[ion] Ion::random()

Change-Id: Ib85055ab3b4bf3dfce991f9990659c744be20f39

ion/include/ion.h

@@ -33,6 +33,9 @@ void reset();
 // Only accepts whole 32bit values
 uint32_t crc32(const uint32_t * data, size_t length);
 
+// Provides a true random number
+uint32_t random();
+
 }
 
 #endif

ion/src/device/device.cpp

@@ -41,6 +41,22 @@ uint32_t Ion::crc32(const uint32_t * data, size_t length) {
   return result;
 }
 
+uint32_t Ion::random() {
+  bool initialRNGEngineState = RCC.AHB2ENR()->getRNGEN();
+  RCC.AHB2ENR()->setRNGEN(true);
+
+  RNG.CR()->setRNGEN(true);
+
+  while (RNG.SR()->getDRDY() == 0) {
+  }
+  uint32_t result = RNG.DR()->get();
+
+  RNG.CR()->setRNGEN(false);
+  RCC.AHB2ENR()->setRNGEN(initialRNGEngineState);
+
+  return result;
+}
+
 void Ion::reset() {
   CM4.AIRCR()->requestReset();
 }

ion/src/shared/random.cpp

@@ -0,0 +1,6 @@
+#include <ion.h>
+#include <stdlib.h>
+
+uint32_t Ion::random() {
+  return rand();
+}

ion/src/simulator/Makefile

@@ -12,6 +12,7 @@ objs += $(addprefix ion/src/shared/, \
   events_keyboard.o \
   log_printf.o \
   power.o \
+  random.o \
 )
 
 SFLAGS += `fltk-config --cflags`