1 ------------------------------------------------------------------------------
3 -- GNAT 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) 1998-2005 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, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, 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
38 package body System
.OS_Primitives
is
40 ---------------------------
41 -- Win32 API Definitions --
42 ---------------------------
44 -- These definitions are copied from System.OS_Interface because we do not
45 -- want to depend on gnarl here.
47 type DWORD
is new Interfaces
.C
.unsigned_long
;
49 type LARGE_INTEGER
is delta 1.0 range -2.0**63 .. 2.0**63 - 1.0;
51 type BOOL
is new Boolean;
52 for BOOL
'Size use Interfaces
.C
.unsigned_long
'Size;
54 procedure GetSystemTimeAsFileTime
(lpFileTime
: access Long_Long_Integer);
55 pragma Import
(Stdcall
, GetSystemTimeAsFileTime
, "GetSystemTimeAsFileTime");
57 function QueryPerformanceCounter
58 (lpPerformanceCount
: access LARGE_INTEGER
) return BOOL
;
60 (Stdcall
, QueryPerformanceCounter
, "QueryPerformanceCounter");
62 function QueryPerformanceFrequency
63 (lpFrequency
: access LARGE_INTEGER
) return BOOL
;
65 (Stdcall
, QueryPerformanceFrequency
, "QueryPerformanceFrequency");
67 procedure Sleep
(dwMilliseconds
: DWORD
);
68 pragma Import
(Stdcall
, Sleep
, External_Name
=> "Sleep");
70 ----------------------------------------
71 -- Data for the high resolution clock --
72 ----------------------------------------
74 -- Declare some pointers to access multi-word data above. This is needed
75 -- to workaround a limitation in the GNU/Linker auto-import feature used
76 -- to build the GNAT runtime DLLs. In fact the Clock and Monotonic_Clock
77 -- routines are inlined and they are using some multi-word variables.
78 -- GNU/Linker will fail to auto-import those variables when building
79 -- libgnarl.dll. The indirection level introduced here has no measurable
82 -- Note that access variables below must not be declared as constant
83 -- otherwise the compiler optimization will remove this indirect access.
85 type DA
is access all Duration;
86 -- Use to have indirect access to multi-word variables
88 type LIA
is access all LARGE_INTEGER
;
89 -- Use to have indirect access to multi-word variables
91 type LLIA
is access all Long_Long_Integer;
92 -- Use to have indirect access to multi-word variables
94 Tick_Frequency
: aliased LARGE_INTEGER
;
95 TFA
: constant LIA
:= Tick_Frequency
'Access;
96 -- Holds frequency of high-performance counter used by Clock
97 -- Windows NT uses a 1_193_182 Hz counter on PCs.
99 Base_Ticks
: aliased LARGE_INTEGER
;
100 BTA
: constant LIA
:= Base_Ticks
'Access;
101 -- Holds the Tick count for the base time.
103 Base_Monotonic_Ticks
: aliased LARGE_INTEGER
;
104 BMTA
: constant LIA
:= Base_Monotonic_Ticks
'Access;
105 -- Holds the Tick count for the base monotonic time
107 Base_Clock
: aliased Duration;
108 BCA
: constant DA
:= Base_Clock
'Access;
109 -- Holds the current clock for the standard clock's base time
111 Base_Monotonic_Clock
: aliased Duration;
112 BMCA
: constant DA
:= Base_Monotonic_Clock
'Access;
113 -- Holds the current clock for monotonic clock's base time
115 Base_Time
: aliased Long_Long_Integer;
116 BTiA
: constant LLIA
:= Base_Time
'Access;
117 -- Holds the base time used to check for system time change, used with
118 -- the standard clock.
120 procedure Get_Base_Time
;
121 -- Retrieve the base time and base ticks. These values will be used by
122 -- clock to compute the current time by adding to it a fraction of the
123 -- performance counter. This is for the implementation of a
124 -- high-resolution clock. Note that this routine does not change the base
125 -- monotonic values used by the monotonic clock.
131 -- This implementation of clock provides high resolution timer values
132 -- using QueryPerformanceCounter. This call return a 64 bits values (based
133 -- on the 8253 16 bits counter). This counter is updated every 1/1_193_182
134 -- times per seconds. The call to QueryPerformanceCounter takes 6
135 -- microsecs to complete.
137 function Clock
return Duration is
138 Max_Shift
: constant Duration := 2.0;
139 Hundreds_Nano_In_Sec
: constant Long_Long_Float := 1.0E7
;
140 Current_Ticks
: aliased LARGE_INTEGER
;
141 Elap_Secs_Tick
: Duration;
142 Elap_Secs_Sys
: Duration;
143 Now
: aliased Long_Long_Integer;
146 if not QueryPerformanceCounter
(Current_Ticks
'Access) then
150 GetSystemTimeAsFileTime
(Now
'Access);
153 Duration (Long_Long_Float (abs (Now
- BTiA
.all)) /
154 Hundreds_Nano_In_Sec
);
157 Duration (Long_Long_Float (Current_Ticks
- BTA
.all) /
158 Long_Long_Float (TFA
.all));
160 -- If we have a shift of more than Max_Shift seconds we resynchonize the
161 -- Clock. This is probably due to a manual Clock adjustment, an DST
162 -- adjustment or an NTP synchronisation. And we want to adjust the
163 -- time for this system (non-monotonic) clock.
165 if abs (Elap_Secs_Sys
- Elap_Secs_Tick
) > Max_Shift
then
169 Duration (Long_Long_Float (Current_Ticks
- BTA
.all) /
170 Long_Long_Float (TFA
.all));
173 return BCA
.all + Elap_Secs_Tick
;
180 procedure Get_Base_Time
is
181 -- The resolution for GetSystemTime is 1 millisecond.
183 -- The time to get both base times should take less than 1 millisecond.
184 -- Therefore, the elapsed time reported by GetSystemTime between both
185 -- actions should be null.
187 Max_Elapsed
: constant := 0;
189 Test_Now
: aliased Long_Long_Integer;
191 epoch_1970
: constant := 16#
19D_B1DE_D53E_8000#
; -- win32 UTC epoch
192 system_time_ns
: constant := 100; -- 100 ns per tick
193 Sec_Unit
: constant := 10#
1#E9
;
196 -- Here we must be sure that both of these calls are done in a short
197 -- amount of time. Both are base time and should in theory be taken
198 -- at the very same time.
201 GetSystemTimeAsFileTime
(Base_Time
'Access);
203 if not QueryPerformanceCounter
(Base_Ticks
'Access) then
206 "Could not query high performance counter in Clock");
210 GetSystemTimeAsFileTime
(Test_Now
'Access);
212 exit when Test_Now
- Base_Time
= Max_Elapsed
;
215 Base_Clock
:= Duration
216 (Long_Long_Float ((Base_Time
- epoch_1970
) * system_time_ns
) /
217 Long_Long_Float (Sec_Unit
));
220 ---------------------
221 -- Monotonic_Clock --
222 ---------------------
224 function Monotonic_Clock
return Duration is
225 Current_Ticks
: aliased LARGE_INTEGER
;
226 Elap_Secs_Tick
: Duration;
228 if not QueryPerformanceCounter
(Current_Ticks
'Access) then
233 Duration (Long_Long_Float (Current_Ticks
- BMTA
.all) /
234 Long_Long_Float (TFA
.all));
236 return BMCA
.all + Elap_Secs_Tick
;
243 procedure Timed_Delay
(Time
: Duration; Mode
: Integer) is
246 Check_Time
: Duration := Monotonic_Clock
;
249 if Mode
= Relative
then
251 Abs_Time
:= Time
+ Check_Time
;
253 Rel_Time
:= Time
- Check_Time
;
257 if Rel_Time
> 0.0 then
259 Sleep
(DWORD
(Rel_Time
* 1000.0));
260 Check_Time
:= Monotonic_Clock
;
262 exit when Abs_Time
<= Check_Time
;
264 Rel_Time
:= Abs_Time
- Check_Time
;
273 Initialized
: Boolean := False;
275 procedure Initialize
is
283 -- Get starting time as base
285 if not QueryPerformanceFrequency
(Tick_Frequency
'Access) then
287 with "cannot get high performance counter frequency";
292 -- Keep base clock and ticks for the monotonic clock. These values
293 -- should never be changed to ensure proper behavior of the monotonic
296 Base_Monotonic_Clock
:= Base_Clock
;
297 Base_Monotonic_Ticks
:= Base_Ticks
;
300 end System
.OS_Primitives
;