+++ /dev/null
-------------------------------------------------------------------------------
--- --
--- GNU ADA 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 --
--- --
--- $Revision: 1.1.16.1 $
--- --
--- 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- --
--- 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 --
--- 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 --
--- 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. --
--- --
--- 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 on Alpha/VMS
-
--- 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
-
-package System.OS_Primitives is
-
- subtype OS_Time is Long_Integer;
- -- System time on VMS is used for performance reasons.
- -- Note that OS_Time is *not* the same as Ada.Calendar.Time, the
- -- difference being that relative OS_Time is negative, but relative
- -- Calendar.Time is positive.
- -- See Ada.Calendar.Delays for more information on VMS Time.
-
- 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
- -- 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).
-
- function OS_Clock return OS_Time;
- -- Returns "absolute" time, represented as an offset
- -- relative to "the Epoch", which is Nov 17, 1858 on VMS.
-
- 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.
-
- 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.
- -- 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.
-
- function To_Duration (T : OS_Time; Mode : Integer) return Duration;
- -- Convert VMS system time to Duration
- -- Mode is one of the three values above
-
- function To_OS_Time (D : Duration; Mode : Integer) return OS_Time;
- -- Convert Duration to VMS system time
- -- Mode is one of the three values above
-
-end System.OS_Primitives;
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