foo.diff

diff --git a/.gitignore b/.gitignore
index 37727f9..3a6f03f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,5 +7,7 @@
 # Executables
 *.exe
 
+*.swp
+
 # Generated by Cargo
 /target/
diff --git a/src/game/.bitboard.rs.swp b/src/game/.bitboard.rs.swp
deleted file mode 100644
index 06d61aa..0000000
Binary files a/src/game/.bitboard.rs.swp and /dev/null differ
diff --git a/src/game/bitboard.rs b/src/game/bitboard.rs
index 08ac932..2d31f05 100644
--- a/src/game/bitboard.rs
+++ b/src/game/bitboard.rs
@@ -1,3 +1,5 @@
+use game::position::Position;
+
 #[allow(dead_code)]
 const BOARD_STATE_EMPTY: u64 = 0x123456789ABCDEF0;
 
@@ -8,28 +10,89 @@ pub struct BitBoard {
 
 #[allow(dead_code)]
 impl BitBoard {
-  fn new() -> BitBoard {
+  pub fn new() -> BitBoard {
     BitBoard { data: BOARD_STATE_EMPTY }
   }
 
-  fn is_solved(&self) -> bool {
+  pub fn is_solved(&self) -> bool {
     self.data == BOARD_STATE_EMPTY
   }
+
+  pub fn set(&self, pos: Position, value: u8) -> BitBoard {
+    let offset = pos.to_offset() as u64;
+
+    // reset value at position to zero
+    let zeroed_data = self.data & !(0xF << offset);
+
+    // update value at position to new value
+    let updated_data = zeroed_data | ((value as u64) << (offset));
+
+    BitBoard { data: updated_data }
+  }
+
+  pub fn get(&self, pos: Position) -> u8 {
+    let offset = pos.to_offset();
+
+    let and = self.data & (0xF << offset);
+
+    ((and >> offset as u64) & 0xF) as u8
+  }
 }
 
 #[cfg(test)]
 mod tests {
   use super::*;
+  use game::position::Position;
 
   #[test]
-  fn constructs_with_empty_state() {
+  fn new_bitboard_uses_empty_state() {
     let b: BitBoard = BitBoard::new();
     assert!(b.data == super::BOARD_STATE_EMPTY);
   }
 
   #[test]
-  fn new_board_is_solved() {
+  fn is_solved_true_for_new_board() {
     let b: BitBoard = BitBoard::new();
     assert!(b.is_solved());
   }
+
+  #[test]
+  fn set_value_at_valid_position() {
+    let b: BitBoard = BitBoard::new()
+      .set(
+        Position::new(0, 3),
+        7
+      );
+
+    assert_eq!(
+      7,
+      b.get(
+        Position::new(0, 3)
+      )
+    );
+  }
+
+  #[test]
+  fn set_values_at_valid_positions() {
+    for value in 0..16 {
+      for row in 0..4 {
+        for col in 0..4 {
+
+          let b = BitBoard::new()
+            .set(
+              Position::new(row, col),
+              value
+            );
+
+          assert_eq!(
+            value,
+            b.get(Position::new(row, col))
+          );
+        }
+      }
+    }
+  }
+
+  //fn set_negative_value_should_panic() {
+  //}
 }
diff --git a/src/game/mod.rs b/src/game/mod.rs
index 7e255be..61f833c 100644
--- a/src/game/mod.rs
+++ b/src/game/mod.rs
@@ -1,2 +1,5 @@
 pub use self::bitboard::BitBoard;
+pub use self::position::Position;
 mod bitboard;
+mod position;
+
diff --git a/src/game/position.rs b/src/game/position.rs
new file mode 100644
index 0000000..d40dc8e
--- /dev/null
+++ b/src/game/position.rs
@@ -0,0 +1,43 @@
+#[allow(dead_code)]
+const MAX_ROW_INDEX: u8 = 3;
+#[allow(dead_code)]
+const MAX_COL_INDEX: u8 = 3;
+
+#[allow(dead_code)]
+pub struct Position {
+  row: u8,
+  col: u8,
+}
+
+#[allow(dead_code)]
+impl Position {
+  pub fn new(row: u8, col: u8) -> Position {
+    if row > MAX_ROW_INDEX || col > MAX_COL_INDEX {
+      panic!("Invalid argument for position");
+    }
+
+    Position { row: row, col: col }
+  }
+
+  pub fn to_offset(&self) -> u8 {
+    let index = (self.row * 4) + self.col;
+    4 * (15 - index)
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  #[test]
+  #[should_panic]
+  fn high_col_position_should_panic() {
+      Position::new(0, 4);
+  }
+
+  #[test]
+  #[should_panic]
+  fn high_row_position_should_panic() {
+      Position::new(141, 0);
+  }
+}