-- --
-- S p e c --
-- --
--- Copyright (C) 1992-2004 Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2009, 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 --
-- --
-- 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- --
+-- ware Foundation; either version 3, 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. --
+-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
--- 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. --
+-- As a special exception under Section 7 of GPL version 3, you are granted --
+-- additional permissions described in the GCC Runtime Library Exception, --
+-- version 3.1, as published by the Free Software Foundation. --
+-- --
+-- You should have received a copy of the GNU General Public License and --
+-- a copy of the GCC Runtime Library Exception along with this program; --
+-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
+-- <http://www.gnu.org/licenses/>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- these do NOT constrain the possible stored values of time which may well
-- permit a larger range of times (this is explicitly allowed in Ada 95).
- subtype Year_Number is Integer range 1901 .. 2099;
+ subtype Year_Number is Integer range 1901 .. 2399;
subtype Month_Number is Integer range 1 .. 12;
subtype Day_Number is Integer range 1 .. 31;
+ -- A Day_Duration value of 86_400.0 designates a new day
+
subtype Day_Duration is Duration range 0.0 .. 86_400.0;
function Clock return Time;
+ -- The returned time value is the number of nanoseconds since the start
+ -- of Ada time (1901-01-01 00:00:00.0 UTC). If leap seconds are enabled,
+ -- the result will contain all elapsed leap seconds since the start of
+ -- Ada time until now.
function Year (Date : Time) return Year_Number;
function Month (Date : Time) return Month_Number;
Month : out Month_Number;
Day : out Day_Number;
Seconds : out Day_Duration);
+ -- Break down a time value into its date components set in the current
+ -- time zone. If Split is called on a time value created using Ada 2005
+ -- Time_Of in some arbitrary time zone, the input value will always be
+ -- interpreted as relative to the local time zone.
function Time_Of
(Year : Year_Number;
function "+" (Left : Duration; Right : Time) return Time;
function "-" (Left : Time; Right : Duration) return Time;
function "-" (Left : Time; Right : Time) return Duration;
+ -- The first three functions will raise Time_Error if the resulting time
+ -- value is less than the start of Ada time in UTC or greater than the
+ -- end of Ada time in UTC. The last function will raise Time_Error if the
+ -- resulting difference cannot fit into a duration value.
function "<" (Left, Right : Time) return Boolean;
function "<=" (Left, Right : Time) return Boolean;
pragma Inline (">");
pragma Inline (">=");
- -- Time is represented as a signed duration from the base point which is
- -- what Unix calls the EPOCH (i.e. 12 midnight (24:00:00), Dec 31st, 1969,
- -- or if you prefer 0:00:00 on Jan 1st, 1970). Since Ada allows dates
- -- before this EPOCH value, the stored duration value may be negative.
-
- -- The time value stored is typically a GMT value, as provided in standard
- -- Unix environments. If this is the case then Split and Time_Of perform
- -- required conversions to and from local times. The range of times that
- -- can be stored in Time values depends on the declaration of the type
- -- Duration, which must at least cover the required Ada range represented
- -- by the declaration of Year_Number, but may be larger (we take full
- -- advantage of the new permission in Ada 95 to store time values outside
- -- the range that would be acceptable to Split). The Duration type is a
- -- real value representing a time interval in seconds.
-
- type Time is new Duration;
+ -- The units used in this version of Ada.Calendar are nanoseconds. The
+ -- following constants provide values used in conversions of seconds or
+ -- days to the underlying units.
+
+ Nano : constant := 1_000_000_000;
+ Nano_F : constant := 1_000_000_000.0;
+ Nanos_In_Day : constant := 86_400_000_000_000;
+ Secs_In_Day : constant := 86_400;
+
+ ----------------------------
+ -- Implementation of Time --
+ ----------------------------
+
+ -- Time is represented as a signed 64 bit integer count of nanoseconds
+ -- since the start of Ada time (1901-01-01 00:00:00.0 UTC). Time values
+ -- produced by Time_Of are internally normalized to UTC regardless of their
+ -- local time zone. This representation ensures correct handling of leap
+ -- seconds as well as performing arithmetic. In Ada 95, Split and Time_Of
+ -- will treat a time value as being in the local time zone, in Ada 2005,
+ -- Split and Time_Of will treat a time value as being in the designated
+ -- time zone by the formal parameter or in UTC by default. The size of the
+ -- type is large enough to cover the Ada 2005 range of time (1901-01-01
+ -- 00:00:00.0 UTC - 2399-12-31-23:59:59.999999999 UTC).
+
+ ------------------
+ -- Leap seconds --
+ ------------------
+
+ -- Due to Earth's slowdown, the astronomical time is not as precise as the
+ -- International Atomic Time. To compensate for this inaccuracy, a single
+ -- leap second is added after the last day of June or December. The count
+ -- of seconds during those occurrences becomes:
+
+ -- ... 58, 59, leap second 60, 0, 1, 2 ...
+
+ -- Unlike leap days, leap seconds occur simultaneously around the world.
+ -- In other words, if a leap second occurs at 23:59:60 UTC, it also occurs
+ -- on 18:59:60 -5 the same day or 2:59:60 +2 on the next day.
+
+ -- Leap seconds do not follow a formula. The International Earth Rotation
+ -- and Reference System Service decides when to add one. Leap seconds are
+ -- included in the representation of time in Ada 95 mode. As a result,
+ -- the following two time values will differ by two seconds:
+
+ -- 1972-06-30 23:59:59.0
+ -- 1972-07-01 00:00:00.0
+
+ -- When a new leap second is introduced, the following steps must be
+ -- carried out:
+
+ -- 1) Increment Leap_Seconds_Count in a-calend.adb by one
+ -- 2) Increment LS_Count in xleaps.adb by one
+ -- 3) Add the new date to the aggregate of array LS_Dates in
+ -- xleaps.adb
+ -- 4) Compile and execute xleaps
+ -- 5) Replace the values of Leap_Second_Times in a-calend.adb with the
+ -- aggregate generated by xleaps
+
+ -- The algorithms that build the actual leap second values and discover
+ -- how many leap seconds have occurred between two dates do not need any
+ -- modification.
+
+ ------------------------------
+ -- Non-leap centennial years --
+ ------------------------------
+
+ -- Over the range of Ada time, centennial years 2100, 2200 and 2300 are
+ -- non-leap. As a consequence, seven non-leap years occur over the period
+ -- of year - 4 to year + 4. Internally, routines Split and Time_Of add or
+ -- subtract a "fake" February 29 to facilitate the arithmetic involved.
+
+ -- The underlying type of Time has been chosen to be a 64 bit signed
+ -- integer number since it allows for easier processing of sub seconds
+ -- and arithmetic.
+
+ type Time_Rep is range -2 ** 63 .. +2 ** 63 - 1;
+ type Time is new Time_Rep;
+
+ Days_In_Month : constant array (Month_Number) of Day_Number :=
+ (31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
+
+ Invalid_Time_Zone_Offset : Long_Integer;
+ pragma Import (C, Invalid_Time_Zone_Offset, "__gnat_invalid_tzoff");
+
+ function Is_Leap (Year : Year_Number) return Boolean;
+ -- Determine whether a given year is leap
+
+ -- The following packages provide a target independent interface to the
+ -- children of Calendar - Arithmetic, Conversions, Delays, Formatting and
+ -- Time_Zones.
+
+ ---------------------------
+ -- Arithmetic_Operations --
+ ---------------------------
+
+ package Arithmetic_Operations is
+
+ function Add (Date : Time; Days : Long_Integer) return Time;
+ -- Add a certain number of days to a time value
+
+ procedure Difference
+ (Left : Time;
+ Right : Time;
+ Days : out Long_Integer;
+ Seconds : out Duration;
+ Leap_Seconds : out Integer);
+ -- Calculate the difference between two time values in terms of days,
+ -- seconds and leap seconds elapsed. The leap seconds are not included
+ -- in the seconds returned. If Left is greater than Right, the returned
+ -- values are positive, negative otherwise.
+
+ function Subtract (Date : Time; Days : Long_Integer) return Time;
+ -- Subtract a certain number of days from a time value
+
+ end Arithmetic_Operations;
+
+ ---------------------------
+ -- Conversion_Operations --
+ ---------------------------
+
+ package Conversion_Operations is
+
+ function To_Ada_Time (Unix_Time : Long_Integer) return Time;
+ -- Unix to Ada Epoch conversion
+
+ function To_Ada_Time
+ (tm_year : Integer;
+ tm_mon : Integer;
+ tm_day : Integer;
+ tm_hour : Integer;
+ tm_min : Integer;
+ tm_sec : Integer;
+ tm_isdst : Integer) return Time;
+ -- Struct tm to Ada Epoch conversion
+
+ function To_Duration
+ (tv_sec : Long_Integer;
+ tv_nsec : Long_Integer) return Duration;
+ -- Struct timespec to Duration conversion
+
+ procedure To_Struct_Timespec
+ (D : Duration;
+ tv_sec : out Long_Integer;
+ tv_nsec : out Long_Integer);
+ -- Duration to struct timespec conversion
+
+ procedure To_Struct_Tm
+ (T : Time;
+ tm_year : out Integer;
+ tm_mon : out Integer;
+ tm_day : out Integer;
+ tm_hour : out Integer;
+ tm_min : out Integer;
+ tm_sec : out Integer);
+ -- Time to struct tm conversion
+
+ function To_Unix_Time (Ada_Time : Time) return Long_Integer;
+ -- Ada to Unix Epoch conversion
+
+ end Conversion_Operations;
+
+ ----------------------
+ -- Delay_Operations --
+ ----------------------
+
+ package Delay_Operations is
+
+ function To_Duration (Date : Time) return Duration;
+ -- Given a time value in nanoseconds since 1901, convert it into a
+ -- duration value giving the number of nanoseconds since the Unix Epoch.
+
+ end Delay_Operations;
+
+ ---------------------------
+ -- Formatting_Operations --
+ ---------------------------
+
+ package Formatting_Operations is
+
+ function Day_Of_Week (Date : Time) return Integer;
+ -- Determine which day of week Date falls on. The returned values are
+ -- within the range of 0 .. 6 (Monday .. Sunday).
+
+ procedure Split
+ (Date : Time;
+ Year : out Year_Number;
+ Month : out Month_Number;
+ Day : out Day_Number;
+ Day_Secs : out Day_Duration;
+ Hour : out Integer;
+ Minute : out Integer;
+ Second : out Integer;
+ Sub_Sec : out Duration;
+ Leap_Sec : out Boolean;
+ Is_Ada_05 : Boolean;
+ Time_Zone : Long_Integer);
+ -- Split a time value into its components. Set Is_Ada_05 to use the
+ -- local time zone (the value in Time_Zone is ignored) when splitting
+ -- a time value.
+
+ function Time_Of
+ (Year : Year_Number;
+ Month : Month_Number;
+ Day : Day_Number;
+ Day_Secs : Day_Duration;
+ Hour : Integer;
+ Minute : Integer;
+ Second : Integer;
+ Sub_Sec : Duration;
+ Leap_Sec : Boolean := False;
+ Use_Day_Secs : Boolean := False;
+ Is_Ada_05 : Boolean := False;
+ Time_Zone : Long_Integer := 0) return Time;
+ -- Given all the components of a date, return the corresponding time
+ -- value. Set Use_Day_Secs to use the value in Day_Secs, otherwise the
+ -- day duration will be calculated from Hour, Minute, Second and Sub_
+ -- Sec. Set Is_Ada_05 to use the local time zone (the value in formal
+ -- Time_Zone is ignored) when building a time value and to verify the
+ -- validity of a requested leap second.
+
+ end Formatting_Operations;
+
+ ---------------------------
+ -- Time_Zones_Operations --
+ ---------------------------
+
+ package Time_Zones_Operations is
+
+ function UTC_Time_Offset (Date : Time) return Long_Integer;
+ -- Return the offset in seconds from UTC
+
+ end Time_Zones_Operations;
end Ada.Calendar;
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