feat: stub 0xff0f and 0xffff from interrupt

src/interrupt.rs

@@ -0,0 +1,74 @@
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Interrupt {
+    pub flag: InterruptFlag,
+    pub enable: InterruptEnable,
+}
+
+#[derive(Debug, Clone, Copy, Default)]
+pub struct InterruptEnable {
+    vblank: bool,
+    lcd_stat: bool,
+    timer: bool,
+    serial: bool,
+    joypad: bool,
+}
+impl From<u8> for InterruptEnable {
+    fn from(byte: u8) -> Self {
+        Self {
+            vblank: (byte >> 0 & 0x01) == 0x01,
+            lcd_stat: (byte >> 1 & 0x01) == 0x01,
+            timer: (byte >> 2 & 0x01) == 0x01,
+            serial: (byte >> 3 & 0x01) == 0x01,
+            joypad: (byte >> 4 & 0x01) == 0x01,
+        }
+    }
+}
+
+impl From<InterruptEnable> for u8 {
+    fn from(flag: InterruptEnable) -> Self {
+        (flag.joypad as u8) << 4
+            | (flag.serial as u8) << 3
+            | (flag.timer as u8) << 2
+            | (flag.lcd_stat as u8) << 1
+            | (flag.vblank as u8) << 0
+    }
+}
+
+#[derive(Debug, Clone, Copy, Default)]
+pub struct InterruptFlag {
+    vblank: bool,
+    lcd_stat: bool,
+    timer: bool,
+    serial: bool,
+    joypad: bool,
+}
+
+impl From<u8> for InterruptFlag {
+    fn from(byte: u8) -> Self {
+        Self {
+            vblank: (byte >> 0 & 0x01) == 0x01,
+            lcd_stat: (byte >> 1 & 0x01) == 0x01,
+            timer: (byte >> 2 & 0x01) == 0x01,
+            serial: (byte >> 3 & 0x01) == 0x01,
+            joypad: (byte >> 4 & 0x01) == 0x01,
+        }
+    }
+}
+
+impl From<InterruptFlag> for u8 {
+    fn from(flag: InterruptFlag) -> Self {
+        (flag.joypad as u8) << 4
+            | (flag.serial as u8) << 3
+            | (flag.timer as u8) << 2
+            | (flag.lcd_stat as u8) << 1
+            | (flag.vblank as u8) << 0
+    }
+}
+
+enum InterruptType {
+    VBlank,
+    LCDStat,
+    Timer,
+    Serial,
+    Joypad,
+}