From 232108c5226a8d8f1268ed9d9051e62fcdfa0cdd Mon Sep 17 00:00:00 2001
From: JakeBreath <tolozacdcmo@gmail.com>
Date: Sun, 9 Aug 2026 14:47:16 -0500
Subject: [PATCH] temporal backup

---
 src/cpu.rs  |  2 +-
 src/main.rs | 29 +++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/src/cpu.rs b/src/cpu.rs
index 68ede6b..e1a85c1 100644
--- a/src/cpu.rs
+++ b/src/cpu.rs
@@ -17,7 +17,7 @@ pub struct Cpu {
     sp: u8, // Stack Pointer
     pc: u16, // Program Counter
     p: u8, // Status Register
-    cycles: u64,
+    pub cycles: u64,
     irq_pending: bool,
     nmi_pending: bool,
 }
diff --git a/src/main.rs b/src/main.rs
index be4e454..bc14733 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -8,6 +8,35 @@ use crate::cartridge::Cartridge;
 use crate::cpu::Cpu;
 
 fn main() {
+    let args: Vec<String> = std::env::args().collect();
+
+    if args.len() > 1 {
+        run_blargg(&args[1]);
+    } else {
+        run_nestest();
+    }
+}
+
+fn run_blargg(path: &str) {
+    let cart = Cartridge::from_file(path).unwrap();
+    let mut bus = NesBus::new(cart);
+    let mut cpu = Cpu::new();
+    cpu.reset(&mut bus);                 // boots from $FFFC-$FFFD via MMC1 PRG banking
+
+    let cycle_cap: u64 = 5_000_000;      // blargg tests complete well under this; tune if needed
+    while cpu.cycles < cycle_cap {
+        cpu.step(&mut bus);
+    }
+
+    let r0 = bus.read(0x6000);
+    let r1 = bus.read(0x6001);
+    let r2 = bus.read(0x6002);
+    let r3 = bus.read(0x6003);
+    println!("result: $6000={:02X} $6001={:02X} $6002={:02X} $6003={:02X}", r0, r1, r2, r3);
+    if r0 == 0 { println!("PASS"); } else { println!("FAIL (error {:#04X})", r0); }
+}
+
+fn run_nestest() {
     let cart: Cartridge = Cartridge::from_file("roms/test/cpu/nestest/nestest.nes").unwrap();
     let mut bus: NesBus = NesBus::new(cart);
     let mut cpu = Cpu::new();