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------------------------------------------------------------------------------

--                                                                          --

--                 GNAT 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) 1995-2009, AdaCore                     --

--                                                                          --

-- GNARL is free software; you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 2,  or (at your option) any later ver- --

-- sion. GNARL is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --

-- for  more details.  You should have  received  a copy of the GNU General --

-- Public License  distributed with GNARL; see file COPYING.  If not, write --

-- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --

-- Boston, MA 02110-1301, USA.                                              --

--                                                                          --

-- As a special exception,  if other files  instantiate  generics from this --

-- unit, or you link  this unit with other files  to produce an executable, --

-- this  unit  does not  by itself cause  the resulting  executable  to  be --

-- covered  by the  GNU  General  Public  License.  This exception does not --

-- however invalidate  any other reasons why  the executable file  might be --

-- covered by the  GNU Public License.                                      --

--                                                                          --

-- GNARL was developed by the GNARL team at Florida State University.       --

-- Extensive contributions were provided by Ada Core Technologies, Inc.     --

--                                                                          --

------------------------------------------------------------------------------

--  This is the Alpha/VMS version

with System.OS_Primitives;

with System.Soft_Links;

package body Ada.Calendar.Delays is

   package OSP renames System.OS_Primitives;

   package TSL renames System.Soft_Links;

   use type TSL.Timed_Delay_Call;

   -----------------------

   -- 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

      TSL.Timed_Delay.all

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

   end Delay_For;

   -----------------

   -- Delay_Until --

   -----------------

   procedure Delay_Until (T : Time) is

   begin

      TSL.Timed_Delay.all (To_Duration (T), OSP.Absolute_Calendar);

   end Delay_Until;

   -----------------

   -- To_Duration --

   -----------------

   function To_Duration (T : Time) return Duration is

      Safe_Ada_High : constant Time := Time_Of (2250, 1, 1, 0.0);

      --  A value distant enough to emulate "end of time" but which does not

      --  cause overflow.

      Safe_T : constant Time :=

                 (if T > Safe_Ada_High then Safe_Ada_High else T);

   begin

      return OSP.To_Duration (OSP.OS_Time (Safe_T), OSP.Absolute_Calendar);

   end To_Duration;

   --------------------

   -- Timed_Delay_NT --

   --------------------

   procedure Timed_Delay_NT (Time : Duration; Mode : Integer) is

   begin

      OSP.Timed_Delay (Time, Mode);

   end Timed_Delay_NT;

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 TSL.Timed_Delay = null then

      TSL.Timed_Delay := Timed_Delay_NT'Access;

   end if;

end Ada.Calendar.Delays;