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-rw-r--r--src/board.rs183
-rw-r--r--src/moves.rs2
-rw-r--r--src/square.rs14
3 files changed, 158 insertions, 41 deletions
diff --git a/src/board.rs b/src/board.rs
index efe0b80..1c06c9b 100644
--- a/src/board.rs
+++ b/src/board.rs
@@ -158,10 +158,12 @@ impl Board {
pub fn generate_moves(&self, color: Color) -> Vec<Move> {
let mut moves = Vec::with_capacity(1024);
- let opponent_occupancy = self.color_occupancy(Color::from(color as u8).flip());
+ let opponent_occupancy = self.color_occupancy(color.flip());
let empty = self.empty();
let available_targets = opponent_occupancy | empty;
- for (piece_type, piece) in self.pieces_by_color(color).iter().enumerate() {
+ 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) {
@@ -200,6 +202,56 @@ impl Board {
for target in serialize_bitboard(self.attacks.king[source as usize] & opponent_occupancy) {
moves.push(Move { source, target, kind: MoveKind::Capture });
};
+
+ // 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 {
+ moves.push(Move {
+ source: king_home_position,
+ target: king_home_position.west_one().west_one(),
+ kind: MoveKind::Castle,
+ })
+ }
+ },
+ 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 {
+ moves.push(Move {
+ source: king_home_position,
+ target: king_home_position.east_one().east_one(),
+ kind: MoveKind::Castle,
+ })
+ }
+ },
+ _ => {},
+ }
+ }
+ }
}
}
PieceType::Knight => {
@@ -270,14 +322,13 @@ impl Board {
};
// En Passant captures diffirently
- captured_piece = match mov.kind {
- MoveKind::EnPassant => {
- debug_assert!(captured_piece.is_none(), "No capture should be found at this point");
- let captured_bb = Square::from(mov.source.rank() * 8 + mov.target.file()).to_bitboard();
- match self.pieces
- .iter()
- .enumerate()
- .find(|(piece_type, bitboard)| *bitboard & captured_bb > 0)
+ if mov.kind == MoveKind::EnPassant {
+ debug_assert!(captured_piece.is_none(), "No capture should be found at this point");
+ let captured_bb = Square::from_coords(mov.source.rank(), mov.target.file()).to_bitboard();
+ captured_piece = match self.pieces
+ .iter()
+ .enumerate()
+ .find(|(piece_type, bitboard)| *bitboard & captured_bb > 0)
{
Some((pawn_type, _)) => {
self.pieces[pawn_type] ^= captured_bb;
@@ -285,9 +336,7 @@ impl Board {
}
None => panic!("Pawn captured by En Passant was not found"),
}
- },
- _ => captured_piece,
- };
+ }
// Move a piece from source square to target
match self.pieces
@@ -305,20 +354,42 @@ impl Board {
None => panic!("Move is malformed: source piece not found"),
};
- // Double push should set En Passant target square
- match mov.kind {
- MoveKind::DoublePush => {
- self.ep_target = match mov.source.rank() {
- 1 => Some(mov.source.nort_one()),
- 6 => Some(mov.source.sout_one()),
- rank => panic!("Double-push was used from invalid rank({}) when trying to make {:?}", rank, mov),
- };
- },
- _ => {
- self.ep_target = None
- },
+ // When castling, also move a rook
+ if mov.kind == MoveKind::Castle {
+ debug_assert!(mov.source.file() == 4, "Castle can only be done from E file");
+ let (rook_source_file, rook_target_file) = match mov.target.file() {
+ 2 => (0, 3),
+ 6 => (7, 5),
+ _ => panic!("Malformed castle, target square invalid: {:?}", mov),
+ };
+ let rook_source_bb = Square::from_coords(mov.target.rank(), rook_source_file).to_bitboard();
+ let rook_target_bb = Square::from_coords(mov.target.rank(), rook_target_file).to_bitboard();
+
+ match self.pieces
+ .iter()
+ .enumerate()
+ .find(|(rook_type, bitboard)| *bitboard & rook_source_bb > 0)
+ {
+ Some((rook_type, _)) => {
+ self.pieces[rook_type] ^= rook_source_bb;
+ self.occupancy ^= rook_source_bb;
+
+ self.pieces[rook_type] |= rook_target_bb;
+ self.occupancy |= rook_target_bb;
+ },
+ None => panic!("Rook was not found when castling"),
+ }
}
+ // Double push should set En Passant target square
+ self.ep_target = if mov.kind == MoveKind::DoublePush {
+ match mov.source.rank() {
+ 1 => Some(mov.source.nort_one()),
+ 6 => Some(mov.source.sout_one()),
+ rank => panic!("Double-push was used from invalid rank({}) when trying to make {:?}", rank, mov),
+ }
+ } else { None };
+
self.ply += 1;
captured_piece
@@ -345,13 +416,39 @@ impl Board {
None => panic!("Trying to unmake move which was not made: no piece was found on target square"),
};
+ // If unmaking castle, also return rook to its place
+ if mov.kind == MoveKind::Castle {
+ let (rook_source_file, rook_target_file) = match mov.target.file() {
+ 2 => (0, 3),
+ 6 => (7, 5),
+ _ => panic!("Malformed castle, target square invalid: {:?}", mov),
+ };
+ let rook_source_bb = Square::from_coords(mov.target.rank(), rook_source_file).to_bitboard();
+ let rook_target_bb = Square::from_coords(mov.target.rank(), rook_target_file).to_bitboard();
+
+ match self.pieces
+ .iter()
+ .enumerate()
+ .find(|(rook_type, bitboard)| *bitboard & rook_target_bb > 0)
+ {
+ Some((rook_type, _)) => {
+ self.pieces[rook_type] |= rook_source_bb;
+ self.occupancy |= rook_source_bb;
+
+ self.pieces[rook_type] ^= rook_target_bb;
+ self.occupancy ^= rook_target_bb;
+ },
+ None => panic!("Rook was not found when castling"),
+ }
+ }
+
// Return captured piece to target square
match captured_piece {
Some(target_piece) => {
match mov.kind {
// Return pawn captured by En Passant pawn if needed
MoveKind::EnPassant => {
- let original_dead_pawn_bb = Square::from(mov.source.rank() * 8 + mov.target.file()).to_bitboard();
+ let original_dead_pawn_bb = Square::from_coords(mov.source.rank(), mov.target.file()).to_bitboard();
self.pieces[target_piece as usize] |= original_dead_pawn_bb;
self.occupancy |= original_dead_pawn_bb;
},
@@ -369,9 +466,9 @@ impl Board {
self.ply -= 1;
}
- fn perft(&mut self, depth: u8, print: bool) -> (u64, u64, u64, u64) {
+ fn perft(&mut self, depth: u8, print: bool) -> (u64, u64, u64, u64, u64) {
if depth == 0 {
- return (1, 0, 0, 0) // This a leaf, exactly one node
+ return (1, 0, 0, 0, 0) // This a leaf, exactly one node
}
let color = self.color_to_move();
@@ -385,6 +482,7 @@ impl Board {
let mut total = 0;
let mut captures = 0;
let mut checks = 0;
+ let mut castles = 0;
let mut en_passants = 0;
for mov in moves {
@@ -401,6 +499,9 @@ impl Board {
en_passants += 1;
captures += 1;
}
+ MoveKind::Castle => {
+ castles += 1;
+ }
_ => {}
}
if self.is_king_in_check(color.flip()) {
@@ -412,10 +513,11 @@ impl Board {
println!("{:?}", mov);
self.print();
}
- let (children_total, children_tactical, children_checks, children_ep) = self.perft(depth - 1, print);
+ let (children_total, children_tactical, children_checks, children_castles, children_ep) = self.perft(depth - 1, print);
total += children_total;
captures += children_tactical;
checks += children_checks;
+ castles += children_castles;
en_passants += children_ep;
}
@@ -426,7 +528,7 @@ impl Board {
println!("Found {} nodes in this subtree (depth {})", total, depth);
}
- (total, captures, checks, en_passants)
+ (total, captures, checks, castles, en_passants)
}
fn is_square_attacked(&self, square: Square, attacker_color: Color) -> bool {
@@ -609,22 +711,23 @@ mod tests {
fn test_perft() {
let mut board = Board::new();
- assert_eq!(board.perft(0, false), (1, 0, 0, 0));
- assert_eq!(board.perft(1, false), (20, 0, 0, 0));
- assert_eq!(board.perft(2, false), (400, 0, 0, 0));
- assert_eq!(board.perft(3, false), (8902, 34, 12, 0));
- assert_eq!(board.perft(4, false), (197281, 1576, 469, 0));
- // assert_eq!(board.perft(5, false), (4865609, 82719, 27351, 258));
- // assert_eq!(board.perft(6, false), (119060324 , 2812008, 809099 , 5248));
+ assert_eq!(board.perft(0, false), (1, 0, 0, 0, 0));
+ assert_eq!(board.perft(1, false), (20, 0, 0, 0, 0));
+ assert_eq!(board.perft(2, false), (400, 0, 0, 0, 0));
+ assert_eq!(board.perft(3, false), (8902, 34, 12, 0, 0));
+ assert_eq!(board.perft(4, false), (197281, 1576, 469, 0, 0));
+ // assert_eq!(board.perft(5, false), (4865609, 82719, 27351, 0, 258));
+ // assert_eq!(board.perft(6, false), (119060324, 2812008, 809099, 0, 5248));
}
#[test]
fn test_position_perft() {
let fen = String::from("r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq - ");
let mut board = Board::from_FEN(fen);
- assert_eq!(board.perft(0, false), (1, 0, 0, 0));
- assert_eq!(board.perft(1, false), (48, 8, 0, 0));
- assert_eq!(board.perft(2, false), (2039, 351, 3, 1));
+ assert_eq!(board.perft(0, false), (1, 0, 0, 0, 0));
+ assert_eq!(board.perft(1, false), (48, 8, 0, 2, 0));
+ assert_eq!(board.perft(2, false), (2039, 351, 3, 91, 1));
+ assert_eq!(board.perft(3, false), (97862, 17102, 993, 3162, 45));
}
#[test]
diff --git a/src/moves.rs b/src/moves.rs
index d0e3eb6..f31d864 100644
--- a/src/moves.rs
+++ b/src/moves.rs
@@ -1,6 +1,6 @@
use crate::{square::Square, bitboard::print};
-#[derive(Debug, Clone, Copy)]
+#[derive(Debug, Clone, PartialEq, Eq, Copy)]
pub enum MoveKind {
Quiet,
Capture,
diff --git a/src/square.rs b/src/square.rs
index 1adca83..efa682c 100644
--- a/src/square.rs
+++ b/src/square.rs
@@ -16,6 +16,10 @@ pub enum Square {
A8, B8, C8, D8, E8, F8, G8, H8,
}
impl Square {
+ pub fn from_coords(rank: u8, file: u8) -> Self {
+ Self::from(rank * 8 + file)
+ }
+
pub fn to_bitboard(&self) -> Bitboard {
1u64 << *self as u8
}
@@ -35,6 +39,16 @@ impl Square {
pub fn sout_one(&self) -> Self {
Self::from(*self as u8 - 8)
}
+
+ /// Warning: this wraps which is not what you might expect!
+ pub fn west_one(&self) -> Self {
+ Self::from(*self as u8 - 1)
+ }
+
+ /// Warning: this wraps which is not what you might expect!
+ pub fn east_one(&self) -> Self {
+ Self::from(*self as u8 + 1)
+ }
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-26 19:23:18 +0000