sdl2: Add silent mode

Former-commit-id: b8e3a8809501f32f819b74a1e4dd094d77a4b367
Former-commit-id: 027be1f05ae9f274e6a3527d209ac5ff696d8c56

platform/rustboyadvance-sdl2/src/audio.rs

@@ -11,6 +11,10 @@ struct GbaAudioCallback {
     spec: AudioSpec,
 }
 
+pub struct DummyAudioPlayer {}
+
+impl AudioInterface for DummyAudioPlayer {}
+
 pub struct Sdl2AudioPlayer {
     _device: AudioDevice<GbaAudioCallback>,
     producer: Producer<StereoSample<i16>>,
@@ -87,3 +91,8 @@ pub fn create_audio_player(sdl: &sdl2::Sdl) -> Sdl2AudioPlayer {
         producer: producer.unwrap(),
     }
 }
+
+pub fn create_dummy_player() -> DummyAudioPlayer {
+    info!("Dummy audio device");
+    DummyAudioPlayer {}
+}

platform/rustboyadvance-sdl2/src/cli.yml

@@ -34,6 +34,9 @@ args:
     - debug:
         long: debug
         help: Use the custom debugger
+    - silent:
+        long: silent
+        help: Do not output sound
     - with_gdbserver:
         long: with-gdbserver
         help: Start with experimental gdbserver

platform/rustboyadvance-sdl2/src/main.rs

@@ -36,7 +36,7 @@ mod audio;
 mod input;
 mod video;
 
-use audio::create_audio_player;
+use audio::{create_audio_player, create_dummy_player};
 use input::create_input;
 use video::{create_video_interface, SCREEN_HEIGHT, SCREEN_WIDTH};
 
@@ -131,6 +131,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let skip_bios = matches.occurrences_of("skip_bios") != 0;
 
     let debug = matches.occurrences_of("debug") != 0;
+    let silent = matches.occurrences_of("silent") != 0;
     let with_gdbserver = matches.occurrences_of("with_gdbserver") != 0;
 
     info!("Initializing SDL2 context");
@@ -183,7 +184,11 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     };
 
     let video = Rc::new(RefCell::new(create_video_interface(canvas)));
-    let audio = Rc::new(RefCell::new(create_audio_player(&sdl_context)));
+    let audio: Rc<RefCell<dyn AudioInterface>> = if silent {
+        Rc::new(RefCell::new(create_dummy_player()))
+    } else {
+        Rc::new(RefCell::new(create_audio_player(&sdl_context)))
+    };
     let input = Rc::new(RefCell::new(create_input()));
 
     let mut savestate_path = get_savestate_path(&Path::new(&rom_path));