lib/libc/stdlib/remque.c

   1 /*
   2  *  Copyright (c) 1993 John Brezak
   3  *  All rights reserved.
   4  *
   5  *  Redistribution and use in source and binary forms, with or without
   6  *  modification, are permitted provided that the following conditions
   7  *  are met:
   8  *  1. Redistributions of source code must retain the above copyright
   9  *     notice, this list of conditions and the following disclaimer.
  10  *  2. Redistributions in binary form must reproduce the above copyright
  11  *     notice, this list of conditions and the following disclaimer in the
  12  *     documentation and/or other materials provided with the distribution.
  13  *  3. The name of the author may be used to endorse or promote products
  14  *     derived from this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  18  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  19  * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
  20  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  21  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  22  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  24  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  25  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  26  * POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 #include <sys/cdefs.h>
  30 #if defined(LIBC_SCCS) && !defined(lint)
  31 __RCSID("$NetBSD: remque.c,v 1.3 2012/06/25 22:32:45 abs Exp $");
  32 #endif /* LIBC_SCCS and not lint */
  33
  34 #include <assert.h>
  35 #include <search.h>
  36
  37 struct qelem {
  38         struct qelem *q_forw;
  39         struct qelem *q_back;
  40 };
  41
  42 void
  43 remque(void *element)
  44 {
  45         struct qelem *e = (struct qelem *) element;
  46
  47         _DIAGASSERT(e != 0);
  48
  49         if (e->q_forw)
  50                 e->q_forw->q_back = e->q_back;
  51         if (e->q_back)
  52                 e->q_back->q_forw = e->q_forw;
  53 }