File : s-osprim.ads
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-- --
-- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
-- --
5 -- S Y S T E M . O S _ P R I M I T I V E S --
-- --
-- S p e c --
-- --
-- $Revision: 1.11 $
10 -- --
-- Copyright (C) 1998-2001 Free Software Foundation, Inc. --
-- --
-- GNARL is free software; you can redistribute it and/or modify it under --
-- 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- --
-- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- 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 --
-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, USA. --
-- --
-- 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, --
-- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
30 -- --
-- GNARL was developed by the GNARL team at Florida State University. It is --
-- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
-- State University (http://www.gnat.com). --
-- --
35 ------------------------------------------------------------------------------
-- This package provides low level primitives used to implement clock and
-- delays in non tasking applications.
40 -- The choice of the real clock/delay implementation (depending on whether
-- tasking is involved or not) is done via soft links (see s-tasoli.ads)
-- NEVER add any dependency to tasking packages here
45 package System.OS_Primitives is
Max_Sensible_Delay : constant Duration := 183 * 24 * 60 * 60.0;
-- Max of half a year delay, needed to prevent exceptions for large
-- delay values. It seems unlikely that any test will notice this
50 -- restriction, except in the case of applications setting the clock at
-- at run time (see s-tastim.adb). Also note that a larger value might
-- cause problems (e.g overflow, or more likely OS limitation in the
-- primitives used).
55 function Clock return Duration;
pragma Inline (Clock);
-- Returns "absolute" time, represented as an offset
-- relative to "the Epoch", which is Jan 1, 1970 on unixes.
-- This implementation is affected by system's clock changes.
60
function Monotonic_Clock return Duration;
pragma Inline (Monotonic_Clock);
-- Returns "absolute" time, represented as an offset
-- relative to "the Epoch", which is Jan 1, 1970.
65 -- This clock implementation is immune to the system's clock changes.
Relative : constant := 0;
Absolute_Calendar : constant := 1;
Absolute_RT : constant := 2;
70 -- Values for Mode call below. Note that the compiler (exp_ch9.adb)
-- relies on these values. So any change here must be reflected in
-- corresponding changes in the compiler.
procedure Timed_Delay (Time : Duration; Mode : Integer);
75 -- Implements the semantics of the delay statement when no tasking is
-- used in the application.
--
-- Mode is one of the three values above
--
80 -- Time is a relative or absolute duration value, depending on Mode.
--
-- Note that currently Ada.Real_Time always uses the tasking run time, so
-- this procedure should never be called with Mode set to Absolute_RT.
-- This may change in future or bare board implementations.
85
end System.OS_Primitives;