lib/libc/stdlib/insque.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: insque.c,v 1.2 2005/07/06 17:17:15 drochner 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 insque(entry, pred)
  44         void *entry;
  45         void *pred;
  46 {
  47         struct qelem *e = (struct qelem *) entry;
  48         struct qelem *p = (struct qelem *) pred;
  49
  50         _DIAGASSERT(e != 0);
  51
  52         e->q_back = p;
  53         if (p) {
  54                 e->q_forw = p->q_forw;
  55                 if (p->q_forw)
  56                         p->q_forw->q_back = e;
  57                 p->q_forw = e;
  58         } else
  59                 e->q_forw = 0;
  60 }