gcc/ada/a-caldel.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS               --
   4 --                                                                          --
   5 --                   A D A . C A L E N D A R . D E L A Y S                  --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --                             $Revision: 1.37 $
  10 --                                                                          --
  11 --             Copyright (C) 1991-2001 Florida State University             --
  12 --                                                                          --
  13 -- GNARL is free software; you can  redistribute it  and/or modify it under --
  14 -- 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- --
  16 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
  17 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  18 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  19 -- for  more details.  You should have  received  a copy of the GNU General --
  20 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  21 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  22 -- MA 02111-1307, USA.                                                      --
  23 --                                                                          --
  24 -- 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, --
  26 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  27 -- covered  by the  GNU  General  Public  License.  This exception does not --
  28 -- however invalidate  any other reasons why  the executable file  might be --
  29 -- covered by the  GNU Public License.                                      --
  30 --                                                                          --
  31 -- GNARL was developed by the GNARL team at Florida State University. It is --
  32 -- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
  33 -- State University (http://www.gnat.com).                                  --
  34 --                                                                          --
  35 ------------------------------------------------------------------------------
  36
  37 with System.OS_Primitives;
  38 --  Used for Delay_Modes
  39 --           Max_Sensible_Delay
  40
  41 with System.Soft_Links;
  42 --  Used for Timed_Delay
  43
  44 package body Ada.Calendar.Delays is
  45
  46    package OSP renames System.OS_Primitives;
  47    package SSL renames System.Soft_Links;
  48
  49    use type SSL.Timed_Delay_Call;
  50
  51    --  Earlier, the following operations were implemented using
  52    --  System.Time_Operations.  The idea was to avoid sucking in the tasking
  53    --  packages.  This did not work.  Logically, we can't have it both ways.
  54    --  There is no way to implement time delays that will have correct task
  55    --  semantics without reference to the tasking run-time system.
  56    --  To achieve this goal, we now use soft links.
  57
  58    -----------------------
  59    -- Local Subprograms --
  60    -----------------------
  61
  62    procedure Timed_Delay_NT (Time : Duration; Mode : Integer);
  63    --  Timed delay procedure used when no tasking is active
  64
  65    ---------------
  66    -- Delay_For --
  67    ---------------
  68
  69    procedure Delay_For (D : Duration) is
  70    begin
  71       SSL.Timed_Delay.all (Duration'Min (D, OSP.Max_Sensible_Delay),
  72         OSP.Relative);
  73    end Delay_For;
  74
  75    -----------------
  76    -- Delay_Until --
  77    -----------------
  78
  79    procedure Delay_Until (T : Time) is
  80    begin
  81       SSL.Timed_Delay.all (To_Duration (T), OSP.Absolute_Calendar);
  82    end Delay_Until;
  83
  84    --------------------
  85    -- Timed_Delay_NT --
  86    --------------------
  87
  88    procedure Timed_Delay_NT (Time : Duration; Mode : Integer) is
  89    begin
  90       OSP.Timed_Delay (Time, Mode);
  91    end Timed_Delay_NT;
  92
  93    -----------------
  94    -- To_Duration --
  95    -----------------
  96
  97    function To_Duration (T : Time) return Duration is
  98    begin
  99       return Duration (T);
 100    end To_Duration;
 101
 102 begin
 103    --  Set up the Timed_Delay soft link to the non tasking version
 104    --  if it has not been already set.
 105
 106    --  If tasking is present, Timed_Delay has already set this soft
 107    --  link, or this will be overriden during the elaboration of
 108    --  System.Tasking.Initialization
 109
 110    if SSL.Timed_Delay = null then
 111       SSL.Timed_Delay := Timed_Delay_NT'Access;
 112    end if;
 113 end Ada.Calendar.Delays;