Implement -mmemcpy-strategy= and -mmemset-strategy= options
[official-gcc.git] / gcc / ada / s-osprim-mingw.adb
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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
4 -- --
5 -- S Y S T E M . O S _ P R I M I T I V E S --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1998-2013, Free Software Foundation, Inc. --
10 -- --
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 3, or (at your option) any later ver- --
14 -- sion. GNAT 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. --
17 -- --
18 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
21 -- --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
26 -- --
27 -- GNARL was developed by the GNARL team at Florida State University. --
28 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
29 -- --
30 ------------------------------------------------------------------------------
32 -- This is the NT version of this package
34 with System.Task_Lock;
35 with System.Win32.Ext;
37 package body System.OS_Primitives is
39 use System.Task_Lock;
40 use System.Win32;
41 use System.Win32.Ext;
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_Monotonic_Ticks : LARGE_INTEGER;
52 -- Holds the Tick count for the base monotonic time
54 Base_Monotonic_Clock : Duration;
55 -- Holds the current clock for monotonic clock's base time
57 type Clock_Data is record
58 Base_Ticks : LARGE_INTEGER;
59 -- Holds the Tick count for the base time
61 Base_Time : Long_Long_Integer;
62 -- Holds the base time used to check for system time change, used with
63 -- the standard clock.
65 Base_Clock : Duration;
66 -- Holds the current clock for the standard clock's base time
67 end record;
69 type Clock_Data_Access is access all Clock_Data;
71 -- Two base clock buffers. This is used to be able to update a buffer while
72 -- the other buffer is read. The point is that we do not want to use a lock
73 -- inside the Clock routine for performance reasons. We still use a lock
74 -- in the Get_Base_Time which is called very rarely. Current is a pointer,
75 -- the pragma Atomic is there to ensure that the value can be set or read
76 -- atomically. That's it, when Get_Base_Time has updated a buffer the
77 -- switch to the new value is done by changing Current pointer.
79 First, Second : aliased Clock_Data;
81 Current : Clock_Data_Access := First'Access;
82 pragma Atomic (Current);
84 -- The following signature is to detect change on the base clock data
85 -- above. The signature is a modular type, it will wrap around without
86 -- raising an exception. We would need to have exactly 2**32 updates of
87 -- the base data for the changes to get undetected.
89 type Signature_Type is mod 2**32;
90 Signature : Signature_Type := 0;
91 pragma Atomic (Signature);
93 procedure Get_Base_Time (Data : out Clock_Data);
94 -- Retrieve the base time and base ticks. These values will be used by
95 -- clock to compute the current time by adding to it a fraction of the
96 -- performance counter. This is for the implementation of a
97 -- high-resolution clock. Note that this routine does not change the base
98 -- monotonic values used by the monotonic clock.
100 -----------
101 -- Clock --
102 -----------
104 -- This implementation of clock provides high resolution timer values
105 -- using QueryPerformanceCounter. This call return a 64 bits values (based
106 -- on the 8253 16 bits counter). This counter is updated every 1/1_193_182
107 -- times per seconds. The call to QueryPerformanceCounter takes 6
108 -- microsecs to complete.
110 function Clock return Duration is
111 Max_Shift : constant Duration := 2.0;
112 Hundreds_Nano_In_Sec : constant Long_Long_Float := 1.0E7;
113 Data : Clock_Data;
114 Current_Ticks : aliased LARGE_INTEGER;
115 Elap_Secs_Tick : Duration;
116 Elap_Secs_Sys : Duration;
117 Now : aliased Long_Long_Integer;
118 Sig1, Sig2 : Signature_Type;
120 begin
121 -- Try ten times to get a coherent set of base data. For this we just
122 -- check that the signature hasn't changed during the copy of the
123 -- current data.
125 -- This loop will always be done once if there is no interleaved call
126 -- to Get_Base_Time.
128 for K in 1 .. 10 loop
129 Sig1 := Signature;
130 Data := Current.all;
131 Sig2 := Signature;
132 exit when Sig1 = Sig2;
133 end loop;
135 if QueryPerformanceCounter (Current_Ticks'Access) = Win32.FALSE then
136 return 0.0;
137 end if;
139 GetSystemTimeAsFileTime (Now'Access);
141 Elap_Secs_Sys :=
142 Duration (Long_Long_Float (abs (Now - Data.Base_Time)) /
143 Hundreds_Nano_In_Sec);
145 Elap_Secs_Tick :=
146 Duration (Long_Long_Float (Current_Ticks - Data.Base_Ticks) /
147 Long_Long_Float (Tick_Frequency));
149 -- If we have a shift of more than Max_Shift seconds we resynchronize
150 -- the Clock. This is probably due to a manual Clock adjustment, a DST
151 -- adjustment or an NTP synchronisation. And we want to adjust the time
152 -- for this system (non-monotonic) clock.
154 if abs (Elap_Secs_Sys - Elap_Secs_Tick) > Max_Shift then
155 Get_Base_Time (Data);
157 Elap_Secs_Tick :=
158 Duration (Long_Long_Float (Current_Ticks - Data.Base_Ticks) /
159 Long_Long_Float (Tick_Frequency));
160 end if;
162 return Data.Base_Clock + Elap_Secs_Tick;
163 end Clock;
165 -------------------
166 -- Get_Base_Time --
167 -------------------
169 procedure Get_Base_Time (Data : out Clock_Data) is
171 -- The resolution for GetSystemTime is 1 millisecond
173 -- The time to get both base times should take less than 1 millisecond.
174 -- Therefore, the elapsed time reported by GetSystemTime between both
175 -- actions should be null.
177 epoch_1970 : constant := 16#19D_B1DE_D53E_8000#; -- win32 UTC epoch
178 system_time_ns : constant := 100; -- 100 ns per tick
179 Sec_Unit : constant := 10#1#E9;
181 Max_Elapsed : constant LARGE_INTEGER :=
182 LARGE_INTEGER (Tick_Frequency / 100_000);
183 -- Look for a precision of 0.01 ms
185 Sig : constant Signature_Type := Signature;
187 Loc_Ticks, Ctrl_Ticks : aliased LARGE_INTEGER;
188 Loc_Time, Ctrl_Time : aliased Long_Long_Integer;
189 Elapsed : LARGE_INTEGER;
190 Current_Max : LARGE_INTEGER := LARGE_INTEGER'Last;
191 New_Data : Clock_Data_Access;
193 begin
194 -- Here we must be sure that both of these calls are done in a short
195 -- amount of time. Both are base time and should in theory be taken
196 -- at the very same time.
198 -- The goal of the following loop is to synchronize the system time
199 -- with the Win32 performance counter by getting a base offset for both.
200 -- Using these offsets it is then possible to compute actual time using
201 -- a performance counter which has a better precision than the Win32
202 -- time API.
204 -- Try at most 10 times to reach the best synchronisation (below 1
205 -- millisecond) otherwise the runtime will use the best value reached
206 -- during the runs.
208 Lock;
210 -- First check that the current value has not been updated. This
211 -- could happen if another task has called Clock at the same time
212 -- and that Max_Shift has been reached too.
214 -- But if the current value has been changed just before we entered
215 -- into the critical section, we can safely return as the current
216 -- base data (time, clock, ticks) have already been updated.
218 if Sig /= Signature then
219 return;
220 end if;
222 -- Check for the unused data buffer and set New_Data to point to it
224 if Current = First'Access then
225 New_Data := Second'Access;
226 else
227 New_Data := First'Access;
228 end if;
230 for K in 1 .. 10 loop
231 if QueryPerformanceCounter (Loc_Ticks'Access) = Win32.FALSE then
232 pragma Assert
233 (Standard.False,
234 "Could not query high performance counter in Clock");
235 null;
236 end if;
238 GetSystemTimeAsFileTime (Ctrl_Time'Access);
240 -- Scan for clock tick, will take up to 16ms/1ms depending on PC.
241 -- This cannot be an infinite loop or the system hardware is badly
242 -- damaged.
244 loop
245 GetSystemTimeAsFileTime (Loc_Time'Access);
247 if QueryPerformanceCounter (Ctrl_Ticks'Access) = Win32.FALSE then
248 pragma Assert
249 (Standard.False,
250 "Could not query high performance counter in Clock");
251 null;
252 end if;
254 exit when Loc_Time /= Ctrl_Time;
255 Loc_Ticks := Ctrl_Ticks;
256 end loop;
258 -- Check elapsed Performance Counter between samples
259 -- to choose the best one.
261 Elapsed := Ctrl_Ticks - Loc_Ticks;
263 if Elapsed < Current_Max then
264 New_Data.Base_Time := Loc_Time;
265 New_Data.Base_Ticks := Loc_Ticks;
266 Current_Max := Elapsed;
268 -- Exit the loop when we have reached the expected precision
270 exit when Elapsed <= Max_Elapsed;
271 end if;
272 end loop;
274 New_Data.Base_Clock :=
275 Duration
276 (Long_Long_Float
277 ((New_Data.Base_Time - epoch_1970) * system_time_ns) /
278 Long_Long_Float (Sec_Unit));
280 -- At this point all the base values have been set into the new data
281 -- record. Change the pointer (atomic operation) to these new values.
283 Current := New_Data;
284 Data := New_Data.all;
286 -- Set new signature for this data set
288 Signature := Signature + 1;
290 Unlock;
292 exception
293 when others =>
294 Unlock;
295 raise;
296 end Get_Base_Time;
298 ---------------------
299 -- Monotonic_Clock --
300 ---------------------
302 function Monotonic_Clock return Duration is
303 Current_Ticks : aliased LARGE_INTEGER;
304 Elap_Secs_Tick : Duration;
306 begin
307 if QueryPerformanceCounter (Current_Ticks'Access) = Win32.FALSE then
308 return 0.0;
310 else
311 Elap_Secs_Tick :=
312 Duration (Long_Long_Float (Current_Ticks - Base_Monotonic_Ticks) /
313 Long_Long_Float (Tick_Frequency));
314 return Base_Monotonic_Clock + Elap_Secs_Tick;
315 end if;
316 end Monotonic_Clock;
318 -----------------
319 -- Timed_Delay --
320 -----------------
322 procedure Timed_Delay (Time : Duration; Mode : Integer) is
324 function Mode_Clock return Duration;
325 pragma Inline (Mode_Clock);
326 -- Return the current clock value using either the monotonic clock or
327 -- standard clock depending on the Mode value.
329 ----------------
330 -- Mode_Clock --
331 ----------------
333 function Mode_Clock return Duration is
334 begin
335 case Mode is
336 when Absolute_RT =>
337 return Monotonic_Clock;
338 when others =>
339 return Clock;
340 end case;
341 end Mode_Clock;
343 -- Local Variables
345 Base_Time : constant Duration := Mode_Clock;
346 -- Base_Time is used to detect clock set backward, in this case we
347 -- cannot ensure the delay accuracy.
349 Rel_Time : Duration;
350 Abs_Time : Duration;
351 Check_Time : Duration := Base_Time;
353 -- Start of processing for Timed Delay
355 begin
356 if Mode = Relative then
357 Rel_Time := Time;
358 Abs_Time := Time + Check_Time;
359 else
360 Rel_Time := Time - Check_Time;
361 Abs_Time := Time;
362 end if;
364 if Rel_Time > 0.0 then
365 loop
366 Sleep (DWORD (Rel_Time * 1000.0));
367 Check_Time := Mode_Clock;
369 exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
371 Rel_Time := Abs_Time - Check_Time;
372 end loop;
373 end if;
374 end Timed_Delay;
376 ----------------
377 -- Initialize --
378 ----------------
380 Initialized : Boolean := False;
382 procedure Initialize is
383 begin
384 if Initialized then
385 return;
386 end if;
388 Initialized := True;
390 -- Get starting time as base
392 if QueryPerformanceFrequency (Tick_Frequency'Access) = Win32.FALSE then
393 raise Program_Error with
394 "cannot get high performance counter frequency";
395 end if;
397 Get_Base_Time (Current.all);
399 -- Keep base clock and ticks for the monotonic clock. These values
400 -- should never be changed to ensure proper behavior of the monotonic
401 -- clock.
403 Base_Monotonic_Clock := Current.Base_Clock;
404 Base_Monotonic_Ticks := Current.Base_Ticks;
405 end Initialize;
407 end System.OS_Primitives;