From d4407cf8499d761ebf4575a43388f60db70dddb1 Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Tue, 3 Aug 2021 19:33:27 -0500
Subject: [PATCH] fix(apu): implement NR50 volume controls

---
 src/apu.rs       | 10 +++++++---
 src/apu/types.rs | 18 ++++++++++++++----
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/src/apu.rs b/src/apu.rs
index 3416b91..734a48f 100644
--- a/src/apu.rs
+++ b/src/apu.rs
@@ -154,8 +154,11 @@ impl Apu {
                     let ch4_left = self.ctrl.output.ch4_left() as u8 as f32 * ch4_amplitude;
                     let ch4_right = self.ctrl.output.ch4_right() as u8 as f32 * ch4_amplitude;
 
-                    let left = (ch1_left + ch2_left + ch3_left + ch4_left) / 4.0;
-                    let right = (ch1_right + ch2_right + ch3_right + ch4_right) / 4.0;
+                    let left_mixed = (ch1_left + ch2_left + ch3_left + ch4_left) / 4.0;
+                    let right_mixed = (ch1_right + ch2_right + ch3_right + ch4_right) / 4.0;
+
+                    let left = (self.ctrl.channel.left_volume() + 1.0) * left_mixed;
+                    let right = (self.ctrl.channel.right_volume() + 1.0) * right_mixed;
 
                     prod.push(left)
                         .and(prod.push(right))
@@ -742,7 +745,8 @@ impl Channel3 {
     }
 
     fn amplitude(&self) -> f32 {
-        let dac_input = self.read_sample(self.offset) >> self.volume.shift_count();
+        let dac_input =
+            (self.read_sample(self.offset) >> self.volume.shift_count()) * self.enabled as u8;
 
         (dac_input as f32 / 7.5) - 1.0
     }
diff --git a/src/apu/types.rs b/src/apu/types.rs
index 4b304a5..f8a69b9 100644
--- a/src/apu/types.rs
+++ b/src/apu/types.rs
@@ -503,10 +503,20 @@ impl From<SoundOutput> for u8 {
 bitfield! {
     pub struct ChannelControl(u8);
     impl Debug;
-    vin_so2, _: 7;
-    so2_level, _: 6, 4;
-    vin_so1, _: 3;
-    so1_level, _: 2, 0;
+    vin_left, _: 7;
+    _left_volume, _: 6, 4;
+    vin_right, _: 3;
+    _right_volume, _: 2, 0;
+}
+
+impl ChannelControl {
+    pub(crate) fn left_volume(&self) -> f32 {
+        self._left_volume() as f32
+    }
+
+    pub(crate) fn right_volume(&self) -> f32 {
+        self._right_volume() as f32
+    }
 }
 
 impl Copy for ChannelControl {}