diff --git a/src/day2.rs b/src/day2.rs
index b9bdde5..27c50a7 100644
--- a/src/day2.rs
+++ b/src/day2.rs
@@ -1,24 +1,70 @@
 use std;
 
-fn compute_intcode(p: &mut Vec<usize>) {
-    for idx in (0..(p.len())).step_by(4) {
-        match p[idx] {
-            1 => {
-                let left = p[idx + 1];
-                let right = p[idx + 2];
-                let res = p[idx + 3];
-                p[res] = p[left] + p[right];
-            }
-            2 => {
-                let left = p[idx + 1];
-                let right = p[idx + 2];
-                let res = p[idx + 3];
-                p[res] = p[left] * p[right];
-            }
-            99 => break,
-            _ => panic!("invalid opcode"),
+struct Params {
+    op1: usize,
+    op2: usize,
+    result: usize,
+}
+
+enum Instruction {
+    Add(Params),
+    Mul(Params),
+    GetParam(usize),
+    Start,
+    Halt,
+}
+
+struct IntcodeComputer {
+    memory: Vec<usize>,
+    output: Vec<usize>,
+    instruction: Instruction,
+    ip: usize, // instruction pointer
+}
+
+impl IntcodeComputer {
+    fn new(memory: Vec<usize>) -> Self {
+	IntcodeComputer {
+	    memory,
+	    output: vec![],
+	    instruction: Instruction::Start,
+	    ip: 0,
+	}
+    }
+    fn add(&mut self) {
+        let op = self.get_params();
+        self.memory[op.result] = self.memory[op.op1] + self.memory[op.op2]
+    }
+    fn mul(&mut self) {
+        let op = self.get_params();
+        self.memory[op.result] = self.memory[op.op1] * self.memory[op.op2]
+    }
+    fn get_params(&mut self) -> Params {
+        Params {
+            op1: self.next(),
+            op2: self.next(),
+            result: self.next(),
         }
     }
+    fn halt(&mut self) {
+        self.instruction = Instruction::Halt;
+    }
+    fn next(&mut self) -> usize {
+        self.ip += 1;
+        self.memory[self.ip]
+    }
+    fn tick(&mut self) {
+        match self.next() {
+            1 => self.add(),
+            2 => self.mul(),
+            99 => self.halt(),
+            _ => panic!("invalid input code"),
+        }
+    }
+}
+
+fn compute_intcode(p: &mut Vec<usize>) -> Vec<usize> {
+    let computer = IntcodeComputer::new(p); 
+    while 
 }
 
 pub fn part_one() {
@@ -31,9 +77,7 @@ pub fn part_one() {
     input[1] = 12;
     input[2] = 2;
 
-    compute_intcode(&mut input);
-
-    println!("Intcode [0] is: {}", input[0]);
+    println!("Intcode [0] is: {}", compute_intcode(&mut input)[0]);
 }
 
 pub fn part_two() {
@@ -53,8 +97,8 @@ pub fn part_two() {
         input[1] = i;
         for j in 0..99 {
             input[2] = j;
-            let mut computed = input.clone();
-            compute_intcode(&mut computed);
+            let mut input_guess = input.clone();
+            let computed = compute_intcode(&mut input_guess);
 
             found = computed[0] == lookup_num;
 
@@ -77,19 +121,20 @@ pub fn part_two() {
 
 #[test]
 fn test_part_one() {
-    let mut intcode = vec![1, 0, 0, 0, 99];
-    compute_intcode(&mut intcode);
-    assert_eq!(intcode, vec!(2, 0, 0, 0, 99));
-
-    let mut intcode = vec![2, 3, 0, 3, 99];
-    compute_intcode(&mut intcode);
-    assert_eq!(intcode, vec!(2, 3, 0, 6, 99));
-
-    let mut intcode = vec![2, 4, 4, 5, 99, 0];
-    compute_intcode(&mut intcode);
-    assert_eq!(intcode, vec!(2, 4, 4, 5, 99, 9801));
-
-    let mut intcode = vec![1, 1, 1, 4, 99, 5, 6, 0, 99];
-    compute_intcode(&mut intcode);
-    assert_eq!(intcode, vec!(30, 1, 1, 4, 2, 5, 6, 0, 99));
+    assert_eq!(
+        compute_intcode(&mut vec!(1, 0, 0, 0, 99)),
+        vec!(2, 0, 0, 0, 99)
+    );
+    assert_eq!(
+        compute_intcode(&mut vec!(2, 3, 0, 3, 99)),
+        vec!(2, 3, 0, 6, 99)
+    );
+    assert_eq!(
+        compute_intcode(&mut vec!(2, 4, 4, 5, 99, 0)),
+        vec!(2, 4, 4, 5, 99, 9801)
+    );
+    assert_eq!(
+        compute_intcode(&mut vec!(1, 1, 1, 4, 99, 5, 6, 0, 99)),
+        vec!(30, 1, 1, 4, 2, 5, 6, 0, 99)
+    );
 }