some optimisation

gb-emu/src/main.rs

@@ -224,7 +224,7 @@ impl EmulatorHandler {
     }
 
     fn cycle(&mut self) {
-        if self.since.elapsed() >= Duration::from_millis(10) {
+        if self.since.elapsed() >= UPDATE_INTERVAL {
             self.window_manager.update_events();
             self.since = Instant::now();
         }
@@ -234,3 +234,5 @@ impl EmulatorHandler {
         }
     }
 }
+
+const UPDATE_INTERVAL: Duration = Duration::from_millis(1);

lib/src/processor/memory/mmio/apu.rs

@@ -16,14 +16,14 @@ mod types;
 
 impl DacSample {
     fn mixed(&self, mixer: &Mixer) -> [f32; 2] {
-        let left = (self.one * mixer.ch1.left.scale())
+        let left = mixer.ch1.left.gate(self.one)
-            + (self.two * mixer.ch2.left.scale())
+            + mixer.ch2.left.gate(self.two)
-            + (self.three * mixer.ch3.left.scale())
+            + mixer.ch3.left.gate(self.three)
-            + (self.four * mixer.ch4.left.scale());
+            + mixer.ch4.left.gate(self.four);
-        let right = (self.one * mixer.ch1.right.scale())
+        let right = mixer.ch1.right.gate(self.one)
-            + (self.two * mixer.ch2.right.scale())
+            + mixer.ch2.right.gate(self.two)
-            + (self.three * mixer.ch3.right.scale())
+            + mixer.ch3.right.gate(self.three)
-            + (self.four * mixer.ch4.right.scale());
+            + mixer.ch4.right.gate(self.four);
         [
             self.mix_channel(left, mixer.vol_left),
             self.mix_channel(right, mixer.vol_right),

lib/src/processor/memory/mmio/apu/types.rs

@@ -34,10 +34,10 @@ pub(super) enum Volume {
 }
 
 impl Volume {
-    pub(super) fn scale(&self) -> f32 {
+    pub(super) fn gate(&self, val: f32) -> f32 {
         match self {
             Volume::Muted => 0.,
-            Volume::Enabled => 1.,
+            Volume::Enabled => val,
         }
     }