feat: compute board occupancy and empty squares

1 files changed, 24 insertions, 3 deletions

diff --git a/src/board.rs b/src/board.rs
index 241412e..b76356f 100644
--- a/src/board.rs
+++ b/src/board.rs
@@ -3,6 +3,9 @@ use crate::bitboard::Bitboard;
 #[derive(Debug)]
 pub struct Board {
     pub pieces: [Bitboard; 12],
+
+    pub occupancy: Bitboard,
+    pub ply: u16,
 }
 
 
@@ -80,7 +83,21 @@ impl Board {
             }
         }
 
-        Self { pieces }
+        let mut board = Self { pieces, occupancy: 0, ply: 0 };
+        board.update_occupancy();
+        board
+    }
+
+    fn update_occupancy(&mut self) {
+        self.occupancy = 0;
+        // TODO: reduce
+        for piece in self.pieces {
+            self.occupancy |= piece;
+        }
+    }
+
+    fn empty(&self) -> Bitboard {
+        !self.occupancy
     }
 
     pub fn print(&self) {
@@ -130,7 +147,7 @@ pub enum Square {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::bitboard::{pop_count, bitscan};
+    use crate::bitboard::{pop_count, bitscan, print};
 
     #[test]
     fn test_square_enum() {
@@ -144,6 +161,9 @@ mod tests {
         let fen = String::from("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1");
         let board = Board::from_FEN(fen);
 
+        board.print();
+        print(board.empty(), "Empty squares");
+
         assert_eq!(pop_count(board.pieces[PieceTypes::Pawn as usize]), 8);
         assert_eq!(pop_count(board.pieces[PieceTypes::Knight as usize]), 2);
         assert_eq!(pop_count(board.pieces[PieceTypes::Bishop as usize]), 2);
@@ -161,6 +181,7 @@ mod tests {
         assert_eq!(bitscan(board.pieces[PieceTypes::King as usize]), Square::E1 as u8);
         assert_eq!(bitscan(board.pieces[PieceTypes::QueenBlack as usize]), Square::D8 as u8);
 
-        board.print();
+        assert_eq!(pop_count(board.occupancy), 32);
+        assert_eq!(pop_count(board.empty()), 32);
     }
 }