------------------------------------------------------------------------------
--                                                                          --
--                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
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--                   A D A . C A L E N D A R . D E L A Y S                  --
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------------------------------------------------------------------------------

with System.OS_Primitives;
with System.Soft_Links;

package body Ada.Calendar.Delays is

   package OSP renames System.OS_Primitives;
   package SSL renames System.Soft_Links;

   use type SSL.Timed_Delay_Call;

   --  Earlier, System.Time_Operations was used to implement the following
   --  operations. The idea was to avoid sucking in the tasking packages. This
   --  did not work. Logically, we can't have it both ways. There is no way to
   --  implement time delays that will have correct task semantics without
   --  reference to the tasking run-time system. To achieve this goal, we now
   --  use soft links.

   -----------------------
   -- Local Subprograms --
   -----------------------

   procedure Timed_Delay_NT (Time : Duration; Mode : Integer);
   --  Timed delay procedure used when no tasking is active

   ---------------
   -- Delay_For --
   ---------------

   procedure Delay_For (D : Duration) is
   begin
      SSL.Timed_Delay.all (Duration'Min (D, OSP.Max_Sensible_Delay),
                           OSP.Relative);
   end Delay_For;

   -----------------
   -- Delay_Until --
   -----------------

   procedure Delay_Until (T : Time) is
      D : constant Duration := To_Duration (T);

   begin
      SSL.Timed_Delay.all (D, OSP.Absolute_Calendar);
   end Delay_Until;

   --------------------
   -- Timed_Delay_NT --
   --------------------

   procedure Timed_Delay_NT (Time : Duration; Mode : Integer) is
   begin
      OSP.Timed_Delay (Time, Mode);
   end Timed_Delay_NT;

   -----------------
   -- To_Duration --
   -----------------

   function To_Duration (T : Time) return Duration is
   begin
      --  Since time has multiple representations on different platforms, a
      --  target independent operation in Ada.Calendar is used to perform
      --  this conversion.

      return Delay_Operations.To_Duration (T);
   end To_Duration;

begin
   --  Set up the Timed_Delay soft link to the non tasking version if it has
   --  not been already set. If tasking is present, Timed_Delay has already set
   --  this soft link, or this will be overridden during the elaboration of
   --  System.Tasking.Initialization

   if SSL.Timed_Delay = null then
      SSL.Timed_Delay := Timed_Delay_NT'Access;
   end if;

end Ada.Calendar.Delays;
