+++ /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 --
--- --
--- B o d y --
--- --
--- $Revision: 1.1.16.2 $
--- --
--- 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 NT version of this package
-
-with Ada.Exceptions;
-with System.OS_Interface;
-
-package body System.OS_Primitives is
-
- use System.OS_Interface;
-
- ---------------------------------------
- -- Data for the high resolution clock --
- ---------------------------------------
-
- Tick_Frequency : aliased LARGE_INTEGER;
- -- Holds frequency of high-performance counter used by Clock
- -- Windows NT uses a 1_193_182 Hz counter on PCs.
-
- Base_Ticks : aliased LARGE_INTEGER;
- -- Holds the Tick count for the base time.
-
- Base_Clock : Duration;
- -- Holds the current clock for the standard clock's base time
-
- Base_Monotonic_Clock : Duration;
- -- Holds the current clock for monotonic clock's base time
-
- Base_Time : aliased Long_Long_Integer;
- -- Holds the base time used to check for system time change, used with
- -- the standard clock.
-
- procedure Get_Base_Time;
- -- Retrieve the base time. This base time will be used by clock to
- -- compute the current time by adding to it a fraction of the
- -- performance counter. This is for the implementation of a
- -- high-resolution clock.
-
- -----------
- -- Clock --
- -----------
-
- -- This implementation of clock provides high resolution timer values
- -- using QueryPerformanceCounter. This call return a 64 bits values (based
- -- on the 8253 16 bits counter). This counter is updated every 1/1_193_182
- -- times per seconds. The call to QueryPerformanceCounter takes 6
- -- microsecs to complete.
-
- function Clock return Duration is
- Max_Shift : constant Duration := 2.0;
- Hundreds_Nano_In_Sec : constant := 1E7;
- Current_Ticks : aliased LARGE_INTEGER;
- Elap_Secs_Tick : Duration;
- Elap_Secs_Sys : Duration;
- Now : aliased Long_Long_Integer;
-
- begin
- if not QueryPerformanceCounter (Current_Ticks'Access) then
- return 0.0;
- end if;
-
- GetSystemTimeAsFileTime (Now'Access);
-
- Elap_Secs_Sys :=
- Duration (abs (Now - Base_Time) / Hundreds_Nano_In_Sec);
-
- Elap_Secs_Tick :=
- Duration (Long_Long_Float (Current_Ticks - Base_Ticks) /
- Long_Long_Float (Tick_Frequency));
-
- -- If we have a shift of more than Max_Shift seconds we resynchonize the
- -- Clock. This is probably due to a manual Clock adjustment, an DST
- -- adjustment or an NNTP synchronisation. And we want to adjust the
- -- time for this system (non-monotonic) clock.
-
- if abs (Elap_Secs_Sys - Elap_Secs_Tick) > Max_Shift then
- Get_Base_Time;
-
- Elap_Secs_Tick :=
- Duration (Long_Long_Float (Current_Ticks - Base_Ticks) /
- Long_Long_Float (Tick_Frequency));
- end if;
-
- return Base_Clock + Elap_Secs_Tick;
- end Clock;
-
- -------------------
- -- Get_Base_Time --
- -------------------
-
- procedure Get_Base_Time is
- use System.OS_Interface;
-
- -- The resolution for GetSystemTime is 1 millisecond.
-
- -- The time to get both base times should take less than 1 millisecond.
- -- Therefore, the elapsed time reported by GetSystemTime between both
- -- actions should be null.
-
- Max_Elapsed : constant := 0;
-
- Test_Now : aliased Long_Long_Integer;
-
- epoch_1970 : constant := 16#19D_B1DE_D53E_8000#; -- win32 UTC epoch
- system_time_ns : constant := 100; -- 100 ns per tick
- Sec_Unit : constant := 10#1#E9;
-
- begin
- -- Here we must be sure that both of these calls are done in a short
- -- amount of time. Both are base time and should in theory be taken
- -- at the very same time.
-
- loop
- GetSystemTimeAsFileTime (Base_Time'Access);
-
- if not QueryPerformanceCounter (Base_Ticks'Access) then
- pragma Assert
- (Standard.False,
- "Could not query high performance counter in Clock");
- null;
- end if;
-
- GetSystemTimeAsFileTime (Test_Now'Access);
-
- exit when Test_Now - Base_Time = Max_Elapsed;
- end loop;
-
- Base_Clock := Duration
- (Long_Long_Float ((Base_Time - epoch_1970) * system_time_ns) /
- Long_Long_Float (Sec_Unit));
- end Get_Base_Time;
-
- ---------------------
- -- Monotonic_Clock --
- ---------------------
-
- function Monotonic_Clock return Duration is
- Current_Ticks : aliased LARGE_INTEGER;
- Elap_Secs_Tick : Duration;
- begin
- if not QueryPerformanceCounter (Current_Ticks'Access) then
- return 0.0;
- end if;
-
- Elap_Secs_Tick :=
- Duration (Long_Long_Float (Current_Ticks - Base_Ticks) /
- Long_Long_Float (Tick_Frequency));
-
- return Base_Monotonic_Clock + Elap_Secs_Tick;
- end Monotonic_Clock;
-
- -----------------
- -- Timed_Delay --
- -----------------
-
- procedure Timed_Delay (Time : Duration; Mode : Integer) is
- Rel_Time : Duration;
- Abs_Time : Duration;
- Check_Time : Duration := Monotonic_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
- Sleep (DWORD (Rel_Time * 1000.0));
- Check_Time := Monotonic_Clock;
-
- exit when Abs_Time <= Check_Time;
-
- Rel_Time := Abs_Time - Check_Time;
- end loop;
- end if;
- end Timed_Delay;
-
--- Package elaboration, get starting time as base
-
-begin
- if not QueryPerformanceFrequency (Tick_Frequency'Access) then
- Ada.Exceptions.Raise_Exception
- (Program_Error'Identity,
- "cannot get high performance counter frequency");
- end if;
-
- Get_Base_Time;
-
- Base_Monotonic_Clock := Base_Clock;
-end System.OS_Primitives;
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