gcc/ada/a-calari.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --              A D A . C A L E N D A R . A R I T H M E T I C               --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --         Copyright (C) 2005-2008, Free Software Foundation, Inc.          --
  10 --                                                                          --
  11 -- This specification is derived from the Ada Reference Manual for use with --
  12 -- GNAT.  In accordance with the copyright of that document, you can freely --
  13 -- copy and modify this specification,  provided that if you redistribute a --
  14 -- modified version,  any changes that you have made are clearly indicated. --
  15 --                                                                          --
  16 ------------------------------------------------------------------------------
  17
  18 --  This package provides arithmetic operations of time values using days
  19 --  and leap seconds. Ada.Calendar.Arithmetic is defined in the Ada 2005
  20 --  RM (9.6.1).
  21
  22 package Ada.Calendar.Arithmetic is
  23
  24    --  Arithmetic on days:
  25
  26    --  Rough estimate on the number of days over the range of Ada time
  27
  28    type Day_Count is range
  29      -(366 * (1 + Year_Number'Last - Year_Number'First))
  30         ..
  31      +(366 * (1 + Year_Number'Last - Year_Number'First));
  32
  33    subtype Leap_Seconds_Count is Integer range -2047 .. 2047;
  34    --  Count of leap seconds. Negative leap seconds occur whenever the
  35    --  astronomical time is faster than the atomic time or as a result of
  36    --  Difference when Left < Right.
  37
  38    procedure Difference
  39      (Left         : Time;
  40       Right        : Time;
  41       Days         : out Day_Count;
  42       Seconds      : out Duration;
  43       Leap_Seconds : out Leap_Seconds_Count);
  44    --  Returns the difference between Left and Right. Days is the number of
  45    --  days of difference, Seconds is the remainder seconds of difference
  46    --  excluding leap seconds, and Leap_Seconds is the number of leap seconds.
  47    --  If Left < Right, then Seconds <= 0.0, Days <= 0, and Leap_Seconds <= 0,
  48    --  otherwise all values are nonnegative. The absolute value of Seconds is
  49    --  always less than 86_400.0. For the returned values, if Days = 0, then
  50    --  Seconds + Duration (Leap_Seconds) = Calendar."-" (Left, Right)
  51
  52    function "+" (Left : Time;      Right : Day_Count) return Time;
  53    function "+" (Left : Day_Count; Right : Time)      return Time;
  54    --  Adds a number of days to a time value. Time_Error is raised if the
  55    --  result is not representable as a value of type Time.
  56
  57    function "-" (Left : Time;      Right : Day_Count) return Time;
  58    --  Subtracts a number of days from a time value. Time_Error is raised if
  59    --  the result is not representable as a value of type Time.
  60
  61    function "-" (Left : Time;      Right : Time)      return Day_Count;
  62    --  Subtracts two time values, and returns the number of days between them.
  63    --  This is the same value that Difference would return in Days.
  64
  65 end Ada.Calendar.Arithmetic;