proportional spark cut #3427

firmware/controllers/algo/engine.h

@@ -115,6 +115,7 @@ public:
 
 	GearControllerBase *gearController;
 	LaunchControlBase launchController;
+	SoftSparkLimiter softSparkLimiter;
 
 	efitick_t mostRecentSparkEvent;
 	efitick_t mostRecentTimeBetweenSparkEvents;

firmware/controllers/algo/launch_control.cpp

@@ -137,6 +137,21 @@ bool LaunchControlBase::isLaunchFuelRpmRetardCondition() const {
 	return isLaunchRpmRetardCondition() && engineConfiguration->launchFuelCutEnable;
 }
 
+void SoftSparkLimiter::setTargetSkipRatio(float targetSkipRatio) {
+	this->targetSkipRatio = targetSkipRatio;
+}
+
+bool SoftSparkLimiter::shouldSkip()  {
+	if (targetSkipRatio == 0 || wasJustSkipped) {
+		wasJustSkipped = false;
+		return false;
+	}
+
+	float r = static_cast <float> (rand()) / static_cast <float> (RAND_MAX);
+	wasJustSkipped = r < 2 * targetSkipRatio;
+	return wasJustSkipped;
+}
+
 void initLaunchControl() {
 	engine->launchController.inject();
 }

firmware/controllers/algo/launch_control.h

@@ -35,3 +35,17 @@ private:
 
 	Timer m_launchTimer;
 };
+
+
+class SoftSparkLimiter {
+public:
+	/**
+	 * targetSkipRatio of '0' means 'do not skip', would always return false
+	 */
+	void setTargetSkipRatio(float targetSkipRatio);
+
+	bool shouldSkip();
+private:
+	bool wasJustSkipped = false;
+	float targetSkipRatio = 0;
+};

firmware/controllers/lua/lua_hooks.cpp

@@ -486,6 +486,12 @@ void configureRusefiLuaHooks(lua_State* l) {
 			return 1;
 	});
 
+	lua_register(l, "setSparkSkipRatio", [](lua_State* l) {
+		auto targetSkipRatio = luaL_checknumber(l, 1);
+		engine->softSparkLimiter.setTargetSkipRatio(targetSkipRatio);
+		return 1;
+	});
+
 #if !EFI_UNIT_TEST
 	lua_register(l, "startPwm", lua_startPwm);
 	lua_register(l, "setPwmDuty", lua_setPwmDuty);