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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) 2005-2008, Free Software Foundation, Inc. --
-- --
-- This specification is derived from the Ada Reference Manual for use with --
-- GNAT. In accordance with the copyright of that document, you can freely --
-- copy and modify this specification, provided that if you redistribute a --
-- modified version, any changes that you have made are clearly indicated. --
-- --
------------------------------------------------------------------------------
-- 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));
subtype Leap_Seconds_Count is Integer range -2047 .. 2047;
-- Count of leap seconds. Negative leap seconds occur whenever the
-- astronomical time is faster than the atomic time or as a result of
-- Difference when Left < Right.
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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