Partial PPU implementation

.gitignore

@@ -4,3 +4,7 @@ AGENTS/
 AGENTS.md
 Cargo.lock
 renders/
+renders_saved/
+debug_out/*
+debug_out/pctrace.txt
+debug_out/state.txt

debug_out/pctrace.txt

@@ -1,180 +0,0 @@
-90D4 CYC:29781
-90DE CYC:59566
-90DE CYC:89351
-90DE CYC:119136
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-90DE CYC:506341
-90DE CYC:536126
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-90DE CYC:4914493
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-90DE CYC:5003848
-90D4 CYC:5033629
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src/main.rs

@@ -79,7 +79,7 @@ fn run_dbg(path: &str) {
     let mut cpu = Cpu::new();
     cpu.reset(&mut bus);
     let mut dumper = dump::Dumper::new();
-    let frames: u32 = 180;
+    let frames: u32 = 360;
 
     for f in 0..frames {
         while !bus.frame_done() {

src/ppu.rs

@@ -41,8 +41,10 @@ impl Ppu {
         // vblank flag + NMI
         if self.cycle == 0 && self.scanline == 241 {
             self.status |= 0x80;
+            if self.ctrl & 0x80 != 0 {
                 self.nmi_pending = true;
             }
+        }
         // clear vblank
         if self.cycle == 0 && self.scanline == 261 {
             self.status &= !0x80;