rom/exec/addhead.c

   1 /*
   2     Copyright © 1995-2012, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Add a node to the head of a list
   6     Lang: english
   7 */
   8 #include <aros/debug.h>
   9 #include <exec/lists.h>
  10 #include <proto/exec.h>
  11
  12 /*****************************************************************************
  13
  14     NAME */
  15
  16         AROS_LH2I(void, AddHead,
  17
  18 /*  SYNOPSIS */
  19         AROS_LHA(struct List *, list, A0),
  20         AROS_LHA(struct Node *, node, A1),
  21
  22 /*  LOCATION */
  23         struct ExecBase *, SysBase, 40, Exec)
  24
  25 /*  FUNCTION
  26         Insert Node node as the first node of the list.
  27
  28     INPUTS
  29         list - The list to insert the node into
  30         node - This node is to be inserted
  31
  32     RESULT
  33         None.
  34
  35     NOTES
  36
  37     EXAMPLE
  38         struct List * list;
  39         struct Node * pred;
  40
  41         // Insert Node at top
  42         AddHead (list, node);
  43
  44     BUGS
  45
  46     SEE ALSO
  47         libamiga/NewList(), AddTail(), Insert(), Remove(), RemHead(), RemTail(),
  48         Enqueue()
  49
  50     INTERNALS
  51
  52 ******************************************************************************/
  53 {
  54     AROS_LIBFUNC_INIT
  55     ASSERT_VALID_PTR(node);
  56     ASSERT_VALID_PTR(list);
  57
  58     /*
  59         Make the node point to the old first node in the list and to the
  60         head of the list.
  61     */
  62     node->ln_Succ          = list->lh_Head;
  63     node->ln_Pred          = (struct Node *)&list->lh_Head;
  64
  65     /*
  66         New we come before the old first node which must now point to us
  67         and the same applies to the pointer to-the-first-node in the
  68         head of the list.
  69     */
  70     list->lh_Head->ln_Pred = node;
  71     list->lh_Head          = node;
  72     AROS_LIBFUNC_EXIT
  73 } /* AddHead */
  74