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