gcc/ada/a-caldel-vms.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNAT 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 --             Copyright (C) 1991-1994, Florida State University            --
  10 --                     Copyright (C) 1995-2012, AdaCore                     --
  11 --                                                                          --
  12 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  13 -- terms of the  GNU General Public License as published  by the Free Soft- --
  14 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  15 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  16 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  17 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  18 --                                                                          --
  19 -- As a special exception under Section 7 of GPL version 3, you are granted --
  20 -- additional permissions described in the GCC Runtime Library Exception,   --
  21 -- version 3.1, as published by the Free Software Foundation.               --
  22 --                                                                          --
  23 -- You should have received a copy of the GNU General Public License and    --
  24 -- a copy of the GCC Runtime Library Exception along with this program;     --
  25 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  26 -- <http://www.gnu.org/licenses/>.                                          --
  27 --                                                                          --
  28 -- GNARL was developed by the GNARL team at Florida State University.       --
  29 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  30 --                                                                          --
  31 ------------------------------------------------------------------------------
  32
  33 --  This is the Alpha/VMS version
  34
  35 with System.OS_Primitives;
  36 with System.Soft_Links;
  37
  38 package body Ada.Calendar.Delays is
  39
  40    package OSP renames System.OS_Primitives;
  41    package TSL renames System.Soft_Links;
  42
  43    use type TSL.Timed_Delay_Call;
  44
  45    -----------------------
  46    -- Local Subprograms --
  47    -----------------------
  48
  49    procedure Timed_Delay_NT (Time : Duration; Mode : Integer);
  50    --  Timed delay procedure used when no tasking is active
  51
  52    ---------------
  53    -- Delay_For --
  54    ---------------
  55
  56    procedure Delay_For (D : Duration) is
  57    begin
  58       TSL.Timed_Delay.all
  59         (Duration'Min (D, OSP.Max_Sensible_Delay), OSP.Relative);
  60    end Delay_For;
  61
  62    -----------------
  63    -- Delay_Until --
  64    -----------------
  65
  66    procedure Delay_Until (T : Time) is
  67    begin
  68       TSL.Timed_Delay.all (To_Duration (T), OSP.Absolute_Calendar);
  69    end Delay_Until;
  70
  71    -----------------
  72    -- To_Duration --
  73    -----------------
  74
  75    function To_Duration (T : Time) return Duration is
  76       Safe_Ada_High : constant Time := Time_Of (2250, 1, 1, 0.0);
  77       --  A value distant enough to emulate "end of time" but which does not
  78       --  cause overflow.
  79
  80       Safe_T : constant Time :=
  81         (if T > Safe_Ada_High then Safe_Ada_High else T);
  82
  83    begin
  84       return OSP.To_Duration (OSP.OS_Time (Safe_T), OSP.Absolute_Calendar);
  85    end To_Duration;
  86
  87    --------------------
  88    -- Timed_Delay_NT --
  89    --------------------
  90
  91    procedure Timed_Delay_NT (Time : Duration; Mode : Integer) is
  92    begin
  93       OSP.Timed_Delay (Time, Mode);
  94    end Timed_Delay_NT;
  95
  96 begin
  97    --  Set up the Timed_Delay soft link to the non tasking version if it has
  98    --  not been already set. If tasking is present, Timed_Delay has already set
  99    --  this soft link, or this will be overridden during the elaboration of
 100    --  System.Tasking.Initialization
 101
 102    if TSL.Timed_Delay = null then
 103       TSL.Timed_Delay := Timed_Delay_NT'Access;
 104    end if;
 105 end Ada.Calendar.Delays;