lib/libc/stdlib/insque.c

   1 /*
   2  * Initial implementation:
   3  * Copyright (c) 2002 Robert Drehmel
   4  * All rights reserved.
   5  *
   6  * As long as the above copyright statement and this notice remain
   7  * unchanged, you can do what ever you want with this file.
   8  *
   9  * $FreeBSD: src/lib/libc/stdlib/insque.c,v 1.3 2003/01/04 07:34:41 tjr Exp $
  10  */
  11
  12 #define _SEARCH_PRIVATE
  13 #include <search.h>
  14 #ifdef DEBUG
  15 #include <stdio.h>
  16 #else
  17 #include <stdlib.h>     /* for NULL */
  18 #endif
  19
  20 void
  21 insque(void *element, void *pred)
  22 {
  23         struct que_elem *prev, *next, *elem;
  24
  25         elem = (struct que_elem *)element;
  26         prev = (struct que_elem *)pred;
  27
  28         if (prev == NULL) {
  29                 elem->prev = elem->next = NULL;
  30                 return;
  31         }
  32
  33         next = prev->next;
  34         if (next != NULL) {
  35 #ifdef DEBUG
  36                 if (next->prev != prev) {
  37                         fprintf(stderr, "insque: Inconsistency detected:"
  38                             " next(%p)->prev(%p) != prev(%p)\n",
  39                             next, next->prev, prev);
  40                 }
  41 #endif
  42                 next->prev = elem;
  43         }
  44         prev->next = elem;
  45         elem->prev = prev;
  46         elem->next = next;
  47 }