From 7b427164d8df562030edb6f6bd629365e1f14e89 Mon Sep 17 00:00:00 2001
From: Brooke Chalmers <breq@breq.dev>
Date: Fri, 26 Apr 2024 23:13:34 -0400
Subject: [PATCH] Blank screen on CA2 write

---
 src/memory/mos652x/pia.rs | 20 ++++++++++++++++++--
 src/systems/pet/mod.rs    | 21 +++++++++++++++++++--
 2 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/src/memory/mos652x/pia.rs b/src/memory/mos652x/pia.rs
index 0d8ffd8..baae66f 100644
--- a/src/memory/mos652x/pia.rs
+++ b/src/memory/mos652x/pia.rs
@@ -156,9 +156,25 @@ impl Memory for Pia {
   fn write(&mut self, address: u16, value: u8) {
     match address % 0x04 {
       0x00 => self.a.write(value),
-      0x01 => self.a.control = value,
+      0x01 => {
+        self.a.control = value;
+        if self.a.control & pia_control_bits::C2_DIRECTION != 0 {
+          self
+            .a
+            .port
+            .write_cx2(self.a.control & pia_control_bits::C2_OUTPUT_TYPE != 0);
+        }
+      }
       0x02 => self.b.write(value),
-      0x03 => self.b.control = value,
+      0x03 => {
+        self.b.control = value;
+        if self.b.control & pia_control_bits::C2_DIRECTION != 0 {
+          self
+            .b
+            .port
+            .write_cx2(self.b.control & pia_control_bits::C2_OUTPUT_TYPE != 0);
+        }
+      }
       _ => unreachable!(),
     }
   }
diff --git a/src/systems/pet/mod.rs b/src/systems/pet/mod.rs
index e66b171..915dd49 100644
--- a/src/systems/pet/mod.rs
+++ b/src/systems/pet/mod.rs
@@ -34,6 +34,7 @@ pub struct PetPia1PortA {
   keyboard_row: Rc<Cell<u8>>,
   last_draw_instant: Option<Instant>,
   last_draw_cycle: u64,
+  blank_screen: Rc<Cell<bool>>,
 }
 
 impl PetPia1PortA {
@@ -42,12 +43,17 @@ impl PetPia1PortA {
       keyboard_row: Rc::new(Cell::new(0)),
       last_draw_instant: None,
       last_draw_cycle: 0,
+      blank_screen: Rc::new(Cell::new(false)),
     }
   }
 
   pub fn get_keyboard_row(&self) -> Rc<Cell<u8>> {
     self.keyboard_row.clone()
   }
+
+  pub fn get_blank_screen(&self) -> Rc<Cell<bool>> {
+    self.blank_screen.clone()
+  }
 }
 
 impl Port for PetPia1PortA {
@@ -90,8 +96,11 @@ impl Port for PetPia1PortA {
     self.keyboard_row.set(0);
   }
 
-  fn write_cx2(&mut self, _value: bool) {
-    // TODO: on old PETs, this blanks the screen lol
+  fn write_cx2(&mut self, value: bool) {
+    // On old PETs, this blanks the screen
+    // ("Killer Poke")
+    println!("poke!");
+    self.blank_screen.set(!value);
   }
 }
 
@@ -179,6 +188,7 @@ impl BuildableSystem<PetSystemRoms, PetSystemConfig> for PetSystem {
     let editor_rom = BlockMemory::from_file(0x1000, roms.editor);
 
     let port_a = PetPia1PortA::new();
+    let blank_screen = port_a.get_blank_screen();
     let port_b = PetPia1PortB::new(port_a.get_keyboard_row(), config.mapping, platform);
     let pia1 = Pia::new(Box::new(port_a), Box::new(port_b), true);
     let pia2 = Pia::new(Box::new(NullPort::new()), Box::new(NullPort::new()), true);
@@ -204,6 +214,7 @@ impl BuildableSystem<PetSystemRoms, PetSystemConfig> for PetSystem {
     Box::new(PetSystem {
       cpu,
       characters: roms.character.get_data(),
+      blank_screen,
     })
   }
 }
@@ -212,6 +223,7 @@ impl BuildableSystem<PetSystemRoms, PetSystemConfig> for PetSystem {
 pub struct PetSystem {
   cpu: Mos6502,
   characters: Vec<u8>,
+  blank_screen: Rc<Cell<bool>>,
 }
 
 impl System for PetSystem {
@@ -228,6 +240,11 @@ impl System for PetSystem {
   }
 
   fn render(&mut self, framebuffer: &mut [u8], config: WindowConfig) {
+    if self.blank_screen.get() {
+      framebuffer.iter_mut().for_each(|x| *x = 0);
+      return;
+    }
+
     for y in 0..HEIGHT {
       for x in 0..WIDTH {
         let index = (y * WIDTH + x) as u16;