Updated love.timer.getTime to be microsecond-precise and monotonic (thanks Boolsheet), removed the now-obsolete love.timer.getMicroTime (issue #492)

src/modules/timer/Timer.h

@@ -63,21 +63,19 @@ public:
 	 * @return The "current" FPS.
 	 **/
 	virtual int getFPS() const = 0;
+
+	/**
+	 * Gets the average delta time (seconds per frame) over the last second.
+	 **/
 	virtual double getAverageDelta() const = 0;
 
 	/**
-	 * Gets the amount of time since the program started. Only useful for timing
-	 * code or measuring intervals.
-	 * @return The time (in seconds) since the program started.
-	 **/
-	virtual double getTime() const = 0;
-
-	/**
-	 * Gets the amount of time passed since an unspecified time. The time is accurate
-	 * to the microsecond, and is limited to 24 hours.
+	 * Gets the amount of time passed since an unspecified time. Useful for
+	 * profiling code or measuring intervals. The time is microsecond-precise,
+	 * and increases monotonically.
 	 * @return The time (in seconds)
 	 **/
-	virtual double getMicroTime() const = 0;
+	virtual double getTime() const = 0;
 
 }; // Timer
 

src/modules/timer/sdl/Timer.cpp

@@ -18,17 +18,38 @@
  * 3. This notice may not be removed or altered from any source distribution.
  **/
 
+// LOVE
 #include "common/config.h"
-#include "common/delay.h"
+#include "Timer.h"
 
-#ifdef LOVE_WINDOWS
-#	include <windows.h>
-#	include <time.h>
-#else
-#	include <sys/time.h>
+#include "common/delay.h"
+#include "common/int.h"
+
+// SDL
+#include <SDL.h>
+
+#if defined(LOVE_WINDOWS)
+#include <windows.h>
+#elif defined(LOVE_MACOSX)
+#include <mach/mach_time.h>
+#include <sys/time.h>
+#elif defined(LOVE_LINUX)
+#include <unistd.h>
+#include <time.h>
+#include <sys/time.h>
 #endif
 
-#include "Timer.h"
+namespace
+{
+#if defined(LOVE_LINUX)
+inline double getTimeOfDay()
+{
+	timeval t;
+	gettimeofday(&t, NULL);
+	return (double) t.tv_sec + (double) t.tv_usec / 1000000.0;
+}
+#endif
+}
 
 namespace love
 {
@@ -45,12 +66,13 @@ Timer::Timer()
 	, fpsUpdateFrequency(1)
 	, frames(0)
 	, dt(0)
+	, timerFrequency(getTimerFrequency())
 {
-	// Init the SDL timer system.
+	// Init the SDL timer system (needed for SDL_Delay.)
 	if (SDL_InitSubSystem(SDL_INIT_TIMER) < 0)
-		throw Exception(SDL_GetError());
+		throw love::Exception("%s", SDL_GetError());
 
-	prevFpsUpdate = currTime = getMicroTime();
+	prevFpsUpdate = currTime = getTime();
 }
 
 Timer::~Timer()
@@ -72,10 +94,10 @@ void Timer::step()
 	// "Current" time is previous time by now.
 	prevTime = currTime;
 
-	// Get ticks from SDL
-	currTime = getMicroTime();
+	// Get ticks from system.
+	currTime = getTime();
 
-	// Convert to number of seconds
+	// Convert to number of seconds.
 	dt = currTime - prevTime;
 
 	double timeSinceLast = currTime - prevFpsUpdate;
@@ -110,35 +132,45 @@ double Timer::getAverageDelta() const
 	return averageDelta;
 }
 
-double Timer::getTime() const
+double Timer::getTimerFrequency()
 {
-	return SDL_GetTicks()/1000.0;
+#if defined(LOVE_MACOSX)
+	mach_timebase_info_data_t info;
+	mach_timebase_info(&info);
+	return (double) info.numer / (double) info.denom / 1000000000.0;
+#elif defined(LOVE_WINDOWS)
+	LARGE_INTEGER temp;
+	if (QueryPerformanceFrequency(&temp) != 0 && temp.QuadPart != 0)
+		return 1.0 / (double) temp.QuadPart;
+#endif
+	return 0;
 }
 
-double Timer::getMicroTime() const
+double Timer::getTime() const
 {
-#ifdef LOVE_WINDOWS
-	static __int64 freq = 0;
-
-	if (!freq)
-	{
-		LARGE_INTEGER temp;
-		QueryPerformanceFrequency(&temp);
-
-		freq = (__int64) temp.QuadPart;
-	}
-
+#if defined(LOVE_LINUX)
+	double mt;
+	// Check for POSIX timers and monotonic clocks. If not supported, use the gettimeofday fallback.
+#if _POSIX_TIMERS > 0 && defined(_POSIX_MONOTONIC_CLOCK) \
+&& (defined(CLOCK_MONOTONIC_RAW) || defined(CLOCK_MONOTONIC))
+	timespec t;
+#ifdef CLOCK_MONOTONIC_RAW
+	clockid_t clk_id = CLOCK_MONOTONIC_RAW;
+#else
+	clockid_t clk_id = CLOCK_MONOTONIC;
+#endif
+	if (clock_gettime(clk_id, &t) == 0)
+		mt = (double) t.tv_sec + (double) t.tv_nsec / 1000000000.0;
+	else
+#endif
+		mt = getTimeOfDay();
+	return mt;
+#elif defined(LOVE_MACOSX)
+	return (double) mach_absolute_time() * timerFrequency;
+#elif defined(LOVE_WINDOWS)
 	LARGE_INTEGER microTime;
 	QueryPerformanceCounter(&microTime);
-
-	// The 64 to 32 bit integer conversion, assuming the fraction part down
-	// to microseconds takes 20 bits, should not be a problem unless the
-	// system has an uptime of a few decades.
-	return (double) microTime.QuadPart / (double) freq;
-#else
-	timeval t;
-	gettimeofday(&t, NULL);
-	return t.tv_sec + t.tv_usec/1000000.0;
+	return (double) microTime.QuadPart * timerFrequency;
 #endif
 }
 

src/modules/timer/sdl/Timer.h

@@ -21,11 +21,8 @@
 #ifndef LOVE_TIMER_SDL_TIMER_H
 #define LOVE_TIMER_SDL_TIMER_H
 
-// SDL
-#include <SDL.h>
-
 // LOVE
-#include <timer/Timer.h>
+#include "timer/Timer.h"
 
 namespace love
 {
@@ -59,7 +56,6 @@ public:
 	int getFPS() const;
 	double getAverageDelta() const;
 	double getTime() const;
-	double getMicroTime() const;
 
 private:
 
@@ -81,6 +77,12 @@ private:
 	// The current timestep.
 	double dt;
 
+	// The reciprocal of the timer frequency.
+	const double timerFrequency;
+
+	// Returns the timer frequency on some platforms.
+	static double getTimerFrequency();
+	
 }; // Timer
 
 } // sdl

src/modules/timer/wrap_Timer.cpp

@@ -68,12 +68,6 @@ int w_getTime(lua_State *L)
 	return 1;
 }
 
-int w_getMicroTime(lua_State *L)
-{
-	lua_pushnumber(L, instance->getMicroTime());
-	return 1;
-}
-
 // List of functions to wrap.
 static const luaL_Reg functions[] =
 {
@@ -83,7 +77,6 @@ static const luaL_Reg functions[] =
 	{ "getAverageDelta", w_getAverageDelta },
 	{ "sleep", w_sleep },
 	{ "getTime", w_getTime },
-	{ "getMicroTime", w_getMicroTime },
 	{ 0, 0 }
 };
 

src/modules/timer/wrap_Timer.h

@@ -35,7 +35,6 @@ int w_getFPS(lua_State *L);
 int w_getAverageDelta(lua_State *L);
 int w_sleep(lua_State *L);
 int w_getTime(lua_State *L);
-int w_getMicroTime(lua_State *L);
 extern "C" LOVE_EXPORT int luaopen_love_timer(lua_State *L);
 
 } // timer