Use PendSV for EventResponder attachInterrupt

teensy3/EventResponder.cpp

 			_prev->_next = this;
 			lastYield = this;
 		}
+		_pending = true;
 	} else if (_type == EventTypeInterrupt) {
 		// interrupt, called from software interrupt
 		if (firstInterrupt == nullptr) {
 			_prev->_next = this;
 			lastInterrupt = this;
 		}
-		// TODO set interrupt pending
+		_pending = true;
+		SCB_ICSR = SCB_ICSR_PENDSVSET; // set PendSV interrupt
 	} else {
 		// detached, easy :-)
+		_pending = true;
 	}
-	_pending = true;
 }
 
 void pendablesrvreq_isr(void)
 
 void EventResponder::runFromInterrupt()
 {
-	// FIXME: this will fail if the handler function triggers
-	// its own or other EventResponder instances.  The list will
-	// change while we're holding a pointers to it.
-	for (EventResponder *first=firstInterrupt; first; first = first->_next) {
-		first->_pending = false;
-		(*(first->_function))(*first);
+	while (1) {
+		EventResponder *first = firstInterrupt;
+		if (first) {
+			firstInterrupt = first->_next;
+			if (firstInterrupt) {
+				firstInterrupt->_prev = nullptr;
+			} else {
+				lastInterrupt = nullptr;
+			}
+			first->_pending = false;
+			(*(first->_function))(*first);
+		} else {
+			break;
+		}
 	}
-	firstInterrupt = nullptr;
-	lastInterrupt = nullptr;
 }
 
 bool EventResponder::clearEvent()

teensy3/EventResponder.h

 		detach();
 		_function = function;
 		_type = EventTypeInterrupt;
-		// TODO: configure PendSV
+		SCB_SHPR3 |= 0x00FF0000; // configure PendSV, lowest priority
 	}
 
 	// Attach a function to be called as its own thread.  Boards not running
 
 	static void runFromYield() {
 		EventResponder *first = firstYield;
+		// FIXME: also check if yield() called from an interrupt
+		// never run these functions from any interrupt context
 		if (first && !runningFromYield) {
 			runningFromYield = true;
 			firstYield = first->_next;

teensy3/kinetis.h

 // System Control Space (SCS), ARMv7 ref manual, B3.2, page 708
 #define SCB_CPUID		(*(const    uint32_t *)0xE000ED00) // CPUID Base Register
 #define SCB_ICSR		(*(volatile uint32_t *)0xE000ED04) // Interrupt Control and State
+#define SCB_ICSR_NMIPENDSET		((uint32_t)0x80000000)
+#define SCB_ICSR_PENDSVSET		((uint32_t)0x10000000)
+#define SCB_ICSR_PENDSVCLR		((uint32_t)0x08000000)
 #define SCB_ICSR_PENDSTSET		((uint32_t)0x04000000)
+#define SCB_ICSR_PENDSTCLR		((uint32_t)0x02000000)
+#define SCB_ICSR_ISRPREEMPT		((uint32_t)0x00800000)
+#define SCB_ICSR_ISRPENDING		((uint32_t)0x00400000)
+#define SCB_ICSR_RETTOBASE		((uint32_t)0x00000800)
 #define SCB_VTOR		(*(volatile uint32_t *)0xE000ED08) // Vector Table Offset
 #define SCB_AIRCR		(*(volatile uint32_t *)0xE000ED0C) // Application Interrupt and Reset Control
 #define SCB_SCR			(*(volatile uint32_t *)0xE000ED10) // System Control Register