SENT glue to LUA (#4700)

* use tabs

* SENT: Lua glue: getSentValue returns ETB position now

Can be tested with following LUA script:
setTickRate(100)
function onTick()
	pos = getSentValue(1)
	setLuaGauge(1, 10000 * pos)
	print(pos)
end

firmware/controllers/lua/lua_hooks.cpp

@@ -676,7 +676,7 @@ void configureRusefiLuaHooks(lua_State* l) {
 #if EFI_SENT_SUPPORT
 	lua_register(l, "getSentValue",
 			[](lua_State* l) {
-    		auto humanIndex = luaL_checkinteger(l, 1);
+			auto humanIndex = luaL_checkinteger(l, 1);
 			auto value = getSentValue(humanIndex - 1);
 			lua_pushnumber(l, value);
 			return 1;

firmware/hw_layer/drivers/sent/sent.cpp

@@ -605,9 +605,21 @@ static void printSentInfo()
 	}
 }
 
-float getSentValue(int index) {
-    // todo: just return ETB 0 to 100% for now?
-    return 23;
+/* Don't be confused: this actually returns throttle body position */
+float getSentValue(size_t index) {
+	if (index < SENT_CHANNELS_NUM) {
+		uint16_t sig0, sig1;
+		sent_channel &ch = channels[index];
+
+		if (ch.GetSignals(NULL, &sig0, &sig1) == 0) {
+			if (sig0 + sig1 == 0xfff) {
+				/* scale to 0.0 .. 1.0 */
+				return (float)sig1 / 0xfff;
+			}
+		}
+	}
+
+    return NAN;
 }
 
 /* Should be called once */

firmware/hw_layer/drivers/sent/sent.h

@@ -19,4 +19,4 @@ void SENT_ISR_Handler(uint8_t ch, uint16_t val_res);
 void startSent(void);
 void stopSent(void);
 
-float getSentValue(int index);
+float getSentValue(size_t index);