Add Interrupt module

src/interrupt.ml

@@ -0,0 +1,39 @@
+(**
+ * Copyright (c) 2016, Fabien Freling
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD 2-clause license found in the
+ * LICENSE file at the top level directory of this source tree.
+ *)
+
+(* let IME = ref false;; *)
+
+type t =
+  |  V_Blank
+  |  LCD_Stat
+  |  Timer
+  |  Serial
+  |  Joypad
+
+let get_flags byte =
+
+  let nth_interrupt i =
+    match i with
+    | 0 -> V_Blank
+    | 1 -> LCD_Stat
+    | 2 -> Timer
+    | 3 -> Serial
+    | 4 -> Joypad
+    | _ -> failwith "Invalid interrupt index." in
+
+  let rec get_flag byte i accu =
+    match i with
+    | 0 | 1 | 2 | 3 | 4 ->
+      if Bit.is_set byte i then
+        let interrupt = nth_interrupt i in
+        get_flag byte (i + 1) (interrupt :: accu)
+      else
+        get_flag byte (i + 1) accu
+    | _ -> accu in
+
+  get_flag byte 0 []