--- /dev/null
+/*-
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * 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.
+ *
+ */
+
+#ifndef _SYS_QUEUE_H_
+#define _SYS_QUEUE_H_
+
+/*
+ * This file defines tail queues.
+ *
+ * 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.
+ *
+ * Below is a summary of implemented functions where:
+ * + means the macro is available
+ * - means the macro is not available
+ * s means the macro is available but is slow (runs in O(n) time)
+ *
+ * TAILQ
+ * _HEAD +
+ * _CLASS_HEAD +
+ * _HEAD_INITIALIZER +
+ * _ENTRY +
+ * _CLASS_ENTRY +
+ * _INIT +
+ * _EMPTY +
+ * _FIRST +
+ * _NEXT +
+ * _PREV +
+ * _LAST +
+ * _LAST_FAST +
+ * _FOREACH +
+ * _FOREACH_FROM +
+ * _FOREACH_SAFE +
+ * _FOREACH_FROM_SAFE +
+ * _FOREACH_REVERSE +
+ * _FOREACH_REVERSE_FROM +
+ * _FOREACH_REVERSE_SAFE +
+ * _FOREACH_REVERSE_FROM_SAFE +
+ * _INSERT_HEAD +
+ * _INSERT_BEFORE +
+ * _INSERT_AFTER +
+ * _INSERT_TAIL +
+ * _CONCAT +
+ * _REMOVE_AFTER -
+ * _REMOVE_HEAD -
+ * _REMOVE +
+ * _SWAP +
+ *
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define QMD_TRACE_ELEM(elem)
+#define QMD_TRACE_HEAD(head)
+#define TRACEBUF
+#define TRACEBUF_INITIALIZER
+
+#define TRASHIT(x)
+#define QMD_IS_TRASHED(x) 0
+
+#define QMD_SAVELINK(name, link)
+
+#ifdef __cplusplus
+/*
+ * In C++ there can be structure lists and class lists:
+ */
+#define QUEUE_TYPEOF(type) type
+#else
+#define QUEUE_TYPEOF(type) struct type
+#endif
+
+/*
+ * Tail queue declarations.
+ */
+#define TAILQ_HEAD(name, type) \
+struct name { \
+ struct type *tqh_first; /* first element */ \
+ struct type **tqh_last; /* addr of last next element */ \
+ TRACEBUF \
+}
+
+#define TAILQ_CLASS_HEAD(name, type) \
+struct name { \
+ class type *tqh_first; /* first element */ \
+ class type **tqh_last; /* addr of last next element */ \
+ TRACEBUF \
+}
+
+#define TAILQ_HEAD_INITIALIZER(head) \
+ { NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }
+
+#define TAILQ_ENTRY(type) \
+struct { \
+ struct type *tqe_next; /* next element */ \
+ struct type **tqe_prev; /* address of previous next element */ \
+ TRACEBUF \
+}
+
+#define TAILQ_CLASS_ENTRY(type) \
+struct { \
+ class type *tqe_next; /* next element */ \
+ class type **tqe_prev; /* address of previous next element */ \
+ TRACEBUF \
+}
+
+/*
+ * Tail queue functions.
+ */
+#define QMD_TAILQ_CHECK_HEAD(head, field)
+#define QMD_TAILQ_CHECK_TAIL(head, headname)
+#define QMD_TAILQ_CHECK_NEXT(elm, field)
+#define QMD_TAILQ_CHECK_PREV(elm, field)
+
+#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)); \
+ QMD_TRACE_HEAD(head1); \
+ QMD_TRACE_HEAD(head2); \
+ } \
+} while (0)
+
+#define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
+
+#define TAILQ_FIRST(head) ((head)->tqh_first)
+
+#define TAILQ_FOREACH(var, head, field) \
+ for ((var) = TAILQ_FIRST((head)); \
+ (var); \
+ (var) = TAILQ_NEXT((var), field))
+
+#define TAILQ_FOREACH_FROM(var, head, field) \
+ for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
+ (var); \
+ (var) = TAILQ_NEXT((var), field))
+
+#define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
+ for ((var) = TAILQ_FIRST((head)); \
+ (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
+ (var) = (tvar))
+
+#define TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar) \
+ for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
+ (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
+ (var) = (tvar))
+
+#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
+ for ((var) = TAILQ_LAST((head), headname); \
+ (var); \
+ (var) = TAILQ_PREV((var), headname, field))
+
+#define TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field) \
+ for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
+ (var); \
+ (var) = TAILQ_PREV((var), headname, field))
+
+#define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
+ for ((var) = TAILQ_LAST((head), headname); \
+ (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
+ (var) = (tvar))
+
+#define TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar) \
+ for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
+ (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
+ (var) = (tvar))
+
+#define TAILQ_INIT(head) do { \
+ TAILQ_FIRST((head)) = NULL; \
+ (head)->tqh_last = &TAILQ_FIRST((head)); \
+ QMD_TRACE_HEAD(head); \
+} while (0)
+
+#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
+ QMD_TAILQ_CHECK_NEXT(listelm, field); \
+ TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field); \
+ if (TAILQ_NEXT((listelm), field) != NULL) \
+ TAILQ_NEXT((elm), field)->field.tqe_prev = \
+ &TAILQ_NEXT((elm), field); \
+ else { \
+ (head)->tqh_last = &TAILQ_NEXT((elm), field); \
+ QMD_TRACE_HEAD(head); \
+ } \
+ TAILQ_NEXT((listelm), field) = (elm); \
+ (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
+ QMD_TRACE_ELEM(&(elm)->field); \
+ QMD_TRACE_ELEM(&(listelm)->field); \
+} while (0)
+
+#define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
+ QMD_TAILQ_CHECK_PREV(listelm, field); \
+ (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
+ TAILQ_NEXT((elm), field) = (listelm); \
+ *(listelm)->field.tqe_prev = (elm); \
+ (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
+ QMD_TRACE_ELEM(&(elm)->field); \
+ QMD_TRACE_ELEM(&(listelm)->field); \
+} while (0)
+
+#define TAILQ_INSERT_HEAD(head, elm, field) do { \
+ QMD_TAILQ_CHECK_HEAD(head, field); \
+ TAILQ_NEXT((elm), field) = TAILQ_FIRST((head)); \
+ if (TAILQ_FIRST((head)) != NULL) \
+ TAILQ_FIRST((head))->field.tqe_prev = \
+ &TAILQ_NEXT((elm), field); \
+ else \
+ (head)->tqh_last = &TAILQ_NEXT((elm), field); \
+ TAILQ_FIRST((head)) = (elm); \
+ (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
+ QMD_TRACE_HEAD(head); \
+ QMD_TRACE_ELEM(&(elm)->field); \
+} while (0)
+
+#define TAILQ_INSERT_TAIL(head, elm, field) do { \
+ QMD_TAILQ_CHECK_TAIL(head, field); \
+ TAILQ_NEXT((elm), field) = NULL; \
+ (elm)->field.tqe_prev = (head)->tqh_last; \
+ *(head)->tqh_last = (elm); \
+ (head)->tqh_last = &TAILQ_NEXT((elm), field); \
+ QMD_TRACE_HEAD(head); \
+ QMD_TRACE_ELEM(&(elm)->field); \
+} while (0)
+
+#define TAILQ_LAST(head, headname) \
+ (*(((struct headname *)((head)->tqh_last))->tqh_last))
+
+/*
+ * The FAST function is fast in that it causes no data access other
+ * then the access to the head. The standard LAST function above
+ * will cause a data access of both the element you want and
+ * the previous element. FAST is very useful for instances when
+ * you may want to prefetch the last data element.
+ */
+#define TAILQ_LAST_FAST(head, type, field) \
+ (TAILQ_EMPTY(head) ? NULL : __containerof((head)->tqh_last, \
+ QUEUE_TYPEOF(type), field.tqe_next))
+
+#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
+
+#define TAILQ_PREV(elm, headname, field) \
+ (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
+
+#define TAILQ_REMOVE(head, elm, field) do { \
+ QMD_SAVELINK(oldnext, (elm)->field.tqe_next); \
+ QMD_SAVELINK(oldprev, (elm)->field.tqe_prev); \
+ QMD_TAILQ_CHECK_NEXT(elm, field); \
+ QMD_TAILQ_CHECK_PREV(elm, field); \
+ if ((TAILQ_NEXT((elm), field)) != NULL) \
+ TAILQ_NEXT((elm), field)->field.tqe_prev = \
+ (elm)->field.tqe_prev; \
+ else { \
+ (head)->tqh_last = (elm)->field.tqe_prev; \
+ QMD_TRACE_HEAD(head); \
+ } \
+ *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
+ TRASHIT(*oldnext); \
+ TRASHIT(*oldprev); \
+ QMD_TRACE_ELEM(&(elm)->field); \
+} while (0)
+
+#define TAILQ_SWAP(head1, head2, type, field) do { \
+ QUEUE_TYPEOF(type) * swap_first = (head1)->tqh_first; \
+ QUEUE_TYPEOF(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; \
+ swap_first = (head1)->tqh_first; \
+ if (swap_first != NULL) \
+ swap_first->field.tqe_prev = &(head1)->tqh_first; \
+ else \
+ (head1)->tqh_last = &(head1)->tqh_first; \
+ swap_first = (head2)->tqh_first; \
+ if (swap_first != NULL) \
+ swap_first->field.tqe_prev = &(head2)->tqh_first; \
+ else \
+ (head2)->tqh_last = &(head2)->tqh_first; \
+} while (0)
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _SYS_QUEUE_H_ */