| ------------------------------------------------------------------------------ |
| -- -- |
| -- 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) 1998-2009, 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. |
| |
| -- 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. |
| |
| 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. |
| |
| function Monotonic_Clock return Duration; |
| pragma Inline (Monotonic_Clock); |
| -- Returns "absolute" time, represented as an offset relative to "the Unix |
| -- Epoch", which is Jan 1, 1970 00:00:00 UTC. This clock implementation is |
| -- immune to the 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; |
