start from cli

README.md

@@ -2,7 +2,17 @@
 
 Just another implementation of a NES emulator written in Rust.
 
-**A note of warning:** This is an exploratory coding project with the aim to understand concepts of assembler and emulation in general. If you are looking for a cycle-accurate ready-to-use NES emulator to play some games, this is the wrong one. 
+**A note of warning:** This is an exploratory coding project with the aim to understand concepts of assembler and emulation in general. If you are looking for a cycle-accurate ready-to-use NES emulator to play some games, this is the wrong one.
+
+Usage:
+``` bash
+./jane super_mario.nes
+
+# With optional start address for the CPU (mainly for debugging)
+./jane nestest.nes C000
+```
+
+Make sure to compile with `--release` for 60 fps.
 
 ## what works
 * CPU

src/main.rs

@@ -10,6 +10,7 @@ extern crate fps_counter;
 
 mod nes;
 
+use std::env;
 use crate::nes::*;
 use std::path::Path;
 use piston_window::*;
@@ -35,14 +36,23 @@ lazy_static! {
 }
 
 fn main() -> Result<(), Error> {
-    simple_logger::init_with_level(Level::Warn).unwrap();
-  
+    simple_logger::init_with_level(Level::Info).unwrap();
+    let args: Vec<String> = env::args().collect();
+    if args.len() < 2 {
+        bail!("No cartridge supplied. Usage: ./jane cartridge.nes");
+    } else {
+        println!("Loading cartridge: {}", args[1]);
+    }
+
     let mut nes = NES::new();
-    let cartridge = Path::new("test_roms/nestest.nes");
-    let cartridge = Cartridge::new(cartridge)?;
+    let cartridge = Cartridge::new(Path::new(&args[1]))?;
     nes.insert_cartridge(cartridge);
     nes.start();
-    // nes.cpu.regs.pc = 0xC000;
+    if args.len() > 2 {
+        let pc = Addr::from_str_radix(&args[2], 16)?;
+        println!("Setting PC to {:#06x}", pc);
+        nes.cpu.regs.pc = pc;
+    }
 
     // disassemble instructions
     let disasm = Disasm::disassemble(&nes.memory, 0xC000, 0xFFFF).unwrap();

src/nes.rs

@@ -85,6 +85,7 @@ impl NES {
             self.clock();
         }
         self.ppu.borrow_mut().frame_ready = false;
+        info!("clock {}", self.clock_count);
     }
 }
 

src/nes/cpu.rs

@@ -86,7 +86,7 @@ impl CPU {
             self.curr_op = opcode;
             let instruction = Instruction::decode_op(opcode);
             
-            info!("{:#06X}  {:02X} {}          A:{:02X} X:{:02X} Y:{:02X} P:{:02X} SP:{:02X} CYC:{}",
+            debug!("{:#06X}  {:02X} {}          A:{:02X} X:{:02X} Y:{:02X} P:{:02X} SP:{:02X} CYC:{}",
                 self.regs.pc-1, opcode, instruction.operation,
                 self.regs.a, self.regs.x, self.regs.y, self.regs.flags, self.regs.sp, self.cycles);
             self.cycles_ahead += self.run_instruction(mem, instruction);