Add Interrupt module

Makefile

@@ -6,6 +6,7 @@ debug:
 
 check:
 	ocamlbuild -use-ocamlfind -I src -lflag -g test/test_bit.byte --
+	ocamlbuild -use-ocamlfind -I src -lflag -g test/test_interrupt.byte --
 
 clean:
 	rm -rf _build

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 []

test/test_bit.ml

@@ -1,7 +1,7 @@
 open OUnit2
 
 
-let test_signed test_ctx =
+let test_signed _ =
   let n = 0xFA in
   let s = Bit.signed_byte n in
   assert_equal s (-6)

test/test_interrupt.ml

@@ -0,0 +1,30 @@
+open OUnit2
+
+
+let test_interrupt _ =
+  let input_refs = [
+    ( 0b00000000, [] );
+    ( 0b00000001, [ Interrupt.V_Blank ] );
+    ( 0b00000010, [ Interrupt.LCD_Stat ] );
+    ( 0b00000100, [ Interrupt.Timer ] );
+    ( 0b00001000, [ Interrupt.Serial ] );
+    ( 0b00010000, [ Interrupt.Joypad ] );
+  ] in
+
+  let test =
+    function ( byte, ref_flags ) ->
+      let computed_flags = Interrupt.get_flags byte in
+      List.iter2 (fun f1 f2 -> assert_equal f1 f2) ref_flags computed_flags in
+
+  List.iter test input_refs
+
+
+(* Name the test cases and group them together *)
+let suite =
+"suite">:::
+ [
+   "test interrupt parsing">:: test_interrupt
+ ]
+
+let () =
+  run_test_tt_main suite