Windows: Always set the system timer resolution to 1ms by default.

An existing hint lets apps that don't need the timer resolution changed avoid
this, to save battery, etc, but this fixes several problems in timing, audio
callbacks not firing fast enough, etc.

Fixes Bugzilla #2944.

--HG--
extra : rebase_source : 42542a47baca5460939d3aab79b433ec450b5f91
extra : amend_source : 2c057ab8e81da3fcfbcda0bfc47986b1e023881b

src/timer/windows/SDL_systimer.c

@@ -43,7 +43,7 @@ static LARGE_INTEGER hires_ticks_per_second;
 
 #ifndef __WINRT__
 static void
-timeSetPeriod(UINT uPeriod)
+timeSetPeriod(const UINT uPeriod)
 {
     static UINT timer_period = 0;
 
@@ -87,6 +87,11 @@ SDL_TicksInit(void)
     }
     ticks_started = SDL_TRUE;
 
+    /* if we didn't set a precision, set it high. This affects lots of things
+       on Windows besides the SDL timers, like audio callbacks, etc. */
+    SDL_AddHintCallback(SDL_HINT_TIMER_RESOLUTION,
+                        SDL_TimerResolutionChanged, NULL);
+
     /* Set first ticks value */
 #ifdef USE_GETTICKCOUNT
     start = GetTickCount();
@@ -102,11 +107,7 @@ SDL_TicksInit(void)
 #ifdef __WINRT__
         start = 0;            /* the timer failed to start! */
 #else
-        timeSetPeriod(1);     /* use 1 ms timer precision */
         start = timeGetTime();
-
-        SDL_AddHintCallback(SDL_HINT_TIMER_RESOLUTION,
-                            SDL_TimerResolutionChanged, NULL);
 #endif /* __WINRT__ */
     }
 #endif /* USE_GETTICKCOUNT */
@@ -120,12 +121,14 @@ SDL_TicksQuit(void)
 #ifndef __WINRT__
         SDL_DelHintCallback(SDL_HINT_TIMER_RESOLUTION,
                             SDL_TimerResolutionChanged, NULL);
-
-        timeSetPeriod(0);
 #endif /* __WINRT__ */
     }
 #endif /* USE_GETTICKCOUNT */
 
+#ifndef __WINRT__
+    timeSetPeriod(0);  /* always release our timer resolution request. */
+#endif
+
     ticks_started = SDL_FALSE;
 }