diff --git a/day10/common.rs b/day10/common.rs
new file mode 100644
index 0000000..d2458e1
--- /dev/null
+++ b/day10/common.rs
@@ -0,0 +1,107 @@
+// Copyright 2022 Christian Ulrich
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+use std::io;
+use std::str::FromStr;
+
+#[derive(Debug, Clone, Copy)]
+pub enum Instruction {
+    Noop,
+    Addx { arg: i64 },
+}
+
+impl Instruction {
+    pub fn duration(&self) -> usize {
+        match self {
+            Self::Noop => 1,
+            Self::Addx { arg: _ } => 2,
+        }
+    }
+}
+
+pub struct Processor {
+    x: i64,
+    instruction: Instruction,
+    cycle_count: usize,
+}
+
+impl FromStr for Instruction {
+    type Err = &'static str;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "noop" => Ok(Self::Noop),
+            _ if { s.starts_with("addx ") } => Ok(Self::Addx {
+                arg: s[5..].parse().map_err(|_| "cannot parse instrution")?,
+            }),
+            _ => Err("cannot parse instruction"),
+        }
+    }
+}
+
+impl Processor {
+    pub fn new() -> Self {
+        Self {
+            x: 1,
+            instruction: Instruction::Noop,
+            cycle_count: 0,
+        }
+    }
+
+    fn set_instruction(&mut self, instruction: Instruction) {
+        self.instruction = instruction;
+        self.cycle_count = instruction.duration();
+    }
+
+    pub fn step(&mut self) -> Result<i64, &'static str> {
+        match self.instruction {
+            Instruction::Noop => self.cycle_count -= 1,
+            Instruction::Addx { arg } => {
+                self.cycle_count -= 1;
+                if self.cycle_count == 0 {
+                    self.x += arg;
+                }
+            }
+        }
+        Ok(self.x)
+    }
+
+    pub fn cycles(&mut self) -> Cycles {
+        Cycles { processor: self }
+    }
+}
+
+pub struct Cycles<'a> {
+    processor: &'a mut Processor,
+}
+
+impl Iterator for Cycles<'_> {
+    type Item = Result<i64, &'static str>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.processor.cycle_count == 0 {
+            let mut line = String::new();
+            match io::stdin().read_line(&mut line) {
+                Ok(_) if { line == "" || line == "\n" } => return None,
+                Ok(_) => match Instruction::from_str(line.trim()) {
+                    Ok(instruction) => self.processor.set_instruction(instruction),
+                    Err(e) => return Some(Err(e)),
+                },
+                Err(_) => assert!(false),
+            }
+        }
+        Some(self.processor.step())
+    }
+}
diff --git a/day10/input b/day10/input
new file mode 100644
index 0000000..e6119e8
--- /dev/null
+++ b/day10/input
@@ -0,0 +1,140 @@
+noop
+noop
+noop
+addx 5
+noop
+addx 1
+addx 2
+addx 5
+addx 2
+addx 1
+noop
+addx 5
+noop
+addx -1
+noop
+addx 5
+noop
+noop
+addx 5
+addx 1
+noop
+noop
+addx 3
+addx 2
+noop
+addx -38
+noop
+addx 3
+addx 2
+addx -5
+addx 12
+addx 2
+addx 27
+addx -40
+addx 19
+addx 2
+addx 19
+addx -18
+addx 2
+addx 5
+addx 2
+addx -23
+addx 22
+addx 4
+addx -34
+addx -1
+addx 5
+noop
+addx 2
+addx 1
+addx 20
+addx -17
+noop
+addx 25
+addx -17
+addx -2
+noop
+addx 3
+addx 19
+addx -12
+addx 3
+addx -2
+addx 3
+addx 1
+noop
+addx 5
+noop
+noop
+addx -37
+addx 3
+addx 4
+noop
+addx 24
+addx -6
+addx -15
+addx 2
+noop
+addx 6
+addx -2
+addx 6
+addx -12
+addx -2
+addx 19
+noop
+noop
+noop
+addx 3
+noop
+addx 7
+addx -2
+addx -24
+addx -11
+addx 4
+addx 3
+addx -2
+noop
+addx 7
+addx -2
+addx 2
+noop
+addx 3
+addx 7
+noop
+addx -2
+addx 5
+addx 2
+addx 5
+noop
+noop
+noop
+addx 3
+addx -35
+addx 35
+addx -21
+addx -14
+noop
+addx 5
+addx 2
+addx 33
+addx -7
+addx -23
+addx 5
+addx 2
+addx 1
+noop
+noop
+addx 5
+addx -1
+noop
+addx 3
+addx -23
+addx 30
+addx 1
+noop
+addx 4
+addx -17
+addx 11
+noop
+noop
+
diff --git a/day10/part1.rs b/day10/part1.rs
new file mode 100644
index 0000000..b597705
--- /dev/null
+++ b/day10/part1.rs
@@ -0,0 +1,32 @@
+// Copyright 2022 Christian Ulrich
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+// usage: ./part1 < input
+
+pub mod common;
+
+use common::Processor;
+
+fn main() -> Result<(), &'static str> {
+    let mut processor = Processor::new();
+    let mut result = 0;
+    for (count, register_x) in processor.cycles().enumerate() {
+        if [20, 60, 100, 140, 180, 220].contains(&(count + 2)) {
+            result += (count + 2) as i64 * register_x?;
+        }
+    }
+    println!("{result}");
+    Ok(())
+}
diff --git a/day10/testinput b/day10/testinput
new file mode 100644
index 0000000..37ee8ee
--- /dev/null
+++ b/day10/testinput
@@ -0,0 +1,146 @@
+addx 15
+addx -11
+addx 6
+addx -3
+addx 5
+addx -1
+addx -8
+addx 13
+addx 4
+noop
+addx -1
+addx 5
+addx -1
+addx 5
+addx -1
+addx 5
+addx -1
+addx 5
+addx -1
+addx -35
+addx 1
+addx 24
+addx -19
+addx 1
+addx 16
+addx -11
+noop
+noop
+addx 21
+addx -15
+noop
+noop
+addx -3
+addx 9
+addx 1
+addx -3
+addx 8
+addx 1
+addx 5
+noop
+noop
+noop
+noop
+noop
+addx -36
+noop
+addx 1
+addx 7
+noop
+noop
+noop
+addx 2
+addx 6
+noop
+noop
+noop
+noop
+noop
+addx 1
+noop
+noop
+addx 7
+addx 1
+noop
+addx -13
+addx 13
+addx 7
+noop
+addx 1
+addx -33
+noop
+noop
+noop
+addx 2
+noop
+noop
+noop
+addx 8
+noop
+addx -1
+addx 2
+addx 1
+noop
+addx 17
+addx -9
+addx 1
+addx 1
+addx -3
+addx 11
+noop
+noop
+addx 1
+noop
+addx 1
+noop
+noop
+addx -13
+addx -19
+addx 1
+addx 3
+addx 26
+addx -30
+addx 12
+addx -1
+addx 3
+addx 1
+noop
+noop
+noop
+addx -9
+addx 18
+addx 1
+addx 2
+noop
+noop
+addx 9
+noop
+noop
+noop
+addx -1
+addx 2
+addx -37
+addx 1
+addx 3
+noop
+addx 15
+addx -21
+addx 22
+addx -6
+addx 1
+noop
+addx 2
+addx 1
+noop
+addx -10
+noop
+noop
+addx 20
+addx 1
+addx 2
+addx 2
+addx -6
+addx -11
+noop
+noop
+noop