fix: do not overcount EP square in move generation

1 files changed, 14 insertions, 23 deletions

diff --git a/src/board/engine.rs b/src/board/engine.rs
index 6491289..18abaa0 100644
--- a/src/board/engine.rs
+++ b/src/board/engine.rs
@@ -244,16 +244,11 @@ impl Board {
     }
 
     /// Evaluate a position relative to the current player
-    pub fn evaluate(&self, precomputed_mobility: Option<f32>) -> f32 {
+    pub fn evaluate(&self) -> f32 {
         let color = self.color();
         let opponent_color = color.flip();
 
-        let opponent_mobility = self.mobility(opponent_color);
-        let player_mobility = match precomputed_mobility {
-            Some(m) => m,
-            None => self.mobility(color),
-        };
-        let mobility_advantage = player_mobility - opponent_mobility as f32;
+        let mobility_advantage = self.mobility(color) - self.mobility(opponent_color);
 
         let opponent_material = self.material(opponent_color);
         let material_advantage = self.material(color) - opponent_material;
@@ -477,11 +472,7 @@ impl Board {
         let mut moves = self.generate_pseudolegal_moves(color);
         moves = self.order_moves(moves, Vec::new());
 
-        let queen_squares = match color {
-            Color::White => self.pieces[PieceType::Queen as usize],
-            Color::Black => self.pieces[PieceType::QueenBlack as usize],
-        };
-        let stand_pat = self.evaluate(Some(moves.iter().filter(|m| m.source.to_bitboard() & queen_squares == 0).count() as f32));
+        let stand_pat = self.evaluate();
 
         if stand_pat >= beta {
             return beta;
@@ -614,7 +605,7 @@ mod tests {
 
         assert_eq!(board.perft(1, false), PerftResult { leaf_nodes: 14, captures: 1, en_passants: 0, castles: 0 , checks: 2 });
         assert_eq!(board.perft(2, false), PerftResult { leaf_nodes: 191, captures: 14, en_passants: 0, castles: 0 , checks: 10 });
-        // assert_eq!(board.perft(3, false), PerftResult { leaf_nodes: 2182, captures: 209, en_passants: 2, castles: 0 , checks: 267 });
+        // assert_eq!(board.perft(3, false), PerftResult { leaf_nodes: 2812, captures: 209, en_passants: 2, castles: 0 , checks: 267 });
     }
 
     #[test]
@@ -688,14 +679,14 @@ mod tests {
         #[test]
         fn initial_eval() {
             let board = Board::new();
-            assert_eq!(board.evaluate(None), 0.0);
+            assert_eq!(board.evaluate(), 0.0);
         }
 
         #[test]
         fn king_tropism() {
             let mut board = Board::new();
             board.make_move(Move { source: Square::D1, target: Square::F5, kind: MoveKind::Quiet });
-            let score = board.evaluate(None);
+            let score = board.evaluate();
             board.print();
             println!("Score {}", score);
 
@@ -707,7 +698,7 @@ mod tests {
         fn white_winning() {
             let fen = String::from("8/5pk1/6p1/R4b1p/3P4/1P2N3/P1r2PPP/R5K1 b - - 1 27");
             let board = Board::from_FEN(fen);
-            let score = board.evaluate(None);
+            let score = board.evaluate();
             board.print();
             println!("Score {}", score);
 
@@ -718,7 +709,7 @@ mod tests {
         fn black_winning() {
             let fen = String::from("8/p7/1k4K1/8/4P3/8/PP5r/8 b - - 1 38");
             let board = Board::from_FEN(fen);
-            let score = board.evaluate(None);
+            let score = board.evaluate();
             board.print();
             println!("Score {}", score);
 
@@ -730,7 +721,7 @@ mod tests {
             let score1 = {
                 let fen = String::from("rnbqkbnr/pppp1ppp/8/4p3/4P3/8/PPPP1PPP/RNBQKBNR w KQkq - 0 2");
                 let board = Board::from_FEN(fen);
-                let score = board.evaluate(None);
+                let score = board.evaluate();
                 board.print();
                 println!("Score {}", score);
                 score
@@ -739,7 +730,7 @@ mod tests {
             let score2 = {
                 let fen = String::from("rnbqkbnr/pppp1ppp/8/4p3/2P5/8/PP1PPPPP/RNBQKBNR w KQkq - 0 2");
                 let board = Board::from_FEN(fen);
-                let score = board.evaluate(None);
+                let score = board.evaluate();
                 board.print();
                 println!("Score {}", score);
                 score
@@ -753,7 +744,7 @@ mod tests {
             let score1 = {
                 let fen = String::from("r1bqkbnr/pppp1ppp/2n5/4p3/4P3/5N2/PPPP1PPP/RNBQKB1R w KQkq - 2 3");
                 let board = Board::from_FEN(fen);
-                let score = board.evaluate(None);
+                let score = board.evaluate();
                 board.print();
                 println!("Score {}", score);
                 score
@@ -762,7 +753,7 @@ mod tests {
             let score2 = {
                 let fen = String::from("r1bqkbnr/pppp1ppp/2n5/4p3/4P3/7N/PPPP1PPP/RNBQKB1R w KQkq - 2 3");
                 let board = Board::from_FEN(fen);
-                let score = board.evaluate(None);
+                let score = board.evaluate();
                 board.print();
                 println!("Score {}", score);
                 score
@@ -776,7 +767,7 @@ mod tests {
             let score1 = {
                 let fen = String::from("r3k2r/Pppp1ppp/1b3nbN/nP6/BBP1P3/q4N2/Pp1P2PP/R2Q1RK1 w kq - 0 1");
                 let board = Board::from_FEN(fen);
-                let score = board.evaluate(None);
+                let score = board.evaluate();
                 board.print();
                 println!("Score {}", score);
                 score
@@ -786,7 +777,7 @@ mod tests {
                 let fen = String::from("r2q1rk1/pP1p2pp/Q4n2/bbp1p3/Np6/1B3NBn/pPPP1PPP/R3K2R b KQ - 0 1 ");
                 let mut board = Board::from_FEN(fen);
                 board.ply += 1; // TODO: remove me when FEN parsing includes side to move
-                let score = board.evaluate(None);
+                let score = board.evaluate();
                 board.print();
                 println!("Score {}", score);
                 score