diff --git a/2019/07/Cargo.toml b/2019/07/Cargo.toml
index 567152c..0088cae 100644
--- a/2019/07/Cargo.toml
+++ b/2019/07/Cargo.toml
@@ -8,3 +8,4 @@ edition = "2018"
 
 [dependencies]
 itertools = "0.8.2"
+intcode = { path = "../intcode" }
diff --git a/2019/07/input b/2019/07/input
new file mode 100644
index 0000000..d1550e6
--- /dev/null
+++ b/2019/07/input
@@ -0,0 +1 @@
+3,8,1001,8,10,8,105,1,0,0,21,30,51,76,101,118,199,280,361,442,99999,3,9,102,5,9,9,4,9,99,3,9,102,4,9,9,1001,9,3,9,102,2,9,9,101,2,9,9,4,9,99,3,9,1002,9,3,9,1001,9,4,9,102,5,9,9,101,3,9,9,1002,9,3,9,4,9,99,3,9,101,5,9,9,102,4,9,9,1001,9,3,9,1002,9,2,9,101,4,9,9,4,9,99,3,9,1002,9,2,9,1001,9,3,9,102,5,9,9,4,9,99,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,1001,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,99,3,9,1001,9,1,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,101,1,9,9,4,9,3,9,102,2,9,9,4,9,3,9,101,1,9,9,4,9,3,9,102,2,9,9,4,9,99,3,9,1001,9,1,9,4,9,3,9,1001,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,101,1,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,1001,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,1001,9,1,9,4,9,3,9,101,1,9,9,4,9,99,3,9,1001,9,1,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,1001,9,1,9,4,9,3,9,1002,9,2,9,4,9,99,3,9,102,2,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,102,2,9,9,4,9,3,9,101,2,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,101,1,9,9,4,9,3,9,101,1,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,1001,9,2,9,4,9,99
diff --git a/2019/07/src/main.rs b/2019/07/src/main.rs
index b837d2b..b92fce7 100644
--- a/2019/07/src/main.rs
+++ b/2019/07/src/main.rs
@@ -1,212 +1,7 @@
-use itertools::Itertools;
-use std::io;
-use std::io::BufRead;
-use std::ops::Range;
-
-#[derive(Debug)]
-enum Operation {
-    Add { x: i64, y: i64, addr: usize },
-    Multiply { x: i64, y: i64, addr: usize },
-    Input { value: i64, addr: usize },
-    Output { value: i64 },
-    JumpIfTrue { value: i64, addr: i64 },
-    JumpIfFalse { value: i64, addr: i64 },
-    LessThan { first: i64, second: i64, addr: i64 },
-    Equals { first: i64, second: i64, addr: i64 },
-}
-
-#[derive(Debug)]
-enum Mode {
-    Immediate,
-    Position,
-}
-
-enum ParameterPosition {
-    First,
-    Second,
-}
-
-struct Machine {
-    pos: i64,
-    tape: Vec<i64>,
-    params: Vec<i64>,
-}
-
-impl Into<usize> for ParameterPosition {
-    fn into(self) -> usize {
-        match self {
-            ParameterPosition::First => 2,
-            ParameterPosition::Second => 3,
-        }
-    }
-}
-
-impl Into<Mode> for &char {
-    fn into(self) -> Mode {
-        match self {
-            '0' => Mode::Position,
-            '1' => Mode::Immediate,
-            _ => unreachable!(),
-        }
-    }
-}
-
-fn get_next(input: &[i64], pos: &mut i64, mode: Mode) -> i64 {
-    let value = input[*pos as usize];
-    let next = match mode {
-        Mode::Position => input[value as usize],
-        Mode::Immediate => value,
-    };
-    *pos += 1;
-    next
-}
-
-fn get_mode(raw_opcode: &[char], pos: ParameterPosition) -> Mode {
-    raw_opcode.get::<usize>(pos.into()).unwrap_or(&'0').into()
-}
-
-#[rustfmt::skip]
-fn next_operation(machine: &mut Machine) -> Option<Operation> {
-    let next = get_next(&machine.tape, &mut machine.pos, Mode::Immediate);
-    let mut raw_opcode: Vec<_> = next.to_string().chars().collect();
-    raw_opcode.reverse();
-    match raw_opcode[0] {
-        '1' => Some(Operation::Add {
-            x: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::First)),
-            y: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::Second)),
-            addr: get_next(&machine.tape, &mut machine.pos, Mode::Immediate) as usize,
-        }),
-        '2' => Some(Operation::Multiply {
-            x: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::First)),
-            y: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::Second)),
-            addr: get_next(&machine.tape, &mut machine.pos, Mode::Immediate) as usize,
-        }),
-        '3' => Some(Operation::Input {
-            value: machine.params.pop().unwrap(),
-            addr: get_next(&machine.tape, &mut machine.pos, Mode::Immediate) as usize,
-        }),
-        '4' => Some(Operation::Output {
-            value: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::First)),
-        }),
-        '5' => Some(Operation::JumpIfTrue {
-            value: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::First)),
-            addr: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::Second)),
-        }),
-        '6' => Some(Operation::JumpIfFalse {
-            value: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::First)),
-            addr: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::Second)),
-        }),
-        '7' => Some(Operation::LessThan {
-            first: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::First)),
-            second: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::Second)),
-            addr: get_next(&machine.tape, &mut machine.pos, Mode::Immediate),
-        }),
-        '8' => Some(Operation::Equals {
-            first: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::First)),
-            second: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::Second)),
-            addr: get_next(&machine.tape, &mut machine.pos, Mode::Immediate),
-        }),
-        '9' => None,
-        _ => unreachable!(),
-    }
-}
-
-fn execute(op: Operation, input: &mut Vec<i64>, pos: &mut i64) -> Option<i64> {
-    match op {
-        Operation::Add { x, y, addr } => {
-            input[addr as usize] = x + y;
-            None
-        }
-        Operation::Multiply { x, y, addr } => {
-            input[addr as usize] = x * y;
-            None
-        }
-        Operation::Input { value, addr } => {
-            input[addr] = value;
-            None
-        }
-        Operation::Output { value } => Some(value),
-        Operation::JumpIfTrue { value, addr } => {
-            if value != 0 {
-                *pos = addr
-            }
-            None
-        }
-        Operation::JumpIfFalse { value, addr } => {
-            if value == 0 {
-                *pos = addr
-            }
-            None
-        }
-        Operation::LessThan {
-            first,
-            second,
-            addr,
-        } => {
-            input[addr as usize] = (first < second) as i64;
-            None
-        }
-        Operation::Equals {
-            first,
-            second,
-            addr,
-        } => {
-            input[addr as usize] = (first == second) as i64;
-            None
-        }
-    }
-}
-
-fn find_max(range: Range<i64>, input: &Vec<i64>) -> i64 {
-    range
-        .permutations(5)
-        .scan(0, |&mut mut acc, amps| {
-            let mut machines: Vec<_> = amps
-                .into_iter()
-                .map(|amp| Machine {
-                    tape: input.clone(),
-                    pos: 0,
-                    params: vec![amp],
-                })
-                .collect();
-            for state in (0..5).cycle() {
-                let mut machine = machines.get_mut(state).unwrap();
-                machine.params.insert(0, acc);
-                match execute_machine(&mut machine) {
-                    Err(output) => acc = output,
-                    Ok(_) => break,
-                }
-            }
-            Some(acc)
-        })
-        .max()
-        .unwrap()
-}
-
-fn execute_machine(machine: &mut Machine) -> Result<i64, i64> {
-    loop {
-        match next_operation(machine) {
-            Some(op) => {
-                if let Some(o) = execute(op, &mut machine.tape, &mut machine.pos) {
-                    return Err(o);
-                }
-            }
-            None => return Ok(machine.params.pop().unwrap()),
-        }
-    }
-}
+use intcode::*;
 
 pub fn main() {
-    let input: Vec<_> = io::stdin()
-        .lock()
-        .lines()
-        .next()
-        .unwrap()
-        .unwrap()
-        .split(',')
-        .map(|n| n.parse().unwrap())
-        .collect();
-
+    let input = read_input();
     println!("Part 1: {}", find_max(0..5, &input));
     println!("Part 2: {}", find_max(5..10, &input));
 }
diff --git a/2019/intcode/Cargo.toml b/2019/intcode/Cargo.toml
new file mode 100644
index 0000000..dcd59b0
--- /dev/null
+++ b/2019/intcode/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "intcode"
+version = "0.1.0"
+authors = ["kageru <kageru@encode.moe>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+itertools = "0.8.2"
diff --git a/2019/intcode/src/lib.rs b/2019/intcode/src/lib.rs
new file mode 100644
index 0000000..d1294ab
--- /dev/null
+++ b/2019/intcode/src/lib.rs
@@ -0,0 +1,204 @@
+use itertools::Itertools;
+use std::io::{self, BufRead};
+use std::ops::Range;
+
+#[derive(Debug)]
+enum Operation {
+    Add { x: i64, y: i64, addr: usize },
+    Multiply { x: i64, y: i64, addr: usize },
+    Input { value: i64, addr: usize },
+    Output { value: i64 },
+    JumpIfTrue { value: i64, addr: i64 },
+    JumpIfFalse { value: i64, addr: i64 },
+    LessThan { first: i64, second: i64, addr: i64 },
+    Equals { first: i64, second: i64, addr: i64 },
+}
+
+#[derive(Debug)]
+enum Mode {
+    Immediate,
+    Position,
+}
+
+enum ParameterPosition {
+    First,
+    Second,
+}
+
+struct Machine {
+    pos: i64,
+    tape: Vec<i64>,
+    params: Vec<i64>,
+}
+
+impl Into<usize> for ParameterPosition {
+    fn into(self) -> usize {
+        match self {
+            ParameterPosition::First => 2,
+            ParameterPosition::Second => 3,
+        }
+    }
+}
+
+impl Into<Mode> for &char {
+    fn into(self) -> Mode {
+        match self {
+            '0' => Mode::Position,
+            '1' => Mode::Immediate,
+            _ => unreachable!(),
+        }
+    }
+}
+
+fn get_next(input: &[i64], pos: &mut i64, mode: Mode) -> i64 {
+    let value = input[*pos as usize];
+    let next = match mode {
+        Mode::Position => input[value as usize],
+        Mode::Immediate => value,
+    };
+    *pos += 1;
+    next
+}
+
+fn get_mode(raw_opcode: &[char], pos: ParameterPosition) -> Mode {
+    raw_opcode.get::<usize>(pos.into()).unwrap_or(&'0').into()
+}
+
+#[rustfmt::skip]
+fn decode_next(machine: &mut Machine) -> Option<Operation> {
+    let next = get_next(&machine.tape, &mut machine.pos, Mode::Immediate);
+    let mut raw_opcode: Vec<_> = next.to_string().chars().collect();
+    raw_opcode.reverse();
+    match raw_opcode[0] {
+        '1' => Some(Operation::Add {
+            x: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::First)),
+            y: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::Second)),
+            addr: get_next(&machine.tape, &mut machine.pos, Mode::Immediate) as usize,
+        }),
+        '2' => Some(Operation::Multiply {
+            x: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::First)),
+            y: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::Second)),
+            addr: get_next(&machine.tape, &mut machine.pos, Mode::Immediate) as usize,
+        }),
+        '3' => Some(Operation::Input {
+            value: machine.params.pop().unwrap(),
+            addr: get_next(&machine.tape, &mut machine.pos, Mode::Immediate) as usize,
+        }),
+        '4' => Some(Operation::Output {
+            value: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::First)),
+        }),
+        '5' => Some(Operation::JumpIfTrue {
+            value: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::First)),
+            addr: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::Second)),
+        }),
+        '6' => Some(Operation::JumpIfFalse {
+            value: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::First)),
+            addr: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::Second)),
+        }),
+        '7' => Some(Operation::LessThan {
+            first: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::First)),
+            second: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::Second)),
+            addr: get_next(&machine.tape, &mut machine.pos, Mode::Immediate),
+        }),
+        '8' => Some(Operation::Equals {
+            first: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::First)),
+            second: get_next(&machine.tape, &mut machine.pos, get_mode(&raw_opcode, ParameterPosition::Second)),
+            addr: get_next(&machine.tape, &mut machine.pos, Mode::Immediate),
+        }),
+        '9' => None,
+        _ => unreachable!(),
+    }
+}
+
+fn execute(op: Operation, input: &mut Vec<i64>, pos: &mut i64) -> Option<i64> {
+    match op {
+        Operation::Add { x, y, addr } => {
+            input[addr as usize] = x + y;
+            None
+        }
+        Operation::Multiply { x, y, addr } => {
+            input[addr as usize] = x * y;
+            None
+        }
+        Operation::Input { value, addr } => {
+            input[addr] = value;
+            None
+        }
+        Operation::Output { value } => Some(value),
+        Operation::JumpIfTrue { value, addr } => {
+            if value != 0 {
+                *pos = addr
+            }
+            None
+        }
+        Operation::JumpIfFalse { value, addr } => {
+            if value == 0 {
+                *pos = addr
+            }
+            None
+        }
+        Operation::LessThan {
+            first,
+            second,
+            addr,
+        } => {
+            input[addr as usize] = (first < second) as i64;
+            None
+        }
+        Operation::Equals {
+            first,
+            second,
+            addr,
+        } => {
+            input[addr as usize] = (first == second) as i64;
+            None
+        }
+    }
+}
+
+pub fn find_max(range: Range<i64>, input: &Vec<i64>) -> i64 {
+    range
+        .permutations(5)
+        .scan(0, |&mut mut acc, amps| {
+            let mut machines: Vec<_> = amps
+                .into_iter()
+                .map(|amp| Machine {
+                    tape: input.clone(),
+                    pos: 0,
+                    params: vec![amp],
+                })
+                .collect();
+            for state in (0..5).cycle() {
+                let mut machine = machines.get_mut(state).unwrap();
+                machine.params.insert(0, acc);
+                match execute_machine(&mut machine) {
+                    Err(output) => acc = output,
+                    Ok(_) => break,
+                }
+            }
+            Some(acc)
+        })
+        .max()
+        .unwrap()
+}
+
+fn execute_machine(machine: &mut Machine) -> Result<i64, i64> {
+    loop {
+        match decode_next(machine) {
+            Some(op) => {
+                if let Some(o) = execute(op, &mut machine.tape, &mut machine.pos) {
+                    return Err(o);
+                }
+            }
+            None => return Ok(machine.params.pop().unwrap()),
+        }
+    }
+}
+
+#[rustfmt::skip]
+pub fn read_input() -> Vec<i64> {
+    io::stdin().lock().lines().next().unwrap().unwrap().split(',').map(|n| n.parse().unwrap()).collect()
+}
+
+#[cfg(test)]
+mod tests;
diff --git a/2019/intcode/src/tests.rs b/2019/intcode/src/tests.rs
new file mode 100644
index 0000000..2a5bf3a
--- /dev/null
+++ b/2019/intcode/src/tests.rs
@@ -0,0 +1,49 @@
+use super::*;
+
+#[allow(dead_code)]
+fn parse_test_input(raw: &str) -> Vec<i64> {
+    raw.split(",").map(|x| x.parse().unwrap()).collect()
+}
+
+#[test]
+fn test_find_max() {
+    assert_eq!(
+        find_max(
+            0..5,
+            &parse_test_input("3,15,3,16,1002,16,10,16,1,16,15,15,4,15,99,0,0")
+        ),
+        43210
+    );
+    assert_eq!(
+        find_max(
+            0..5,
+            &parse_test_input("3,23,3,24,1002,24,10,24,1002,23,-1,23,101,5,23,23,1,24,23,23,4,23,99,0,0")
+        ),
+        54321
+    );
+    assert_eq!(
+        find_max(
+            0..5,
+            &parse_test_input("3,31,3,32,1002,32,10,32,1001,31,-2,31,1007,31,0,33,1002,33,7,33,1,33,31,31,1,32,31,31,4,31,99,0,0,0")
+        ),
+        65210
+    );
+}
+
+#[test]
+fn test_find_max_with_loops() {
+    assert_eq!(
+        find_max(
+            5..10,
+            &parse_test_input("3,26,1001,26,-4,26,3,27,1002,27,2,27,1,27,26,27,4,27,1001,28,-1,28,1005,28,6,99,0,0,5")
+        ),
+        139629729
+    );
+    assert_eq!(
+        find_max(
+            5..10,
+            &parse_test_input("3,52,1001,52,-5,52,3,53,1,52,56,54,1007,54,5,55,1005,55,26,1001,54,-5,54,1105,1,12,1,53,54,53,1008,54,0,55,1001,55,1,55,2,53,55,53,4,53,1001,56,-1,56,1005,56,6,99,0,0,0,0,10")
+        ),
+        18216
+    );
+}