After extensive test Gary says:
"So, after 16k games at 10"+1" on an i7, the undefended rook test
looks to be not good (albeit by a very small margin).
3063 - 3093 - 9844 (-1).
I doubt that is causing the regression, but even so, it looks like
it's not worth keeping, and we can go back to the simpler undefended
minors check."
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
// happen in Chess960 games.
const Score TrappedBishopA1H1Penalty = make_score(100, 100);
// happen in Chess960 games.
const Score TrappedBishopA1H1Penalty = make_score(100, 100);
- // Penalty for BNR that is not defended by anything
- const Score UndefendedPiecePenalty = make_score(25, 10);
+ // Penalty for an undefended bishop or knight
+ const Score UndefendedMinorPenalty = make_score(25, 10);
// The SpaceMask[Color] contains the area of the board which is considered
// by the space evaluation. In the middle game, each side is given a bonus
// The SpaceMask[Color] contains the area of the board which is considered
// by the space evaluation. In the middle game, each side is given a bonus
const Color Them = (Us == WHITE ? BLACK : WHITE);
const Color Them = (Us == WHITE ? BLACK : WHITE);
- Bitboard b, undefended, undefendedMinors, weakEnemies;
+ Bitboard b, undefendedMinors, weakEnemies;
Score score = SCORE_ZERO;
Score score = SCORE_ZERO;
- // Undefended pieces get penalized even if not under attack
- undefended = pos.pieces(Them) & ~ei.attackedBy[Them][0];
- undefendedMinors = undefended & (pos.pieces(BISHOP) | pos.pieces(KNIGHT));
+ // Undefended minors get penalized even if not under attack
+ undefendedMinors = pos.pieces(Them)
+ & (pos.pieces(BISHOP) | pos.pieces(KNIGHT))
+ & ~ei.attackedBy[Them][0];
- score += single_bit(undefendedMinors) ? UndefendedPiecePenalty
- : UndefendedPiecePenalty * 2;
- if (undefended & pos.pieces(ROOK))
- score += UndefendedPiecePenalty;
+ score += single_bit(undefendedMinors) ? UndefendedMinorPenalty
+ : UndefendedMinorPenalty * 2;
// Enemy pieces not defended by a pawn and under our attack
weakEnemies = pos.pieces(Them)
// Enemy pieces not defended by a pawn and under our attack
weakEnemies = pos.pieces(Them)