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Calculate min distance between king and his pawns

Browse source 
Just added infrastructure.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2012-06-17 09:03:05 +01:00
parent 0446fc85de
commit 9793fa1906
4 changed files with 14 additions and 0 deletions
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7
src/bitboard.cpp
View file

@ -45,6 +45,7 @@ Bitboard ThisAndAdjacentFilesBB[8];
Bitboard InFrontBB[2][8];
Bitboard StepAttacksBB[16][64];
Bitboard BetweenBB[64][64];
Bitboard DistanceRingsBB[64][8];
Bitboard ForwardBB[2][64];
Bitboard PassedPawnMask[2][64];
Bitboard AttackSpanMask[2][64];
@ -195,6 +196,12 @@ void Bitboards::init() {
for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
SquareDistance[s1][s2] = std::max(file_distance(s1, s2), rank_distance(s1, s2));
for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
for (int d = 1; d < 8; d++)
for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
if (SquareDistance[s1][s2] == d)
DistanceRingsBB[s1][d - 1] |= s2;
for (int i = 0; i < 64; i++)
if (!Is64Bit) // Matt Taylor's folding trick for 32 bit systems
{

1
src/bitboard.h
View file

@ -50,6 +50,7 @@ extern Bitboard ThisAndAdjacentFilesBB[8];
extern Bitboard InFrontBB[2][8];
extern Bitboard StepAttacksBB[16][64];
extern Bitboard BetweenBB[64][64];
extern Bitboard DistanceRingsBB[64][8];
extern Bitboard ForwardBB[2][64];
extern Bitboard PassedPawnMask[2][64];
extern Bitboard AttackSpanMask[2][64];

5
src/pawns.cpp
View file

@ -261,6 +261,11 @@ Score PawnEntry::update_safety(const Position& pos, Square ksq) {
kingSquares[Us] = ksq;
castleRights[Us] = pos.can_castle(Us);
minKPdistance[Us] = 0;
Bitboard pawns = pos.pieces(Us, PAWN);
if (pawns)
while (!(DistanceRingsBB[ksq][minKPdistance[Us]++] & pawns)) {}
if (relative_rank(Us, ksq) > RANK_4)
return kingSafety[Us] = SCORE_ZERO;

1
src/pawns.h
View file

@ -59,6 +59,7 @@ private:
Bitboard passedPawns[2];
Bitboard pawnAttacks[2];
Square kingSquares[2];
int minKPdistance[2];
int castleRights[2];
Score value;
int halfOpenFiles[2];