toyvm: print next instruction during execution

toy_cpu_4bit/src/cpu.rs

@@ -36,6 +36,10 @@ impl Cpu {
         }
     }
 
+    pub fn next_instruction(&self) -> String {
+        format!("{:?}", decode(self.code[self.IP.0 as usize]))
+    }
+
     fn load(&mut self, reg: Register, addr: u4) {
         match reg {
             Register::R0 => self.R0 = Wrapping(self.data[u8::from(addr) as usize]),

toyvm/src/main.rs

@@ -35,6 +35,7 @@ fn main() -> Result<(), Box<dyn Error>> {
     let code = read_code(args.code)?;
     let mut cpu = Cpu::new(&code);
     loop {
+        println!("{}", cpu.next_instruction());
         if cpu.step() {
             break;
         }
@@ -42,5 +43,6 @@ fn main() -> Result<(), Box<dyn Error>> {
             cpu.visualize();
         }
     }
+    cpu.visualize();
     Ok(())
 }