Functional interrupt (#1728)

* Initial

* Implementation

* Add to CMakelist.txt

* Add example

* Add IRAM_ATTR

cores/esp32/FunctionalInterrupt.cpp

@@ -0,0 +1,44 @@
+/*
+ * FunctionalInterrupt.cpp
+ *
+ *  Created on: 8 jul. 2018
+ *      Author: Herman
+ */
+
+#include "FunctionalInterrupt.h"
+#include "Arduino.h"
+
+typedef void (*voidFuncPtr)(void);
+typedef void (*voidFuncPtrArg)(void*);
+
+extern "C"
+{
+	extern void __attachInterruptFunctionalArg(uint8_t pin, voidFuncPtrArg userFunc, void * arg, int intr_type, bool functional);
+}
+
+void IRAM_ATTR interruptFunctional(void* arg)
+{
+    InterruptArgStructure* localArg = (InterruptArgStructure*)arg;
+	if (localArg->interruptFunction)
+	{
+	  localArg->interruptFunction();
+	}
+}
+
+void attachInterrupt(uint8_t pin, std::function<void(void)> intRoutine, int mode)
+{
+	// use the local interrupt routine which takes the ArgStructure as argument
+	__attachInterruptFunctionalArg (pin, (voidFuncPtrArg)interruptFunctional, new InterruptArgStructure{intRoutine}, mode, true);
+}
+
+extern "C"
+{
+   void cleanupFunctional(void* arg)
+   {
+	 delete (InterruptArgStructure*)arg;
+   }
+}
+
+
+
+