--- /dev/null
+/* $OpenBSD: queue.h,v 1.38 2013/07/03 15:05:21 fgsch 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 circular queues.
+ *
+ *
+ * A singly-linked list is headed by a single forward pointer. The elements
+ * are singly linked for minimum space and pointer manipulation overhead at
+ * the expense of O(n) removal for arbitrary elements. New elements can be
+ * added to the list after an existing element or at the head of the list.
+ * Elements being removed from the head of the list should use the explicit
+ * macro for this purpose for optimum efficiency. A singly-linked list may
+ * only be traversed in the forward direction. Singly-linked lists are ideal
+ * for applications with large datasets and few or no removals or for
+ * implementing a LIFO queue.
+ *
+ * A list is headed by a single forward pointer (or an array of forward
+ * pointers for a hash table header). The elements are doubly linked
+ * so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before
+ * or after an existing element or at the head of the list. A list
+ * may only be traversed in the forward direction.
+ *
+ * A simple queue is headed by a pair of pointers, one the head of the
+ * list and the other to the tail of the list. The elements are singly
+ * linked to save space, so elements can only be removed from the
+ * head of the list. New elements can be added to the list before or after
+ * an existing element, at the head of the list, or at the end of the
+ * list. A simple queue may only be traversed in the forward direction.
+ *
+ * A tail queue is headed by a pair of pointers, one to the head of the
+ * list and the other to the tail of the list. The elements are doubly
+ * linked so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before or
+ * after an existing element, at the head of the list, or at the end of
+ * the list. A tail queue may be traversed in either direction.
+ *
+ * A circle queue is headed by a pair of pointers, one to the head of the
+ * list and the other to the tail of the list. The elements are doubly
+ * linked so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before or after
+ * an existing element, at the head of the list, or at the end of the list.
+ * A circle queue may be traversed in either direction, but has a more
+ * complex end of list detection.
+ *
+ * For details on the use of these macros, see the queue(3) manual page.
+ */
+
+#if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
+#define _Q_INVALIDATE(a) (a) = ((void *)-1)
+#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)
+
+#define SLIST_SWAP(head1, head2, type) do { \
+ struct type *swap_first = SLIST_FIRST(head1); \
+ SLIST_FIRST(head1) = SLIST_FIRST(head2); \
+ SLIST_FIRST(head2) = swap_first; \
+} 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)
+
+#define LIST_SWAP(head1, head2, type, field) do { \
+ struct type *swap_tmp = LIST_FIRST((head1)); \
+ LIST_FIRST((head1)) = LIST_FIRST((head2)); \
+ LIST_FIRST((head2)) = swap_tmp; \
+ if ((swap_tmp = LIST_FIRST((head1))) != NULL) \
+ swap_tmp->field.le_prev = &LIST_FIRST((head1)); \
+ if ((swap_tmp = LIST_FIRST((head2))) != NULL) \
+ swap_tmp->field.le_prev = &LIST_FIRST((head2)); \
+} 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)
+
+/*
+ * 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_SWAP(head1, head2, type, field) do { \
+ struct type *swap_first = (head1)->tqh_first; \
+ struct type **swap_last = (head1)->tqh_last; \
+ (head1)->tqh_first = (head2)->tqh_first; \
+ (head1)->tqh_last = (head2)->tqh_last; \
+ (head2)->tqh_first = swap_first; \
+ (head2)->tqh_last = swap_last; \
+ if ((swap_first = (head1)->tqh_first) != NULL) \
+ swap_first->field.tqe_prev = &(head1)->tqh_first; \
+ else \
+ (head1)->tqh_last = &(head1)->tqh_first; \
+ if ((swap_first = (head2)->tqh_first) != NULL) \
+ swap_first->field.tqe_prev = &(head2)->tqh_first; \
+ else \
+ (head2)->tqh_last = &(head2)->tqh_first; \
+} while (0)
+
+/*
+ * Circular queue definitions.
+ */
+#define CIRCLEQ_HEAD(name, type) \
+struct name { \
+ struct type *cqh_first; /* first element */ \
+ struct type *cqh_last; /* last element */ \
+}
+
+#define CIRCLEQ_HEAD_INITIALIZER(head) \
+ { CIRCLEQ_END(&head), CIRCLEQ_END(&head) }
+
+#define CIRCLEQ_ENTRY(type) \
+struct { \
+ struct type *cqe_next; /* next element */ \
+ struct type *cqe_prev; /* previous element */ \
+}
+
+/*
+ * Circular queue access methods
+ */
+#define CIRCLEQ_FIRST(head) ((head)->cqh_first)
+#define CIRCLEQ_LAST(head) ((head)->cqh_last)
+#define CIRCLEQ_END(head) ((void *)(head))
+#define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next)
+#define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev)
+#define CIRCLEQ_EMPTY(head) \
+ (CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
+
+#define CIRCLEQ_FOREACH(var, head, field) \
+ for((var) = CIRCLEQ_FIRST(head); \
+ (var) != CIRCLEQ_END(head); \
+ (var) = CIRCLEQ_NEXT(var, field))
+
+#define CIRCLEQ_FOREACH_SAFE(var, head, field, tvar) \
+ for ((var) = CIRCLEQ_FIRST(head); \
+ (var) != CIRCLEQ_END(head) && \
+ ((tvar) = CIRCLEQ_NEXT(var, field), 1); \
+ (var) = (tvar))
+
+#define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
+ for((var) = CIRCLEQ_LAST(head); \
+ (var) != CIRCLEQ_END(head); \
+ (var) = CIRCLEQ_PREV(var, field))
+
+#define CIRCLEQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
+ for ((var) = CIRCLEQ_LAST(head, headname); \
+ (var) != CIRCLEQ_END(head) && \
+ ((tvar) = CIRCLEQ_PREV(var, headname, field), 1); \
+ (var) = (tvar))
+
+/*
+ * Circular queue functions.
+ */
+#define CIRCLEQ_INIT(head) do { \
+ (head)->cqh_first = CIRCLEQ_END(head); \
+ (head)->cqh_last = CIRCLEQ_END(head); \
+} while (0)
+
+#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
+ (elm)->field.cqe_next = (listelm)->field.cqe_next; \
+ (elm)->field.cqe_prev = (listelm); \
+ if ((listelm)->field.cqe_next == CIRCLEQ_END(head)) \
+ (head)->cqh_last = (elm); \
+ else \
+ (listelm)->field.cqe_next->field.cqe_prev = (elm); \
+ (listelm)->field.cqe_next = (elm); \
+} while (0)
+
+#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
+ (elm)->field.cqe_next = (listelm); \
+ (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
+ if ((listelm)->field.cqe_prev == CIRCLEQ_END(head)) \
+ (head)->cqh_first = (elm); \
+ else \
+ (listelm)->field.cqe_prev->field.cqe_next = (elm); \
+ (listelm)->field.cqe_prev = (elm); \
+} while (0)
+
+#define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
+ (elm)->field.cqe_next = (head)->cqh_first; \
+ (elm)->field.cqe_prev = CIRCLEQ_END(head); \
+ if ((head)->cqh_last == CIRCLEQ_END(head)) \
+ (head)->cqh_last = (elm); \
+ else \
+ (head)->cqh_first->field.cqe_prev = (elm); \
+ (head)->cqh_first = (elm); \
+} while (0)
+
+#define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
+ (elm)->field.cqe_next = CIRCLEQ_END(head); \
+ (elm)->field.cqe_prev = (head)->cqh_last; \
+ if ((head)->cqh_first == CIRCLEQ_END(head)) \
+ (head)->cqh_first = (elm); \
+ else \
+ (head)->cqh_last->field.cqe_next = (elm); \
+ (head)->cqh_last = (elm); \
+} while (0)
+
+#define CIRCLEQ_REMOVE(head, elm, field) do { \
+ if ((elm)->field.cqe_next == CIRCLEQ_END(head)) \
+ (head)->cqh_last = (elm)->field.cqe_prev; \
+ else \
+ (elm)->field.cqe_next->field.cqe_prev = \
+ (elm)->field.cqe_prev; \
+ if ((elm)->field.cqe_prev == CIRCLEQ_END(head)) \
+ (head)->cqh_first = (elm)->field.cqe_next; \
+ else \
+ (elm)->field.cqe_prev->field.cqe_next = \
+ (elm)->field.cqe_next; \
+ _Q_INVALIDATE((elm)->field.cqe_prev); \
+ _Q_INVALIDATE((elm)->field.cqe_next); \
+} while (0)
+
+#define CIRCLEQ_REPLACE(head, elm, elm2, field) do { \
+ if (((elm2)->field.cqe_next = (elm)->field.cqe_next) == \
+ CIRCLEQ_END(head)) \
+ (head)->cqh_last = (elm2); \
+ else \
+ (elm2)->field.cqe_next->field.cqe_prev = (elm2); \
+ if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) == \
+ CIRCLEQ_END(head)) \
+ (head)->cqh_first = (elm2); \
+ else \
+ (elm2)->field.cqe_prev->field.cqe_next = (elm2); \
+ _Q_INVALIDATE((elm)->field.cqe_prev); \
+ _Q_INVALIDATE((elm)->field.cqe_next); \
+} while (0)
+
+#endif /* !_SYS_QUEUE_H_ */