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Small bonus for all safe pawn pushes

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Pawn flexibility: add a small bonus for all safe pawn pushes

STC:
LLR: 2.70 (-2.94,2.94) [-1.50,4.50]
Total: 18233 W: 3705 L: 3557 D: 10971

LTC:
LLR: 2.97 (-2.94,2.94) [0.00,6.00]
Total: 17684 W: 3042 L: 2854 D: 11788

Bench: 7369224

Resolves #253
This commit is contained in:
snicolet 2015-02-13 21:33:00 +00:00 • committed by Joona Kiiski
parent 44a571c1c7
commit a8f9c7a790
1 changed files with 7 additions and 2 deletions
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9
src/evaluate.cpp
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@ -163,6 +163,7 @@ namespace {
const Score Unstoppable = S( 0, 20); const Score Unstoppable = S( 0, 20);
const Score Hanging = S(31, 26); const Score Hanging = S(31, 26);
const Score PawnAttackThreat = S(20, 20); const Score PawnAttackThreat = S(20, 20);
const Score PawnSafePush = S( 5 , 5);
// Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
// a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
@ -547,14 +548,18 @@ namespace {
score += more_than_one(b) ? KingOnMany : KingOnOne; score += more_than_one(b) ? KingOnMany : KingOnOne;
} }
// Add bonus for safe pawn pushes which attacks an enemy piece // Add a small bonus for safe pawn pushes
b = pos.pieces(Us, PAWN) & ~TRank7BB; b = pos.pieces(Us, PAWN) & ~TRank7BB;
b = shift_bb<Up>(b | (shift_bb<Up>(b & TRank2BB) & ~pos.pieces())); b = shift_bb<Up>(b | (shift_bb<Up>(b & TRank2BB) & ~pos.pieces()));
b &= ~pos.pieces() b &= ~pos.pieces()
& ~ei.attackedBy[Them][PAWN] & ~ei.attackedBy[Them][PAWN]
& (ei.attackedBy[Us][PAWN] | ~ei.attackedBy[Them][ALL_PIECES]); & (ei.attackedBy[Us][ALL_PIECES] | ~ei.attackedBy[Them][ALL_PIECES]);
if (b)
score += popcount<Full>(b) * PawnSafePush;
// Add another bonus if the pawn push attacks an enemy piece
b = (shift_bb<Left>(b) | shift_bb<Right>(b)) b = (shift_bb<Left>(b) | shift_bb<Right>(b))
& pos.pieces(Them) & pos.pieces(Them)
& ~ei.attackedBy[Us][PAWN]; & ~ei.attackedBy[Us][PAWN];