File : a-calend.adb
------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
5 -- A D A . C A L E N D A R --
-- --
-- B o d y --
-- --
-- $Revision: 1.14 $
10 -- --
-- Copyright (C) 1997-2001 Free Software Foundation, Inc. --
-- --
-- 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- --
15 -- ware Foundation; either version 2, 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 --
20 -- 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. --
-- --
-- As a special exception, if other files instantiate generics from this --
25 -- 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. --
30 -- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
-- --
------------------------------------------------------------------------------
35
-- This is the Windows NT/95 version.
with System.OS_Primitives;
-- used for Clock
40
with System.OS_Interface;
package body Ada.Calendar is
45 use System.OS_Interface;
------------------------------
-- Use of Pragma Unsuppress --
------------------------------
50
-- This implementation of Calendar takes advantage of the permission in
-- Ada 95 of using arithmetic overflow checks to check for out of bounds
-- time values. This means that we must catch the constraint error that
-- results from arithmetic overflow, so we use pragma Unsuppress to make
55 -- sure that overflow is enabled, using software overflow checking if
-- necessary. That way, compiling Calendar with options to suppress this
-- checking will not affect its correctness.
------------------------
60 -- Local Declarations --
------------------------
Ada_Year_Min : constant := 1901;
Ada_Year_Max : constant := 2099;
65
-- Win32 time constants
epoch_1970 : constant := 16#19D_B1DE_D53E_8000#; -- win32 UTC epoch
system_time_ns : constant := 100; -- 100 ns per tick
70 Sec_Unit : constant := 10#1#E9;
---------
-- "+" --
---------
75
function "+" (Left : Time; Right : Duration) return Time is
pragma Unsuppress (Overflow_Check);
begin
return (Left + Time (Right));
80
exception
when Constraint_Error =>
raise Time_Error;
end "+";
85
function "+" (Left : Duration; Right : Time) return Time is
pragma Unsuppress (Overflow_Check);
begin
return (Time (Left) + Right);
90
exception
when Constraint_Error =>
raise Time_Error;
end "+";
95
---------
-- "-" --
---------
100 function "-" (Left : Time; Right : Duration) return Time is
pragma Unsuppress (Overflow_Check);
begin
return Left - Time (Right);
105 exception
when Constraint_Error =>
raise Time_Error;
end "-";
110 function "-" (Left : Time; Right : Time) return Duration is
pragma Unsuppress (Overflow_Check);
begin
return Duration (Left) - Duration (Right);
115 exception
when Constraint_Error =>
raise Time_Error;
end "-";
120 ---------
-- "<" --
---------
function "<" (Left, Right : Time) return Boolean is
125 begin
return Duration (Left) < Duration (Right);
end "<";
----------
130 -- "<=" --
----------
function "<=" (Left, Right : Time) return Boolean is
begin
135 return Duration (Left) <= Duration (Right);
end "<=";
---------
-- ">" --
140 ---------
function ">" (Left, Right : Time) return Boolean is
begin
return Duration (Left) > Duration (Right);
145 end ">";
----------
-- ">=" --
----------
150
function ">=" (Left, Right : Time) return Boolean is
begin
return Duration (Left) >= Duration (Right);
end ">=";
155
-----------
-- Clock --
-----------
160 -- The Ada.Calendar.Clock function gets the time from the soft links
-- interface which will call the appropriate function depending wether
-- tasking is involved or not.
function Clock return Time is
165 begin
return Time (System.OS_Primitives.Clock);
end Clock;
---------
170 -- Day --
---------
function Day (Date : Time) return Day_Number is
DY : Year_Number;
175 DM : Month_Number;
DD : Day_Number;
DS : Day_Duration;
begin
180 Split (Date, DY, DM, DD, DS);
return DD;
end Day;
-----------
185 -- Month --
-----------
function Month (Date : Time) return Month_Number is
DY : Year_Number;
190 DM : Month_Number;
DD : Day_Number;
DS : Day_Duration;
begin
195 Split (Date, DY, DM, DD, DS);
return DM;
end Month;
-------------
200 -- Seconds --
-------------
function Seconds (Date : Time) return Day_Duration is
DY : Year_Number;
205 DM : Month_Number;
DD : Day_Number;
DS : Day_Duration;
begin
210 Split (Date, DY, DM, DD, DS);
return DS;
end Seconds;
-----------
215 -- Split --
-----------
procedure Split
(Date : Time;
220 Year : out Year_Number;
Month : out Month_Number;
Day : out Day_Number;
Seconds : out Day_Duration)
is
225
Date_Int : aliased Long_Long_Integer;
Date_Loc : aliased Long_Long_Integer;
Timbuf : aliased SYSTEMTIME;
Int_Date : Long_Long_Integer;
230 Sub_Seconds : Duration;
begin
-- We take the sub-seconds (decimal part) of Date and this is added
-- to compute the Seconds. This way we keep the precision of the
235 -- high-precision clock that was lost with the Win32 API calls
-- below.
if Date < 0.0 then
240 -- this is a Date before Epoch (January 1st, 1970)
Sub_Seconds := Duration (Date) -
Duration (Long_Long_Integer (Date + Duration'(0.5)));
245 Int_Date := Long_Long_Integer (Date - Sub_Seconds);
-- For Date = -86400.1 we are 2 days before Epoch at 0.1 seconds
-- from day 1 before Epoch. It means that it is 23h 59m 59.9s.
-- here we adjust for that.
250
if Sub_Seconds < 0.0 then
Int_Date := Int_Date - 1;
Sub_Seconds := 1.0 + Sub_Seconds;
end if;
255
else
-- this is a Date after Epoch (January 1st, 1970)
260 Sub_Seconds := Duration (Date) -
Duration (Long_Long_Integer (Date - Duration'(0.5)));
Int_Date := Long_Long_Integer (Date - Sub_Seconds);
265 end if;
-- Date_Int is the number of seconds from Epoch.
Date_Int := Long_Long_Integer
270 (Int_Date * Sec_Unit / system_time_ns) + epoch_1970;
if not FileTimeToLocalFileTime (Date_Int'Access, Date_Loc'Access) then
raise Time_Error;
end if;
275
if not FileTimeToSystemTime (Date_Loc'Access, Timbuf'Access) then
raise Time_Error;
end if;
280 if Timbuf.wYear not in Ada_Year_Min .. Ada_Year_Max then
raise Time_Error;
end if;
Seconds :=
285 Duration (Timbuf.wHour) * 3_600.0 +
Duration (Timbuf.wMinute) * 60.0 +
Duration (Timbuf.wSecond) +
Sub_Seconds;
290 Day := Integer (Timbuf.wDay);
Month := Integer (Timbuf.wMonth);
Year := Integer (Timbuf.wYear);
end Split;
295 -------------
-- Time_Of --
-------------
function Time_Of
300 (Year : Year_Number;
Month : Month_Number;
Day : Day_Number;
Seconds : Day_Duration := 0.0)
return Time
305 is
Timbuf : aliased SYSTEMTIME;
Now : aliased Long_Long_Integer;
Loc : aliased Long_Long_Integer;
310 Int_Secs : Integer;
Secs : Integer;
Add_One_Day : Boolean := False;
Date : Time;
315 begin
-- The following checks are redundant with respect to the constraint
-- error checks that should normally be made on parameters, but we
-- decide to raise Constraint_Error in any case if bad values come
-- in (as a result of checks being off in the caller, or for other
320 -- erroneous or bounded error cases).
if not Year 'Valid
or else not Month 'Valid
or else not Day 'Valid
325 or else not Seconds'Valid
then
raise Constraint_Error;
end if;
330 if Seconds = 0.0 then
Int_Secs := 0;
else
Int_Secs := Integer (Seconds - 0.5);
end if;
335
-- Timbuf.wMillisec is to keep the msec. We can't use that because the
-- high-resolution clock has a precision of 1 Microsecond.
-- Anyway the sub-seconds part is not needed to compute the number
-- of seconds in UTC.
340
if Int_Secs = 86_400 then
Secs := 0;
Add_One_Day := True;
else
345 Secs := Int_Secs;
end if;
Timbuf.wMilliseconds := 0;
Timbuf.wSecond := WORD (Secs mod 60);
350 Timbuf.wMinute := WORD ((Secs / 60) mod 60);
Timbuf.wHour := WORD (Secs / 3600);
Timbuf.wDay := WORD (Day);
Timbuf.wMonth := WORD (Month);
Timbuf.wYear := WORD (Year);
355
if not SystemTimeToFileTime (Timbuf'Access, Loc'Access) then
raise Time_Error;
end if;
360 if not LocalFileTimeToFileTime (Loc'Access, Now'Access) then
raise Time_Error;
end if;
-- Here we have the UTC now translate UTC to Epoch time (UNIX style
365 -- time based on 1 january 1970) and add there the sub-seconds part.
declare
Sub_Sec : Duration := Seconds - Duration (Int_Secs);
begin
370 Date := Time ((Now - epoch_1970) * system_time_ns / Sec_Unit) +
Sub_Sec;
end;
if Add_One_Day then
375 Date := Date + Duration (86400.0);
end if;
return Date;
end Time_Of;
380
----------
-- Year --
----------
385 function Year (Date : Time) return Year_Number is
DY : Year_Number;
DM : Month_Number;
DD : Day_Number;
DS : Day_Duration;
390
begin
Split (Date, DY, DM, DD, DS);
return DY;
end Year;
395
end Ada.Calendar;