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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
-- --
-- S Y S T E M . O S _ P R I M I T I V E S --
-- --
-- S p e c --
-- --
-- Copyright (C) 1998-2018, 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- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT 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. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- GNARL was developed by the GNARL team at Florida State University. --
-- Extensive contributions were provided by Ada Core Technologies, Inc. --
-- --
------------------------------------------------------------------------------
-- This package provides low level primitives used to implement clock and
-- delays in non tasking applications, for LynxOS.
-- The choice of the real clock/delay implementation (depending on whether
-- tasking is involved or not) is done via soft links (see s-soflin.ads)
-- NEVER add any dependency to tasking packages here
package System.OS_Primitives is
pragma Preelaborate;
Max_Sensible_Delay : constant Duration := 16#10_0000.0#;
-- LynxOS does not support delays as long as half a year, so we set this to
-- a shorter, but still fairly long, duration. Experiments show that if
-- pthread_cond_timedwait is passed an abstime much greater than about
-- 2**21, it fails, returning EAGAIN. The cutoff is somewhere between
-- 16#20_8000.0# and 16#20_F000.0#. This behavior is not documented.
procedure Initialize;
-- Initialize global settings related to this package. This procedure
-- should be called before any other subprograms in this package. Note
-- that this procedure can be called several times.
function Clock return Duration;
pragma Inline (Clock);
-- Returns "absolute" time, represented as an offset relative to "the
-- Epoch", which is Jan 1, 1970 00:00:00 UTC on UNIX systems. This
-- implementation is affected by system's clock changes.
Relative : constant := 0;
Absolute_Calendar : constant := 1;
Absolute_RT : constant := 2;
-- 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);
-- Implements the semantics of the delay statement when no tasking is used
-- in the application.
--
-- Mode is one of the three values above
--
-- 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.
end System.OS_Primitives;
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