-- --
-- B o d y --
-- --
--- Copyright (C) 1998-2008, Free Software Foundation, Inc. --
+-- Copyright (C) 1998-2009, 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- --
+-- 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. 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, 51 Franklin Street, Fifth Floor, --
--- Boston, MA 02110-1301, USA. --
+-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
--- 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. --
+-- 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. --
-- 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;
+ Max_Elapsed : constant LARGE_INTEGER :=
+ LARGE_INTEGER (Tick_Frequency / 100_000);
+ -- Look for a precision of 0.01 ms
+
+ 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;
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);
+ -- 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 10th times to reach the best synchronisation (below 1
+ -- millisecond) otherwise the runtime will use the best value reached
+ -- during the runs.
- if QueryPerformanceCounter (Base_Ticks'Access) = Win32.FALSE then
+ 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 (Test_Now'Access);
+ GetSystemTimeAsFileTime (Ctrl_Time'Access);
+
+ -- Scan for clock tick, will take upto 16ms/1ms depending on PC.
+ -- This cannot be an infinite loop or the system hardware is badly
+ -- dammaged.
+
+ 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.
- exit when Test_Now - Base_Time = Max_Elapsed;
+ Elapsed := Ctrl_Ticks - Loc_Ticks;
+
+ if Elapsed < Current_Max then
+ Base_Time := Loc_Time;
+ 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;
Base_Clock := Duration
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 - BMTA.all) /
+ Long_Long_Float (TFA.all));
+ return BMCA.all + Elap_Secs_Tick;
end if;
-
- Elap_Secs_Tick :=
- Duration (Long_Long_Float (Current_Ticks - BMTA.all) /
- Long_Long_Float (TFA.all));
-
- return BMCA.all + Elap_Secs_Tick;
end Monotonic_Clock;
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