const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW);
const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE);
- Bitboard b, p, doubled, connected;
+ Bitboard b, p, doubled, connected, supported;
Square s;
- bool passed, isolated, opposed, phalanx, backward, unsupported, lever;
+ bool passed, isolated, opposed, phalanx, backward, lever;
Score score = SCORE_ZERO;
const Square* pl = pos.list<PAWN>(Us);
const Bitboard* pawnAttacksBB = StepAttacksBB[make_piece(Us, PAWN)];
e->semiopenFiles[Us] &= ~(1 << f);
// Previous rank
- p = rank_bb(s - pawn_push(Us));
+ p = rank_bb(s - Up);
- // Flag the pawn as passed, isolated, doubled,
- // unsupported or connected (but not the backward one).
+ // Flag the pawn
connected = ourPawns & adjacent_files_bb(f) & (rank_bb(s) | p);
phalanx = connected & rank_bb(s);
- unsupported = !(ourPawns & adjacent_files_bb(f) & p);
+ supported = connected & p;
isolated = !(ourPawns & adjacent_files_bb(f));
doubled = ourPawns & forward_bb(Us, s);
opposed = theirPawns & forward_bb(Us, s);
backward = false;
else
{
- // We now know that there are no friendly pawns beside or behind this
+ // We now know there are no friendly pawns beside or behind this
// pawn on adjacent files. We now check whether the pawn is
// backward by looking in the forward direction on the adjacent
// files, and picking the closest pawn there.
if (isolated)
score -= Isolated[opposed][f];
- if (unsupported && !isolated)
+ if (!supported && !isolated)
score -= UnsupportedPawnPenalty;
if (doubled)
if (backward)
score -= Backward[opposed][f];
- if (connected)
+ if (connected) {
score += Connected[opposed][phalanx][relative_rank(Us, s)];
+ if (more_than_one(supported)) {
+ //apex bonus: pawn on s is supported twice
+ score += Connected[opposed][phalanx][relative_rank(Us, s)] / 2;
+ }
+ }
if (lever)
score += Lever[relative_rank(Us, s)];