--- /dev/null
+/*!\file sys/queue.h
+ *
+ */
+
+/*
+ * 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. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. 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 three types of data structures: lists, tail queues,
+ * and circular queues.
+ *
+ * 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 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 only be traversed in the forward 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_ENTRY(type) \
+struct { \
+ struct type *le_next; /* next element */ \
+ struct type **le_prev; /* address of previous next element */ \
+}
+
+/*
+ * List functions.
+ */
+#define LIST_INIT(head) { \
+ (head)->lh_first = NULL; \
+}
+
+#define LIST_INSERT_AFTER(listelm, elm, field) { \
+ 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; \
+}
+
+#define LIST_INSERT_BEFORE(listelm, elm, field) { \
+ (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; \
+}
+
+#define LIST_INSERT_HEAD(head, elm, field) { \
+ 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; \
+}
+
+#define LIST_REMOVE(elm, field) { \
+ 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; \
+}
+
+/*
+ * 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_ENTRY(type) \
+struct { \
+ struct type *tqe_next; /* next element */ \
+ struct type **tqe_prev; /* address of previous next element */ \
+}
+
+/*
+ * Tail queue functions.
+ */
+#define TAILQ_INIT(head) { \
+ (head)->tqh_first = NULL; \
+ (head)->tqh_last = &(head)->tqh_first; \
+}
+
+#define TAILQ_INSERT_HEAD(head, elm, field) { \
+ 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; \
+}
+
+#define TAILQ_INSERT_TAIL(head, elm, field) { \
+ (elm)->field.tqe_next = NULL; \
+ (elm)->field.tqe_prev = (head)->tqh_last; \
+ *(head)->tqh_last = (elm); \
+ (head)->tqh_last = &(elm)->field.tqe_next; \
+}
+
+#define TAILQ_INSERT_AFTER(head, listelm, elm, field) { \
+ 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; \
+}
+
+#define TAILQ_INSERT_BEFORE(listelm, elm, field) { \
+ (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; \
+}
+
+#define TAILQ_REMOVE(head, elm, field) { \
+ 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; \
+}
+
+/*
+ * Circular queue definitions.
+ */
+#define CIRCLEQ_HEAD(name, type) \
+struct name { \
+ struct type *cqh_first; /* first element */ \
+ struct type *cqh_last; /* last element */ \
+}
+
+#define CIRCLEQ_ENTRY(type) \
+struct { \
+ struct type *cqe_next; /* next element */ \
+ struct type *cqe_prev; /* previous element */ \
+}
+
+/*
+ * Circular queue functions.
+ */
+#define CIRCLEQ_INIT(head) { \
+ (head)->cqh_first = (void *)(head); \
+ (head)->cqh_last = (void *)(head); \
+}
+
+#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) { \
+ (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); \
+}
+
+#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) { \
+ (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); \
+}
+
+#define CIRCLEQ_INSERT_HEAD(head, elm, field) { \
+ (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); \
+}
+
+#define CIRCLEQ_INSERT_TAIL(head, elm, field) { \
+ (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); \
+}
+
+#define CIRCLEQ_REMOVE(head, elm, field) { \
+ 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; \
+}
+#endif
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