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Remove DistanceRing #2107

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Remove the DistanceRing array. This reduces the
memory footprint by about 4kb.

http://tests.stockfishchess.org/tests/view/5cba35350ebc5925cf020d7f
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 101421 W: 22491 L: 22528 D: 56402

No functional change.
This commit is contained in:
protonspring 2019-04-17 12:38:38 -06:00 • committed by Marco Costalba
parent bdeb01dec0
commit a858b5a84e
3 changed files with 8 additions and 9 deletions
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4
src/bitboard.cpp
View file

@ -28,7 +28,6 @@ uint8_t PopCnt16[1 << 16];
uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
Bitboard LineBB[SQUARE_NB][SQUARE_NB];
Bitboard DistanceRingBB[SQUARE_NB][8];
Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
Bitboard SquareBB[SQUARE_NB];
@ -83,10 +82,7 @@ void Bitboards::init() {
for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
{
SquareDistance[s1][s2] = std::max(distance<File>(s1, s2), distance<Rank>(s1, s2));
DistanceRingBB[s1][SquareDistance[s1][s2]] |= s2;
}
int steps[][5] = { {}, { 7, 9 }, { 6, 10, 15, 17 }, {}, {}, {}, { 1, 7, 8, 9 } };

1
src/bitboard.h
View file

@ -69,7 +69,6 @@ extern uint8_t PopCnt16[1 << 16];
extern uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
extern Bitboard DistanceRingBB[SQUARE_NB][8];
extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
extern Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
extern Bitboard KingFlank[FILE_NB];

12
src/pawns.cpp
View file

@ -212,11 +212,15 @@ Score Entry::do_king_safety(const Position& pos) {
Square ksq = pos.square<KING>(Us);
kingSquares[Us] = ksq;
castlingRights[Us] = pos.castling_rights(Us);
int minKingPawnDistance = 0;
Bitboard pawns = pos.pieces(Us, PAWN);
if (pawns)
while (!(DistanceRingBB[ksq][++minKingPawnDistance] & pawns)) {}
int minPawnDist = pawns ? 8 : 0;
if (pawns & PseudoAttacks[KING][ksq])
minPawnDist = 1;
else while (pawns)
minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(&pawns)));
Value bonus = evaluate_shelter<Us>(pos, ksq);
@ -227,7 +231,7 @@ Score Entry::do_king_safety(const Position& pos) {
if (pos.can_castle(Us | QUEEN_SIDE))
bonus = std::max(bonus, evaluate_shelter<Us>(pos, relative_square(Us, SQ_C1)));
return make_score(bonus, -16 * minKingPawnDistance);
return make_score(bonus, -16 * minPawnDist);
}
// Explicit template instantiation