------------------------------------------------------------------------------
--                                                                          --
--                         GNAT RUN-TIME COMPONENTS                         --
--                                                                          --
--              A D A . C A L E N D A R . T I M E _ Z O N E S               --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--            Copyright (C) 2006, 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- --
-- 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 --
-- 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 --
-- 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.                                      --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
--                                                                          --
------------------------------------------------------------------------------

package body Ada.Calendar.Time_Zones is

   ---------------------
   -- UTC_Time_Offset --
   ---------------------

   function UTC_Time_Offset (Date : Time := Clock) return Time_Offset is
      Year    : Year_Number;
      Month   : Month_Number;
      Day     : Day_Number;
      Seconds : Day_Duration;
      Offset  : Long_Integer;

   begin
      Split_With_Offset (Date, Year, Month, Day, Seconds, Offset);

      --  The system dependent code does not support time zones

      if Offset = Invalid_TZ_Offset then
         raise Unknown_Zone_Error;
      end if;

      Offset := Offset / 60;

      if Offset < Long_Integer (Time_Offset'First)
        or else Offset > Long_Integer (Time_Offset'Last)
      then
         raise Unknown_Zone_Error;
      end if;

      return Time_Offset (Offset);
   end UTC_Time_Offset;

end Ada.Calendar.Time_Zones;