1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME COMPONENTS --
5 -- A D A . C A L E N D A R . A R I T H M E T I C --
9 -- Copyright (C) 2005-2006, Free Software Foundation, Inc. --
11 -- This specification is derived from the Ada Reference Manual for use with --
12 -- GNAT. The copyright notice above, and the license provisions that follow --
13 -- apply solely to the contents of the part following the private keyword. --
15 -- GNAT is free software; you can redistribute it and/or modify it under --
16 -- terms of the GNU General Public License as published by the Free Soft- --
17 -- ware Foundation; either version 2, or (at your option) any later ver- --
18 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
19 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
20 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
21 -- for more details. You should have received a copy of the GNU General --
22 -- Public License distributed with GNAT; see file COPYING. If not, write --
23 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
24 -- MA 02111-1307, USA. --
26 -- As a special exception, if other files instantiate generics from this --
27 -- unit, or you link this unit with other files to produce an executable, --
28 -- this unit does not by itself cause the resulting executable to be --
29 -- covered by the GNU General Public License. This exception does not --
30 -- however invalidate any other reasons why the executable file might be --
31 -- covered by the GNU Public License. --
33 -- GNAT was originally developed by the GNAT team at New York University. --
34 -- Extensive contributions were provided by Ada Core Technologies Inc. --
36 ------------------------------------------------------------------------------
38 -- This package provides arithmetic operations of time values using days
39 -- and leap seconds. Ada.Calendar.Arithmetic is defined in the Ada 2005
42 package Ada.Calendar.Arithmetic is
44 -- Arithmetic on days:
46 -- Rough estimate on the number of days over the range of Ada time
48 type Day_Count is range
49 -(366 * (1 + Year_Number'Last - Year_Number'First))
51 +(366 * (1 + Year_Number'Last - Year_Number'First));
53 -- Negative leap seconds occur whenever the astronomical time is faster
54 -- than the atomic time or as a result of Difference when Left < Right.
56 subtype Leap_Seconds_Count is Integer range -2047 .. 2047;
62 Seconds : out Duration;
63 Leap_Seconds : out Leap_Seconds_Count);
64 -- Returns the difference between Left and Right. Days is the number of
65 -- days of difference, Seconds is the remainder seconds of difference
66 -- excluding leap seconds, and Leap_Seconds is the number of leap seconds.
67 -- If Left < Right, then Seconds <= 0.0, Days <= 0, and Leap_Seconds <= 0,
68 -- otherwise all values are nonnegative. The absolute value of Seconds is
69 -- always less than 86_400.0. For the returned values, if Days = 0, then
70 -- Seconds + Duration (Leap_Seconds) = Calendar."-" (Left, Right)
72 function "+" (Left : Time; Right : Day_Count) return Time;
73 function "+" (Left : Day_Count; Right : Time) return Time;
74 -- Adds a number of days to a time value. Time_Error is raised if the
75 -- result is not representable as a value of type Time.
77 function "-" (Left : Time; Right : Day_Count) return Time;
78 -- Subtracts a number of days from a time value. Time_Error is raised if
79 -- the result is not representable as a value of type Time.
81 function "-" (Left : Time; Right : Time) return Day_Count;
82 -- Subtracts two time values, and returns the number of days between them.
83 -- This is the same value that Difference would return in Days.
85 end Ada.Calendar.Arithmetic;