including sys/queue.h to support TAILQ_LAST() macro
authorMartin Willi <martin@strongswan.org>
Fri, 20 Jun 2008 08:17:03 +0000 (08:17 -0000)
committerMartin Willi <martin@strongswan.org>
Fri, 20 Jun 2008 08:17:03 +0000 (08:17 -0000)
src/include/Makefile.am
src/include/sys/queue.h [new file with mode: 0644]

index c7e9ca9..6aeb84b 100644 (file)
@@ -1,2 +1,3 @@
 EXTRA_DIST = linux/ipsec.h linux/netlink.h linux/rtnetlink.h \
-             linux/pfkeyv2.h linux/udp.h linux/xfrm.h
+             linux/pfkeyv2.h linux/udp.h linux/xfrm.h linux/types.h \
+             sys/queue.h
diff --git a/src/include/sys/queue.h b/src/include/sys/queue.h
new file mode 100644 (file)
index 0000000..b0e6b38
--- /dev/null
@@ -0,0 +1,557 @@
+/*
+ * 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 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.
+ */
+
+/*
+ * 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 functions.
+ */
+#define        LIST_INIT(head) do {                                            \
+       (head)->lh_first = NULL;                                        \
+} while (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/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;                   \
+} while (/*CONSTCOND*/0)
+
+#define        LIST_FOREACH(var, head, field)                                  \
+       for ((var) = ((head)->lh_first);                                \
+               (var);                                                  \
+               (var) = ((var)->field.le_next))
+
+/*
+ * List access methods.
+ */
+#define        LIST_EMPTY(head)                ((head)->lh_first == NULL)
+#define        LIST_FIRST(head)                ((head)->lh_first)
+#define        LIST_NEXT(elm, field)           ((elm)->field.le_next)
+
+
+/*
+ * 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 functions.
+ */
+#define        SLIST_INIT(head) do {                                           \
+       (head)->slh_first = NULL;                                       \
+} while (/*CONSTCOND*/0)
+
+#define        SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
+       (elm)->field.sle_next = (slistelm)->field.sle_next;             \
+       (slistelm)->field.sle_next = (elm);                             \
+} while (/*CONSTCOND*/0)
+
+#define        SLIST_INSERT_HEAD(head, elm, field) do {                        \
+       (elm)->field.sle_next = (head)->slh_first;                      \
+       (head)->slh_first = (elm);                                      \
+} while (/*CONSTCOND*/0)
+
+#define        SLIST_REMOVE_HEAD(head, field) do {                             \
+       (head)->slh_first = (head)->slh_first->field.sle_next;          \
+} while (/*CONSTCOND*/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;             \
+       }                                                               \
+} while (/*CONSTCOND*/0)
+
+#define        SLIST_FOREACH(var, head, field)                                 \
+       for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
+
+/*
+ * Singly-linked List access methods.
+ */
+#define        SLIST_EMPTY(head)       ((head)->slh_first == NULL)
+#define        SLIST_FIRST(head)       ((head)->slh_first)
+#define        SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
+
+
+/*
+ * 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 functions.
+ */
+#define        STAILQ_INIT(head) do {                                          \
+       (head)->stqh_first = NULL;                                      \
+       (head)->stqh_last = &(head)->stqh_first;                                \
+} while (/*CONSTCOND*/0)
+
+#define        STAILQ_INSERT_HEAD(head, elm, field) do {                       \
+       if (((elm)->field.stqe_next = (head)->stqh_first) == NULL)      \
+               (head)->stqh_last = &(elm)->field.stqe_next;            \
+       (head)->stqh_first = (elm);                                     \
+} while (/*CONSTCOND*/0)
+
+#define        STAILQ_INSERT_TAIL(head, elm, field) do {                       \
+       (elm)->field.stqe_next = NULL;                                  \
+       *(head)->stqh_last = (elm);                                     \
+       (head)->stqh_last = &(elm)->field.stqe_next;                    \
+} while (/*CONSTCOND*/0)
+
+#define        STAILQ_INSERT_AFTER(head, listelm, elm, field) do {             \
+       if (((elm)->field.stqe_next = (listelm)->field.stqe_next) == NULL)\
+               (head)->stqh_last = &(elm)->field.stqe_next;            \
+       (listelm)->field.stqe_next = (elm);                             \
+} while (/*CONSTCOND*/0)
+
+#define        STAILQ_REMOVE_HEAD(head, field) do {                            \
+       if (((head)->stqh_first = (head)->stqh_first->field.stqe_next) == NULL) \
+               (head)->stqh_last = &(head)->stqh_first;                        \
+} while (/*CONSTCOND*/0)
+
+#define        STAILQ_REMOVE(head, elm, type, field) do {                      \
+       if ((head)->stqh_first == (elm)) {                              \
+               STAILQ_REMOVE_HEAD((head), field);                      \
+       } else {                                                        \
+               struct type *curelm = (head)->stqh_first;               \
+               while (curelm->field.stqe_next != (elm))                        \
+                       curelm = curelm->field.stqe_next;               \
+               if ((curelm->field.stqe_next =                          \
+                       curelm->field.stqe_next->field.stqe_next) == NULL) \
+                           (head)->stqh_last = &(curelm)->field.stqe_next; \
+       }                                                               \
+} while (/*CONSTCOND*/0)
+
+#define        STAILQ_FOREACH(var, head, field)                                \
+       for ((var) = ((head)->stqh_first);                              \
+               (var);                                                  \
+               (var) = ((var)->field.stqe_next))
+
+/*
+ * Singly-linked Tail queue access methods.
+ */
+#define        STAILQ_EMPTY(head)      ((head)->stqh_first == NULL)
+#define        STAILQ_FIRST(head)      ((head)->stqh_first)
+#define        STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
+
+
+/*
+ * 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 functions.
+ */
+#define        SIMPLEQ_INIT(head) do {                                         \
+       (head)->sqh_first = NULL;                                       \
+       (head)->sqh_last = &(head)->sqh_first;                          \
+} while (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/0)
+
+#define        SIMPLEQ_REMOVE(head, elm, type, field) do {                     \
+       if ((head)->sqh_first == (elm)) {                               \
+               SIMPLEQ_REMOVE_HEAD((head), field);                     \
+       } else {                                                        \
+               struct type *curelm = (head)->sqh_first;                \
+               while (curelm->field.sqe_next != (elm))                 \
+                       curelm = curelm->field.sqe_next;                \
+               if ((curelm->field.sqe_next =                           \
+                       curelm->field.sqe_next->field.sqe_next) == NULL) \
+                           (head)->sqh_last = &(curelm)->field.sqe_next; \
+       }                                                               \
+} while (/*CONSTCOND*/0)
+
+#define        SIMPLEQ_FOREACH(var, head, field)                               \
+       for ((var) = ((head)->sqh_first);                               \
+               (var);                                                  \
+               (var) = ((var)->field.sqe_next))
+
+/*
+ * Simple queue access methods.
+ */
+#define        SIMPLEQ_EMPTY(head)             ((head)->sqh_first == NULL)
+#define        SIMPLEQ_FIRST(head)             ((head)->sqh_first)
+#define        SIMPLEQ_NEXT(elm, field)        ((elm)->field.sqe_next)
+
+
+/*
+ * Tail queue definitions.
+ */
+#define        _TAILQ_HEAD(name, type, qual)                                   \
+struct name {                                                          \
+       qual type *tqh_first;           /* first element */             \
+       qual type *qual *tqh_last;      /* addr of last next element */ \
+}
+#define TAILQ_HEAD(name, type) _TAILQ_HEAD(name, struct type,)
+
+#define        TAILQ_HEAD_INITIALIZER(head)                                    \
+       { NULL, &(head).tqh_first }
+
+#define        _TAILQ_ENTRY(type, qual)                                        \
+struct {                                                               \
+       qual type *tqe_next;            /* next element */              \
+       qual type *qual *tqe_prev;      /* address of previous next element */\
+}
+#define TAILQ_ENTRY(type)      _TAILQ_ENTRY(struct type,)
+
+/*
+ * Tail queue functions.
+ */
+#define        TAILQ_INIT(head) do {                                           \
+       (head)->tqh_first = NULL;                                       \
+       (head)->tqh_last = &(head)->tqh_first;                          \
+} while (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/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;                 \
+} while (/*CONSTCOND*/0)
+
+#define        TAILQ_FOREACH(var, head, field)                                 \
+       for ((var) = ((head)->tqh_first);                               \
+               (var);                                                  \
+               (var) = ((var)->field.tqe_next))
+
+#define        TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
+       for ((var) = (*(((struct headname *)((head)->tqh_last))->tqh_last));    \
+               (var);                                                  \
+               (var) = (*(((struct headname *)((var)->field.tqe_prev))->tqh_last)))
+
+/*
+ * Tail queue access methods.
+ */
+#define        TAILQ_EMPTY(head)               ((head)->tqh_first == NULL)
+#define        TAILQ_FIRST(head)               ((head)->tqh_first)
+#define        TAILQ_NEXT(elm, field)          ((elm)->field.tqe_next)
+
+#define        TAILQ_LAST(head, headname) \
+       (*(((struct headname *)((head)->tqh_last))->tqh_last))
+#define        TAILQ_PREV(elm, headname, field) \
+       (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
+
+
+/*
+ * 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)                                  \
+       { (void *)&head, (void *)&head }
+
+#define        CIRCLEQ_ENTRY(type)                                             \
+struct {                                                               \
+       struct type *cqe_next;          /* next element */              \
+       struct type *cqe_prev;          /* previous element */          \
+}
+
+/*
+ * Circular queue functions.
+ */
+#define        CIRCLEQ_INIT(head) do {                                         \
+       (head)->cqh_first = (void *)(head);                             \
+       (head)->cqh_last = (void *)(head);                              \
+} while (/*CONSTCOND*/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 == (void *)(head))                \
+               (head)->cqh_last = (elm);                               \
+       else                                                            \
+               (listelm)->field.cqe_next->field.cqe_prev = (elm);      \
+       (listelm)->field.cqe_next = (elm);                              \
+} while (/*CONSTCOND*/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 == (void *)(head))                \
+               (head)->cqh_first = (elm);                              \
+       else                                                            \
+               (listelm)->field.cqe_prev->field.cqe_next = (elm);      \
+       (listelm)->field.cqe_prev = (elm);                              \
+} while (/*CONSTCOND*/0)
+
+#define        CIRCLEQ_INSERT_HEAD(head, elm, field) do {                      \
+       (elm)->field.cqe_next = (head)->cqh_first;                      \
+       (elm)->field.cqe_prev = (void *)(head);                         \
+       if ((head)->cqh_last == (void *)(head))                         \
+               (head)->cqh_last = (elm);                               \
+       else                                                            \
+               (head)->cqh_first->field.cqe_prev = (elm);              \
+       (head)->cqh_first = (elm);                                      \
+} while (/*CONSTCOND*/0)
+
+#define        CIRCLEQ_INSERT_TAIL(head, elm, field) do {                      \
+       (elm)->field.cqe_next = (void *)(head);                         \
+       (elm)->field.cqe_prev = (head)->cqh_last;                       \
+       if ((head)->cqh_first == (void *)(head))                        \
+               (head)->cqh_first = (elm);                              \
+       else                                                            \
+               (head)->cqh_last->field.cqe_next = (elm);               \
+       (head)->cqh_last = (elm);                                       \
+} while (/*CONSTCOND*/0)
+
+#define        CIRCLEQ_REMOVE(head, elm, field) do {                           \
+       if ((elm)->field.cqe_next == (void *)(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 == (void *)(head))                    \
+               (head)->cqh_first = (elm)->field.cqe_next;              \
+       else                                                            \
+               (elm)->field.cqe_prev->field.cqe_next =                 \
+                   (elm)->field.cqe_next;                              \
+} while (/*CONSTCOND*/0)
+
+#define        CIRCLEQ_FOREACH(var, head, field)                               \
+       for ((var) = ((head)->cqh_first);                               \
+               (var) != (const void *)(head);                          \
+               (var) = ((var)->field.cqe_next))
+
+#define        CIRCLEQ_FOREACH_REVERSE(var, head, field)                       \
+       for ((var) = ((head)->cqh_last);                                \
+               (var) != (const void *)(head);                          \
+               (var) = ((var)->field.cqe_prev))
+
+/*
+ * Circular queue access methods.
+ */
+#define        CIRCLEQ_EMPTY(head)             ((head)->cqh_first == (void *)(head))
+#define        CIRCLEQ_FIRST(head)             ((head)->cqh_first)
+#define        CIRCLEQ_LAST(head)              ((head)->cqh_last)
+#define        CIRCLEQ_NEXT(elm, field)        ((elm)->field.cqe_next)
+#define        CIRCLEQ_PREV(elm, field)        ((elm)->field.cqe_prev)
+
+#define CIRCLEQ_LOOP_NEXT(head, elm, field)                            \
+       (((elm)->field.cqe_next == (void *)(head))                      \
+           ? ((head)->cqh_first)                                       \
+           : (elm->field.cqe_next))
+#define CIRCLEQ_LOOP_PREV(head, elm, field)                            \
+       (((elm)->field.cqe_prev == (void *)(head))                      \
+           ? ((head)->cqh_last)                                        \
+           : (elm->field.cqe_prev))
+
+#endif /* sys/queue.h */