#define SIMPLEQ_FOREACH(var, head, field) \
for ((var) = SIMPLEQ_FIRST(head); (var) != SIMPLEQ_END(head); \
(var) = SIMPLEQ_NEXT(var, field))
#define SIMPLEQ_FOREACH_SAFE(var, head, field, tvar) \
for ((var) = SIMPLEQ_FIRST(head); \
(var) && ((tvar) = SIMPLEQ_NEXT(var, field), 1); (var) = (tvar))
/*
* Simple queue functions.
*/
#define SIMPLEQ_INIT(head) \
do { \
(head)->sqh_first = NULL; \
(head)->sqh_last = &(head)->sqh_first; \
} while (0)
#define SIMPLEQ_INSERT_HEAD(head, elm, field) \
do { \
if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
(head)->sqh_last = &(elm)->field.sqe_next; \
(head)->sqh_first = (elm); \
} while (0)
#define SIMPLEQ_INSERT_TAIL(head, elm, field) \
do { \
(elm)->field.sqe_next = NULL; \
*(head)->sqh_last = (elm); \
(head)->sqh_last = &(elm)->field.sqe_next; \
} while (0)
#define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) \
do { \
if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL) \
(head)->sqh_last = &(elm)->field.sqe_next; \
(listelm)->field.sqe_next = (elm); \
} while (0)
#define SIMPLEQ_REMOVE_HEAD(head, field) \
do { \
if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
(head)->sqh_last = &(head)->sqh_first; \
} while (0)
#define SIMPLEQ_REMOVE_AFTER(head, elm, field) \
do { \
if (((elm)->field.sqe_next = (elm)->field.sqe_next->field.sqe_next) == \
NULL) \
(head)->sqh_last = &(elm)->field.sqe_next; \
} while (0)
#define SIMPLEQ_CONCAT(head1, head2) \
do { \
if (!SIMPLEQ_EMPTY((head2))) { \
*(head1)->sqh_last = (head2)->sqh_first; \
(head1)->sqh_last = (head2)->sqh_last; \
SIMPLEQ_INIT((head2)); \
} \
} while (0)
/*
* XOR Simple queue definitions.
*/
#define XSIMPLEQ_HEAD(name, type) \
struct name { \
struct type *sqx_first; /* first element */ \
struct type **sqx_last; /* addr of last next element */ \
unsigned long sqx_cookie; \
}
#define XSIMPLEQ_ENTRY(type) \
struct { \
struct type *sqx_next; /* next element */ \
}
/*
* XOR Simple queue access methods.
*/
#define XSIMPLEQ_XOR(head, ptr) \
((__typeof(ptr))((head)->sqx_cookie ^ (unsigned long)(ptr)))
#define XSIMPLEQ_FIRST(head) XSIMPLEQ_XOR(head, ((head)->sqx_first))
#define XSIMPLEQ_END(head) NULL
#define XSIMPLEQ_EMPTY(head) (XSIMPLEQ_FIRST(head) == XSIMPLEQ_END(head))
#define XSIMPLEQ_NEXT(head, elm, field) \
XSIMPLEQ_XOR(head, ((elm)->field.sqx_next))
#define XSIMPLEQ_FOREACH(var, head, field) \
for ((var) = XSIMPLEQ_FIRST(head); (var) != XSIMPLEQ_END(head); \
(var) = XSIMPLEQ_NEXT(head, var, field))
#define XSIMPLEQ_FOREACH_SAFE(var, head, field, tvar) \
for ((var) = XSIMPLEQ_FIRST(head); \
(var) && ((tvar) = XSIMPLEQ_NEXT(head, var, field), 1); (var) = (tvar))
/*
* XOR Simple queue functions.
*/
#define XSIMPLEQ_INIT(head) \
do { \
arc4random_buf(&(head)->sqx_cookie, sizeof((head)->sqx_cookie)); \
(head)->sqx_first = XSIMPLEQ_XOR(head, NULL); \
(head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first); \
} while (0)
#define XSIMPLEQ_INSERT_HEAD(head, elm, field) \
do { \
if (((elm)->field.sqx_next = (head)->sqx_first) == \
XSIMPLEQ_XOR(head, NULL)) \
(head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
(head)->sqx_first = XSIMPLEQ_XOR(head, (elm)); \
} while (0)
#define XSIMPLEQ_INSERT_TAIL(head, elm, field) \
do { \
(elm)->field.sqx_next = XSIMPLEQ_XOR(head, NULL); \
*(XSIMPLEQ_XOR(head, (head)->sqx_last)) = XSIMPLEQ_XOR(head, (elm)); \
(head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
} while (0)
#define XSIMPLEQ_INSERT_AFTER(head, listelm, elm, field) \
do { \
if (((elm)->field.sqx_next = (listelm)->field.sqx_next) == \
XSIMPLEQ_XOR(head, NULL)) \
(head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
(listelm)->field.sqx_next = XSIMPLEQ_XOR(head, (elm)); \
} while (0)
#define XSIMPLEQ_REMOVE_HEAD(head, field) \
do { \
if (((head)->sqx_first = \
XSIMPLEQ_XOR(head, (head)->sqx_first)->field.sqx_next) == \
XSIMPLEQ_XOR(head, NULL)) \
(head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first); \
} while (0)
#define XSIMPLEQ_REMOVE_AFTER(head, elm, field) \
do { \
if (((elm)->field.sqx_next = \
XSIMPLEQ_XOR(head, (elm)->field.sqx_next)->field.sqx_next) == \
XSIMPLEQ_XOR(head, NULL)) \
(head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
} while (0)
/*
* Tail queue definitions.
*/
#define TAILQ_HEAD(name, type) \
struct name { \
struct type *tqh_first; /* first element */ \
struct type **tqh_last; /* addr of last next element */ \
}
#define TAILQ_HEAD_INITIALIZER(head) \
{ NULL, &(head).tqh_first }
#define TAILQ_ENTRY(type) \
struct { \
struct type *tqe_next; /* next element */ \
struct type **tqe_prev; /* address of previous next element */ \
}
/*
* Tail queue access methods.
*/
#define TAILQ_FIRST(head) ((head)->tqh_first)
#define TAILQ_END(head) NULL
#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
#define TAILQ_LAST(head, headname) \
(*(((struct headname *)((head)->tqh_last))->tqh_last))
/* XXX */
#define TAILQ_PREV(elm, headname, field) \
(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
#define TAILQ_EMPTY(head) (TAILQ_FIRST(head) == TAILQ_END(head))
#define TAILQ_FOREACH(var, head, field) \
for ((var) = TAILQ_FIRST(head); (var) != TAILQ_END(head); \
(var) = TAILQ_NEXT(var, field))
#define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
for ((var) = TAILQ_FIRST(head); \
(var) != TAILQ_END(head) && ((tvar) = TAILQ_NEXT(var, field), 1); \
(var) = (tvar))
#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
for ((var) = TAILQ_LAST(head, headname); (var) != TAILQ_END(head); \
(var) = TAILQ_PREV(var, headname, field))
#define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
for ((var) = TAILQ_LAST(head, headname); \
(var) != TAILQ_END(head) && \
((tvar) = TAILQ_PREV(var, headname, field), 1); \
(var) = (tvar))
/*
* Tail queue functions.
*/
#define TAILQ_INIT(head) \
do { \
(head)->tqh_first = NULL; \
(head)->tqh_last = &(head)->tqh_first; \
} while (0)
#define TAILQ_INSERT_HEAD(head, elm, field) \
do { \
if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
(head)->tqh_first->field.tqe_prev = &(elm)->field.tqe_next; \
else \
(head)->tqh_last = &(elm)->field.tqe_next; \
(head)->tqh_first = (elm); \
(elm)->field.tqe_prev = &(head)->tqh_first; \
} while (0)
#define TAILQ_INSERT_TAIL(head, elm, field) \
do { \
(elm)->field.tqe_next = NULL; \
(elm)->field.tqe_prev = (head)->tqh_last; \
*(head)->tqh_last = (elm); \
(head)->tqh_last = &(elm)->field.tqe_next; \
} while (0)
#define TAILQ_INSERT_AFTER(head, listelm, elm, field) \
do { \
if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL) \
(elm)->field.tqe_next->field.tqe_prev = &(elm)->field.tqe_next; \
else \
(head)->tqh_last = &(elm)->field.tqe_next; \
(listelm)->field.tqe_next = (elm); \
(elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
} while (0)
#define TAILQ_INSERT_BEFORE(listelm, elm, field) \
do { \
(elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
(elm)->field.tqe_next = (listelm); \
*(listelm)->field.tqe_prev = (elm); \
(listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
} while (0)
#define TAILQ_REMOVE(head, elm, field) \
do { \
if (((elm)->field.tqe_next) != NULL) \
(elm)->field.tqe_next->field.tqe_prev = (elm)->field.tqe_prev; \
else \
(head)->tqh_last = (elm)->field.tqe_prev; \
*(elm)->field.tqe_prev = (elm)->field.tqe_next; \
_Q_INVALIDATE((elm)->field.tqe_prev); \
_Q_INVALIDATE((elm)->field.tqe_next); \
} while (0)
#define TAILQ_REPLACE(head, elm, elm2, field) \
do { \
if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
(elm2)->field.tqe_next->field.tqe_prev = &(elm2)->field.tqe_next; \
else \
(head)->tqh_last = &(elm2)->field.tqe_next; \
(elm2)->field.tqe_prev = (elm)->field.tqe_prev; \
*(elm2)->field.tqe_prev = (elm2); \
_Q_INVALIDATE((elm)->field.tqe_prev); \
_Q_INVALIDATE((elm)->field.tqe_next); \
} while (0)
#define TAILQ_CONCAT(head1, head2, field) \
do { \
if (!TAILQ_EMPTY(head2)) { \
*(head1)->tqh_last = (head2)->tqh_first; \
(head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
(head1)->tqh_last = (head2)->tqh_last; \
TAILQ_INIT((head2)); \
} \
} while (0)
/*
* Singly-linked Tail queue declarations.
*/
#define STAILQ_HEAD(name, type) \
struct name { \
struct type *stqh_first; /* first element */ \
struct type **stqh_last; /* addr of last next element */ \
}
#define STAILQ_HEAD_INITIALIZER(head) \
{ NULL, &(head).stqh_first }
#define STAILQ_ENTRY(type) \
struct { \
struct type *stqe_next; /* next element */ \
}
/*
* Singly-linked Tail queue access methods.
*/
#define STAILQ_FIRST(head) ((head)->stqh_first)
#define STAILQ_END(head) NULL
#define STAILQ_EMPTY(head) (STAILQ_FIRST(head) == STAILQ_END(head))
#define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
#define STAILQ_FOREACH(var, head, field) \
for ((var) = STAILQ_FIRST(head); (var) != STAILQ_END(head); \
(var) = STAILQ_NEXT(var, field))
#define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
for ((var) = STAILQ_FIRST(head); \
(var) && ((tvar) = STAILQ_NEXT(var, field), 1); (var) = (tvar))
/*
* Singly-linked Tail queue functions.
*/
#define STAILQ_INIT(head) \
do { \
STAILQ_FIRST((head)) = NULL; \
(head)->stqh_last = &STAILQ_FIRST((head)); \
} while (0)
#define STAILQ_INSERT_HEAD(head, elm, field) \
do { \
if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
(head)->stqh_last = &STAILQ_NEXT((elm), field); \
STAILQ_FIRST((head)) = (elm); \
} while (0)
#define STAILQ_INSERT_TAIL(head, elm, field) \
do { \
STAILQ_NEXT((elm), field) = NULL; \
*(head)->stqh_last = (elm); \
(head)->stqh_last = &STAILQ_NEXT((elm), field); \
} while (0)
#define STAILQ_INSERT_AFTER(head, listelm, elm, field) \
do { \
if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((elm), field)) == NULL) \
(head)->stqh_last = &STAILQ_NEXT((elm), field); \
STAILQ_NEXT((elm), field) = (elm); \
} while (0)
#define STAILQ_REMOVE_HEAD(head, field) \
do { \
if ((STAILQ_FIRST((head)) = STAILQ_NEXT(STAILQ_FIRST((head)), field)) == \
NULL) \
(head)->stqh_last = &STAILQ_FIRST((head)); \
} while (0)
#define STAILQ_REMOVE_AFTER(head, elm, field) \
do { \
if ((STAILQ_NEXT(elm, field) = \
STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL) \
(head)->stqh_last = &STAILQ_NEXT((elm), field); \
} while (0)
#define STAILQ_REMOVE(head, elm, type, field) \
do { \
if (STAILQ_FIRST((head)) == (elm)) { \
STAILQ_REMOVE_HEAD((head), field); \
} else { \
struct type *curelm = (head)->stqh_first; \
while (STAILQ_NEXT(curelm, field) != (elm)) \
curelm = STAILQ_NEXT(curelm, field); \
STAILQ_REMOVE_AFTER(head, curelm, field); \
} \
} while (0)
#define STAILQ_CONCAT(head1, head2) \
do { \
if (!STAILQ_EMPTY((head2))) { \
*(head1)->stqh_last = (head2)->stqh_first; \
(head1)->stqh_last = (head2)->stqh_last; \
STAILQ_INIT((head2)); \
} \
} while (0)
#define STAILQ_LAST(head, type, field) \
(STAILQ_EMPTY((head)) \
? NULL \
: ((struct type *)(void *)((char *)((head)->stqh_last) - \
offsetof(struct type, field))))
#endif /* !_SYS_QUEUE_H_ */