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rules: rework castling rules

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dece 2020-06-11 19:32:47 +02:00
parent cef59b9913
commit b334d55abf
1 changed files with 32 additions and 10 deletions
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42
src/rules.rs
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@ -39,7 +39,14 @@ pub const CASTLING_BL_MASK: u8 = 0b00001100;
pub const CASTLING_K_MASK: u8 = 0b00000101; pub const CASTLING_K_MASK: u8 = 0b00000101;
pub const CASTLING_Q_MASK: u8 = 0b00001010; pub const CASTLING_Q_MASK: u8 = 0b00001010;
pub const CASTLING_MASK: u8 = 0b00001111; pub const CASTLING_MASK: u8 = 0b00001111;
pub const CASTLING_SIDES: [(i8, u8); 2] = [(5i8, CASTLING_K_MASK), (3i8, CASTLING_Q_MASK)];
/// Castling sides parameters.
///
/// For both sides, the 3-uple contains files that should be empty
/// and not attacked, an optional file that should be empty for
/// queen-side, and the castling side-mask.
pub const CASTLING_SIDES: [([i8; 2], Option<i8>, u8); 2] =
[([5i8, 6i8], None, CASTLING_K_MASK), ([3i8, 2i8], Some(1i8), CASTLING_Q_MASK)];
pub const START_WH_K_POS: Pos = pos("e1"); pub const START_WH_K_POS: Pos = pos("e1");
pub const START_BL_K_POS: Pos = pos("e8"); pub const START_BL_K_POS: Pos = pos("e8");
@ -447,24 +454,39 @@ fn get_king_moves(
}; };
// Check for castling if the king is on its castling rank (R1) // Check for castling if the king is on its castling rank (R1)
// and is not in check (R4) // and is not in check (R4).
if if
*r == castling_rank && *r == castling_rank &&
!is_attacked(board, game_state, at) !is_attacked(board, game_state, at)
{ {
// Check for both castling sides. // Check for both castling sides.
for (through_f, castling_side_mask) in CASTLING_SIDES.iter() { for (path_files, opt_empty_file, castling_side_mask) in CASTLING_SIDES.iter() {
// Check for castling availability for this color and side. // Check for castling availability for this color and side.
if (game_state.castling & castling_color_mask & castling_side_mask) != 0 { if (game_state.castling & castling_color_mask & castling_side_mask) != 0 {
// R3, R5, R6: check that files on the way are empty and not attacked. // Check that squares in the king's path are empty and not attacked (R3.1, R5, R6).
let p = (*through_f, castling_rank); let mut path_is_clear = true;
if is_empty(board, &p) && !is_illegal(board, game_state, &(*at, p, None)) { for path_f in path_files {
let castle = CASTLING_K_MASK & castling_color_mask; let p = (*path_f, castling_rank);
let m = get_castle_move(castle); if !is_empty(board, &p) || is_illegal(board, game_state, &(*at, p, None)) {
if can_register(commit, board, game_state, &m) { path_is_clear = false;
moves.push(m); break;
} }
} }
if !path_is_clear {
continue;
}
// Check that rook jumps over an empty square on queen-side (R3.2).
if let Some(rook_path_f) = opt_empty_file {
let p = (*rook_path_f, castling_rank);
if !is_empty(board, &p) {
continue;
}
}
let castle = castling_side_mask & castling_color_mask;
let m = get_castle_move(castle);
if can_register(commit, board, game_state, &m) {
moves.push(m);
}
} }
} }
} }