[aud] Add audio

src/sdl_audio_adapter.rs

@@ -0,0 +1,46 @@
+use std::sync::{Arc, Mutex, RwLock};
+use log::warn;
+use sdl2::audio::AudioCallback;
+
+pub struct SquareWave {
+    sound_timer: Arc<Mutex<u8>>,
+    phase_inc: f32,
+    phase: f32,
+    volume: f32,
+}
+
+impl SquareWave {
+    pub fn new(sound_timer: Arc<Mutex<u8>>,
+               phase_inc: f32,
+               volume: f32)->SquareWave {
+        SquareWave {
+            sound_timer,
+            phase: 0f32,
+            phase_inc,
+            volume,
+        }
+    }
+}
+
+impl AudioCallback for SquareWave {
+    type Channel = f32;
+
+    fn callback(&mut self, out: &mut [f32]) {
+        let sound_timer = self.sound_timer.lock().expect("Could not lock to play audio");
+        let sound_timer = sound_timer.clone();
+        // log::info!("Processing audio buffer length {}",out.len());
+        // Generate a square wave
+        for x in out.iter_mut() {
+            *x = if sound_timer > 0 {
+                if self.phase <= 0.5 {
+                    self.volume
+                } else {
+                    -self.volume
+                }
+            } else {
+                0f32
+            };
+            self.phase = (self.phase + self.phase_inc) % 1.0;
+        }
+    }
+}