/* Copyright (C) 1992-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <stddef.h>

#include <search.h>

/* Insert ELEM into a doubly-linked list, after PREV.  */

void

insque (void *elem, void *prev)

{

  if (prev == NULL)

    {

      ((struct qelem *) elem)->q_forw = NULL;

      ((struct qelem *) elem)->q_back = NULL;

    }

  else

    {

      struct qelem *next = ((struct qelem *) prev)->q_forw;

      ((struct qelem *) prev)->q_forw = (struct qelem *) elem;

      if (next != NULL)

	next->q_back = (struct qelem *) elem;

      ((struct qelem *) elem)->q_forw = next;

      ((struct qelem *) elem)->q_back = (struct qelem *) prev;

    }

}

/* Unlink ELEM from the doubly-linked list that it is in.  */

void

remque (void *elem)

{

  struct qelem *next = ((struct qelem *) elem)->q_forw;

  struct qelem *prev = ((struct qelem *) elem)->q_back;

  if (next != NULL)

    next->q_back = prev;

  if (prev != NULL)

    prev->q_forw = (struct qelem *) next;

}