queue.h

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/*
 * 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
 * $FreeBSD: src/sys/sys/queue.h,v 1.24.2.4 2000/05/05 01:41:41 archie Exp $
 */

#ifndef _SYS_QUEUE_H_
#define _SYS_QUEUE_H_

/*
 * This file defines five types of data structures: singly-linked lists,
 * singly-linked tail queues, lists, 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 singly-linked 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
 * 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, at the head of the list, or at the
 * end of the list. Elements being removed from the head of the tail queue
 * should use the explicit macro for this purpose for optimum efficiency.
 * A singly-linked tail queue may only be traversed in the forward direction.
 * Singly-linked tail queues are ideal for applications with large datasets
 * and few or no removals or for implementing a FIFO 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 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.
 *
 *
 * SLIST LIST STAILQ TAILQ CIRCLEQ
 * _HEAD + + + + +
 * _ENTRY + + + + +
 * _INIT + + + + +
 * _EMPTY + + + + +
 * _FIRST + + + + +
 * _NEXT + + + + +
 * _PREV - - - + +
 * _LAST - - + + +
 * _FOREACH + + + + +
 * _FOREACH_REVERSE - - - + +
 * _INSERT_HEAD + + + + +
 * _INSERT_BEFORE - + - + +
 * _INSERT_AFTER + + + + +
 * _INSERT_TAIL - - + + +
 * _REMOVE_HEAD + - + - -
 * _REMOVE + + + + +
 *
 */

/*
 * 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_EMPTY(head) ((head)->slh_first == NULL)

#define SLIST_FIRST(head) ((head)->slh_first)

#define SLIST_FOREACH(var, head, field) \
 for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)

#define SLIST_INIT(head) { \
 (head)->slh_first = NULL; \
}

#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_NEXT(elm, field) ((elm)->field.sle_next)

#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; \
 } \
} while (0)

/*
 * Singly-linked Tail queue definitions.
 */
#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_EMPTY(head) ((head)->stqh_first == NULL)

#define STAILQ_INIT(head) do { \
 (head)->stqh_first = NULL; \
 (head)->stqh_last = &(head)->stqh_first; \
} while (0)

#define STAILQ_FIRST(head) ((head)->stqh_first)
#define STAILQ_LAST(head) (*(head)->stqh_last)

#define STAILQ_FOREACH(var, head, field) \
 for((var) = (head)->stqh_first; (var); (var) = (var)->field.stqe_next)

#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 (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 (0)

#define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
 if (((elm)->field.stqe_next = (tqelm)->field.stqe_next) == NULL)\
 (head)->stqh_last = &(elm)->field.stqe_next; \
 (tqelm)->field.stqe_next = (elm); \
} while (0)

#define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)

#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 (0)

#define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \
 if (((head)->stqh_first = (elm)->field.stqe_next) == NULL) \
 (head)->stqh_last = &(head)->stqh_first; \
} while (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 (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 functions.
 */

#define LIST_EMPTY(head) ((head)->lh_first == NULL)

#define LIST_FIRST(head) ((head)->lh_first)

#define LIST_FOREACH(var, head, field) \
 for((var) = (head)->lh_first; (var); (var) = (var)->field.le_next)

#define LIST_INIT(head) do { \
 (head)->lh_first = NULL; \
} 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_NEXT(elm, field) ((elm)->field.le_next)

#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 (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 functions.
 */
#define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)

#define TAILQ_FOREACH(var, head, field) \
 for (var = TAILQ_FIRST(head); var; var = TAILQ_NEXT(var, field))

#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
 for ((var) = TAILQ_LAST((head), headname); \
 (var); \
 (var) = TAILQ_PREV((var), headname, field))

#define TAILQ_FIRST(head) ((head)->tqh_first)

#define TAILQ_LAST(head, headname) \
 (*(((struct headname *)((head)->tqh_last))->tqh_last))

#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_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; \
} 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_ENTRY(type) \
struct { \
 struct type *cqe_next; /* next element */ \
 struct type *cqe_prev; /* previous element */ \
}

/*
 * Circular queue functions.
 */
#define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))

#define CIRCLEQ_FIRST(head) ((head)->cqh_first)

#define CIRCLEQ_FOREACH(var, head, field) \
 for((var) = (head)->cqh_first; \
 (var) != (void *)(head); \
 (var) = (var)->field.cqe_next)

#define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
 for((var) = (head)->cqh_last; \
 (var) != (void *)(head); \
 (var) = (var)->field.cqe_prev)

#define CIRCLEQ_INIT(head) do { \
 (head)->cqh_first = (void *)(head); \
 (head)->cqh_last = (void *)(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 == (void *)(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 == (void *)(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 = (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 (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 (0)

#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_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 (0)

#ifdef KERNEL

/*
 * XXX insque() and remque() are an old way of handling certain queues.
 * They bogusly assumes that all queue heads look alike.
 */

struct quehead {
 struct quehead *qh_link;
 struct quehead *qh_rlink;
};

#ifdef __GNUC__

static __inline void
insque(void *a, void *b)
{
 struct quehead *element = a, *head = b;

 element->qh_link = head->qh_link;
 element->qh_rlink = head;
 head->qh_link = element;
 element->qh_link->qh_rlink = element;
}

static __inline void
remque(void *a)
{
 struct quehead *element = a;

 element->qh_link->qh_rlink = element->qh_rlink;
 element->qh_rlink->qh_link = element->qh_link;
 element->qh_rlink = 0;
}

#else /* !__GNUC__ */

void insque __P((void *a, void *b));
void remque __P((void *a));

#endif /* __GNUC__ */

#endif /* KERNEL */

#endif /* !_SYS_QUEUE_H_ */