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Space inflate evaluate_passed_pawns()

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No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2009-01-06 15:49:33 +01:00
parent d0804341c5
commit e236a0c652
1 changed files with 134 additions and 124 deletions
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258
src/evaluate.cpp
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@ -905,148 +905,158 @@ namespace {
// evaluate_passed_pawns() evaluates the passed pawns for both sides. // evaluate_passed_pawns() evaluates the passed pawns for both sides.
void evaluate_passed_pawns(const Position &pos, EvalInfo &ei) { void evaluate_passed_pawns(const Position &pos, EvalInfo &ei) {
bool hasUnstoppable[2] = {false, false}; bool hasUnstoppable[2] = {false, false};
int movesToGo[2] = {100, 100}; int movesToGo[2] = {100, 100};
for(Color us = WHITE; us <= BLACK; us++) { for (Color us = WHITE; us <= BLACK; us++)
Color them = opposite_color(us); {
Square ourKingSq = pos.king_square(us); Color them = opposite_color(us);
Square theirKingSq = pos.king_square(them); Square ourKingSq = pos.king_square(us);
Bitboard b = ei.pi->passed_pawns() & pos.pawns(us), b2, b3, b4; Square theirKingSq = pos.king_square(them);
Bitboard b = ei.pi->passed_pawns() & pos.pawns(us), b2, b3, b4;
while(b) { while (b)
Square s = pop_1st_bit(&b); {
assert(pos.piece_on(s) == pawn_of_color(us)); Square s = pop_1st_bit(&b);
assert(pos.pawn_is_passed(us, s));
int r = int(relative_rank(us, s) - RANK_2); assert(pos.piece_on(s) == pawn_of_color(us));
int tr = Max(0, r * (r-1)); assert(pos.pawn_is_passed(us, s));
Square blockSq = s + pawn_push(us);
// Base bonus based on rank: int r = int(relative_rank(us, s) - RANK_2);
Value mbonus = Value(20 * tr); int tr = Max(0, r * (r - 1));
Value ebonus = Value(10 + r * r * 10); Square blockSq = s + pawn_push(us);
// Adjust bonus based on king proximity: // Base bonus based on rank
ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr); Value mbonus = Value(20 * tr);
ebonus -= Value ebonus = Value(10 + r * r * 10);
Value(square_distance(ourKingSq, blockSq + pawn_push(us)) * 1 * tr);
ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
// If the pawn is free to advance, increase bonus: // Adjust bonus based on king proximity
if(pos.square_is_empty(blockSq)) { ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(us)) * 1 * tr);
ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
b2 = squares_in_front_of(us, s); // If the pawn is free to advance, increase bonus
b3 = b2 & ei.attacked_by(them); if (pos.square_is_empty(blockSq))
b4 = b2 & ei.attacked_by(us); {
b2 = squares_in_front_of(us, s);
b3 = b2 & ei.attacked_by(them);
b4 = b2 & ei.attacked_by(us);
// If there is an enemy rook or queen attacking the pawn from behind, // If there is an enemy rook or queen attacking the pawn from behind,
// add all X-ray attacks by the rook or queen. // add all X-ray attacks by the rook or queen.
if(bit_is_set(ei.attacked_by(them,ROOK)|ei.attacked_by(them,QUEEN),s) if ( bit_is_set(ei.attacked_by(them,ROOK) | ei.attacked_by(them,QUEEN),s)
&& squares_behind(us, s) & pos.rooks_and_queens(them)) && (squares_behind(us, s) & pos.rooks_and_queens(them)))
b3 = b2; b3 = b2;
if((b2 & pos.pieces_of_color(them)) == EmptyBoardBB) { if ((b2 & pos.pieces_of_color(them)) == EmptyBoardBB)
// There are no enemy pieces in the pawn's path! Are any of the {
// squares in the pawn's path attacked by the enemy? // There are no enemy pieces in the pawn's path! Are any of the
if(b3 == EmptyBoardBB) // squares in the pawn's path attacked by the enemy?
// No enemy attacks, huge bonus! if (b3 == EmptyBoardBB)
ebonus += Value(tr * ((b2 == b4)? 17 : 15)); // No enemy attacks, huge bonus!
else ebonus += Value(tr * (b2 == b4 ? 17 : 15));
// OK, there are enemy attacks. Are those squares which are else
// attacked by the enemy also attacked by us? If yes, big bonus // OK, there are enemy attacks. Are those squares which are
// (but smaller than when there are no enemy attacks), if no, // attacked by the enemy also attacked by us? If yes, big bonus
// somewhat smaller bonus. // (but smaller than when there are no enemy attacks), if no,
ebonus += Value(tr * (((b3 & b4) == b3)? 13 : 8)); // somewhat smaller bonus.
} ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
else { }
// There are some enemy pieces in the pawn's path. While this is else
// sad, we still assign a moderate bonus if all squares in the path {
// which are either occupied by or attacked by enemy pieces are // There are some enemy pieces in the pawn's path. While this is
// also attacked by us. // sad, we still assign a moderate bonus if all squares in the path
if(((b3 | (b2 & pos.pieces_of_color(them))) & ~b4) == EmptyBoardBB) // which are either occupied by or attacked by enemy pieces are
ebonus += Value(tr * 6); // also attacked by us.
} if (((b3 | (b2 & pos.pieces_of_color(them))) & ~b4) == EmptyBoardBB)
// At last, add a small bonus when there are no *friendly* pieces ebonus += Value(tr * 6);
// in the pawn's path: }
if((b2 & pos.pieces_of_color(us)) == EmptyBoardBB) // At last, add a small bonus when there are no *friendly* pieces
ebonus += Value(tr); // in the pawn's path.
} if ((b2 & pos.pieces_of_color(us)) == EmptyBoardBB)
ebonus += Value(tr);
// If the pawn is supported by a friendly pawn, increase bonus.
b2 = pos.pawns(us) & neighboring_files_bb(s);
if(b2 & rank_bb(s))
ebonus += Value(r * 20);
else if(pos.pawn_attacks(them, s) & b2)
ebonus += Value(r * 12);
// If the other side has only a king, check whether the pawn is
// unstoppable:
if(pos.non_pawn_material(them) == Value(0)) {
Square qsq;
int d;
qsq = relative_square(us, make_square(square_file(s), RANK_8));
d = square_distance(s, qsq) - square_distance(theirKingSq, qsq)
+ ((us == pos.side_to_move())? 0 : 1);
if(d < 0) {
int mtg = RANK_8 - relative_rank(us, s);
int blockerCount =
count_1s_max_15(squares_in_front_of(us,s)&pos.occupied_squares());
mtg += blockerCount;
d += blockerCount;
if(d < 0) {
hasUnstoppable[us] = true;
movesToGo[us] = Min(movesToGo[us], mtg);
} }
}
}
// Rook pawns are a special case: They are sometimes worse, and
// sometimes better than other passed pawns. It is difficult to find
// good rules for determining whether they are good or bad. For now,
// we try the following: Increase the value for rook pawns if the
// other side has no pieces apart from a knight, and decrease the
// value if the other side has a rook or queen.
if(square_file(s) == FILE_A || square_file(s) == FILE_H) {
if(pos.non_pawn_material(them) == KnightValueMidgame
&& pos.piece_count(them, KNIGHT) == 1)
ebonus += ebonus / 4;
else if(pos.rooks_and_queens(them))
ebonus -= ebonus / 4;
}
// Add the scores for this pawn to the middle game and endgame eval. // If the pawn is supported by a friendly pawn, increase bonus
ei.mgValue += apply_weight(Sign[us] * mbonus, WeightPassedPawnsMidgame); b2 = pos.pawns(us) & neighboring_files_bb(s);
ei.egValue += apply_weight(Sign[us] * ebonus, WeightPassedPawnsEndgame); if (b2 & rank_bb(s))
} ebonus += Value(r * 20);
else if (pos.pawn_attacks(them, s) & b2)
ebonus += Value(r * 12);
// If the other side has only a king, check whether the pawn is
// unstoppable
if (pos.non_pawn_material(them) == Value(0))
{
Square qsq;
int d;
qsq = relative_square(us, make_square(square_file(s), RANK_8));
d = square_distance(s, qsq)
- square_distance(theirKingSq, qsq)
+ (us != pos.side_to_move());
if (d < 0)
{
int mtg = RANK_8 - relative_rank(us, s);
int blockerCount = count_1s_max_15(squares_in_front_of(us,s) & pos.occupied_squares());
mtg += blockerCount;
d += blockerCount;
if (d < 0)
{
hasUnstoppable[us] = true;
movesToGo[us] = Min(movesToGo[us], mtg);
}
}
}
// Rook pawns are a special case: They are sometimes worse, and
// sometimes better than other passed pawns. It is difficult to find
// good rules for determining whether they are good or bad. For now,
// we try the following: Increase the value for rook pawns if the
// other side has no pieces apart from a knight, and decrease the
// value if the other side has a rook or queen.
if (square_file(s) == FILE_A || square_file(s) == FILE_H)
{
if( pos.non_pawn_material(them) == KnightValueMidgame // FIXME should be <= ???
&& pos.piece_count(them, KNIGHT) == 1)
ebonus += ebonus / 4;
else if(pos.rooks_and_queens(them))
ebonus -= ebonus / 4;
}
// Add the scores for this pawn to the middle game and endgame eval.
ei.mgValue += apply_weight(Sign[us] * mbonus, WeightPassedPawnsMidgame);
ei.egValue += apply_weight(Sign[us] * ebonus, WeightPassedPawnsEndgame);
}
} }
// Does either side have an unstoppable passed pawn? // Does either side have an unstoppable passed pawn?
if(hasUnstoppable[WHITE] && !hasUnstoppable[BLACK]) if (hasUnstoppable[WHITE] && !hasUnstoppable[BLACK])
ei.egValue += UnstoppablePawnValue - Value(0x40 * movesToGo[WHITE]); ei.egValue += UnstoppablePawnValue - Value(0x40 * movesToGo[WHITE]);
else if(hasUnstoppable[BLACK] && !hasUnstoppable[WHITE]) else if (hasUnstoppable[BLACK] && !hasUnstoppable[WHITE])
ei.egValue -= UnstoppablePawnValue - Value(0x40 * movesToGo[BLACK]); ei.egValue -= UnstoppablePawnValue - Value(0x40 * movesToGo[BLACK]);
else if(hasUnstoppable[BLACK] && hasUnstoppable[WHITE]) { else if (hasUnstoppable[BLACK] && hasUnstoppable[WHITE])
// Both sides have unstoppable pawns! Try to find out who queens {
// first. We begin by transforming 'movesToGo' to the number of // Both sides have unstoppable pawns! Try to find out who queens
// plies until the pawn queens for both sides: // first. We begin by transforming 'movesToGo' to the number of
movesToGo[WHITE] *= 2; // plies until the pawn queens for both sides.
movesToGo[BLACK] *= 2; movesToGo[WHITE] *= 2;
movesToGo[pos.side_to_move()]--; movesToGo[BLACK] *= 2;
movesToGo[pos.side_to_move()]--;
// If one side queens at least three plies before the other, that // If one side queens at least three plies before the other, that
// side wins: // side wins.
if(movesToGo[WHITE] <= movesToGo[BLACK] - 3) if (movesToGo[WHITE] <= movesToGo[BLACK] - 3)
ei.egValue += UnstoppablePawnValue - Value(0x40 * (movesToGo[WHITE]/2)); ei.egValue += UnstoppablePawnValue - Value(0x40 * (movesToGo[WHITE]/2));
else if(movesToGo[BLACK] <= movesToGo[WHITE] - 3) else if(movesToGo[BLACK] <= movesToGo[WHITE] - 3)
ei.egValue -= UnstoppablePawnValue - Value(0x40 * (movesToGo[BLACK]/2)); ei.egValue -= UnstoppablePawnValue - Value(0x40 * (movesToGo[BLACK]/2));
// We could also add some rules about the situation when one side // We could also add some rules about the situation when one side
// queens exactly one ply before the other: Does the first queen // queens exactly one ply before the other: Does the first queen
// check the opponent's king, or attack the opponent's queening square? // check the opponent's king, or attack the opponent's queening square?
// This is slightly tricky to get right, because it is possible that // This is slightly tricky to get right, because it is possible that
// the opponent's king has moved somewhere before the first pawn queens. // the opponent's king has moved somewhere before the first pawn queens.
} }
} }