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      1 /*	$eterna: queue.h,v 1.6 2009/04/18 08:36:03 mrg Exp $	*/
      2 /* from: NetBSD: queue.h,v 1.51 2009/03/11 06:51:53 mrg Exp */
      3 
      4 /*
      5  * Copyright (c) 1991, 1993
      6  *	The Regents of the University of California.  All rights reserved.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  * 3. Neither the name of the University nor the names of its contributors
     17  *    may be used to endorse or promote products derived from this software
     18  *    without specific prior written permission.
     19  *
     20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     30  * SUCH DAMAGE.
     31  *
     32  *	@(#)queue.h	8.5 (Berkeley) 8/20/94
     33  */
     34 
     35 #ifndef	_SYS_QUEUE_H_
     36 #define	_SYS_QUEUE_H_
     37 
     38 /*
     39  * Simple queue definitions.
     40  */
     41 #define SIMPLEQ_HEAD(name, type)					\
     42 struct name {								\
     43 	struct type *sqh_first;	/* first element */			\
     44 	struct type **sqh_last;	/* addr of last next element */		\
     45 }
     46 
     47 #define SIMPLEQ_ENTRY(type)						\
     48 struct {								\
     49 	struct type *sqe_next;	/* next element */			\
     50 }
     51 
     52 /*
     53  * Simple queue functions.
     54  */
     55 #define	SIMPLEQ_INIT(head) do {						\
     56 	(head)->sqh_first = NULL;					\
     57 	(head)->sqh_last = &(head)->sqh_first;				\
     58 } while (/*CONSTCOND*/0)
     59 
     60 #define SIMPLEQ_INSERT_TAIL(head, elm, field) do {			\
     61 	(elm)->field.sqe_next = NULL;					\
     62 	*(head)->sqh_last = (elm);					\
     63 	(head)->sqh_last = &(elm)->field.sqe_next;			\
     64 } while (/*CONSTCOND*/0)
     65 
     66 #define	SIMPLEQ_FOREACH(var, head, field)				\
     67 	for ((var) = ((head)->sqh_first);				\
     68 		(var);							\
     69 		(var) = ((var)->field.sqe_next))
     70 
     71 #define	SIMPLEQ_FOREACH_SAFE(var, head, field, next)			\
     72 	for ((var) = ((head)->sqh_first);				\
     73 		(var) && ((next = ((var)->field.sqe_next)), 1);		\
     74 		(var) = (next))
     75 
     76 /*
     77  * Simple queue access methods.
     78  */
     79 #define	SIMPLEQ_FIRST(head)		((head)->sqh_first)
     80 #define	SIMPLEQ_NEXT(elm, field)	((elm)->field.sqe_next)
     81 
     82 #endif	/* !_SYS_QUEUE_H_ */
     83