66 lines
3.3 KiB
Ada
66 lines
3.3 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- A D A . C A L E N D A R . A R I T H M E T I C --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 2005-2008, Free Software Foundation, Inc. --
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-- --
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-- This specification is derived from the Ada Reference Manual for use with --
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-- GNAT. In accordance with the copyright of that document, you can freely --
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-- copy and modify this specification, provided that if you redistribute a --
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-- modified version, any changes that you have made are clearly indicated. --
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-- --
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------------------------------------------------------------------------------
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-- This package provides arithmetic operations of time values using days
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-- and leap seconds. Ada.Calendar.Arithmetic is defined in the Ada 2005
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-- RM (9.6.1).
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package Ada.Calendar.Arithmetic is
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-- Arithmetic on days:
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-- Rough estimate on the number of days over the range of Ada time
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type Day_Count is range
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-(366 * (1 + Year_Number'Last - Year_Number'First))
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..
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+(366 * (1 + Year_Number'Last - Year_Number'First));
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subtype Leap_Seconds_Count is Integer range -2047 .. 2047;
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-- Count of leap seconds. Negative leap seconds occur whenever the
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-- astronomical time is faster than the atomic time or as a result of
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-- Difference when Left < Right.
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procedure Difference
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(Left : Time;
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Right : Time;
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Days : out Day_Count;
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Seconds : out Duration;
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Leap_Seconds : out Leap_Seconds_Count);
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-- Returns the difference between Left and Right. Days is the number of
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-- days of difference, Seconds is the remainder seconds of difference
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-- excluding leap seconds, and Leap_Seconds is the number of leap seconds.
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-- If Left < Right, then Seconds <= 0.0, Days <= 0, and Leap_Seconds <= 0,
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-- otherwise all values are nonnegative. The absolute value of Seconds is
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-- always less than 86_400.0. For the returned values, if Days = 0, then
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-- Seconds + Duration (Leap_Seconds) = Calendar."-" (Left, Right)
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function "+" (Left : Time; Right : Day_Count) return Time;
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function "+" (Left : Day_Count; Right : Time) return Time;
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-- Adds a number of days to a time value. Time_Error is raised if the
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-- result is not representable as a value of type Time.
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function "-" (Left : Time; Right : Day_Count) return Time;
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-- Subtracts a number of days from a time value. Time_Error is raised if
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-- the result is not representable as a value of type Time.
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function "-" (Left : Time; Right : Time) return Day_Count;
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-- Subtracts two time values, and returns the number of days between them.
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-- This is the same value that Difference would return in Days.
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end Ada.Calendar.Arithmetic;
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