circ-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: ports/misc/44bsd-more/files/queue.h,v 1.1 2001/01/06 03:41:36 hoek Exp $
 */

/*
 * 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)