Display: Allow unthrottle to skip only flipping.

Before, it either flipped continuously, or forced frameskip on.  This
makes it so you can still draw frames, but skip actual flips.

This is useful when games draw things only in a single frame and reuse
later.  It's also useful when measuring speed improvements if you already
get 100% speed on a device.

Core/Config.cpp

@@ -529,11 +529,11 @@ static int DefaultInternalResolution() {
 #endif
 }
 
-static bool DefaultFrameskipUnthrottle() {
+static int DefaultUnthrottleMode() {
 #if PPSSPP_PLATFORM(ANDROID) || defined(USING_QT_UI) || PPSSPP_PLATFORM(UWP) || PPSSPP_PLATFORM(IOS)
-	return true;
+	return (int)UnthrottleMode::SKIP_DRAW;
 #else
-	return false;
+	return (int)UnthrottleMode::CONTINUOUS;
 #endif
 }
 
@@ -705,6 +705,28 @@ struct ConfigTranslator {
 
 typedef ConfigTranslator<GPUBackend, GPUBackendToString, GPUBackendFromString> GPUBackendTranslator;
 
+static int UnthrottleModeFromString(const std::string &s) {
+	if (!strcasecmp(s.c_str(), "CONTINUOUS"))
+		return (int)UnthrottleMode::CONTINUOUS;
+	if (!strcasecmp(s.c_str(), "SKIP_DRAW"))
+		return (int)UnthrottleMode::SKIP_DRAW;
+	if (!strcasecmp(s.c_str(), "SKIP_FLIP"))
+		return (int)UnthrottleMode::SKIP_FLIP;
+	return DefaultUnthrottleMode();
+}
+
+std::string UnthrottleModeToString(int v) {
+	switch (UnthrottleMode(v)) {
+	case UnthrottleMode::CONTINUOUS:
+		return "CONTINUOUS";
+	case UnthrottleMode::SKIP_DRAW:
+		return "SKIP_DRAW";
+	case UnthrottleMode::SKIP_FLIP:
+		return "SKIP_FLIP";
+	}
+	return "CONTINUOUS";
+}
+
 static ConfigSetting graphicsSettings[] = {
 	ConfigSetting("EnableCardboardVR", &g_Config.bEnableCardboardVR, false, true, true),
 	ConfigSetting("CardboardScreenSize", &g_Config.iCardboardScreenSize, 50, true, true),
@@ -734,7 +756,7 @@ static ConfigSetting graphicsSettings[] = {
 	ReportedConfigSetting("AutoFrameSkip", &g_Config.bAutoFrameSkip, false, true, true),
 	ConfigSetting("FrameRate", &g_Config.iFpsLimit1, 0, true, true),
 	ConfigSetting("FrameRate2", &g_Config.iFpsLimit2, -1, true, true),
-	ConfigSetting("FrameSkipUnthrottle", &g_Config.bFrameSkipUnthrottle, &DefaultFrameskipUnthrottle, true, false),
+	ConfigSetting("UnthrottleMode", &g_Config.iUnthrottleMode, &DefaultUnthrottleMode, &UnthrottleModeToString, &UnthrottleModeFromString, true, true),
 #if defined(USING_WIN_UI)
 	ConfigSetting("RestartRequired", &g_Config.bRestartRequired, false, false),
 #endif

Core/Config.h

@@ -161,8 +161,8 @@ public:
 	bool bVSync;
 	int iFrameSkip;
 	int iFrameSkipType;
+	int iUnthrottleMode; // See UnthrottleMode in ConfigValues.h.
 	bool bAutoFrameSkip;
-	bool bFrameSkipUnthrottle;
 
 	bool bEnableCardboardVR; // Cardboard Master Switch
 	int iCardboardScreenSize; // Screen Size (in %)

Core/ConfigValues.h

@@ -110,3 +110,9 @@ enum class AutoLoadSaveState {
 	OLDEST = 1,
 	NEWEST = 2,
 };
+
+enum class UnthrottleMode {
+	CONTINUOUS = 0,
+	SKIP_DRAW = 1,
+	SKIP_FLIP = 2,
+};

Core/HLE/sceDisplay.cpp

@@ -561,7 +561,7 @@ static void DoFrameTiming(bool &throttle, bool &skipFrame, float timestep) {
 	// we have nothing to do here.
 	bool doFrameSkip = g_Config.iFrameSkip != 0;
 
-	bool unthrottleNeedsSkip = g_Config.bFrameSkipUnthrottle;
+	bool unthrottleNeedsSkip = g_Config.iUnthrottleMode == (int)UnthrottleMode::SKIP_DRAW;
 	if (g_Config.bVSync && GetGPUBackend() == GPUBackend::VULKAN) {
 		// Vulkan doesn't support the interval setting, so we force frameskip.
 		unthrottleNeedsSkip = true;
@@ -758,7 +758,7 @@ void __DisplayFlip(int cyclesLate) {
 
 	bool duplicateFrames = g_Config.bRenderDuplicateFrames && g_Config.iFrameSkip == 0;
 
-	bool unthrottleNeedsSkip = g_Config.bFrameSkipUnthrottle;
+	bool unthrottleNeedsSkip = g_Config.iUnthrottleMode != (int)UnthrottleMode::CONTINUOUS;
 	if (g_Config.bVSync && GetGPUBackend() == GPUBackend::VULKAN) {
 		// Vulkan doesn't support the interval setting, so we force frameskip.
 		unthrottleNeedsSkip = true;
@@ -794,11 +794,24 @@ void __DisplayFlip(int cyclesLate) {
 			hasNotifiedSlow = true;
 		}
 
+		bool forceNoFlip = false;
+		// Alternative to frameskip unthrottle, where we draw everything.
+		// Useful if skipping a frame breaks graphics or for checking drawing speed.
+		if (g_Config.iUnthrottleMode == (int)UnthrottleMode::SKIP_FLIP && !FrameTimingThrottled()) {
+			static double lastFlip = 0;
+			double now = time_now_d();
+			if ((now - lastFlip) < 1.0f / System_GetPropertyFloat(SYSPROP_DISPLAY_REFRESH_RATE)) {
+				forceNoFlip = true;
+			} else {
+				lastFlip = now;
+			}
+		}
+
 		// Setting CORE_NEXTFRAME causes a swap.
 		const bool fbReallyDirty = gpu->FramebufferReallyDirty();
 		if (fbReallyDirty || noRecentFlip || postEffectRequiresFlip) {
 			// Check first though, might've just quit / been paused.
-			if (Core_NextFrame()) {
+			if (!forceNoFlip && Core_NextFrame()) {
 				gpu->CopyDisplayToOutput(fbReallyDirty);
 				if (fbReallyDirty) {
 					actualFlips++;

headless/Headless.cpp

@@ -382,7 +382,7 @@ int main(int argc, const char* argv[])
 	g_Config.iButtonPreference = PSP_SYSTEMPARAM_BUTTON_CROSS;
 	g_Config.iLockParentalLevel = 9;
 	g_Config.iInternalResolution = 1;
-	g_Config.bFrameSkipUnthrottle = false;
+	g_Config.iUnthrottleMode = (int)UnthrottleMode::CONTINUOUS;
 	g_Config.bEnableLogging = fullLog;
 	g_Config.iNumWorkerThreads = 1;
 	g_Config.bSoftwareSkinning = true;

libretro/libretro.cpp

@@ -342,7 +342,7 @@ void retro_init(void)
 #endif
 
    g_Config.bEnableLogging = true;
-   g_Config.bFrameSkipUnthrottle = false;
+   g_Config.iUnthrottleMode = (int)UnthrottleMode::CONTINUOUS;
    g_Config.bMemStickInserted = PSP_MEMORYSTICK_STATE_INSERTED;
    g_Config.iGlobalVolume = VOLUME_MAX - 1;
    g_Config.iAltSpeedVolume = -1;