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Merge Gary's bishop_pin patch

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Give a bonus if a bishop can pin a piece or can
give a discovered check through an x-ray attack.

Seems good after 24000 games at 15"+0.05 (single thread):

ELO: 12.30 +- 99%: 5.79 95%: 4.40 LOS: 100.00%
Total: 24000 W: 4931 L: 4082 D: 14987

bench: 4917064
This commit is contained in:
Marco Costalba 2013-02-20 12:19:19 +01:00
commit 9a1d5f0f1d
1 changed files with 10 additions and 14 deletions
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24
src/evaluate.cpp
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@ -150,6 +150,8 @@ namespace {
#undef S
const Score BishopPinBonus = make_score(66, 11);
// Bonus for having the side to move (modified by Joona Kiiski)
const Score Tempo = make_score(24, 11);
@ -577,23 +579,18 @@ Value do_evaluate(const Position& pos, Value& margin) {
mobility += MobilityBonus[Piece][mob];
// Add a bonus if a slider is pinning an enemy piece
if ( (Piece == BISHOP || Piece == ROOK || Piece == QUEEN)
&& (PseudoAttacks[Piece][pos.king_square(Them)] & s))
{
b = BetweenBB[s][pos.king_square(Them)] & pos.pieces();
assert(b);
if (!more_than_one(b) && (b & pos.pieces(Them)))
score += ThreatBonus[Piece][type_of(pos.piece_on(lsb(b)))];
}
// Decrease score if we are attacked by an enemy pawn. Remaining part
// of threat evaluation must be done later when we have full attack info.
if (ei.attackedBy[Them][PAWN] & s)
score -= ThreatenedByPawnPenalty[Piece];
// Otherwise give a bonus if we are a bishop and can pin a piece or
// can give a discovered check through an x-ray attack.
else if ( Piece == BISHOP
&& (PseudoAttacks[Piece][pos.king_square(Them)] & s)
&& !more_than_one(BetweenBB[s][pos.king_square(Them)] & pos.pieces()))
score += BishopPinBonus;
// Bishop and knight outposts squares
if ( (Piece == BISHOP || Piece == KNIGHT)
&& !(pos.pieces(Them, PAWN) & attack_span_mask(Us, s)))
@ -699,8 +696,7 @@ Value do_evaluate(const Position& pos, Value& margin) {
& ~ei.attackedBy[Them][0];
if (undefendedMinors)
score += more_than_one(undefendedMinors) ? UndefendedMinorPenalty * 2
: UndefendedMinorPenalty;
score += UndefendedMinorPenalty;
// Enemy pieces not defended by a pawn and under our attack
weakEnemies = pos.pieces(Them)