| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT 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) 1998-2013, 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 3, or (at your option) any later ver- -- |
| -- sion. GNAT 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. -- |
| -- -- |
| -- As a special exception under Section 7 of GPL version 3, you are granted -- |
| -- additional permissions described in the GCC Runtime Library Exception, -- |
| -- version 3.1, as published by the Free Software Foundation. -- |
| -- -- |
| -- You should have received a copy of the GNU General Public License and -- |
| -- a copy of the GCC Runtime Library Exception along with this program; -- |
| -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- |
| -- <http://www.gnu.org/licenses/>. -- |
| -- -- |
| -- 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 System.Task_Lock; |
| with System.Win32.Ext; |
| |
| package body System.OS_Primitives is |
| |
| use System.Task_Lock; |
| use System.Win32; |
| use System.Win32.Ext; |
| |
| ---------------------------------------- |
| -- 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_Monotonic_Ticks : LARGE_INTEGER; |
| -- Holds the Tick count for the base monotonic time |
| |
| Base_Monotonic_Clock : Duration; |
| -- Holds the current clock for monotonic clock's base time |
| |
| type Clock_Data is record |
| Base_Ticks : LARGE_INTEGER; |
| -- Holds the Tick count for the base time |
| |
| Base_Time : Long_Long_Integer; |
| -- Holds the base time used to check for system time change, used with |
| -- the standard clock. |
| |
| Base_Clock : Duration; |
| -- Holds the current clock for the standard clock's base time |
| end record; |
| |
| type Clock_Data_Access is access all Clock_Data; |
| |
| -- Two base clock buffers. This is used to be able to update a buffer |
| -- while the other buffer is read. The point is that we do not want to |
| -- use a lock inside the Clock routine for performance reasons. We still |
| -- use a lock in the Get_Base_Time which is called very rarely. Current |
| -- is a pointer, the pragma Atomic is there to ensure that the value can |
| -- be set or read atomically. That's it, when Get_Base_Time has updated |
| -- a buffer the switch to the new value is done by changing Current |
| -- pointer. |
| |
| First, Second : aliased Clock_Data; |
| Current : Clock_Data_Access := First'Access; |
| pragma Atomic (Current); |
| |
| -- The following signature is to detect change on the base clock data |
| -- above. The signature is a modular type, it will wrap around without |
| -- raising an exception. We would need to have exactly 2**32 updates of |
| -- the base data for the changes to get undetected. |
| |
| type Signature_Type is mod 2**32; |
| Signature : Signature_Type := 0; |
| pragma Atomic (Signature); |
| |
| procedure Get_Base_Time (Data : out Clock_Data); |
| -- Retrieve the base time and base ticks. These values 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. Note that this routine does not change the base |
| -- monotonic values used by the monotonic 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 Long_Long_Float := 1.0E7; |
| Data : Clock_Data; |
| Current_Ticks : aliased LARGE_INTEGER; |
| Elap_Secs_Tick : Duration; |
| Elap_Secs_Sys : Duration; |
| Now : aliased Long_Long_Integer; |
| Sig1, Sig2 : Signature_Type; |
| |
| begin |
| -- Try ten times to get a coherent set of base data. For this we just |
| -- check that the signature hasn't changed during the copy of the |
| -- current data. |
| -- |
| -- This loop will always be done once if there is no interleaved call |
| -- to Get_Base_Time. |
| |
| for K in 1 .. 10 loop |
| Sig1 := Signature; |
| Data := Current.all; |
| Sig2 := Signature; |
| exit when Sig1 = Sig2; |
| end loop; |
| |
| if QueryPerformanceCounter (Current_Ticks'Access) = Win32.FALSE then |
| return 0.0; |
| end if; |
| |
| GetSystemTimeAsFileTime (Now'Access); |
| |
| Elap_Secs_Sys := |
| Duration (Long_Long_Float (abs (Now - Data.Base_Time)) / |
| Hundreds_Nano_In_Sec); |
| |
| Elap_Secs_Tick := |
| Duration (Long_Long_Float (Current_Ticks - Data.Base_Ticks) / |
| Long_Long_Float (Tick_Frequency)); |
| |
| -- If we have a shift of more than Max_Shift seconds we resynchronize |
| -- the Clock. This is probably due to a manual Clock adjustment, a DST |
| -- adjustment or an NTP 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 (Data); |
| |
| Elap_Secs_Tick := |
| Duration (Long_Long_Float (Current_Ticks - Data.Base_Ticks) / |
| Long_Long_Float (Tick_Frequency)); |
| end if; |
| |
| return Data.Base_Clock + Elap_Secs_Tick; |
| end Clock; |
| |
| ------------------- |
| -- Get_Base_Time -- |
| ------------------- |
| |
| procedure Get_Base_Time (Data : out Clock_Data) is |
| |
| -- 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. |
| |
| 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; |
| Max_Elapsed : constant LARGE_INTEGER := |
| LARGE_INTEGER (Tick_Frequency / 100_000); |
| -- Look for a precision of 0.01 ms |
| Sig : constant Signature_Type := Signature; |
| |
| Loc_Ticks, Ctrl_Ticks : aliased LARGE_INTEGER; |
| Loc_Time, Ctrl_Time : aliased Long_Long_Integer; |
| Elapsed : LARGE_INTEGER; |
| Current_Max : LARGE_INTEGER := LARGE_INTEGER'Last; |
| New_Data : Clock_Data_Access; |
| |
| 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. |
| |
| -- The goal of the following loop is to synchronize the system time |
| -- with the Win32 performance counter by getting a base offset for both. |
| -- Using these offsets it is then possible to compute actual time using |
| -- a performance counter which has a better precision than the Win32 |
| -- time API. |
| |
| -- Try at most 10 times to reach the best synchronisation (below 1 |
| -- millisecond) otherwise the runtime will use the best value reached |
| -- during the runs. |
| |
| Lock; |
| |
| -- First check that the current value has not been updated. This |
| -- could happen if another task has called Clock at the same time |
| -- and that Max_Shift has been reached too. |
| -- |
| -- But if the current value has been changed just before we entered |
| -- into the critical section, we can safely return as the current |
| -- base data (time, clock, ticks) have already been updated. |
| |
| if Sig /= Signature then |
| return; |
| end if; |
| |
| -- Check for the unused data buffer and set New_Data to point to it |
| |
| if Current = First'Access then |
| New_Data := Second'Access; |
| else |
| New_Data := First'Access; |
| end if; |
| |
| for K in 1 .. 10 loop |
| if QueryPerformanceCounter (Loc_Ticks'Access) = Win32.FALSE then |
| pragma Assert |
| (Standard.False, |
| "Could not query high performance counter in Clock"); |
| null; |
| end if; |
| |
| GetSystemTimeAsFileTime (Ctrl_Time'Access); |
| |
| -- Scan for clock tick, will take up to 16ms/1ms depending on PC. |
| -- This cannot be an infinite loop or the system hardware is badly |
| -- damaged. |
| |
| loop |
| GetSystemTimeAsFileTime (Loc_Time'Access); |
| |
| if QueryPerformanceCounter (Ctrl_Ticks'Access) = Win32.FALSE then |
| pragma Assert |
| (Standard.False, |
| "Could not query high performance counter in Clock"); |
| null; |
| end if; |
| |
| exit when Loc_Time /= Ctrl_Time; |
| Loc_Ticks := Ctrl_Ticks; |
| end loop; |
| |
| -- Check elapsed Performance Counter between samples |
| -- to choose the best one. |
| |
| Elapsed := Ctrl_Ticks - Loc_Ticks; |
| |
| if Elapsed < Current_Max then |
| New_Data.Base_Time := Loc_Time; |
| New_Data.Base_Ticks := Loc_Ticks; |
| Current_Max := Elapsed; |
| |
| -- Exit the loop when we have reached the expected precision |
| |
| exit when Elapsed <= Max_Elapsed; |
| end if; |
| end loop; |
| |
| New_Data.Base_Clock := Duration |
| (Long_Long_Float ((New_Data.Base_Time - epoch_1970) * system_time_ns) / |
| Long_Long_Float (Sec_Unit)); |
| |
| -- At this point all the base values have been set into the new data |
| -- record. We just change the pointer (atomic operation) to this new |
| -- values. |
| |
| Current := New_Data; |
| Data := New_Data.all; |
| |
| -- Set new signature for this data set |
| |
| Signature := Signature + 1; |
| |
| Unlock; |
| |
| exception |
| when others => |
| Unlock; |
| raise; |
| end Get_Base_Time; |
| |
| --------------------- |
| -- Monotonic_Clock -- |
| --------------------- |
| |
| function Monotonic_Clock return Duration is |
| Current_Ticks : aliased LARGE_INTEGER; |
| Elap_Secs_Tick : Duration; |
| |
| begin |
| if QueryPerformanceCounter (Current_Ticks'Access) = Win32.FALSE then |
| return 0.0; |
| |
| else |
| Elap_Secs_Tick := |
| Duration (Long_Long_Float (Current_Ticks - Base_Monotonic_Ticks) / |
| Long_Long_Float (Tick_Frequency)); |
| return Base_Monotonic_Clock + Elap_Secs_Tick; |
| end if; |
| end Monotonic_Clock; |
| |
| ----------------- |
| -- Timed_Delay -- |
| ----------------- |
| |
| procedure Timed_Delay (Time : Duration; Mode : Integer) is |
| |
| function Mode_Clock return Duration; |
| pragma Inline (Mode_Clock); |
| -- Return the current clock value using either the monotonic clock or |
| -- standard clock depending on the Mode value. |
| |
| ---------------- |
| -- Mode_Clock -- |
| ---------------- |
| |
| function Mode_Clock return Duration is |
| begin |
| case Mode is |
| when Absolute_RT => |
| return Monotonic_Clock; |
| when others => |
| return Clock; |
| end case; |
| end Mode_Clock; |
| |
| -- Local Variables |
| |
| Base_Time : constant Duration := Mode_Clock; |
| -- Base_Time is used to detect clock set backward, in this case we |
| -- cannot ensure the delay accuracy. |
| |
| Rel_Time : Duration; |
| Abs_Time : Duration; |
| Check_Time : Duration := Base_Time; |
| |
| -- Start of processing for Timed Delay |
| |
| 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 := Mode_Clock; |
| |
| exit when Abs_Time <= Check_Time or else Check_Time < Base_Time; |
| |
| Rel_Time := Abs_Time - Check_Time; |
| end loop; |
| end if; |
| end Timed_Delay; |
| |
| ---------------- |
| -- Initialize -- |
| ---------------- |
| |
| Initialized : Boolean := False; |
| |
| procedure Initialize is |
| begin |
| if Initialized then |
| return; |
| end if; |
| |
| Initialized := True; |
| |
| -- Get starting time as base |
| |
| if QueryPerformanceFrequency (Tick_Frequency'Access) = Win32.FALSE then |
| raise Program_Error with |
| "cannot get high performance counter frequency"; |
| end if; |
| |
| Get_Base_Time (Current.all); |
| |
| -- Keep base clock and ticks for the monotonic clock. These values |
| -- should never be changed to ensure proper behavior of the monotonic |
| -- clock. |
| |
| Base_Monotonic_Clock := Current.Base_Clock; |
| Base_Monotonic_Ticks := Current.Base_Ticks; |
| end Initialize; |
| |
| end System.OS_Primitives; |
