| ------------------------------------------------------------------------------ |
| -- -- |
| -- 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 -- |
| -- -- |
| -- Copyright (C) 1998-2003 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 := |
| 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 |
| -- 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. |
| |
| 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; |
