176 lines
6.3 KiB
Ada
176 lines
6.3 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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-- B o d y --
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-- --
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-- $Revision: 1.7 $
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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 is the OS/2 version of this package
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with Interfaces.C; use Interfaces.C;
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with Interfaces.OS2Lib; use Interfaces.OS2Lib;
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with Interfaces.OS2Lib.Synchronization; use Interfaces.OS2Lib.Synchronization;
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package body System.OS_Primitives is
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----------------
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-- Local Data --
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----------------
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Epoch_Offset : Duration; -- See Set_Epoch_Offset
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Max_Tick_Count : QWORD := 0.0;
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-- This is needed to compensate for small glitches in the
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-- hardware clock or the way it is read by the OS
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-----------------------
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-- Local Subprograms --
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-----------------------
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procedure Set_Epoch_Offset;
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-- Initializes the Epoch_1970_Offset to the offset of the System_Clock
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-- relative to the Unix epoch (Jan 1, 1970), such that
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-- Clock = System_Clock + Epoch_1970_Offset
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function System_Clock return Duration;
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pragma Inline (System_Clock);
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-- Function returning value of system clock with system-dependent timebase.
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-- For OS/2 the system clock returns the elapsed time since system boot.
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-- The clock resolution is approximately 838 ns.
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------------------
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-- System_Clock --
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------------------
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function System_Clock return Duration is
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-- Implement conversion from tick count to Duration
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-- using fixed point arithmetic. The frequency of
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-- the Intel 8254 timer chip is 18.2 * 2**16 Hz.
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Tick_Duration : constant := 1.0 / (18.2 * 2**16);
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Tick_Count : aliased QWORD;
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begin
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Must_Not_Fail (DosTmrQueryTime (Tick_Count'Access));
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-- Read nr of clock ticks since boot time
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Max_Tick_Count := QWORD'Max (Tick_Count, Max_Tick_Count);
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return Max_Tick_Count * Tick_Duration;
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end System_Clock;
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-----------
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-- Clock --
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-----------
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function Clock return Duration is
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begin
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return System_Clock + Epoch_Offset;
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end Clock;
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---------------------
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-- Monotonic_Clock --
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---------------------
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function Monotonic_Clock return Duration renames Clock;
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----------------------
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-- Set_Epoch_Offset --
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----------------------
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procedure Set_Epoch_Offset is
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-- Interface to Unix C style gettimeofday
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type timeval is record
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tv_sec : long;
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tv_usec : long;
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end record;
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procedure gettimeofday
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(time : access timeval;
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zone : System.Address := System.Address'Null_Parameter);
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pragma Import (C, gettimeofday);
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Time_Of_Day : aliased timeval;
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Micro_To_Nano : constant := 1.0E3;
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Sec_To_Nano : constant := 1.0E9;
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Nanos_Since_Epoch : QWORD;
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begin
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gettimeofday (Time_Of_Day'Access);
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Nanos_Since_Epoch := QWORD (Time_Of_Day.tv_sec) * Sec_To_Nano
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+ QWORD (Time_Of_Day.tv_usec) * Micro_To_Nano;
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Epoch_Offset :=
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Duration'(Nanos_Since_Epoch / Sec_To_Nano) - System_Clock;
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end Set_Epoch_Offset;
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-----------------
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-- Timed_Delay --
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-----------------
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procedure Timed_Delay
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(Time : Duration;
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Mode : Integer)
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is
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Rel_Time : Duration;
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Abs_Time : Duration;
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Check_Time : Duration := Clock;
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begin
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if Mode = Relative then
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Rel_Time := Time;
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Abs_Time := Time + Check_Time;
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else
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Rel_Time := Time - Check_Time;
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Abs_Time := Time;
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end if;
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if Rel_Time > 0.0 then
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loop
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Must_Not_Fail (DosSleep (ULONG (Rel_Time * 1000.0)));
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Check_Time := Clock;
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exit when Abs_Time <= Check_Time;
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Rel_Time := Abs_Time - Check_Time;
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end loop;
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end if;
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end Timed_Delay;
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begin
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Set_Epoch_Offset;
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end System.OS_Primitives;
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