1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
5 -- S Y S T E M . O S _ P R I M I T I V E S --
9 -- Copyright (C) 1998-2017, Free Software Foundation, Inc. --
11 -- GNARL is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
18 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
27 -- GNARL was developed by the GNARL team at Florida State University. --
28 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
30 ------------------------------------------------------------------------------
32 -- This package provides low level primitives used to implement clock and
33 -- delays in non tasking applications, for LynxOS.
35 -- The choice of the real clock/delay implementation (depending on whether
36 -- tasking is involved or not) is done via soft links (see s-soflin.ads)
38 -- NEVER add any dependency to tasking packages here
40 package System
.OS_Primitives
is
43 Max_Sensible_Delay
: constant Duration := 16#
10_0000
.0#
;
44 -- LynxOS does not support delays as long as half a year, so we set this to
45 -- a shorter, but still fairly long, duration. Experiments show that if
46 -- pthread_cond_timedwait is passed an abstime much greater than about
47 -- 2**21, it fails, returning EAGAIN. The cutoff is somewhere between
48 -- 16#20_8000.0# and 16#20_F000.0#. This behavior is not documented.
51 -- Initialize global settings related to this package. This procedure
52 -- should be called before any other subprograms in this package. Note
53 -- that this procedure can be called several times.
55 function Clock
return Duration;
56 pragma Inline
(Clock
);
57 -- Returns "absolute" time, represented as an offset relative to "the
58 -- Epoch", which is Jan 1, 1970 00:00:00 UTC on UNIX systems. This
59 -- implementation is affected by system's clock changes.
61 Relative
: constant := 0;
62 Absolute_Calendar
: constant := 1;
63 Absolute_RT
: constant := 2;
64 -- Values for Mode call below. Note that the compiler (exp_ch9.adb) relies
65 -- on these values. So any change here must be reflected in corresponding
66 -- changes in the compiler.
68 procedure Timed_Delay
(Time
: Duration; Mode
: Integer);
69 -- Implements the semantics of the delay statement when no tasking is used
70 -- in the application.
72 -- Mode is one of the three values above
74 -- Time is a relative or absolute duration value, depending on Mode.
76 -- Note that currently Ada.Real_Time always uses the tasking run time,
77 -- so this procedure should never be called with Mode set to Absolute_RT.
78 -- This may change in future or bare board implementations.
80 end System
.OS_Primitives
;