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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
-- A D A . C A L E N D A R . A R I T H M E T I C --
-- --
-- S p e c --
-- --
-- Copyright (C) 2005-2006, 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. --
-- --
-- GNAT 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. GNAT 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 GNAT; see file COPYING. If not, write --
-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, 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. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- This package provides arithmetic operations of time values using days
-- and leap seconds. Ada.Calendar.Arithmetic is defined in the Ada 2005
-- RM (9.6.1).
package Ada.Calendar.Arithmetic is
-- Arithmetic on days:
-- Rough estimate on the number of days over the range of Ada time
type Day_Count is range
-(366 * (1 + Year_Number'Last - Year_Number'First))
..
+(366 * (1 + Year_Number'Last - Year_Number'First));
-- Negative leap seconds occur whenever the astronomical time is faster
-- than the atomic time or as a result of Difference when Left < Right.
subtype Leap_Seconds_Count is Integer range -2047 .. 2047;
procedure Difference
(Left : Time;
Right : Time;
Days : out Day_Count;
Seconds : out Duration;
Leap_Seconds : out Leap_Seconds_Count);
-- Returns the difference between Left and Right. Days is the number of
-- days of difference, Seconds is the remainder seconds of difference
-- excluding leap seconds, and Leap_Seconds is the number of leap seconds.
-- If Left < Right, then Seconds <= 0.0, Days <= 0, and Leap_Seconds <= 0,
-- otherwise all values are nonnegative. The absolute value of Seconds is
-- always less than 86_400.0. For the returned values, if Days = 0, then
-- Seconds + Duration (Leap_Seconds) = Calendar."-" (Left, Right)
function "+" (Left : Time; Right : Day_Count) return Time;
function "+" (Left : Day_Count; Right : Time) return Time;
-- Adds a number of days to a time value. Time_Error is raised if the
-- result is not representable as a value of type Time.
function "-" (Left : Time; Right : Day_Count) return Time;
-- Subtracts a number of days from a time value. Time_Error is raised if
-- the result is not representable as a value of type Time.
function "-" (Left : Time; Right : Time) return Day_Count;
-- Subtracts two time values, and returns the number of days between them.
-- This is the same value that Difference would return in Days.
end Ada.Calendar.Arithmetic;
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