/*      $eterna: queue.h,v 1.6 2009/04/18 08:36:03 mrg Exp $    */
/* from: NetBSD: queue.h,v 1.51 2009/03/11 06:51:53 mrg 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 _SYS_QUEUE_H_
#define _SYS_QUEUE_H_

/*
 * 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_ENTRY(type)                                             \
struct {                                                                \
        struct type *sqe_next;  /* next element */                      \
}

/*
 * Simple queue functions.
 */
#define SIMPLEQ_INIT(head) do {                                         \
        (head)->sqh_first = NULL;                                       \
        (head)->sqh_last = &(head)->sqh_first;                          \
} while (/*CONSTCOND*/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 (/*CONSTCOND*/0)

#define SIMPLEQ_FOREACH(var, head, field)                               \
        for ((var) = ((head)->sqh_first);                               \
                (var);                                                  \
                (var) = ((var)->field.sqe_next))

#define SIMPLEQ_FOREACH_SAFE(var, head, field, next)                    \
        for ((var) = ((head)->sqh_first);                               \
                (var) && ((next = ((var)->field.sqe_next)), 1);         \
                (var) = (next))

/*
 * Simple queue access methods.
 */
#define SIMPLEQ_FIRST(head)             ((head)->sqh_first)
#define SIMPLEQ_NEXT(elm, field)        ((elm)->field.sqe_next)

#endif  /* !_SYS_QUEUE_H_ */