Implement more instructions

src/cpu.rs

@@ -10,6 +10,16 @@ pub struct Cpu {
     state: State,
 }
 
+impl Cpu {
+    pub fn ime(&self) -> bool {
+        self.ime
+    }
+
+    pub fn set_ime(&mut self, enabled: bool) {
+        self.ime = enabled;
+    }
+}
+
 impl Cpu {
     fn fetch(&self) -> u8 {
         self.bus.read_byte(self.reg.pc)