fix(ppu): PPU cycle count increases even if LCDC bit 7 says otherwise

src/bus.rs

@@ -4,7 +4,7 @@ use crate::interrupt::{Interrupt, InterruptFlag};
 use crate::joypad::Joypad;
 use crate::ppu::{Ppu, PpuMode};
 use crate::serial::Serial;
-use crate::sound::{SampleSender, Sound};
+use crate::sound::{AudioSender, Sound};
 use crate::timer::Timer;
 use crate::work_ram::{VariableWorkRam, WorkRam};
 use std::{fs::File, io::Read};
@@ -66,7 +66,7 @@ impl Bus {
         self.cartridge.as_ref()?.title()
     }
 
-    pub(crate) fn pass_audio_src(&mut self, sender: SampleSender) {
+    pub(crate) fn pass_audio_src(&mut self, sender: AudioSender) {
         self.snd.set_audio_src(sender)
     }
 

src/cpu.rs

@@ -3,7 +3,7 @@ use crate::instruction::{Cycle, Instruction};
 use crate::interrupt::{InterruptEnable, InterruptFlag};
 use crate::joypad::Joypad;
 use crate::ppu::Ppu;
-use crate::sound::SampleSender;
+use crate::sound::AudioSender;
 use crate::timer::Timer;
 use bitfield::bitfield;
 use std::fmt::{Display, Formatter, Result as FmtResult};
@@ -45,7 +45,7 @@ impl Cpu {
         })
     }
 
-    pub fn set_audio_src(&mut self, sender: SampleSender) {
+    pub fn set_audio_src(&mut self, sender: AudioSender) {
         self.bus.pass_audio_src(sender)
     }
 
@@ -125,6 +125,8 @@ impl Cpu {
             }
         };
 
+        // FIXME: Regression, this is not a proper fix,
+        // the FIFO behaves weirdly using this code
         let pending: u32 = cycles.into();
         let mut offset = 0;
         for _ in 0..(pending + offset) {
@@ -361,6 +363,25 @@ impl Cpu {
 }
 
 impl Cpu {
+    fn _debug_log(&self, mut w: impl std::io::Write, instr: &Instruction) -> std::io::Result<()> {
+        write!(w, "A: {:02X} ", self.reg.a)?;
+        write!(w, "F: {:02X} ", u8::from(self.flags))?;
+        write!(w, "B: {:02X} ", self.reg.b)?;
+        write!(w, "C: {:02X} ", self.reg.c)?;
+        write!(w, "D: {:02X} ", self.reg.d)?;
+        write!(w, "E: {:02X} ", self.reg.e)?;
+        write!(w, "H: {:02X} ", self.reg.h)?;
+        write!(w, "L: {:02X} ", self.reg.l)?;
+        write!(w, "SP: {:04X} ", self.reg.sp)?;
+        write!(w, "PC: 00:{:04X} ", self.reg.pc)?;
+        write!(w, "({:02X} ", self.read_byte(self.reg.pc))?;
+        write!(w, "{:02X} ", self.read_byte(self.reg.pc + 1))?;
+        write!(w, "{:02X} ", self.read_byte(self.reg.pc + 2))?;
+        write!(w, "{:02X}) ", self.read_byte(self.reg.pc + 3))?;
+        writeln!(w, "| {:?}", instr)?;
+        w.flush()
+    }
+
     fn _log_state(&self, mut writer: impl std::io::Write) -> std::io::Result<()> {
         write!(writer, "A: {:02X} ", self.reg.a)?;
         write!(writer, "F: {:02X} ", u8::from(self.flags))?;
@@ -376,9 +397,7 @@ impl Cpu {
         write!(writer, "{:02X} ", self.read_byte(self.reg.pc + 1))?;
         write!(writer, "{:02X} ", self.read_byte(self.reg.pc + 2))?;
         writeln!(writer, "{:02X})", self.read_byte(self.reg.pc + 3))?;
-        writer.flush()?;
-
-        Ok(())
+        writer.flush()
     }
 }
 

src/lib.rs

@@ -1,6 +1,6 @@
 pub use gui::Egui;
 pub use instruction::Cycle;
-pub use sound::AudioSenderReceiver;
+pub use sound::AudioMPSC;
 
 pub const GB_WIDTH: usize = 160;
 pub const GB_HEIGHT: usize = 144;

src/main.rs

@@ -1,6 +1,6 @@
 use anyhow::{anyhow, Result};
 use clap::{crate_authors, crate_description, crate_name, crate_version, App, Arg};
-use gb::{AudioSenderReceiver, Cycle, Egui, GB_HEIGHT, GB_WIDTH};
+use gb::{AudioMPSC, Cycle, Egui, GB_HEIGHT, GB_WIDTH};
 use gilrs::Gilrs;
 use pixels::{Pixels, SurfaceTexture};
 use rodio::{OutputStream, Sink};
@@ -66,7 +66,7 @@ fn main() -> Result<()> {
         (pixels, egui)
     };
 
-    let (send, recv) = AudioSenderReceiver::new();
+    let (send, recv) = AudioMPSC::new();
     game_boy.set_audio_src(send);
 
     // Initialize Audio

src/ppu.rs

@@ -67,12 +67,12 @@ impl BusIo for Ppu {
 
 impl Ppu {
     pub(crate) fn clock(&mut self) {
+        self.cycle += 1;
+
         if !self.ctrl.lcd_enabled() {
             return;
         }
 
-        self.cycle += 1;
-
         match self.stat.mode() {
             PpuMode::OamScan => {
                 if self.cycle >= 80.into() {

src/sound.rs

@@ -27,7 +27,7 @@ pub(crate) struct Sound {
     frame_seq_state: FrameSequencerState,
     div_prev: Option<u8>,
 
-    sender: Option<SampleSender>,
+    sender: Option<AudioSender>,
     sample_counter: u64,
 
     is_mpsc_full: bool,
@@ -104,7 +104,7 @@ impl Sound {
         }
     }
 
-    pub(crate) fn set_audio_src(&mut self, sender: SampleSender) {
+    pub(crate) fn set_audio_src(&mut self, sender: AudioSender) {
         self.sender = Some(sender);
     }
 
@@ -1172,22 +1172,22 @@ impl From<ChannelControl> for u8 {
     }
 }
 
-pub struct AudioSenderReceiver;
+pub struct AudioMPSC;
 
-impl AudioSenderReceiver {
-    pub fn new() -> (SampleSender, SampleReceiver) {
+impl AudioMPSC {
+    pub fn new() -> (AudioSender, AudioReceiver) {
         let (send, recv) = crossbeam_channel::bounded(AUDIO_BUFFER_LEN * 2);
 
-        (SampleSender { inner: send }, SampleReceiver { inner: recv })
+        (AudioSender { inner: send }, AudioReceiver { inner: recv })
     }
 }
 
 #[derive(Debug, Clone)]
-pub struct SampleSender {
+pub struct AudioSender {
     inner: Sender<f32>,
 }
 
-impl SampleSender {
+impl AudioSender {
     fn send_samples(&self, left: f32, right: f32) -> Result<(), TrySendError<f32>> {
         self.inner.try_send(left).and(self.inner.try_send(right))?;
         Ok(())
@@ -1198,11 +1198,11 @@ impl SampleSender {
     }
 }
 
-pub struct SampleReceiver {
+pub struct AudioReceiver {
     inner: Receiver<f32>,
 }
 
-impl Iterator for SampleReceiver {
+impl Iterator for AudioReceiver {
     type Item = f32;
 
     fn next(&mut self) -> Option<Self::Item> {
@@ -1211,7 +1211,7 @@ impl Iterator for SampleReceiver {
     }
 }
 
-impl Source for SampleReceiver {
+impl Source for AudioReceiver {
     fn current_frame_len(&self) -> Option<usize> {
         // A frame changes when the samples rate or
         // number of channels change. This will never happen, so