Merge pull request #23 from kamtoeddy/add_midi_control_change

Implement MIDI Control Change

bin/midi.ml

@@ -56,6 +56,13 @@ let bend_pitch ~bend ~timestamp ~channel =
   let data2 = char_of_int (bend lsr 7) in
   Event.create ~status ~data1 ~data2 ~timestamp
 
+let control_change ~cc ~value ~timestamp =
+  if cc > 119 then invalid_arg "Sorry, [cc] must be <= 119"
+  else
+    let data1 = char_of_int (cc land 0b1111111) in
+    let data2 = char_of_int (value land 0b1111111) in
+    Event.create ~status:'\176' ~data1 ~data2 ~timestamp
+
 (* Best function ever!! <3 *)
 let handle_error = function Ok _ -> () | Error _ -> ()
 

bin/midi.mli

@@ -16,6 +16,12 @@ val message_off :
   note:char -> timestamp:int32 -> volume:char -> channel:int -> unit -> Event.t
 
 val bend_pitch : bend:int -> timestamp:int32 -> channel:int -> Event.t
+
+val control_change : cc:int -> value:int -> timestamp:int32 -> Event.t
+(** This helps to send MIDI Control Change messages
+
+    @raise Invalid_argument if [cc] is greater than 119 *)
+
 val write_output : Device.t -> Portmidi.Portmidi_event.t list -> unit
 
 module Scale : sig