dlist.h

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#ifndef EVE_DLIST_H_INCLUDED
#define EVE_DLIST_H_INCLUDED

/**********************************************************************/
/*
 * Copyright (c) 2013-2015, Jetro AS
 * 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. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONRIBUTORS ``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 AUTHOR 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.
 *
 * This file is part of the EVE platform.
 */

 /**
 * \file
 * \brief The code implements Dummy Headed Doubly Linked Circularlist (DHDLC) primitive
 *
 * \author DT, Jetro AS
 */ /******************************************************************/

/**
 * \defgroup dlist Doubly linked circularlist
 * \ingroup util
 * @{
 *
 * Dummy Headed Doubly Linked Circularlist (DHDLC) primitive.
 */

/**********************************************************************/
/** Static initializer for the empty list entry structure */
#define DLIST_INIT(dlist) \
  {                       \
    .prev = &dlist,       \
    .next = &dlist,       \
  }

/**********************************************************************/
/** Static initializer for the empty list entry structure, typed version */
#define DLIST_INIT_TYPED(dlist) \
  (struct dlist_t) DLIST_INIT(dlist)

/**********************************************************************/
/**
 * Linked list entry.
 */
struct dlist_t {
  struct dlist_t *prev;                    /**< Pointer to the previous entry in the list */
  struct dlist_t *next;                    /**< Pointer to the next entry in the list */
};

/**********************************************************************/
/**
 * Initialize a linked list head
 * @param list pointer to the linked list head
 */
static inline void dlist_init(struct dlist_t *list)
{
  list->prev = list->next = list;
}

/**********************************************************************/
/**
 * Insert a new list entry between two in a list
 * @param list a new list entry to be inserted
 * @param prev left-hand neighbor of the inserted entry
 * @param next right-hand neighbor of the inserted entry
 */
static inline void dlist_insert(struct dlist_t *list, struct dlist_t *prev, struct dlist_t *next)
{
  list->prev = prev;
  list->next = next;
  prev->next = next->prev = list;
}

/**********************************************************************/
/**
 * Remove an entry from the list
 * @param list the entry to be removed
 */
static inline struct dlist_t *dlist_del(struct dlist_t *list)
{
  list->prev->next = list->next;
  list->next->prev = list->prev;
  dlist_init(list);
  return list;
}

/**********************************************************************/
/**
 * Insert a new list entry to the tail of the list
 * @param list head of the list
 * @param item new entry to be inserted
 */
static inline void dlist_append(struct dlist_t *list, struct dlist_t *item)
{
  dlist_insert(item, list->prev, list);
}

/**********************************************************************/
/**
 * Check if the list is empty
 * @param list head of the list
 * @return true if list is empty, false if not
 */
static inline int dlist_is_empty(struct dlist_t *list)
{
  return list->next == list;
}

/**********************************************************************/
/**
 * Check if list contains exactly one entry (except list head)
 * @param list head of the list
 * @return true if list is singular, false if not
 */
static inline int dlist_is_singular(struct dlist_t *list)
{
  return !dlist_is_empty(list) && (list->next == list->prev);
}

/** @} */ /* dlist */

#endif /* EVE_DLIST_H_INCLUDED */