| ------------------------------------------------------------------------------ |
| -- -- |
| -- 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; |
