[bootloader] Added dual boot

bootloader/boot.cpp

@@ -0,0 +1,52 @@
+#include <bootloader/boot.h>
+#include <bootloader/slot.h>
+#include <ion.h>
+#include <bootloader/interface.h>
+
+#include <assert.h>
+
+namespace Bootloader {
+
+BootMode Boot::mode() {
+  // We use the exam mode driver as storage for the boot mode
+  uint8_t mode = Ion::ExamMode::FetchExamMode();
+
+  if (mode > 3)
+    return Unknown;
+  
+  return (BootMode) mode;
+}
+
+void Boot::setMode(BootMode mode) {
+  BootMode currentMode = Boot::mode();
+  if (currentMode == mode)
+    return;
+
+  assert(mode != BootMode::Unknown);
+  int8_t deltaMode = (int8_t)mode - (int8_t)currentMode;
+  deltaMode = deltaMode < 0 ? deltaMode + 4 : deltaMode;
+  assert(deltaMode > 0);
+  Ion::ExamMode::IncrementExamMode(deltaMode);
+}
+
+[[ noreturn ]] void Boot::boot() {
+  assert(mode() != BootMode::Unknown);
+
+  if (mode() == BootMode::SlotA)
+    Slot::A().boot();
+  else if (mode() == BootMode::SlotB)
+    Slot::B().boot();
+  
+  for(;;);
+}
+
+[[ noreturn ]] void Boot::bootloader() {
+  Bootloader::Interface::draw();
+  for(;;) {
+    Ion::USB::enable();
+    while (!Ion::USB::isEnumerated());
+    Ion::USB::DFU(false);
+  }
+}
+
+}