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 #define _SEARCH_PRIVATE
  10 #include <search.h>
  11 #ifdef DEBUG
  12 #include <stdio.h>
  13 #else
  14 #include <stdlib.h>     /* for NULL */
  15 #endif
  16
  17 void
  18 insque(void *element, void *pred)
  19 {
  20         struct que_elem *prev, *next, *elem;
  21
  22         elem = (struct que_elem *)element;
  23         prev = (struct que_elem *)pred;
  24
  25         if (prev == NULL) {
  26                 elem->prev = elem->next = NULL;
  27                 return;
  28         }
  29
  30         next = prev->next;
  31         if (next != NULL) {
  32 #ifdef DEBUG
  33                 if (next->prev != prev) {
  34                         fprintf(stderr, "insque: Inconsistency detected:"
  35                             " next(%p)->prev(%p) != prev(%p)\n",
  36                             next, next->prev, prev);
  37                 }
  38 #endif
  39                 next->prev = elem;
  40         }
  41         prev->next = elem;
  42         elem->prev = prev;
  43         elem->next = next;
  44 }