Fix bugs on Arduino Due version

SPI.cpp

@@ -337,6 +337,17 @@ void SPIClass::init() {
 	initialized = true;
 }
 
+#ifndef interruptsStatus
+#define interruptsStatus() __interruptsStatus()
+static inline unsigned char __interruptsStatus(void) __attribute__((always_inline, unused));
+static inline unsigned char __interruptsStatus(void) {
+  unsigned int primask;
+  asm volatile ("mrs %0, primask" : "=r" (primask));
+  if (primask) return 0;
+  return 1;
+}
+#endif
+
 void SPIClass::usingInterrupt(uint8_t interruptNumber)
 {
 	uint8_t irestore;

SPI.h

@@ -863,7 +863,7 @@ private:
 			}
 			*/
 		} else {
-			for (div=2; i<255; i++) {
+			for (div=2; div<255; div++) {
 				if (clock >= F_CPU / div) break;
 			}
 		}