Probably too much in 1 commit

agb/src/lib.rs

@@ -51,7 +51,7 @@ static mut GBASINGLE: single::Singleton<Gba> = single::Singleton::new(unsafe { G
 pub struct Gba {
     pub display: display::Display,
     pub sound: sound::dmg::Sound,
-    pub mixer: sound::mixer::Mixer,
+    pub mixer: sound::mixer::MixerController,
 }
 
 impl Gba {
@@ -63,7 +63,7 @@ impl Gba {
         Self {
             display: display::Display::new(),
             sound: sound::dmg::Sound::new(),
-            mixer: sound::mixer::Mixer::new(),
+            mixer: sound::mixer::MixerController::new(),
         }
     }
 }

agb/src/sound/mixer.rs

@@ -1,14 +1,28 @@
 use crate::memory_mapped::MemoryMapped;
 
 #[non_exhaustive]
+pub struct MixerController {}
+
+impl MixerController {
+    pub(crate) const fn new() -> Self {
+        MixerController {}
+    }
+
+    pub fn mixer(&mut self) -> Mixer {
+        Mixer::new()
+    }
+}
+
 pub struct Mixer {
     buffer: MixerBuffer,
+    channels: [Option<SoundChannel>; 16],
 }
 
 impl Mixer {
-    pub(crate) const unsafe fn new() -> Self {
+    fn new() -> Self {
         Mixer {
             buffer: MixerBuffer::new(),
+            channels: Default::default(),
         }
     }
 
@@ -22,6 +36,17 @@ impl Mixer {
     }
 }
 
+struct SoundChannel {
+    data: &'static [u8],
+    pos: usize,
+}
+
+impl SoundChannel {
+    fn new(data: &'static [u8]) -> Self {
+        SoundChannel { data, pos: 0 }
+    }
+}
+
 // I've picked one frequency that works nicely. But there are others that work nicely
 // which we may want to consider in the future: https://web.archive.org/web/20070608011909/http://deku.gbadev.org/program/sound1.html
 const SOUND_FREQUENCY: i32 = 10512;
@@ -37,8 +62,8 @@ struct MixerBuffer {
 impl MixerBuffer {
     fn new() -> Self {
         MixerBuffer {
-            buffer1: Default::default(),
-            buffer2: Default::default(),
+            buffer1: [0; SOUND_BUFFER_SIZE],
+            buffer2: [0; SOUND_BUFFER_SIZE],
 
             buffer_1_active: true,
         }