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) 1991-2017, Florida State University            --
10--                     Copyright (C) 1995-2018, 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
33with System.OS_Primitives;
34with System.Soft_Links;
35
36package body Ada.Calendar.Delays is
37
38   package OSP renames System.OS_Primitives;
39   package SSL renames System.Soft_Links;
40
41   use type SSL.Timed_Delay_Call;
42
43   --  Earlier, System.Time_Operations was used to implement the following
44   --  operations. The idea was to avoid sucking in the tasking packages. This
45   --  did not work. Logically, we can't have it both ways. There is no way to
46   --  implement time delays that will have correct task semantics without
47   --  reference to the tasking run-time system. To achieve this goal, we now
48   --  use soft links.
49
50   -----------------------
51   -- Local Subprograms --
52   -----------------------
53
54   procedure Timed_Delay_NT (Time : Duration; Mode : Integer);
55   --  Timed delay procedure used when no tasking is active
56
57   ---------------
58   -- Delay_For --
59   ---------------
60
61   procedure Delay_For (D : Duration) is
62   begin
63      SSL.Timed_Delay.all (Duration'Min (D, OSP.Max_Sensible_Delay),
64                           OSP.Relative);
65   end Delay_For;
66
67   -----------------
68   -- Delay_Until --
69   -----------------
70
71   procedure Delay_Until (T : Time) is
72      D : constant Duration := To_Duration (T);
73
74   begin
75      SSL.Timed_Delay.all (D, OSP.Absolute_Calendar);
76   end Delay_Until;
77
78   --------------------
79   -- Timed_Delay_NT --
80   --------------------
81
82   procedure Timed_Delay_NT (Time : Duration; Mode : Integer) is
83   begin
84      OSP.Timed_Delay (Time, Mode);
85   end Timed_Delay_NT;
86
87   -----------------
88   -- To_Duration --
89   -----------------
90
91   function To_Duration (T : Time) return Duration is
92   begin
93      --  Since time has multiple representations on different platforms, a
94      --  target independent operation in Ada.Calendar is used to perform
95      --  this conversion.
96
97      return Delay_Operations.To_Duration (T);
98   end To_Duration;
99
100begin
101   --  Set up the Timed_Delay soft link to the non tasking version if it has
102   --  not been already set. If tasking is present, Timed_Delay has already set
103   --  this soft link, or this will be overridden during the elaboration of
104   --  System.Tasking.Initialization
105
106   if SSL.Timed_Delay = null then
107      SSL.Timed_Delay := Timed_Delay_NT'Access;
108   end if;
109
110end Ada.Calendar.Delays;
111