diff options
| -rw-r--r-- | src/board/mod.rs | 113 |
1 files changed, 112 insertions, 1 deletions
diff --git a/src/board/mod.rs b/src/board/mod.rs index d339f1d..2085894 100644 --- a/src/board/mod.rs +++ b/src/board/mod.rs @@ -1,4 +1,4 @@ -use crate::{bitboard::{Bitboard, serialize_bitboard, bitscan}, moves::{Move, MoveKind}, attacks::Attacks, square::Square}; +use crate::{bitboard::{Bitboard, serialize_bitboard, bitscan, pop_count}, moves::{Move, MoveKind}, attacks::Attacks, square::Square}; mod engine; pub enum CastlingSide { @@ -323,6 +323,107 @@ impl Board { moves } + /// Count pseudo-legal moves without actually generating them + pub fn mobility(&self, color: Color) -> f32 { + let mut mobility = 0.; + let opponent_occupancy = self.color_occupancy(color.flip()); + let empty = self.empty(); + let player_pieces = self.pieces_by_color(color); + + for (piece_type, piece) in player_pieces.iter().enumerate() { + match PieceType::from(piece_type) { + PieceType::Pawn => { + for source in serialize_bitboard(*piece) { + let ep_bitboard = match self.ep_target { + Some(square) => square.to_bitboard(), + None => 0, + }; + mobility += pop_count(self.attacks.pawn[color as usize][source as usize] & (opponent_occupancy | ep_bitboard)) as f32; + mobility += pop_count(self.attacks.pawn_pushes[color as usize][source as usize] & empty) as f32; + } + let able_to_double_push_mask = match color { + Color::White => empty >> 8, + Color::Black => empty << 8, + }; + for source in serialize_bitboard(*piece & able_to_double_push_mask) { + mobility += pop_count(self.attacks.pawn_double_pushes[color as usize][source as usize] & empty) as f32; + } + } + PieceType::King => { + for source in serialize_bitboard(*piece) { + mobility += pop_count(self.attacks.king[source as usize] & (empty | opponent_occupancy)) as f32; + + // Castling + let king_home_position = match color { + Color::White => Square::E1, + Color::Black => Square::E8, + }; + if *piece == king_home_position.to_bitboard() { + for rook_square in serialize_bitboard(player_pieces[PieceType::Rook as usize]) + .iter() + .filter(|rook_square| rook_square.rank() == king_home_position.rank()) + { + match rook_square.file() { + 0 => { + let castle_line = [ + king_home_position.west_one(), + king_home_position.west_one().west_one(), + ]; + + let all_empty = castle_line.iter().all(|square| empty & square.to_bitboard() > 0); + let any_checks = castle_line.iter().any(|square| self.is_square_attacked(*square, color.flip())); + + if all_empty && !any_checks && self.castling_rights[color as usize][CastlingSide::Queen as usize] { + mobility += 1.; + } + }, + 7 => { + let castle_line = [ + king_home_position.east_one(), + king_home_position.east_one().east_one(), + ]; + + let all_empty = castle_line.iter().all(|square| empty & square.to_bitboard() > 0); + let any_checks = castle_line.iter().any(|square| self.is_square_attacked(*square, color.flip())); + + if all_empty && !any_checks && self.castling_rights[color as usize][CastlingSide::King as usize] { + mobility += 1.; + } + }, + _ => {}, + } + } + } + } + } + PieceType::Knight => { + for source in serialize_bitboard(*piece) { + mobility += pop_count(self.attacks.knight[source as usize] & (empty | opponent_occupancy)) as f32; + } + } + PieceType::Bishop => { + for source in serialize_bitboard(*piece) { + mobility += pop_count(self.attacks.bishop(self.occupancy, source) & (empty | opponent_occupancy)) as f32; + } + } + PieceType::Rook => { + for source in serialize_bitboard(*piece) { + mobility += pop_count(self.attacks.rook(self.occupancy, source) & (empty | opponent_occupancy)) as f32; + } + } + PieceType::Queen => { + for source in serialize_bitboard(*piece) { + mobility += pop_count(self.attacks.queen(self.occupancy, source) & (empty | opponent_occupancy)) as f32; + } + } + incorrect_type => panic!("Incorrect piece type: {:?}", incorrect_type), + } + } + + mobility + } + + /// *Blindlessly* apply a move without any validation /// Move should be validated beforehand pub fn make_move(&mut self, mov: Move) -> Option<PieceType> { @@ -634,6 +735,16 @@ mod tests { } #[test] + fn mobility() { + let board = Board::new(); + let white = board.mobility(Color::White); + let black = board.mobility(Color::Black); + + assert_eq!(white, 20.); + assert_eq!(black, 20.); + } + + #[test] fn make_move() { let fen = String::from("q1b2k2/5p1p/4p1pb/pPPp4/3N4/3nPB2/P2QKnR1/1R6 w - - 0 25"); let mut board = Board::from_FEN(fen); |