------------------------------------------------------------------------------ -- -- -- 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) 1998-2022, 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 -- -- . -- -- -- -- 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. -- 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 := Duration'Min (183 * 24 * 60 * 60.0, Duration'Last); -- Max of half a year delay, needed to prevent exceptions for large delay -- values. It seems unlikely that any test will notice this restriction, -- except in the case of applications setting the clock 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). In the -- case where half a year is too long (which occurs in high integrity mode -- with 32-bit words, and possibly on some specific ports of GNAT), -- Duration'Last is used instead. Max_System_Delay : constant Duration := Max_Sensible_Delay; -- If the Max_System_Delay is larger it doesn't matter. Setting it equal -- allows optimization of code in some targets delay functions. 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;