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) 1995-2009, AdaCore                     --
  11 --                                                                          --
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  22 --                                                                          --
  23 -- As a special exception,  if other files  instantiate  generics from this --
  24 -- unit, or you link  this unit with other files  to produce an executable, --
  25 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  26 -- covered  by the  GNU  General  Public  License.  This exception does not --
  27 -- however invalidate  any other reasons why  the executable file  might be --
  28 -- covered by the  GNU Public License.                                      --
  29 --                                                                          --
  30 -- GNARL was developed by the GNARL team at Florida State University.       --
  31 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 --  This is the Alpha/VMS version
  36
  37 with System.OS_Primitives;
  38 with System.Soft_Links;
  39
  40 package body Ada.Calendar.Delays is
  41
  42    package OSP renames System.OS_Primitives;
  43    package TSL renames System.Soft_Links;
  44
  45    use type TSL.Timed_Delay_Call;
  46
  47    -----------------------
  48    -- Local Subprograms --
  49    -----------------------
  50
  51    procedure Timed_Delay_NT (Time : Duration; Mode : Integer);
  52    --  Timed delay procedure used when no tasking is active
  53
  54    ---------------
  55    -- Delay_For --
  56    ---------------
  57
  58    procedure Delay_For (D : Duration) is
  59    begin
  60       TSL.Timed_Delay.all
  61         (Duration'Min (D, OSP.Max_Sensible_Delay), OSP.Relative);
  62    end Delay_For;
  63
  64    -----------------
  65    -- Delay_Until --
  66    -----------------
  67
  68    procedure Delay_Until (T : Time) is
  69    begin
  70       TSL.Timed_Delay.all (To_Duration (T), OSP.Absolute_Calendar);
  71    end Delay_Until;
  72
  73    -----------------
  74    -- To_Duration --
  75    -----------------
  76
  77    function To_Duration (T : Time) return Duration is
  78       Safe_Ada_High : constant Time := Time_Of (2250, 1, 1, 0.0);
  79       --  A value distant enough to emulate "end of time" but which does not
  80       --  cause overflow.
  81
  82       Safe_T : constant Time :=
  83                  (if T > Safe_Ada_High then Safe_Ada_High else T);
  84
  85    begin
  86       return OSP.To_Duration (OSP.OS_Time (Safe_T), OSP.Absolute_Calendar);
  87    end To_Duration;
  88
  89    --------------------
  90    -- Timed_Delay_NT --
  91    --------------------
  92
  93    procedure Timed_Delay_NT (Time : Duration; Mode : Integer) is
  94    begin
  95       OSP.Timed_Delay (Time, Mode);
  96    end Timed_Delay_NT;
  97
  98 begin
  99    --  Set up the Timed_Delay soft link to the non tasking version if it has
 100    --  not been already set. If tasking is present, Timed_Delay has already set
 101    --  this soft link, or this will be overridden during the elaboration of
 102    --  System.Tasking.Initialization
 103
 104    if TSL.Timed_Delay = null then
 105       TSL.Timed_Delay := Timed_Delay_NT'Access;
 106    end if;
 107 end Ada.Calendar.Delays;