have udev only log PIUIO LightState upon change

Previously, the PIUIO_Leds code logged every LightState of every PIUIO_Led light with every call of Set()

This commit adds checks to see if each of the PIUIO_Leds have changed LightState since the last Set() and skips logging the current LightState if there is no change.  Each set of lights was already being looped through; the new code here just issues a continue to skip logging where possible.

This helps reduce CPU usage when PIUIO_Leds are in use as the LightsDriver.

src/arch/Lights/LightsDriver_Linux_PIUIO_Leds.cpp

@@ -85,6 +85,13 @@ void LightsDriver_Linux_PIUIO_Leds::Set( const LightsState *ls )
 {
 	FOREACH_CabinetLight(light)
 	{
+		// Only SetLight if LightsState has changed since previous iteration.
+		// This reduces unncessary strain on udev.  -dguzek
+		if (ls->m_bCabinetLights[light] == previousLS.m_bCabinetLights[light] )
+		{
+			continue;
+		}
+
 		if (!SetLight(cabinet_leds[light], ls->m_bCabinetLights[light]))
 		{
 			LOG->Warn("Error setting cabinet light %s",
@@ -101,6 +108,11 @@ void LightsDriver_Linux_PIUIO_Leds::Set( const LightsState *ls )
 		{
 			FOREACH_GameButton_Custom(gb)
 			{
+				if (ls->m_bGameButtonLights[c][gb] == previousLS.m_bGameButtonLights[c][gb])
+				{
+					continue;
+				}
+
 				if (!SetLight(dance_leds[c][gb], ls->m_bGameButtonLights[c][gb]))
 				{
 					LOG->Warn("Error setting button light %s",
@@ -116,6 +128,11 @@ void LightsDriver_Linux_PIUIO_Leds::Set( const LightsState *ls )
 		{
 			FOREACH_GameButton_Custom(gb)
 			{
+				if (ls->m_bGameButtonLights[c][gb] == previousLS.m_bGameButtonLights[c][gb])
+				{
+					continue;
+				}
+
 				if (!SetLight(pump_leds[c][gb], ls->m_bGameButtonLights[c][gb]))
 				{
 					LOG->Warn("Error setting button light %s",
@@ -129,6 +146,8 @@ void LightsDriver_Linux_PIUIO_Leds::Set( const LightsState *ls )
 	{
 		return;
 	}
+
+	previousLS = *ls;
 }
 
 /*

src/arch/Lights/LightsDriver_Linux_PIUIO_Leds.h

@@ -7,6 +7,9 @@
 
 class LightsDriver_Linux_PIUIO_Leds : public LightsDriver
 {
+private:
+	LightsState previousLS;
+
 public:
 	LightsDriver_Linux_PIUIO_Leds();
 	virtual ~LightsDriver_Linux_PIUIO_Leds();