Codechange: switch all video drivers to std::chrono for keeping time

On all OSes we tested the std::chrono::steady_clock is of a high
enough resolution to do millisecond measurements, which is all we
need.

By accident, this fixes a Win32 driver bug, where we would never
hit our targets, as the resolution of the clock was too low to
do accurate millisecond measurements with (it was ~16ms resolution
instead).

7 files changed, 44 insertions, 101 deletions

diff --git a/src/video/allegro_v.cpp b/src/video/allegro_v.cpp
index b62486a98..20f0e65ed 100644
--- a/src/video/allegro_v.cpp
+++ b/src/video/allegro_v.cpp
@@ -445,34 +445,15 @@ void VideoDriver_Allegro::Stop()
 	if (--_allegro_instance_count == 0) allegro_exit();
 }
 
-#if defined(UNIX) || defined(__OS2__)
-# include <sys/time.h> /* gettimeofday */
-
-static uint32 GetTime()
-{
-	struct timeval tim;
-
-	gettimeofday(&tim, nullptr);
-	return tim.tv_usec / 1000 + tim.tv_sec * 1000;
-}
-#else
-static uint32 GetTime()
-{
-	return GetTickCount();
-}
-#endif
-
-
 void VideoDriver_Allegro::MainLoop()
 {
-	uint32 cur_ticks = GetTime();
-	uint32 last_cur_ticks = cur_ticks;
-	uint32 next_tick = cur_ticks + MILLISECONDS_PER_TICK;
+	auto cur_ticks = std::chrono::steady_clock::now();
+	auto last_cur_ticks = cur_ticks;
+	auto next_tick = cur_ticks;
 
 	CheckPaletteAnim();
 
 	for (;;) {
-		uint32 prev_cur_ticks = cur_ticks; // to check for wrapping
 		InteractiveRandom(); // randomness
 
 		PollEvent();
@@ -491,11 +472,11 @@ void VideoDriver_Allegro::MainLoop()
 			_fast_forward = 0;
 		}
 
-		cur_ticks = GetTime();
-		if (cur_ticks >= next_tick || (_fast_forward && !_pause_mode) || cur_ticks < prev_cur_ticks) {
-			_realtime_tick += cur_ticks - last_cur_ticks;
+		cur_ticks = std::chrono::steady_clock::now();
+		if (cur_ticks >= next_tick || (_fast_forward && !_pause_mode)) {
+			_realtime_tick += std::chrono::duration_cast<std::chrono::milliseconds>(cur_ticks - last_cur_ticks).count();
 			last_cur_ticks = cur_ticks;
-			next_tick = cur_ticks + MILLISECONDS_PER_TICK;
+			next_tick = cur_ticks + std::chrono::milliseconds(MILLISECONDS_PER_TICK);
 
 			bool old_ctrl_pressed = _ctrl_pressed;
 
diff --git a/src/video/cocoa/cocoa_v.mm b/src/video/cocoa/cocoa_v.mm
index 4c6ce6cab..122a38be5 100644
--- a/src/video/cocoa/cocoa_v.mm
+++ b/src/video/cocoa/cocoa_v.mm
@@ -634,19 +634,13 @@ bool VideoDriver_Cocoa::PollEvent()
 /** Main game loop. */
 void VideoDriver_Cocoa::GameLoop()
 {
-	uint32 cur_ticks = GetTick();
-	uint32 last_cur_ticks = cur_ticks;
-	uint32 next_tick = cur_ticks + MILLISECONDS_PER_TICK;
-
-#ifdef _DEBUG
-	uint32 et0 = GetTick();
-	uint32 st = 0;
-#endif
+	auto cur_ticks = std::chrono::steady_clock::now();
+	auto last_cur_ticks = cur_ticks;
+	auto next_tick = cur_ticks;
 
 	for (;;) {
 		@autoreleasepool {
 
-			uint32 prev_cur_ticks = cur_ticks; // to check for wrapping
 			InteractiveRandom(); // randomness
 
 			while (this->PollEvent()) {}
@@ -669,11 +663,11 @@ void VideoDriver_Cocoa::GameLoop()
 				_fast_forward = 0;
 			}
 
-			cur_ticks = GetTick();
-			if (cur_ticks >= next_tick || (_fast_forward && !_pause_mode) || cur_ticks < prev_cur_ticks) {
-				_realtime_tick += cur_ticks - last_cur_ticks;
+			cur_ticks = std::chrono::steady_clock::now();
+			if (cur_ticks >= next_tick || (_fast_forward && !_pause_mode)) {
+				_realtime_tick += std::chrono::duration_cast<std::chrono::milliseconds>(cur_ticks - last_cur_ticks).count();
 				last_cur_ticks = cur_ticks;
-				next_tick = cur_ticks + MILLISECONDS_PER_TICK;
+				next_tick = cur_ticks + std::chrono::milliseconds(MILLISECONDS_PER_TICK);
 
 				bool old_ctrl_pressed = _ctrl_pressed;
 
@@ -688,28 +682,13 @@ void VideoDriver_Cocoa::GameLoop()
 				this->CheckPaletteAnim();
 				this->Draw();
 			} else {
-#ifdef _DEBUG
-				uint32 st0 = GetTick();
-#endif
 				CSleep(1);
-#ifdef _DEBUG
-				st += GetTick() - st0;
-#endif
 				NetworkDrawChatMessage();
 				DrawMouseCursor();
 				this->Draw();
 			}
 		}
 	}
-
-#ifdef _DEBUG
-	uint32 et = GetTick();
-
-	DEBUG(driver, 1, "cocoa_v: nextEventMatchingMask took %i ms total", _tEvent);
-	DEBUG(driver, 1, "cocoa_v: game loop took %i ms total (%i ms without sleep)", et - et0, et - et0 - st);
-	DEBUG(driver, 1, "cocoa_v: (nextEventMatchingMask total)/(game loop total) is %f%%", (double)_tEvent / (double)(et - et0) * 100);
-	DEBUG(driver, 1, "cocoa_v: (nextEventMatchingMask total)/(game loop without sleep total) is %f%%", (double)_tEvent / (double)(et - et0 - st) * 100);
-#endif
 }
 
 
diff --git a/src/video/dedicated_v.cpp b/src/video/dedicated_v.cpp
index d237e2d9e..60459099b 100644
--- a/src/video/dedicated_v.cpp
+++ b/src/video/dedicated_v.cpp
@@ -195,14 +195,6 @@ static bool InputWaiting()
 	return select(STDIN + 1, &readfds, nullptr, nullptr, &tv) > 0;
 }
 
-static uint32 GetTime()
-{
-	struct timeval tim;
-
-	gettimeofday(&tim, nullptr);
-	return tim.tv_usec / 1000 + tim.tv_sec * 1000;
-}
-
 #else
 
 static bool InputWaiting()
@@ -210,11 +202,6 @@ static bool InputWaiting()
 	return WaitForSingleObject(_hInputReady, 1) == WAIT_OBJECT_0;
 }
 
-static uint32 GetTime()
-{
-	return GetTickCount();
-}
-
 #endif
 
 static void DedicatedHandleKeyInput()
@@ -248,8 +235,9 @@ static void DedicatedHandleKeyInput()
 
 void VideoDriver_Dedicated::MainLoop()
 {
-	uint32 cur_ticks = GetTime();
-	uint32 next_tick = cur_ticks + MILLISECONDS_PER_TICK;
+	auto cur_ticks = std::chrono::steady_clock::now();
+	auto last_cur_ticks = cur_ticks;
+	auto next_tick = cur_ticks;
 
 	/* Signal handlers */
 #if defined(UNIX)
@@ -290,15 +278,14 @@ void VideoDriver_Dedicated::MainLoop()
 	}
 
 	while (!_exit_game) {
-		uint32 prev_cur_ticks = cur_ticks; // to check for wrapping
 		InteractiveRandom(); // randomness
 
 		if (!_dedicated_forks) DedicatedHandleKeyInput();
 
-		cur_ticks = GetTime();
-		_realtime_tick += cur_ticks - prev_cur_ticks;
-		if (cur_ticks >= next_tick || cur_ticks < prev_cur_ticks || _ddc_fastforward) {
-			next_tick = cur_ticks + MILLISECONDS_PER_TICK;
+		cur_ticks = std::chrono::steady_clock::now();
+		_realtime_tick += std::chrono::duration_cast<std::chrono::milliseconds>(cur_ticks - last_cur_ticks).count();
+		if (cur_ticks >= next_tick || _ddc_fastforward) {
+			next_tick = cur_ticks + std::chrono::milliseconds(MILLISECONDS_PER_TICK);
 
 			GameLoop();
 			UpdateWindows();
diff --git a/src/video/sdl2_v.cpp b/src/video/sdl2_v.cpp
index d41f79d54..0b2e257bd 100644
--- a/src/video/sdl2_v.cpp
+++ b/src/video/sdl2_v.cpp
@@ -734,7 +734,6 @@ void VideoDriver_SDL::LoopOnce()
 	uint32 mod;
 	int numkeys;
 	const Uint8 *keys;
-	uint32 prev_cur_ticks = cur_ticks; // to check for wrapping
 	InteractiveRandom(); // randomness
 
 	while (PollEvent() == -1) {}
@@ -768,11 +767,11 @@ void VideoDriver_SDL::LoopOnce()
 		_fast_forward = 0;
 	}
 
-	cur_ticks = SDL_GetTicks();
-	if (SDL_TICKS_PASSED(cur_ticks, next_tick) || (_fast_forward && !_pause_mode) || cur_ticks < prev_cur_ticks) {
-		_realtime_tick += cur_ticks - last_cur_ticks;
+	cur_ticks = std::chrono::steady_clock::now();
+	if (cur_ticks >= next_tick || (_fast_forward && !_pause_mode)) {
+		_realtime_tick += std::chrono::duration_cast<std::chrono::milliseconds>(cur_ticks - last_cur_ticks).count();
 		last_cur_ticks = cur_ticks;
-		next_tick = cur_ticks + MILLISECONDS_PER_TICK;
+		next_tick = cur_ticks + std::chrono::milliseconds(MILLISECONDS_PER_TICK);
 
 		bool old_ctrl_pressed = _ctrl_pressed;
 
@@ -826,9 +825,9 @@ void VideoDriver_SDL::LoopOnce()
 
 void VideoDriver_SDL::MainLoop()
 {
-	cur_ticks = SDL_GetTicks();
+	cur_ticks = std::chrono::steady_clock::now();
 	last_cur_ticks = cur_ticks;
-	next_tick = cur_ticks + MILLISECONDS_PER_TICK;
+	next_tick = cur_ticks;
 
 	this->CheckPaletteAnim();
 
diff --git a/src/video/sdl2_v.h b/src/video/sdl2_v.h
index d1c4d957c..61d607d56 100644
--- a/src/video/sdl2_v.h
+++ b/src/video/sdl2_v.h
@@ -62,9 +62,9 @@ private:
 	 */
 	bool edit_box_focused;
 
-	uint32 cur_ticks;
-	uint32 last_cur_ticks;
-	uint32 next_tick;
+	std::chrono::steady_clock::time_point cur_ticks;
+	std::chrono::steady_clock::time_point last_cur_ticks;
+	std::chrono::steady_clock::time_point next_tick;
 
 	int startup_display;
 	std::thread draw_thread;
diff --git a/src/video/sdl_v.cpp b/src/video/sdl_v.cpp
index f67d46801..cc6555461 100644
--- a/src/video/sdl_v.cpp
+++ b/src/video/sdl_v.cpp
@@ -648,9 +648,9 @@ void VideoDriver_SDL::Stop()
 
 void VideoDriver_SDL::MainLoop()
 {
-	uint32 cur_ticks = SDL_GetTicks();
-	uint32 last_cur_ticks = cur_ticks;
-	uint32 next_tick = cur_ticks + MILLISECONDS_PER_TICK;
+	auto cur_ticks = std::chrono::steady_clock::now();
+	auto last_cur_ticks = cur_ticks;
+	auto next_tick = cur_ticks;
 	uint32 mod;
 	int numkeys;
 	Uint8 *keys;
@@ -690,7 +690,6 @@ void VideoDriver_SDL::MainLoop()
 	DEBUG(driver, 1, "SDL: using %sthreads", _draw_threaded ? "" : "no ");
 
 	for (;;) {
-		uint32 prev_cur_ticks = cur_ticks; // to check for wrapping
 		InteractiveRandom(); // randomness
 
 		while (PollEvent() == -1) {}
@@ -719,11 +718,11 @@ void VideoDriver_SDL::MainLoop()
 			_fast_forward = 0;
 		}
 
-		cur_ticks = SDL_GetTicks();
-		if (cur_ticks >= next_tick || (_fast_forward && !_pause_mode) || cur_ticks < prev_cur_ticks) {
-			_realtime_tick += cur_ticks - last_cur_ticks;
+		cur_ticks = std::chrono::steady_clock::now();
+		if (cur_ticks >= next_tick || (_fast_forward && !_pause_mode)) {
+			_realtime_tick += std::chrono::duration_cast<std::chrono::milliseconds>(cur_ticks - last_cur_ticks).count();
 			last_cur_ticks = cur_ticks;
-			next_tick = cur_ticks + MILLISECONDS_PER_TICK;
+			next_tick = cur_ticks + std::chrono::milliseconds(MILLISECONDS_PER_TICK);
 
 			bool old_ctrl_pressed = _ctrl_pressed;
 
diff --git a/src/video/win32_v.cpp b/src/video/win32_v.cpp
index 8ccdd803e..714e50942 100644
--- a/src/video/win32_v.cpp
+++ b/src/video/win32_v.cpp
@@ -1133,9 +1133,9 @@ static void CheckPaletteAnim()
 void VideoDriver_Win32::MainLoop()
 {
 	MSG mesg;
-	uint32 cur_ticks = GetTickCount();
-	uint32 last_cur_ticks = cur_ticks;
-	uint32 next_tick = cur_ticks + MILLISECONDS_PER_TICK;
+	auto cur_ticks = std::chrono::steady_clock::now();
+	auto last_cur_ticks = cur_ticks;
+	auto next_tick = cur_ticks;
 
 	std::thread draw_thread;
 	std::unique_lock<std::recursive_mutex> draw_lock;
@@ -1176,8 +1176,6 @@ void VideoDriver_Win32::MainLoop()
 
 	CheckPaletteAnim();
 	for (;;) {
-		uint32 prev_cur_ticks = cur_ticks; // to check for wrapping
-
 		while (PeekMessage(&mesg, nullptr, 0, 0, PM_REMOVE)) {
 			InteractiveRandom(); // randomness
 			/* Convert key messages to char messages if we want text input. */
@@ -1198,11 +1196,11 @@ void VideoDriver_Win32::MainLoop()
 			_fast_forward = 0;
 		}
 
-		cur_ticks = GetTickCount();
-		if (cur_ticks >= next_tick || (_fast_forward && !_pause_mode) || cur_ticks < prev_cur_ticks) {
-			_realtime_tick += cur_ticks - last_cur_ticks;
+		cur_ticks = std::chrono::steady_clock::now();
+		if (cur_ticks >= next_tick || (_fast_forward && !_pause_mode)) {
+			_realtime_tick += std::chrono::duration_cast<std::chrono::milliseconds>(cur_ticks - last_cur_ticks).count();
 			last_cur_ticks = cur_ticks;
-			next_tick = cur_ticks + MILLISECONDS_PER_TICK;
+			next_tick = cur_ticks + std::chrono::milliseconds(MILLISECONDS_PER_TICK);
 
 			bool old_ctrl_pressed = _ctrl_pressed;