| ------------------------------------------------------------------------------ |
| -- -- |
| -- 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: 1.13 $ -- |
| -- -- |
| -- 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. It is -- |
| -- now maintained by Ada Core Technologies Inc. in cooperation with Florida -- |
| -- State University (http://www.gnat.com). -- |
| -- -- |
| ------------------------------------------------------------------------------ |
| |
| -- 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; |
