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) 1998-2007, 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
55 (lpFileTime
: not null access Long_Long_Integer);
56 pragma Import
(Stdcall
, GetSystemTimeAsFileTime
, "GetSystemTimeAsFileTime");
58 function QueryPerformanceCounter
59 (lpPerformanceCount
: not null access LARGE_INTEGER
) return BOOL
;
61 (Stdcall
, QueryPerformanceCounter
, "QueryPerformanceCounter");
63 function QueryPerformanceFrequency
64 (lpFrequency
: not null access LARGE_INTEGER
) return BOOL
;
66 (Stdcall
, QueryPerformanceFrequency
, "QueryPerformanceFrequency");
68 procedure Sleep
(dwMilliseconds
: DWORD
);
69 pragma Import
(Stdcall
, Sleep
, External_Name
=> "Sleep");
71 ----------------------------------------
72 -- Data for the high resolution clock --
73 ----------------------------------------
75 -- Declare some pointers to access multi-word data above. This is needed
76 -- to workaround a limitation in the GNU/Linker auto-import feature used
77 -- to build the GNAT runtime DLLs. In fact the Clock and Monotonic_Clock
78 -- routines are inlined and they are using some multi-word variables.
79 -- GNU/Linker will fail to auto-import those variables when building
80 -- libgnarl.dll. The indirection level introduced here has no measurable
83 -- Note that access variables below must not be declared as constant
84 -- otherwise the compiler optimization will remove this indirect access.
86 type DA
is access all Duration;
87 -- Use to have indirect access to multi-word variables
89 type LIA
is access all LARGE_INTEGER
;
90 -- Use to have indirect access to multi-word variables
92 type LLIA
is access all Long_Long_Integer;
93 -- Use to have indirect access to multi-word variables
95 Tick_Frequency
: aliased LARGE_INTEGER
;
96 TFA
: constant LIA
:= Tick_Frequency
'Access;
97 -- Holds frequency of high-performance counter used by Clock
98 -- Windows NT uses a 1_193_182 Hz counter on PCs.
100 Base_Ticks
: aliased LARGE_INTEGER
;
101 BTA
: constant LIA
:= Base_Ticks
'Access;
102 -- Holds the Tick count for the base time
104 Base_Monotonic_Ticks
: aliased LARGE_INTEGER
;
105 BMTA
: constant LIA
:= Base_Monotonic_Ticks
'Access;
106 -- Holds the Tick count for the base monotonic time
108 Base_Clock
: aliased Duration;
109 BCA
: constant DA
:= Base_Clock
'Access;
110 -- Holds the current clock for the standard clock's base time
112 Base_Monotonic_Clock
: aliased Duration;
113 BMCA
: constant DA
:= Base_Monotonic_Clock
'Access;
114 -- Holds the current clock for monotonic clock's base time
116 Base_Time
: aliased Long_Long_Integer;
117 BTiA
: constant LLIA
:= Base_Time
'Access;
118 -- Holds the base time used to check for system time change, used with
119 -- the standard clock.
121 procedure Get_Base_Time
;
122 -- Retrieve the base time and base ticks. These values will be used by
123 -- clock to compute the current time by adding to it a fraction of the
124 -- performance counter. This is for the implementation of a
125 -- high-resolution clock. Note that this routine does not change the base
126 -- monotonic values used by the monotonic clock.
132 -- This implementation of clock provides high resolution timer values
133 -- using QueryPerformanceCounter. This call return a 64 bits values (based
134 -- on the 8253 16 bits counter). This counter is updated every 1/1_193_182
135 -- times per seconds. The call to QueryPerformanceCounter takes 6
136 -- microsecs to complete.
138 function Clock
return Duration is
139 Max_Shift
: constant Duration := 2.0;
140 Hundreds_Nano_In_Sec
: constant Long_Long_Float := 1.0E7
;
141 Current_Ticks
: aliased LARGE_INTEGER
;
142 Elap_Secs_Tick
: Duration;
143 Elap_Secs_Sys
: Duration;
144 Now
: aliased Long_Long_Integer;
147 if not QueryPerformanceCounter
(Current_Ticks
'Access) then
151 GetSystemTimeAsFileTime
(Now
'Access);
154 Duration (Long_Long_Float (abs (Now
- BTiA
.all)) /
155 Hundreds_Nano_In_Sec
);
158 Duration (Long_Long_Float (Current_Ticks
- BTA
.all) /
159 Long_Long_Float (TFA
.all));
161 -- If we have a shift of more than Max_Shift seconds we resynchonize the
162 -- Clock. This is probably due to a manual Clock adjustment, an DST
163 -- adjustment or an NTP synchronisation. And we want to adjust the time
164 -- for this system (non-monotonic) clock.
166 if abs (Elap_Secs_Sys
- Elap_Secs_Tick
) > Max_Shift
then
170 Duration (Long_Long_Float (Current_Ticks
- BTA
.all) /
171 Long_Long_Float (TFA
.all));
174 return BCA
.all + Elap_Secs_Tick
;
181 procedure Get_Base_Time
is
183 -- The resolution for GetSystemTime is 1 millisecond
185 -- The time to get both base times should take less than 1 millisecond.
186 -- Therefore, the elapsed time reported by GetSystemTime between both
187 -- actions should be null.
189 Max_Elapsed
: constant := 0;
191 Test_Now
: aliased Long_Long_Integer;
193 epoch_1970
: constant := 16#
19D_B1DE_D53E_8000#
; -- win32 UTC epoch
194 system_time_ns
: constant := 100; -- 100 ns per tick
195 Sec_Unit
: constant := 10#
1#E9
;
198 -- Here we must be sure that both of these calls are done in a short
199 -- amount of time. Both are base time and should in theory be taken
200 -- at the very same time.
203 GetSystemTimeAsFileTime
(Base_Time
'Access);
205 if not QueryPerformanceCounter
(Base_Ticks
'Access) then
208 "Could not query high performance counter in Clock");
212 GetSystemTimeAsFileTime
(Test_Now
'Access);
214 exit when Test_Now
- Base_Time
= Max_Elapsed
;
217 Base_Clock
:= Duration
218 (Long_Long_Float ((Base_Time
- epoch_1970
) * system_time_ns
) /
219 Long_Long_Float (Sec_Unit
));
222 ---------------------
223 -- Monotonic_Clock --
224 ---------------------
226 function Monotonic_Clock
return Duration is
227 Current_Ticks
: aliased LARGE_INTEGER
;
228 Elap_Secs_Tick
: Duration;
231 if not QueryPerformanceCounter
(Current_Ticks
'Access) then
236 Duration (Long_Long_Float (Current_Ticks
- BMTA
.all) /
237 Long_Long_Float (TFA
.all));
239 return BMCA
.all + Elap_Secs_Tick
;
246 procedure Timed_Delay
(Time
: Duration; Mode
: Integer) is
248 function Mode_Clock
return Duration;
249 pragma Inline
(Mode_Clock
);
250 -- Return the current clock value using either the monotonic clock or
251 -- standard clock depending on the Mode value.
257 function Mode_Clock
return Duration is
261 return Monotonic_Clock
;
269 Base_Time
: constant Duration := Mode_Clock
;
270 -- Base_Time is used to detect clock set backward, in this case we
271 -- cannot ensure the delay accuracy.
275 Check_Time
: Duration := Base_Time
;
277 -- Start of processing for Timed Delay
280 if Mode
= Relative
then
282 Abs_Time
:= Time
+ Check_Time
;
284 Rel_Time
:= Time
- Check_Time
;
288 if Rel_Time
> 0.0 then
290 Sleep
(DWORD
(Rel_Time
* 1000.0));
291 Check_Time
:= Mode_Clock
;
293 exit when Abs_Time
<= Check_Time
or else Check_Time
< Base_Time
;
295 Rel_Time
:= Abs_Time
- Check_Time
;
304 Initialized
: Boolean := False;
306 procedure Initialize
is
314 -- Get starting time as base
316 if not QueryPerformanceFrequency
(Tick_Frequency
'Access) then
318 with "cannot get high performance counter frequency";
323 -- Keep base clock and ticks for the monotonic clock. These values
324 -- should never be changed to ensure proper behavior of the monotonic
327 Base_Monotonic_Clock
:= Base_Clock
;
328 Base_Monotonic_Ticks
:= Base_Ticks
;
331 end System
.OS_Primitives
;