2 files changed, 41 insertions, 3 deletions
diff --git a/src/core.rs b/src/core.rs
index 0062e1c..6c6eefd 100644
--- a/src/core.rs
+++ b/src/core.rs
@@ -1,14 +1,51 @@
+use std::fmt;
+
+#[derive(Debug)]
+pub enum Op {
+    Nop,
+    Illegal,
+}
+
+impl fmt::Display for Op {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:?}", self)
+    }
+}
+
 pub struct Core {
     pc: u16,
+    ram: [u8; u16::max_value() as usize + 1],
 }
 
 impl Core {
     pub fn new() -> Self {
-        Core { pc: 0 }
+        Core { pc: 0, ram: [0; u16::max_value() as usize + 1] }
     }
 
     pub fn step(&mut self) -> u16 {
-        self.pc += 1;
+        self.pc += self.ram[self.pc as usize].instruction_size();
         self.pc
     }
+
+    pub fn op(&self) -> Op {
+        self.ram[self.pc as usize].op()
+    }
+}
+
+pub trait Isa {
+    fn op(&self) -> Op;
+    fn instruction_size(&self) -> u16;
+}
+
+impl Isa for u8 {
+    fn op(&self) -> Op {
+        match *self {
+            0 => Op::Nop,
+            _ => Op::Illegal
+        }
+    }
+
+    fn instruction_size(&self) -> u16 {
+        1
+    }
 }
diff --git a/src/main.rs b/src/main.rs
index f5af35c..974ff5c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -10,7 +10,8 @@ use self::core::Core;
 fn core_worker(mut core: Core, should_stop: &Mutex<bool>, cvar: &Condvar) {
     loop {
         while false == *should_stop.lock().unwrap() {
-            println!("step {}", core.step());
+            core.step();
+            println!("{}", core.op());
             sleep(time::Duration::from_millis(1000));
         }