From 1b5336309514d0124eb484e3bfd3b5de358d4d28 Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Sun, 3 Jan 2021 01:38:31 -0600
Subject: [PATCH] feat: stub 0xff0f and 0xffff from interrupt

---
 src/bus.rs       | 10 +++++--
 src/interrupt.rs | 74 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/lib.rs       |  1 +
 3 files changed, 83 insertions(+), 2 deletions(-)
 create mode 100644 src/interrupt.rs

diff --git a/src/bus.rs b/src/bus.rs
index ffba980..6d58d21 100644
--- a/src/bus.rs
+++ b/src/bus.rs
@@ -1,7 +1,9 @@
 use super::cartridge::Cartridge;
+use super::interrupt::Interrupt;
 use super::ppu::PPU;
 use super::timer::Timer;
 use super::work_ram::{VariableWorkRAM, WorkRAM};
+
 #[derive(Debug, Clone)]
 pub struct Bus {
     boot: Option<[u8; 256]>, // Boot ROM is 256b long
@@ -10,6 +12,7 @@ pub struct Bus {
     wram: WorkRAM,
     vwram: VariableWorkRAM,
     timer: Timer,
+    interrupt: Interrupt,
 }
 
 impl Default for Bus {
@@ -21,6 +24,7 @@ impl Default for Bus {
             wram: Default::default(),
             vwram: Default::default(),
             timer: Default::default(),
+            interrupt: Default::default(),
         }
     }
 }
@@ -91,6 +95,7 @@ impl Bus {
                 // IO Registers
                 match addr {
                     0xFF07 => self.timer.control.into(),
+                    0xFF0F => self.interrupt.flag.into(),
                     _ => unimplemented!("Unable to read {:#06X} in I/O Registers", addr),
                 }
             }
@@ -100,7 +105,7 @@ impl Bus {
             }
             0xFFFF => {
                 // Interupts Enable Register
-                unimplemented!("Unable to read IE Register {:#06X} ", addr);
+                self.interrupt.enable.into()
             }
         }
     }
@@ -147,6 +152,7 @@ impl Bus {
                 // IO Registers
                 match addr {
                     0xFF07 => self.timer.control = byte.into(),
+                    0xFF0F => self.interrupt.flag = byte.into(),
                     _ => unimplemented!("Unable to write to {:#06X} in I/O Registers", addr),
                 };
             }
@@ -156,7 +162,7 @@ impl Bus {
             }
             0xFFFF => {
                 // Interupts Enable Register
-                unimplemented!("Unable to write to IE Register {:#06X} ", addr);
+                self.interrupt.enable = byte.into();
             }
         }
     }
diff --git a/src/interrupt.rs b/src/interrupt.rs
new file mode 100644
index 0000000..4e97bcc
--- /dev/null
+++ b/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,
+}
diff --git a/src/lib.rs b/src/lib.rs
index 266f13d..e9d0efb 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -2,6 +2,7 @@ mod bus;
 mod cartridge;
 pub mod cpu;
 mod instruction;
+mod interrupt;
 mod ppu;
 mod timer;
 mod work_ram;