------------------------------------------------------------------------------ -- -- -- 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 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;