2 files changed, 46 insertions, 16 deletions
diff --git a/src/bitboard.rs b/src/bitboard.rs
new file mode 100644
index 0000000..a2d34cb
--- /dev/null
+++ b/src/bitboard.rs
@@ -0,0 +1,42 @@
+use std::fmt;
+
+pub struct Bitboard(pub u64);
+
+impl fmt::Display for Bitboard {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        for index in 0..64 {
+            f.write_str(if &self.0 >> index & 1 == 1 { "1" } else { "." });
+            if (index + 1) % 8 == 0 {
+                f.write_str("\n");
+            }
+        }
+        return write!(f, "\n")
+    }
+}
+
+impl Bitboard {
+    pub fn pop_count(&self) -> i32 {
+        if self.0 == 0 {
+            return 0;
+        }
+        return Bitboard::pop_count(&Bitboard(self.0 >> 1)) + (self.0 & 1) as i32;
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_print() {
+        const bb: Bitboard = Bitboard(127);
+        println!("{}", bb);
+    }
+
+    #[test]
+    fn test_pop_count() {
+        const bb: Bitboard = Bitboard(127);
+        assert_eq!(bb.pop_count(), 7);
+    }
+}
+
diff --git a/src/main.rs b/src/main.rs
index 822f773..e0d9912 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,22 +1,10 @@
-use std::fmt;
-
-struct Bitboard(u64);
-
-impl fmt::Display for Bitboard {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        for index in (0..64) {
-            f.write_str(if (&self.0 >> index & 1 == 1) { "1" } else { "." });
-            if ((index + 1) % 8 == 0) {
-                f.write_str("\n");
-            }
-        }
-        return write!(f, "\n")
-    }
-}
+mod bitboard;
+use bitboard::*;
 
 fn main() {
-    const bb:Bitboard  = Bitboard(33);
+    const bb: Bitboard = Bitboard(127);
     println!("Hello, world!");
     println!("{}", bb);
     println!("{}", bb.0);
+    println!("{}", bb.pop_count());
 }