diff --git a/src/emulator/instructions/arithmetic.rs b/src/emulator/instructions/arithmetic.rs
index d3ec5c4..a310d9c 100644
--- a/src/emulator/instructions/arithmetic.rs
+++ b/src/emulator/instructions/arithmetic.rs
@@ -20,7 +20,7 @@ fn set_cc(state: &mut EmulatorState, result: u16, flags: u8) {
 
 /// Add values of `register` and `A`
 pub fn add(register: Register, state: &mut EmulatorState) {
-    let result = get_register(&register, state) as u16 + state.a as u16;
+    let result = get_register(register, state) as u16 + state.a as u16;
     set_cc(state, result, 0b1111);
     state.a = (result & 0xff) as u8;
 }
@@ -34,7 +34,7 @@ pub fn adi(byte: u8, state: &mut EmulatorState) {
 
 /// Add values of `register` and `A` and add +1 if carry bit is set
 pub fn adc(register: Register, state: &mut EmulatorState) {
-    let result = get_register(&register, state) as u16 + state.a as u16 + u16::from(state.cc.c);
+    let result = get_register(register, state) as u16 + state.a as u16 + u16::from(state.cc.c);
     set_cc(state, result, 0b1111);
     state.a = (result & 0xff) as u8;
 }
@@ -64,14 +64,14 @@ pub fn dad(register: Register, state: &mut EmulatorState) {
 
 /// Increase register
 pub fn inr(register: Register, state: &mut EmulatorState) {
-    let (result, _) = get_register(&register, state).overflowing_add(1);
+    let (result, _) = get_register(register, state).overflowing_add(1);
     set_cc(state, result as u16, 0b1101);
-    set_register(&register, result, state);
+    set_register(register, result, state);
 }
 
 /// Decrease register
 pub fn dcr(register: Register, state: &mut EmulatorState) {
-    let (result, _) = get_register(&register, state).overflowing_sub(1);
+    let (result, _) = get_register(register, state).overflowing_sub(1);
     set_cc(state, result as u16, 0b1101);
-    set_register(&register, result, state);
+    set_register(register, result, state);
 }
diff --git a/src/emulator/structs.rs b/src/emulator/structs.rs
index c51c3c3..d5858c6 100644
--- a/src/emulator/structs.rs
+++ b/src/emulator/structs.rs
@@ -1,5 +1,6 @@
 use crate::MEMORY_SIZE;
 
+#[derive(Clone, PartialEq, Eq, Debug)]
 pub struct EmulatorState {
     pub a: u8,
     pub b: u8,
@@ -21,6 +22,7 @@ pub struct EmulatorState {
     pub memory: [u8; MEMORY_SIZE],
 }
 
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub struct ConditionCodes {
     /// Zero (Z), set if the result is zero.
     pub z: bool,
@@ -35,7 +37,7 @@ pub struct ConditionCodes {
     // ac: bool,
 }
 
-#[derive(PartialEq, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub enum Register {
     B,
     C,
@@ -63,7 +65,7 @@ pub fn register_from_num(b: u8) -> Register {
     }
 }
 
-pub fn get_register(register: &Register, state: &EmulatorState) -> u8 {
+pub fn get_register(register: Register, state: &EmulatorState) -> u8 {
     match register {
         Register::B => state.b,
         Register::C => state.c,
@@ -77,7 +79,7 @@ pub fn get_register(register: &Register, state: &EmulatorState) -> u8 {
     }
 }
 
-pub fn set_register(register: &Register, value: u8, state: &mut EmulatorState) {
+pub fn set_register(register: Register, value: u8, state: &mut EmulatorState) {
     match register {
         Register::B => state.b = value,
         Register::C => state.c = value,