Block the emulator thread when idle

src/emulator.rs

@@ -3,7 +3,7 @@ use std::{
     path::{Path, PathBuf},
     sync::{
         atomic::{AtomicBool, Ordering},
-        mpsc::{self, TryRecvError},
+        mpsc::{self, RecvError, TryRecvError},
         Arc,
     },
 };
@@ -94,19 +94,33 @@ impl Emulator {
         let mut eye_contents = vec![0u8; 384 * 224 * 2];
         let mut audio_samples = vec![];
         loop {
+            let mut idle = true;
             if self.running.load(Ordering::Acquire) {
+                idle = false;
                 self.sim.emulate_frame();
             }
             if let Some(renderer) = &mut self.renderer {
                 if self.sim.read_pixels(&mut eye_contents) {
+                    idle = false;
                     renderer.render(&eye_contents);
                 }
             }
             self.sim.read_samples(&mut audio_samples);
             if !audio_samples.is_empty() {
+                idle = false;
                 self.audio.update(&audio_samples);
                 audio_samples.clear();
             }
+            if idle {
+                // The game is paused, and we have output all the video/audio we have.
+                // Block the thread until a new command comes in.
+                match self.commands.recv() {
+                    Ok(command) => self.handle_command(command),
+                    Err(RecvError) => {
+                        return;
+                    }
+                }
+            }
             loop {
                 match self.commands.try_recv() {
                     Ok(command) => self.handle_command(command),