oboy/src/interrupt.ml

(**
 * 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

(** Return the list of interrupt flags sorted by priority. *)
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
    | _ -> List.rev accu in

  get_flag byte 0 []