rough framework
[lemu] / bsd_queue.h
diff --git a/bsd_queue.h b/bsd_queue.h
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@@ -0,0 +1,633 @@
+/*     $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        BSD_QUEUE_H
+#define        BSD_QUEUE_H
+
+// #include <sys/_null.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 /* !BSD_QUEUE_H */