feat: implement fetch, decode, execute loop

src/bus.rs

@@ -1,20 +1,34 @@
-#[derive(Debug, Copy, Clone)]
+const ROM: &[u8; 256] = include_bytes!("../bin/DMG_ROM.bin");
+
+#[derive(Debug, Copy, Clone, Default)]
 pub struct Bus {}
 
 impl Bus {
     pub fn read_byte(&self, addr: u16) -> u8 {
-        unimplemented!()
+        match addr {
+            0x0000..=0x00FF => {
+                // Restart and Interrupt Vectors
+                ROM[addr as usize]
+            }
+            _ => unimplemented!(),
+        }
     }
 
-    pub fn write_byte(&mut self, addr: u16, byte: u8) {
+    pub fn write_byte(&mut self, _addr: u16, _byte: u8) {
         unimplemented!()
     }
 
     pub fn read_word(&self, addr: u16) -> u16 {
-        unimplemented!()
+        match addr {
+            0x0000..=0x00FF => {
+                // Restart and Interrupt Vectors
+                (ROM[(addr + 1) as usize] as u16) << 8 | ROM[addr as usize] as u16
+            }
+            _ => unimplemented!(),
+        }
     }
 
-    pub fn write_word(&mut self, addr: u16, word: u16) {
+    pub fn write_word(&mut self, _addr: u16, _word: u16) {
         unimplemented!()
     }
 }