6cbcc54138
* xeinfo.adb: Don't look for revision numbers. * xnmake.adb: Likewise. * xsinfo.adb: Likewise. * xsnames.adb: Likewise. * xtreeprs.adb: Likewise. From-SVN: r50768
105 lines
5.6 KiB
Ada
105 lines
5.6 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
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-- --
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-- S Y S T E M . O S _ P R I M I T I V E S --
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-- --
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-- S p e c --
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-- --
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-- --
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-- Copyright (C) 1998-2001 Free Software Foundation, Inc. --
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-- --
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-- GNARL is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 2, or (at your option) any later ver- --
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-- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
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-- for more details. You should have received a copy of the GNU General --
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-- Public License distributed with GNARL; see file COPYING. If not, write --
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-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
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-- MA 02111-1307, USA. --
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-- --
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-- As a special exception, if other files instantiate generics from this --
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-- unit, or you link this unit with other files to produce an executable, --
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-- this unit does not by itself cause the resulting executable to be --
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-- covered by the GNU General Public License. This exception does not --
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-- however invalidate any other reasons why the executable file might be --
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-- covered by the GNU Public License. --
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-- --
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-- GNARL was developed by the GNARL team at Florida State University. It is --
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-- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
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-- State University (http://www.gnat.com). --
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-- --
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------------------------------------------------------------------------------
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-- This package provides low level primitives used to implement clock and
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-- delays in non tasking applications on Alpha/VMS
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-- The choice of the real clock/delay implementation (depending on whether
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-- tasking is involved or not) is done via soft links (see s-tasoli.ads)
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-- NEVER add any dependency to tasking packages here
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package System.OS_Primitives is
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subtype OS_Time is Long_Integer;
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-- System time on VMS is used for performance reasons.
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-- Note that OS_Time is *not* the same as Ada.Calendar.Time, the
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-- difference being that relative OS_Time is negative, but relative
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-- Calendar.Time is positive.
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-- See Ada.Calendar.Delays for more information on VMS Time.
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Max_Sensible_Delay : constant Duration := 183 * 24 * 60 * 60.0;
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-- Max of half a year delay, needed to prevent exceptions for large
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-- delay values. It seems unlikely that any test will notice this
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-- restriction, except in the case of applications setting the clock at
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-- at run time (see s-tastim.adb). Also note that a larger value might
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-- cause problems (e.g overflow, or more likely OS limitation in the
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-- primitives used).
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function OS_Clock return OS_Time;
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-- Returns "absolute" time, represented as an offset
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-- relative to "the Epoch", which is Nov 17, 1858 on VMS.
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function Clock return Duration;
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pragma Inline (Clock);
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-- Returns "absolute" time, represented as an offset
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-- relative to "the Epoch", which is Jan 1, 1970 on unixes.
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-- This implementation is affected by system's clock changes.
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function Monotonic_Clock return Duration;
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pragma Inline (Monotonic_Clock);
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-- Returns "absolute" time, represented as an offset
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-- relative to "the Epoch", which is Jan 1, 1970.
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-- This clock implementation is immune to the system's clock changes.
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Relative : constant := 0;
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Absolute_Calendar : constant := 1;
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Absolute_RT : constant := 2;
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-- Values for Mode call below. Note that the compiler (exp_ch9.adb)
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-- relies on these values. So any change here must be reflected in
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-- corresponding changes in the compiler.
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procedure Timed_Delay (Time : Duration; Mode : Integer);
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-- Implements the semantics of the delay statement when no tasking is
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-- used in the application.
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--
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-- Mode is one of the three values above
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--
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-- Time is a relative or absolute duration value, depending on Mode.
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--
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-- Note that currently Ada.Real_Time always uses the tasking run time, so
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-- this procedure should never be called with Mode set to Absolute_RT.
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-- This may change in future or bare board implementations.
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function To_Duration (T : OS_Time; Mode : Integer) return Duration;
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-- Convert VMS system time to Duration
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-- Mode is one of the three values above
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function To_OS_Time (D : Duration; Mode : Integer) return OS_Time;
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-- Convert Duration to VMS system time
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-- Mode is one of the three values above
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end System.OS_Primitives;
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