chore(apu): rename sound/snd to apu

src/apu/gen.rs

@@ -0,0 +1,92 @@
+use super::{AUDIO_BUFFER_LEN, CHANNEL_COUNT, SAMPLE_RATE};
+use crossbeam_channel::{Receiver, Sender, TrySendError};
+use rodio::Source;
+use std::collections::VecDeque;
+
+pub struct AudioMPSC;
+
+impl AudioMPSC {
+    pub fn new() -> (AudioSender<f32>, AudioReceiver<f32>) {
+        // TODO: Can we provide an upper limit for this?
+        // The larger this channel is, the more lag there is between the Audio and
+        // Emulator
+        let (send, recv) = crossbeam_channel::unbounded();
+
+        (AudioSender { inner: send }, AudioReceiver { inner: recv })
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct AudioSender<T> {
+    inner: Sender<T>,
+}
+
+impl<T> AudioSender<T> {
+    pub(crate) fn send_samples(&self, left: T, right: T) -> Result<(), TrySendError<T>> {
+        self.inner.try_send(left).and(self.inner.try_send(right))?;
+        Ok(())
+    }
+}
+
+pub struct AudioReceiver<T> {
+    inner: Receiver<T>,
+}
+
+impl<T> Iterator for AudioReceiver<T> {
+    type Item = T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        // TODO: Should this never return none?
+        self.inner.recv().ok()
+    }
+}
+
+impl<T: rodio::Sample> Source for AudioReceiver<T> {
+    fn current_frame_len(&self) -> Option<usize> {
+        // A frame changes when the samples rate or
+        // number of channels change. This will never happen, so
+        // we return
+        None
+    }
+
+    fn channels(&self) -> u16 {
+        // The Gameboy supports two channels
+        CHANNEL_COUNT as u16
+    }
+
+    fn sample_rate(&self) -> u32 {
+        SAMPLE_RATE
+    }
+
+    fn total_duration(&self) -> Option<std::time::Duration> {
+        // The duration of this source is infinite
+        None
+    }
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct AudioBuffer<T> {
+    inner: VecDeque<T>,
+}
+
+impl<T> Default for AudioBuffer<T> {
+    fn default() -> Self {
+        Self {
+            inner: VecDeque::with_capacity(AUDIO_BUFFER_LEN * CHANNEL_COUNT),
+        }
+    }
+}
+
+impl<T> AudioBuffer<T> {
+    pub(crate) fn push_back(&mut self, value: T) {
+        self.inner.push_back(value)
+    }
+
+    pub(crate) fn pop_front(&mut self) -> Option<T> {
+        self.inner.pop_front()
+    }
+
+    pub(crate) fn len(&self) -> usize {
+        self.inner.len()
+    }
+}