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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
-- A D A . C A L E N D A R --
-- --
-- S p e c --
-- --
-- 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 --
-- 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 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. --
-- --
-- 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. --
-- --
------------------------------------------------------------------------------
package Scanner.Calendar is
type Time_Rep is range -2 ** 63 .. +2 ** 63 - 1;
type Time is new Time_Rep;
-- Declarations representing limits of allowed local time values. Note that
-- 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 .. 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;
function Day (Date : Time) return Day_Number;
function Seconds (Date : Time) return Day_Duration;
procedure Split
(Date : Time;
Year : out Year_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;
Month : Month_Number;
Day : Day_Number;
Seconds : Day_Duration := 0.0) return Time;
-- GNAT Note: Normally when procedure Split is called on a Time value
-- result of a call to function Time_Of, the out parameters of procedure
-- Split are identical to the in parameters of function Time_Of. However,
-- when a non-existent time of day is specified, the values for Seconds
-- may or may not be different. This may happen when Daylight Saving Time
-- (DST) is in effect, on the day when switching to DST, if Seconds
-- specifies a time of day in the hour that does not exist. For example,
-- in New York:
--
-- Time_Of (Year => 1998, Month => 4, Day => 5, Seconds => 10740.0)
--
-- will return a Time value T. If Split is called on T, the resulting
-- Seconds may be 14340.0 (3:59:00) instead of 10740.0 (2:59:00 being
-- a time that not exist).
function "+" (Left : Time; Right : Duration) return Time;
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;
function ">" (Left, Right : Time) return Boolean;
function ">=" (Left, Right : Time) return Boolean;
Time_Error : exception;
private
pragma Inline (Clock);
pragma Inline (Year);
pragma Inline (Month);
pragma Inline (Day);
pragma Inline ("+");
pragma Inline ("-");
pragma Inline ("<");
pragma Inline ("<=");
pragma Inline (">");
pragma Inline (">=");
-- 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.
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 Scanner.Calendar;