------------------------------------------------------------------------------
--                                                                          --
--                GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS               --
--                                                                          --
--                   A D A . C A L E N D A R . D E L A Y S                  --
--                                                                          --
--                                  B o d y                                 --
--                                                                          --
--             Copyright (C) 1991-1994, Florida State University            --
--             Copyright (C) 1995-2003, Ada Core Technologies               --
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-- GNARL is free software; you can  redistribute it  and/or modify it under --
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-- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
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-- As a special exception,  if other files  instantiate  generics from this --
-- unit, or you link  this unit with other files  to produce an executable, --
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------------------------------------------------------------------------------

with System.OS_Primitives;
--  Used for Delay_Modes
--           Max_Sensible_Delay

with System.Soft_Links;
--  Used for Timed_Delay

with System.Traces;
--  Used for Send_Trace_Info

with System.Parameters;
--  used for Runtime_Traces

package body Ada.Calendar.Delays is

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

   use type SSL.Timed_Delay_Call;

   use System.Traces;

   --  Earlier, the following operations were implemented using
   --  System.Time_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
      if System.Parameters.Runtime_Traces then
         Send_Trace_Info (W_Delay, D);
      end if;

      SSL.Timed_Delay.all (Duration'Min (D, OSP.Max_Sensible_Delay),
                           OSP.Relative);

      if System.Parameters.Runtime_Traces then
         Send_Trace_Info (M_Delay, D);
      end if;
   end Delay_For;

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

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

   begin
      if System.Parameters.Runtime_Traces then
         Send_Trace_Info (WU_Delay, D);
      end if;

      SSL.Timed_Delay.all (D, OSP.Absolute_Calendar);

      if System.Parameters.Runtime_Traces then
         Send_Trace_Info (M_Delay, D);
      end if;
   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
      return 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 overriden 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;
