383 lines
16 KiB
Ada
383 lines
16 KiB
Ada
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------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- A D A . C A L E N D A R --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 1992-2014, Free Software Foundation, Inc. --
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-- --
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-- This specification is derived from the Ada Reference Manual for use with --
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-- GNAT. The copyright notice above, and the license provisions that follow --
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-- apply solely to the contents of the part following the private keyword. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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package Ada.Calendar is
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type Time is private;
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-- Declarations representing limits of allowed local time values. Note that
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-- these do NOT constrain the possible stored values of time which may well
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-- permit a larger range of times (this is explicitly allowed in Ada 95).
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subtype Year_Number is Integer range 1901 .. 2399;
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subtype Month_Number is Integer range 1 .. 12;
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subtype Day_Number is Integer range 1 .. 31;
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-- A Day_Duration value of 86_400.0 designates a new day
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subtype Day_Duration is Duration range 0.0 .. 86_400.0;
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function Clock return Time;
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-- The returned time value is the number of nanoseconds since the start
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-- of Ada time (1901-01-01 00:00:00.0 UTC). If leap seconds are enabled,
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-- the result will contain all elapsed leap seconds since the start of
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-- Ada time until now.
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function Year (Date : Time) return Year_Number;
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function Month (Date : Time) return Month_Number;
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function Day (Date : Time) return Day_Number;
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function Seconds (Date : Time) return Day_Duration;
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procedure Split
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(Date : Time;
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Year : out Year_Number;
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Month : out Month_Number;
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Day : out Day_Number;
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Seconds : out Day_Duration);
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-- Break down a time value into its date components set in the current
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-- time zone. If Split is called on a time value created using Ada 2005
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-- Time_Of in some arbitrary time zone, the input value will always be
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-- interpreted as relative to the local time zone.
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function Time_Of
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(Year : Year_Number;
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Month : Month_Number;
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Day : Day_Number;
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Seconds : Day_Duration := 0.0) return Time;
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-- GNAT Note: Normally when procedure Split is called on a Time value
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-- result of a call to function Time_Of, the out parameters of procedure
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-- Split are identical to the in parameters of function Time_Of. However,
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-- when a non-existent time of day is specified, the values for Seconds
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-- may or may not be different. This may happen when Daylight Saving Time
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-- (DST) is in effect, on the day when switching to DST, if Seconds
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-- specifies a time of day in the hour that does not exist. For example,
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-- in New York:
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--
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-- Time_Of (Year => 1998, Month => 4, Day => 5, Seconds => 10740.0)
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--
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-- will return a Time value T. If Split is called on T, the resulting
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-- Seconds may be 14340.0 (3:59:00) instead of 10740.0 (2:59:00 being
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-- a time that not exist).
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function "+" (Left : Time; Right : Duration) return Time;
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function "+" (Left : Duration; Right : Time) return Time;
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function "-" (Left : Time; Right : Duration) return Time;
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function "-" (Left : Time; Right : Time) return Duration;
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-- The first three functions will raise Time_Error if the resulting time
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-- value is less than the start of Ada time in UTC or greater than the
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-- end of Ada time in UTC. The last function will raise Time_Error if the
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-- resulting difference cannot fit into a duration value.
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function "<" (Left, Right : Time) return Boolean;
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function "<=" (Left, Right : Time) return Boolean;
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function ">" (Left, Right : Time) return Boolean;
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function ">=" (Left, Right : Time) return Boolean;
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Time_Error : exception;
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private
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pragma Inline (Clock);
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pragma Inline (Year);
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pragma Inline (Month);
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pragma Inline (Day);
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pragma Inline ("+");
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pragma Inline ("-");
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pragma Inline ("<");
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pragma Inline ("<=");
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pragma Inline (">");
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pragma Inline (">=");
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-- The units used in this version of Ada.Calendar are nanoseconds. The
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-- following constants provide values used in conversions of seconds or
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-- days to the underlying units.
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Nano : constant := 1_000_000_000;
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Nano_F : constant := 1_000_000_000.0;
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Nanos_In_Day : constant := 86_400_000_000_000;
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Secs_In_Day : constant := 86_400;
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----------------------------
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-- Implementation of Time --
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----------------------------
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-- Time is represented as a signed 64 bit integer count of nanoseconds
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-- since the start of Ada time (1901-01-01 00:00:00.0 UTC). Time values
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-- produced by Time_Of are internally normalized to UTC regardless of their
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-- local time zone. This representation ensures correct handling of leap
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-- seconds as well as performing arithmetic. In Ada 95, Split and Time_Of
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-- will treat a time value as being in the local time zone, in Ada 2005,
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-- Split and Time_Of will treat a time value as being in the designated
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-- time zone by the formal parameter or in UTC by default. The size of the
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-- type is large enough to cover the Ada 2005 range of time (1901-01-01
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-- 00:00:00.0 UTC - 2399-12-31-23:59:59.999999999 UTC).
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------------------
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-- Leap Seconds --
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------------------
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-- Due to Earth's slowdown, the astronomical time is not as precise as the
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-- International Atomic Time. To compensate for this inaccuracy, a single
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-- leap second is added after the last day of June or December. The count
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-- of seconds during those occurrences becomes:
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-- ... 58, 59, leap second 60, 0, 1, 2 ...
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-- Unlike leap days, leap seconds occur simultaneously around the world.
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-- In other words, if a leap second occurs at 23:59:60 UTC, it also occurs
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-- on 18:59:60 -5 the same day or 2:59:60 +2 on the next day.
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-- Leap seconds do not follow a formula. The International Earth Rotation
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-- and Reference System Service decides when to add one. Leap seconds are
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-- included in the representation of time in Ada 95 mode. As a result,
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-- the following two time values will differ by two seconds:
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-- 1972-06-30 23:59:59.0
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-- 1972-07-01 00:00:00.0
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-- When a new leap second is introduced, the following steps must be
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-- carried out:
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-- 1) Increment Leap_Seconds_Count in a-calend.adb by one
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-- 2) Increment LS_Count in xleaps.adb by one
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-- 3) Add the new date to the aggregate of array LS_Dates in
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-- xleaps.adb
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-- 4) Compile and execute xleaps
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-- 5) Replace the values of Leap_Second_Times in a-calend.adb with the
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-- aggregate generated by xleaps
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-- The algorithms that build the actual leap second values and discover
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-- how many leap seconds have occurred between two dates do not need any
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-- modification.
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------------------------------
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-- Non-leap Centennial Years --
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------------------------------
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-- Over the range of Ada time, centennial years 2100, 2200 and 2300 are
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-- non-leap. As a consequence, seven non-leap years occur over the period
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-- of year - 4 to year + 4. Internally, routines Split and Time_Of add or
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-- subtract a "fake" February 29 to facilitate the arithmetic involved.
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------------------------
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-- Local Declarations --
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------------------------
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type Time_Rep is new Long_Long_Integer;
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type Time is new Time_Rep;
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-- The underlying type of Time has been chosen to be a 64 bit signed
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-- integer number since it allows for easier processing of sub-seconds
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-- and arithmetic. We use Long_Long_Integer to allow this unit to compile
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-- when using custom target configuration files where the max integer is
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-- 32 bits. This is useful for static analysis tools such as SPARK or
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-- CodePeer.
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--
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-- Note: the reason we have two separate types here is to avoid problems
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-- with overloading ambiguities in the body if we tried to use Time as an
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-- internal computational type.
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Days_In_Month : constant array (Month_Number) of Day_Number :=
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(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
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-- Days in month for non-leap year, leap year case is adjusted in code
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Invalid_Time_Zone_Offset : Long_Integer;
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pragma Import (C, Invalid_Time_Zone_Offset, "__gnat_invalid_tzoff");
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function Is_Leap (Year : Year_Number) return Boolean;
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-- Determine whether a given year is leap
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----------------------------------------------------------
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-- Target-Independent Interface to Children of Calendar --
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----------------------------------------------------------
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-- The following packages provide a target-independent interface to the
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-- children of Calendar - Arithmetic, Conversions, Delays, Formatting and
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-- Time_Zones.
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---------------------------
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-- Arithmetic_Operations --
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---------------------------
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package Arithmetic_Operations is
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function Add (Date : Time; Days : Long_Integer) return Time;
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-- Add a certain number of days to a time value
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procedure Difference
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(Left : Time;
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Right : Time;
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Days : out Long_Integer;
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Seconds : out Duration;
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Leap_Seconds : out Integer);
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-- Calculate the difference between two time values in terms of days,
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-- seconds and leap seconds elapsed. The leap seconds are not included
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-- in the seconds returned. If Left is greater than Right, the returned
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-- values are positive, negative otherwise.
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function Subtract (Date : Time; Days : Long_Integer) return Time;
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-- Subtract a certain number of days from a time value
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end Arithmetic_Operations;
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---------------------------
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-- Conversion_Operations --
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---------------------------
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package Conversion_Operations is
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function To_Ada_Time (Unix_Time : Long_Integer) return Time;
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-- Unix to Ada Epoch conversion
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function To_Ada_Time
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(tm_year : Integer;
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tm_mon : Integer;
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tm_day : Integer;
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tm_hour : Integer;
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tm_min : Integer;
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tm_sec : Integer;
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tm_isdst : Integer) return Time;
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-- Struct tm to Ada Epoch conversion
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function To_Duration
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(tv_sec : Long_Integer;
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tv_nsec : Long_Integer) return Duration;
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-- Struct timespec to Duration conversion
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procedure To_Struct_Timespec
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(D : Duration;
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tv_sec : out Long_Integer;
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tv_nsec : out Long_Integer);
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-- Duration to struct timespec conversion
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procedure To_Struct_Tm
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(T : Time;
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tm_year : out Integer;
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tm_mon : out Integer;
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tm_day : out Integer;
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tm_hour : out Integer;
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tm_min : out Integer;
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tm_sec : out Integer);
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-- Time to struct tm conversion
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function To_Unix_Time (Ada_Time : Time) return Long_Integer;
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-- Ada to Unix Epoch conversion
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end Conversion_Operations;
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----------------------
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-- Delay_Operations --
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----------------------
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package Delay_Operations is
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function To_Duration (Date : Time) return Duration;
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-- Given a time value in nanoseconds since 1901, convert it into a
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-- duration value giving the number of nanoseconds since the Unix Epoch.
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end Delay_Operations;
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---------------------------
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-- Formatting_Operations --
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---------------------------
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package Formatting_Operations is
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function Day_Of_Week (Date : Time) return Integer;
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-- Determine which day of week Date falls on. The returned values are
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-- within the range of 0 .. 6 (Monday .. Sunday).
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procedure Split
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(Date : Time;
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Year : out Year_Number;
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Month : out Month_Number;
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Day : out Day_Number;
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Day_Secs : out Day_Duration;
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Hour : out Integer;
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Minute : out Integer;
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Second : out Integer;
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Sub_Sec : out Duration;
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Leap_Sec : out Boolean;
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Use_TZ : Boolean;
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Is_Historic : Boolean;
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Time_Zone : Long_Integer);
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pragma Export (Ada, Split, "__gnat_split");
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-- Split a time value into its components. If flag Is_Historic is set,
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-- this routine would try to use to the best of the OS's abilities the
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-- time zone offset that was or will be in effect on Date. Set Use_TZ
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-- to use the local time zone (the value in Time_Zone is ignored) when
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-- splitting a time value.
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function Time_Of
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(Year : Year_Number;
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Month : Month_Number;
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Day : Day_Number;
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Day_Secs : Day_Duration;
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Hour : Integer;
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Minute : Integer;
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Second : Integer;
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Sub_Sec : Duration;
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Leap_Sec : Boolean;
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Use_Day_Secs : Boolean;
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Use_TZ : Boolean;
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Is_Historic : Boolean;
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Time_Zone : Long_Integer) return Time;
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pragma Export (Ada, Time_Of, "__gnat_time_of");
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-- Given all the components of a date, return the corresponding time
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-- value. Set Use_Day_Secs to use the value in Day_Secs, otherwise the
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-- day duration will be calculated from Hour, Minute, Second and Sub_
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-- Sec. If flag Is_Historic is set, this routine would try to use to the
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-- best of the OS's abilities the time zone offset that was or will be
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-- in effect on the input date. Set Use_TZ to use the local time zone
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-- (the value in formal Time_Zone is ignored) when building a time value
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-- 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 (in seconds) the difference between the local time zone and
|
||
|
|
-- UTC time at a specific historic date.
|
||
|
|
|
||
|
|
end Time_Zones_Operations;
|
||
|
|
|
||
|
|
end Ada.Calendar;
|