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Space inflate evaluate_king()

Browse source 
This is the most complex piece of software
so far.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2008-09-25 16:43:37 +02:00
parent 2e3faae067
commit b00abed181
1 changed files with 118 additions and 86 deletions
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204
src/evaluate.cpp
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@ -697,6 +697,10 @@ namespace {
}
}
inline Bitboard shiftRowsDown(const Bitboard& b, int num) {
return b >> (num << 3);
}
// evaluate_king() assigns bonuses and penalties to a king of a given
// color on a given square.
@ -705,32 +709,37 @@ namespace {
int shelter = 0, sign = Sign[us];
// King shelter.
if(relative_rank(us, s) <= RANK_4) {
Bitboard pawns = p.pawns(us) & this_and_neighboring_files_bb(s);
Rank r = square_rank(s);
for(int i = 0; i < 3; i++)
shelter += count_1s_8bit(pawns >> ((r+(i+1)*sign) * 8)) * (64>>i);
ei.mgValue += sign * Value(shelter);
// King shelter
if (relative_rank(us, s) <= RANK_4)
{
Bitboard pawns = p.pawns(us) & this_and_neighboring_files_bb(s);
Rank r = square_rank(s);
for (int i = 1; i < 4; i++)
shelter += count_1s_8bit(shiftRowsDown(pawns, r+i*sign)) * (128>>i);
ei.mgValue += sign * Value(shelter);
}
// King safety. This is quite complicated, and is almost certainly far
// from optimally tuned.
Color them = opposite_color(us);
if(p.queen_count(them) >= 1 && ei.kingAttackersCount[them] >= 2
&& p.non_pawn_material(them) >= QueenValueMidgame + RookValueMidgame
&& ei.kingAdjacentZoneAttacksCount[them]) {
if ( p.queen_count(them) >= 1
&& ei.kingAttackersCount[them] >= 2
&& p.non_pawn_material(them) >= QueenValueMidgame + RookValueMidgame
&& ei.kingAdjacentZoneAttacksCount[them])
{
// Is it the attackers turn to move?
bool sente = (them == p.side_to_move());
// Find the attacked squares around the king which has no defenders
// apart from the king itself:
// apart from the king itself
Bitboard undefended =
ei.attacked_by(them) & ~ei.attacked_by(us, PAWN)
& ~ei.attacked_by(us, KNIGHT) & ~ei.attacked_by(us, BISHOP)
& ~ei.attacked_by(us, ROOK) & ~ei.attacked_by(us, QUEEN)
& ei.attacked_by(us, KING);
ei.attacked_by(them) & ~ei.attacked_by(us, PAWN)
& ~ei.attacked_by(us, KNIGHT) & ~ei.attacked_by(us, BISHOP)
& ~ei.attacked_by(us, ROOK) & ~ei.attacked_by(us, QUEEN)
& ei.attacked_by(us, KING);
Bitboard occ = p.occupied_squares(), b, b2;
// Initialize the 'attackUnits' variable, which is used later on as an
@ -739,113 +748,134 @@ namespace {
// undefended squares around the king, the square of the king, and the
// quality of the pawn shelter.
int attackUnits =
Min((ei.kingAttackersCount[them] * ei.kingAttackersWeight[them]) / 2, 25)
+ (ei.kingAdjacentZoneAttacksCount[them] + count_1s_max_15(undefended)) * 3
+ InitKingDanger[relative_square(us, s)] - shelter / 32;
Min((ei.kingAttackersCount[them] * ei.kingAttackersWeight[them]) / 2, 25)
+ (ei.kingAdjacentZoneAttacksCount[them] + count_1s_max_15(undefended)) * 3
+ InitKingDanger[relative_square(us, s)] - shelter / 32;
// Analyse safe queen contact checks:
// Analyse safe queen contact checks
b = undefended & ei.attacked_by(them, QUEEN) & ~p.pieces_of_color(them);
if(b) {
if (b)
{
Bitboard attackedByOthers =
ei.attacked_by(them, PAWN) | ei.attacked_by(them, KNIGHT)
| ei.attacked_by(them, BISHOP) | ei.attacked_by(them, ROOK);
ei.attacked_by(them, PAWN) | ei.attacked_by(them, KNIGHT)
| ei.attacked_by(them, BISHOP) | ei.attacked_by(them, ROOK);
b &= attackedByOthers;
if(b) {
if (b)
{
// The bitboard b now contains the squares available for safe queen
// contact checks.
int count = count_1s_max_15(b);
attackUnits += QueenContactCheckBonus * count * (sente? 2 : 1);
attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
// Is there a mate threat?
if(QueenContactMates && !p.is_check()) {
if (QueenContactMates && !p.is_check())
{
Bitboard escapeSquares =
p.king_attacks(s) & ~p.pieces_of_color(us) & ~attackedByOthers;
while(b) {
Square from, to = pop_1st_bit(&b);
if(!(escapeSquares
& ~queen_attacks_bb(to, occ & clear_mask_bb(s)))) {
// We have a mate, unless the queen is pinned or there
// is an X-ray attack through the queen.
for(int i = 0; i < p.queen_count(them); i++) {
from = p.queen_list(them, i);
if(bit_is_set(p.queen_attacks(from), to)
&& !bit_is_set(p.pinned_pieces(them), from)
&& !(rook_attacks_bb(to, occ & clear_mask_bb(from))
& p.rooks_and_queens(us))
&& !(rook_attacks_bb(to, occ & clear_mask_bb(from))
& p.rooks_and_queens(us)))
ei.mateThreat[them] = make_move(from, to);
p.king_attacks(s) & ~p.pieces_of_color(us) & ~attackedByOthers;
while (b)
{
Square from, to = pop_1st_bit(&b);
if (!(escapeSquares & ~queen_attacks_bb(to, occ & clear_mask_bb(s))))
{
// We have a mate, unless the queen is pinned or there
// is an X-ray attack through the queen.
for (int i = 0; i < p.queen_count(them); i++)
{
from = p.queen_list(them, i);
if ( bit_is_set(p.queen_attacks(from), to)
&& !bit_is_set(p.pinned_pieces(them), from)
&& !(rook_attacks_bb(to, occ & clear_mask_bb(from)) & p.rooks_and_queens(us))
&& !(rook_attacks_bb(to, occ & clear_mask_bb(from)) & p.rooks_and_queens(us)))
ei.mateThreat[them] = make_move(from, to);
}
}
}
}
}
}
}
// Analyse safe rook contact checks:
if(RookContactCheckBonus) {
b = undefended & ei.attacked_by(them, ROOK) & ~p.pieces_of_color(them);
if(b) {
Bitboard attackedByOthers =
ei.attacked_by(them, PAWN) | ei.attacked_by(them, KNIGHT)
| ei.attacked_by(them, BISHOP) | ei.attacked_by(them, QUEEN);
b &= attackedByOthers;
if(b) {
int count = count_1s_max_15(b);
attackUnits += (RookContactCheckBonus * count * (sente? 2 : 1));
if (RookContactCheckBonus)
{
b = undefended & ei.attacked_by(them, ROOK) & ~p.pieces_of_color(them);
if (b)
{
Bitboard attackedByOthers =
ei.attacked_by(them, PAWN) | ei.attacked_by(them, KNIGHT)
| ei.attacked_by(them, BISHOP) | ei.attacked_by(them, QUEEN);
b &= attackedByOthers;
if (b)
{
int count = count_1s_max_15(b);
attackUnits += (RookContactCheckBonus * count * (sente? 2 : 1));
}
}
}
}
// Analyse safe distance checks:
if(QueenCheckBonus > 0 || RookCheckBonus > 0) {
b = p.rook_attacks(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
if (QueenCheckBonus > 0 || RookCheckBonus > 0)
{
b = p.rook_attacks(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
// Queen checks
b2 = b & ei.attacked_by(them, QUEEN);
if(b2) attackUnits += QueenCheckBonus * count_1s_max_15(b2);
// Queen checks
b2 = b & ei.attacked_by(them, QUEEN);
if( b2)
attackUnits += QueenCheckBonus * count_1s_max_15(b2);
// Rook checks
b2 = b & ei.attacked_by(them, ROOK);
if(b2) attackUnits += RookCheckBonus * count_1s_max_15(b2);
// Rook checks
b2 = b & ei.attacked_by(them, ROOK);
if (b2)
attackUnits += RookCheckBonus * count_1s_max_15(b2);
}
if(QueenCheckBonus > 0 || BishopCheckBonus > 0) {
b = p.bishop_attacks(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
// Queen checks
b2 = b & ei.attacked_by(them, QUEEN);
if(b2) attackUnits += QueenCheckBonus * count_1s_max_15(b2);
if (QueenCheckBonus > 0 || BishopCheckBonus > 0)
{
b = p.bishop_attacks(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
// Bishop checks
b2 = b & ei.attacked_by(them, BISHOP);
if(b2) attackUnits += BishopCheckBonus * count_1s_max_15(b2);
// Queen checks
b2 = b & ei.attacked_by(them, QUEEN);
if (b2)
attackUnits += QueenCheckBonus * count_1s_max_15(b2);
// Bishop checks
b2 = b & ei.attacked_by(them, BISHOP);
if (b2)
attackUnits += BishopCheckBonus * count_1s_max_15(b2);
}
if(KnightCheckBonus > 0) {
b = p.knight_attacks(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
// Knight checks
b2 = b & ei.attacked_by(them, KNIGHT);
if(b2) attackUnits += KnightCheckBonus * count_1s_max_15(b2);
if (KnightCheckBonus > 0)
{
b = p.knight_attacks(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
// Knight checks
b2 = b & ei.attacked_by(them, KNIGHT);
if (b2)
attackUnits += KnightCheckBonus * count_1s_max_15(b2);
}
// Analyse discovered checks (only for non-pawns right now, consider
// adding pawns later).
if(DiscoveredCheckBonus) {
if (DiscoveredCheckBonus)
{
b = p.discovered_check_candidates(them) & ~p.pawns();
if(b)
attackUnits +=
DiscoveredCheckBonus * count_1s_max_15(b) * (sente? 2 : 1);
if (b)
attackUnits += DiscoveredCheckBonus * count_1s_max_15(b) * (sente? 2 : 1);
}
// Has a mate threat been found? We don't do anything here if the
// side with the mating move is the side to move, because in that
// case the mating side will get a huge bonus at the end of the main
// evaluation function instead.
if(ei.mateThreat[them] != MOVE_NONE)
attackUnits += MateThreatBonus;
if (ei.mateThreat[them] != MOVE_NONE)
attackUnits += MateThreatBonus;
// Ensure that attackUnits is between 0 and 99, in order to avoid array
// out of bounds errors:
if(attackUnits < 0) attackUnits = 0;
if(attackUnits >= 100) attackUnits = 99;
if (attackUnits < 0)
attackUnits = 0;
if (attackUnits >= 100)
attackUnits = 99;
// Finally, extract the king safety score from the SafetyTable[] array.
// Add the score to the evaluation, and also to ei.futilityMargin. The
@ -854,9 +884,11 @@ namespace {
// capturing a single attacking piece can therefore result in a score
// change far bigger than the value of the captured piece.
Value v = apply_weight(SafetyTable[attackUnits], WeightKingSafety[us]);
ei.mgValue -= sign * v;
if(us == p.side_to_move())
ei.futilityMargin += v;
if (us == p.side_to_move())
ei.futilityMargin += v;
}
}