From c7b7a99cf9da9a351d9576787fb841091327edc8 Mon Sep 17 00:00:00 2001
From: Alex Janka <alex@alexjanka.com>
Date: Mon, 24 Apr 2023 11:35:38 +1000
Subject: [PATCH] cgb pcm registers

---
 lib/src/processor/memory.rs                   |  4 ++--
 lib/src/processor/memory/mmio/apu.rs          |  8 ++++++++
 lib/src/processor/memory/mmio/apu/channels.rs | 19 ++++++++++++++++---
 3 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/lib/src/processor/memory.rs b/lib/src/processor/memory.rs
index de7e5c6..ed04761 100644
--- a/lib/src/processor/memory.rs
+++ b/lib/src/processor/memory.rs
@@ -372,8 +372,8 @@ where
                         CgbIoAddress::Palette(address) => self.gpu.get_cgb_palette(address),
                         CgbIoAddress::ObjPriority => self.gpu.get_obj_priority(),
                         CgbIoAddress::WramBank => ((*selected) & 0b111) as u8,
-                        CgbIoAddress::Pcm12 => todo!(),
-                        CgbIoAddress::Pcm34 => todo!(),
+                        CgbIoAddress::Pcm12 => self.apu.get_pcm_1_2(),
+                        CgbIoAddress::Pcm34 => self.apu.get_pcm_3_4(),
                         CgbIoAddress::Unused(v) => {
                             println!("attempt to get 0x{v:0>4X}");
                             todo!()
diff --git a/lib/src/processor/memory/mmio/apu.rs b/lib/src/processor/memory/mmio/apu.rs
index c865716..b039a79 100644
--- a/lib/src/processor/memory/mmio/apu.rs
+++ b/lib/src/processor/memory/mmio/apu.rs
@@ -153,6 +153,14 @@ impl Apu {
         }
     }
 
+    pub(crate) fn get_pcm_1_2(&self) -> u8 {
+        (self.channels.one.last & 0xF) | ((self.channels.two.last & 0xF0) << 4)
+    }
+
+    pub(crate) fn get_pcm_3_4(&self) -> u8 {
+        (self.channels.one.last & 0xF) | ((self.channels.two.last & 0xF0) << 4)
+    }
+
     fn next_audio(&mut self) {
         self.out_buffer.append(
             &mut self.converter.process(
diff --git a/lib/src/processor/memory/mmio/apu/channels.rs b/lib/src/processor/memory/mmio/apu/channels.rs
index c4d7b6c..8e18045 100644
--- a/lib/src/processor/memory/mmio/apu/channels.rs
+++ b/lib/src/processor/memory/mmio/apu/channels.rs
@@ -127,6 +127,7 @@ impl DutyCycle {
 #[derive(Serialize, Deserialize, Clone, Copy)]
 pub(super) struct PwmChannel {
     pub(super) enabled: bool,
+    pub(super) last: u8,
     sweep: Sweep,
     duty_cycle: DutyCycle,
     length_enable: bool,
@@ -143,6 +144,7 @@ impl PwmChannel {
         let wavelength = 0x7FF;
         Self {
             enabled,
+            last: 0,
             sweep: Sweep::default(),
             duty_cycle: DutyCycle::Fifty,
             length_enable: false,
@@ -181,11 +183,13 @@ impl PwmChannel {
                 })
                 .collect()
         } else {
+            self.last = 0;
             vec![0.; steps]
         }
     }
 
-    fn dac(&self, digital: u8) -> f32 {
+    fn dac(&mut self, digital: u8) -> f32 {
+        self.last = digital;
         (((digital as f32) * (-2.)) + 1.) * ((self.envelope.current_volume as f32) / 15.)
     }
 
@@ -339,6 +343,7 @@ impl WaveRam {
 #[derive(Serialize, Deserialize, Clone, Copy)]
 pub(super) struct WaveChannel {
     pub(super) enabled: bool,
+    pub(super) last: u8,
     dac_enabled: bool,
     length_enable: bool,
     length_timer: u8,
@@ -354,6 +359,7 @@ impl WaveChannel {
         let wavelength = 0x7FF;
         Self {
             enabled,
+            last: 0,
             dac_enabled: false,
             length_enable: false,
             length_timer: 0,
@@ -390,14 +396,17 @@ impl WaveChannel {
                 })
                 .collect()
         } else {
+            self.last = 0;
             vec![0.; steps]
         }
     }
 
-    fn dac(&self, digital: u8) -> f32 {
+    fn dac(&mut self, digital: u8) -> f32 {
         if self.dac_enabled && self.volume != ShiftVolumePercent::Zero {
+            self.last = digital;
             ((((digital >> self.volume.as_shift_amount()) as f32) * (-2.)) + 1.) / 15.
         } else {
+            self.last = 0;
             0.
         }
     }
@@ -545,6 +554,7 @@ impl Default for Lfsr {
 #[derive(Serialize, Deserialize, Clone, Copy)]
 pub(super) struct NoiseChannel {
     pub(super) enabled: bool,
+    pub(super) last: u8,
     length_enable: bool,
     length_timer: u8,
     envelope: Envelope,
@@ -556,6 +566,7 @@ impl NoiseChannel {
     pub(super) fn new(enabled: bool) -> Self {
         Self {
             enabled,
+            last: 0,
             length_enable: false,
             length_timer: 0,
             envelope: Envelope::default(),
@@ -582,11 +593,13 @@ impl NoiseChannel {
                 })
                 .collect()
         } else {
+            self.last = 0;
             vec![0.; steps]
         }
     }
 
-    fn dac(&self, digital: u8) -> f32 {
+    fn dac(&mut self, digital: u8) -> f32 {
+        self.last = digital;
         (((digital as f32) * (-2.)) + 1.) * ((self.envelope.current_volume as f32) / 15.)
     }