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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 Ada.Calendar is type Time is private; -- 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. 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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