------------------------------------------------------------------------------
--                                                                          --
--                         GNAT RUN-TIME COMPONENTS                         --
--                                                                          --
--                         A D A . R E A L _ T I M E                        --
--                                                                          --
--                                  S p e c                                 --
--                                                                          --
--                                                                          --
--          Copyright (C) 1992-2001 Free Software Foundation, Inc.          --
--                                                                          --
-- This specification is derived from the Ada Reference Manual for use with --
-- GNAT. The copyright notice above, and the license provisions that follow --
-- apply solely to the  contents of the part following the private keyword. --
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-- GNAT is free software;  you can  redistribute it  and/or modify it under --
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-- unit, or you link  this unit with other files  to produce an executable, --
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-- covered  by the  GNU  General  Public  License.  This exception does not --
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-- Extensive contributions were provided by Ada Core Technologies Inc.      --
--                                                                          --
------------------------------------------------------------------------------

with System.Task_Primitives.Operations;
pragma Elaborate_All (System.Task_Primitives.Operations);

package Ada.Real_Time is

   type Time is private;
   Time_First : constant Time;
   Time_Last  : constant Time;
   Time_Unit  : constant := 10#1.0#E-9;

   type Time_Span is private;
   Time_Span_First : constant Time_Span;
   Time_Span_Last  :  constant Time_Span;
   Time_Span_Zero  :  constant Time_Span;
   Time_Span_Unit  :  constant Time_Span;

   Tick : constant Time_Span;
   function Clock return Time;

   function "+"  (Left : Time;      Right : Time_Span) return Time;
   function "+"  (Left : Time_Span; Right : Time)      return Time;
   function "-"  (Left : Time;      Right : Time_Span) return Time;
   function "-"  (Left : Time;      Right : Time)      return Time_Span;

   function "<"  (Left, Right : Time) return Boolean;
   function "<=" (Left, Right : Time) return Boolean;
   function ">"  (Left, Right : Time) return Boolean;
   function ">=" (Left, Right : Time) return Boolean;

   function "+"  (Left, Right : Time_Span)             return Time_Span;
   function "-"  (Left, Right : Time_Span)             return Time_Span;
   function "-"  (Right : Time_Span)                   return Time_Span;
   function "*"  (Left : Time_Span; Right : Integer)   return Time_Span;
   function "*"  (Left : Integer;   Right : Time_Span) return Time_Span;
   function "/"  (Left, Right : Time_Span)             return Integer;
   function "/"  (Left : Time_Span; Right : Integer)   return Time_Span;

   function "abs" (Right : Time_Span) return Time_Span;

   function "<"  (Left, Right : Time_Span) return Boolean;
   function "<=" (Left, Right : Time_Span) return Boolean;
   function ">"  (Left, Right : Time_Span) return Boolean;
   function ">=" (Left, Right : Time_Span) return Boolean;

   function To_Duration  (TS : Time_Span) return Duration;
   function To_Time_Span (D : Duration)   return Time_Span;

   function Nanoseconds  (NS : Integer) return Time_Span;
   function Microseconds (US : Integer) return Time_Span;
   function Milliseconds (MS : Integer) return Time_Span;

   --  Seconds_Count needs 64 bits, since Time has the full range of
   --  Duration. The delta of Duration is 10 ** (-9), so the maximum
   --  number of seconds is 2**63/10**9 = 8*10**9 which does not quite
   --  fit in 32 bits.

   type Seconds_Count is range -2 ** 63 .. 2 ** 63 - 1;

   procedure Split (T : Time; SC : out Seconds_Count; TS : out Time_Span);
   function Time_Of (SC : Seconds_Count; TS : Time_Span) return Time;

private
   type Time is new Duration;

   Time_First : constant Time := Time'First;

   Time_Last  : constant Time := Time'Last;

   type Time_Span is new Duration;

   Time_Span_First : constant Time_Span := Time_Span'First;

   Time_Span_Last  : constant Time_Span := Time_Span'Last;

   Time_Span_Zero  : constant Time_Span := 0.0;

   Time_Span_Unit  : constant Time_Span := 10#1.0#E-9;

   Tick : constant Time_Span :=
            Time_Span (System.Task_Primitives.Operations.RT_Resolution);

   --  Time and Time_Span are represented in 64-bit Duration value in
   --  in nanoseconds. For example, 1 second and 1 nanosecond is
   --  represented as the stored integer 1_000_000_001.

   pragma Import (Intrinsic, "<");
   pragma Import (Intrinsic, "<=");
   pragma Import (Intrinsic, ">");
   pragma Import (Intrinsic, ">=");
   pragma Import (Intrinsic, "abs");

end Ada.Real_Time;
