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Make 'ChessBoard::xor' apply square-wise

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This will make it easier to add Zobrist hashing afterwards.
This commit is contained in:
Bruno BELANYI 2024-04-06 17:44:27 +01:00
parent 85ac65408f
commit b2560aa183
1 changed files with 11 additions and 23 deletions
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34
src/board/chess_board/mod.rs
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@ -123,13 +123,12 @@ impl ChessBoard {
self.compute_checkers(self.current_player())
}
/// Quickly do and undo a move on the [Bitboard]s that are part of the [ChessBoard] state. Does
/// not account for all non-revertible changes such as en-passant state or half-move clock.
/// Quickly add/remove a piece on the [Bitboard]s that are part of the [ChessBoard] state.
#[inline(always)]
fn xor(&mut self, color: Color, piece: Piece, start_end: Bitboard) {
*self.piece_occupancy_mut(piece) ^= start_end;
*self.color_occupancy_mut(color) ^= start_end;
self.combined_occupancy ^= start_end;
fn xor(&mut self, color: Color, piece: Piece, square: Square) {
*self.piece_occupancy_mut(piece) ^= square;
*self.color_occupancy_mut(color) ^= square;
self.combined_occupancy ^= square;
}
/// Play the given [Move], return a copy of the board with the resulting state.
@ -186,9 +185,7 @@ impl ChessBoard {
_ => *castle_rights,
};
if let Some(piece) = captured_piece {
*self.piece_occupancy_mut(piece) ^= chess_move.destination();
*self.color_occupancy_mut(opponent) ^= chess_move.destination();
self.combined_occupancy ^= chess_move.destination();
self.xor(opponent, piece, chess_move.destination());
// If a rook is captured, it loses its castling rights
let castle_rights = self.castle_rights_mut(opponent);
*castle_rights = match (piece, chess_move.destination().file()) {
@ -199,11 +196,8 @@ impl ChessBoard {
}
// Revertible state modification
self.xor(
self.current_player(),
move_piece,
chess_move.start() | chess_move.destination(),
);
self.xor(self.current_player(), move_piece, chess_move.start());
self.xor(self.current_player(), move_piece, chess_move.destination());
self.total_plies += 1;
self.side = !self.side;
@ -225,19 +219,13 @@ impl ChessBoard {
.unwrap();
if let Some(piece) = previous.captured_piece {
*self.piece_occupancy_mut(piece) ^= chess_move.destination();
// The capture affected the *current* player, from our post-move POV
*self.color_occupancy_mut(self.current_player()) ^= chess_move.destination();
self.combined_occupancy ^= chess_move.destination();
self.xor(self.current_player(), piece, chess_move.destination());
}
// Restore revertible state
self.xor(
// The move was applied at the turn *before* the current player
!self.current_player(),
move_piece,
chess_move.start() | chess_move.destination(),
);
self.xor(!self.current_player(), move_piece, chess_move.destination());
self.xor(!self.current_player(), move_piece, chess_move.start());
self.total_plies -= 1;
self.side = !self.side;
}