apu

src/apu/mod.rs

@@ -81,7 +81,7 @@ impl Apu {
         }
     }
 
-    pub fn step(&mut self) -> Option<f32> {
+    pub fn clock(&mut self) -> Option<f32> {
         let mut sample = None;
 
         if (self.frame_counter == 4 && FRAME_COUNTER_STEPS[..4].contains(&self.cycle))

src/audio.rs

@@ -3,7 +3,7 @@ extern crate sdl2;
 use sdl2::audio::{AudioCallback, AudioSpecDesired};
 
 pub struct Speaker {
-    buffer: Vec<f32>,
+    buffer: [f32; 4096*4],
     head: usize,
 }
 
@@ -13,7 +13,14 @@ impl AudioCallback for Speaker {
         for (i, x) in out.iter_mut().enumerate() {
             *x = self.buffer[i+self.head]; // get data from apu
         }
-        self.buffer = self.buffer[4096..].to_vec();
+        self.head = (self.head + 4096) % (4096*4)
+    }
+}
+
+impl Speaker {
+    pub fn append(&mut self, sample: f32) {
+        self.buffer[self.head] = sample;
+        self.head = (self.head + 1) % (4096*4);
     }
 }
 
@@ -31,6 +38,6 @@ pub fn initialize(context: &sdl2::Sdl) -> Result<sdl2::audio::AudioDevice<Speake
         println!("{:?}", spec);
 
         // initialize the audio callback
-        Speaker{buffer: vec![], head: 0}
+        Speaker{buffer: [0_f32; 4096*4], head: 0}
     })
 }

src/main.rs

@@ -35,8 +35,9 @@ fn main() -> Result<(), String> {
     let mut screen_buffer = vec![0; byte_width * byte_height]; // contains raw RGB data for the screen
 
     // Set up audio
-    let mut speaker = audio::initialize(&sdl_context).expect("Could not create audio device");
+    let mut audio_device = audio::initialize(&sdl_context).expect("Could not create audio device");
     let mut half_cycle = false;
+    audio_device.resume();
 
     // Initialize hardware components
     let cart = Cartridge::new();
@@ -64,7 +65,10 @@ fn main() -> Result<(), String> {
             }
         }
         for _ in 0..apu_cycles {
-            cpu.apu.step();
+            match cpu.apu.clock() {
+                Some(sample) => audio_device.speaker.append(sample),
+                None => (),
+            }
         }
         // clock PPU three times for every CPU cycle
         for _ in 0..cpu_cycles * 3 {