1 ------------------------------------------------------------------------------
3 -- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
5 -- S Y S T E M . O S _ P R I M I T I V E S --
9 -- Copyright (C) 1998-2001 Free Software Foundation, Inc. --
11 -- GNARL is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 2, or (at your option) any later ver- --
14 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNARL; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
22 -- As a special exception, if other files instantiate generics from this --
23 -- unit, or you link this unit with other files to produce an executable, --
24 -- this unit does not by itself cause the resulting executable to be --
25 -- covered by the GNU General Public License. This exception does not --
26 -- however invalidate any other reasons why the executable file might be --
27 -- covered by the GNU Public License. --
29 -- GNARL was developed by the GNARL team at Florida State University. --
30 -- Extensive contributions were provided by Ada Core Technologies Inc. --
32 ------------------------------------------------------------------------------
34 -- This is the NT version of this package
37 with System
.OS_Interface
;
39 package body System
.OS_Primitives
is
41 use System
.OS_Interface
;
43 ---------------------------------------
44 -- Data for the high resolution clock --
45 ---------------------------------------
47 Tick_Frequency
: aliased LARGE_INTEGER
;
48 -- Holds frequency of high-performance counter used by Clock
49 -- Windows NT uses a 1_193_182 Hz counter on PCs.
51 Base_Ticks
: aliased LARGE_INTEGER
;
52 -- Holds the Tick count for the base time.
54 Base_Clock
: Duration;
55 -- Holds the current clock for the standard clock's base time
57 Base_Monotonic_Clock
: Duration;
58 -- Holds the current clock for monotonic clock's base time
60 Base_Time
: aliased Long_Long_Integer;
61 -- Holds the base time used to check for system time change, used with
62 -- the standard clock.
64 procedure Get_Base_Time
;
65 -- Retrieve the base time. This base time will be used by clock to
66 -- compute the current time by adding to it a fraction of the
67 -- performance counter. This is for the implementation of a
68 -- high-resolution clock.
74 -- This implementation of clock provides high resolution timer values
75 -- using QueryPerformanceCounter. This call return a 64 bits values (based
76 -- on the 8253 16 bits counter). This counter is updated every 1/1_193_182
77 -- times per seconds. The call to QueryPerformanceCounter takes 6
78 -- microsecs to complete.
80 function Clock
return Duration is
81 Max_Shift
: constant Duration := 2.0;
82 Hundreds_Nano_In_Sec
: constant := 1E7
;
83 Current_Ticks
: aliased LARGE_INTEGER
;
84 Elap_Secs_Tick
: Duration;
85 Elap_Secs_Sys
: Duration;
86 Now
: aliased Long_Long_Integer;
89 if not QueryPerformanceCounter
(Current_Ticks
'Access) then
93 GetSystemTimeAsFileTime
(Now
'Access);
96 Duration (abs (Now
- Base_Time
) / Hundreds_Nano_In_Sec
);
99 Duration (Long_Long_Float (Current_Ticks
- Base_Ticks
) /
100 Long_Long_Float (Tick_Frequency
));
102 -- If we have a shift of more than Max_Shift seconds we resynchonize the
103 -- Clock. This is probably due to a manual Clock adjustment, an DST
104 -- adjustment or an NNTP synchronisation. And we want to adjust the
105 -- time for this system (non-monotonic) clock.
107 if abs (Elap_Secs_Sys
- Elap_Secs_Tick
) > Max_Shift
then
111 Duration (Long_Long_Float (Current_Ticks
- Base_Ticks
) /
112 Long_Long_Float (Tick_Frequency
));
115 return Base_Clock
+ Elap_Secs_Tick
;
122 procedure Get_Base_Time
is
123 use System
.OS_Interface
;
125 -- The resolution for GetSystemTime is 1 millisecond.
127 -- The time to get both base times should take less than 1 millisecond.
128 -- Therefore, the elapsed time reported by GetSystemTime between both
129 -- actions should be null.
131 Max_Elapsed
: constant := 0;
133 Test_Now
: aliased Long_Long_Integer;
135 epoch_1970
: constant := 16#
19D_B1DE_D53E_8000#
; -- win32 UTC epoch
136 system_time_ns
: constant := 100; -- 100 ns per tick
137 Sec_Unit
: constant := 10#
1#E9
;
140 -- Here we must be sure that both of these calls are done in a short
141 -- amount of time. Both are base time and should in theory be taken
142 -- at the very same time.
145 GetSystemTimeAsFileTime
(Base_Time
'Access);
147 if not QueryPerformanceCounter
(Base_Ticks
'Access) then
150 "Could not query high performance counter in Clock");
154 GetSystemTimeAsFileTime
(Test_Now
'Access);
156 exit when Test_Now
- Base_Time
= Max_Elapsed
;
159 Base_Clock
:= Duration
160 (Long_Long_Float ((Base_Time
- epoch_1970
) * system_time_ns
) /
161 Long_Long_Float (Sec_Unit
));
164 ---------------------
165 -- Monotonic_Clock --
166 ---------------------
168 function Monotonic_Clock
return Duration is
169 Current_Ticks
: aliased LARGE_INTEGER
;
170 Elap_Secs_Tick
: Duration;
172 if not QueryPerformanceCounter
(Current_Ticks
'Access) then
177 Duration (Long_Long_Float (Current_Ticks
- Base_Ticks
) /
178 Long_Long_Float (Tick_Frequency
));
180 return Base_Monotonic_Clock
+ Elap_Secs_Tick
;
187 procedure Timed_Delay
(Time
: Duration; Mode
: Integer) is
190 Check_Time
: Duration := Monotonic_Clock
;
193 if Mode
= Relative
then
195 Abs_Time
:= Time
+ Check_Time
;
197 Rel_Time
:= Time
- Check_Time
;
201 if Rel_Time
> 0.0 then
203 Sleep
(DWORD
(Rel_Time
* 1000.0));
204 Check_Time
:= Monotonic_Clock
;
206 exit when Abs_Time
<= Check_Time
;
208 Rel_Time
:= Abs_Time
- Check_Time
;
213 -- Package elaboration, get starting time as base
216 if not QueryPerformanceFrequency
(Tick_Frequency
'Access) then
217 Ada
.Exceptions
.Raise_Exception
218 (Program_Error
'Identity,
219 "cannot get high performance counter frequency");
224 Base_Monotonic_Clock
:= Base_Clock
;
225 end System
.OS_Primitives
;