backup

src/bus.rs

@@ -12,14 +12,18 @@ pub struct NesBus {
     cart: Cartridge,
     ppu: Ppu,
     openbus: u8, // last byte on the CPU data bus
-    controller: Controller,
+    controller: Controller,   // P1 ($4016)
+    controller2: Controller,  // P2 ($4017) - no controller plugged in for now
 }
 
 impl NesBus {
     pub fn new(cart: Cartridge) -> Self {
-        Self { ram: [0; 0x800],
-            cart, ppu: Ppu::new(), 
-            openbus: 0, controller: Controller::new(Box::new(MaskInput::new())), }
+        Self {
+            ram: [0; 0x800],
+            cart, ppu: Ppu::new(), openbus: 0,
+            controller: Controller::new(Box::new(MaskInput::new())),
+            controller2: Controller::new(Box::new(MaskInput::new())),  // reads 0 forever
+        }
     }
 
     pub fn tick_ppu(&mut self, cycles: u64) {
@@ -48,7 +52,8 @@ impl Bus for NesBus {
         let result = match address {
             0x0000..=0x1FFF => self.ram[(address & 0x07FF) as usize], // Zero-Page my beloved
             0x2000..=0x3FFF => self.ppu.read(&mut self.cart, address, self.openbus),
-            0x4016 | 0x4017 => self.controller.read(),
+            0x4016 => self.controller.read(),
+            0x4017 => self.controller2.read(),
             0x4000..=0x401F => self.openbus,  // APU regs: unmapped reads return bus contents
             0x4020..=0x5FFF => self.openbus,  // expansion: open bus
             0x6000..=0x7FFF => self.cart.read_prg_ram(address), // SRAM reads from the cartridge
@@ -63,7 +68,8 @@ impl Bus for NesBus {
             0x0000..=0x1FFF => self.ram[(address & 0x07FF) as usize] = value,
             0x2000..=0x3FFF => self.ppu.write(&mut self.cart, address, value),
             0x4014 => self.ppu.oam_dma(&self.ram, value),
-            0x4016 | 0x4017 => self.controller.write_strobe(value),
+            0x4016 => self.controller.write_strobe(value),
+            0x4017 => self.controller2.write_strobe(value),
             0x6000..=0x7FFF => self.cart.write_prg_ram(address, value),
             0x8000..=0xFFFF => self.cart.write_prg(address, value),
             _ => {} // Everything else dropped for now

src/main.rs

@@ -122,10 +122,11 @@ impl GuiApp {
 impl eframe::App for GuiApp {
     // Non-UI work: emulation runs here, before painting.
     fn logic(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
-        self.renderer.poll_input(self.bus.controller_mut());  // keyboard -> $4016/$4017
-        run_one_frame(&mut self.bus, &mut self.cpu);          // one emulated frame
+        self.renderer.poll_input(self.bus.controller_mut());
+        run_one_frame(&mut self.bus, &mut self.cpu);
         self.renderer.present(self.bus.framebuffer(), 256, 240);
-        ctx.request_repaint();                                // keep it running at 60fps
+        // cap at 60fps: one emulated frame per 16.67ms, not "as fast as possible"
+        ctx.request_repaint_after(std::time::Duration::from_millis(16));
     }
 
     // Painting: draw the framebuffer texture.

src/ppu.rs

@@ -1,6 +1,7 @@
 use crate::cartridge::Cartridge;
 use crate::mapper::Mirroring;
 
+
 // 4-byte OAM entry: Y, tile, attribute, X
 #[derive(Clone, Copy, Default)]
 struct Sprite {