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 #include <sys/cdefs.h>
  10 #define _SEARCH_PRIVATE
  11 #include <search.h>
  12 #ifdef DEBUG
  13 #include <stdio.h>
  14 #else
  15 #include <stdlib.h>     /* for NULL */
  16 #endif
  17
  18 void
  19 insque(void *element, void *pred)
  20 {
  21         struct que_elem *prev, *next, *elem;
  22
  23         elem = (struct que_elem *)element;
  24         prev = (struct que_elem *)pred;
  25
  26         if (prev == NULL) {
  27                 elem->prev = elem->next = NULL;
  28                 return;
  29         }
  30
  31         next = prev->next;
  32         if (next != NULL) {
  33 #ifdef DEBUG
  34                 if (next->prev != prev) {
  35                         fprintf(stderr, "insque: Inconsistency detected:"
  36                             " next(%p)->prev(%p) != prev(%p)\n",
  37                             next, next->prev, prev);
  38                 }
  39 #endif
  40                 next->prev = elem;
  41         }
  42         prev->next = elem;
  43         elem->prev = prev;
  44         elem->next = next;
  45 }