- Color them = opposite_color(us);
- Bitboard ourPawns = pos.pawns(us);
- Bitboard theirPawns = pos.pawns(them);
- Bitboard pawns = ourPawns;
- int bonus;
-
- // Initialize pawn storm scores by giving bonuses for open files
- for (File f = FILE_A; f <= FILE_H; f++)
- if (pos.file_is_half_open(us, f))
- {
- pi->ksStormValue[us] += KStormOpenFileBonus[f];
- pi->qsStormValue[us] += QStormOpenFileBonus[f];
- }
-
- // Loop through all pawns of the current color and score each pawn
- while (pawns)
- {
- bool passed, doubled, isolated, backward, chain, candidate;
- Square s = pop_1st_bit(&pawns);
- File f = square_file(s);
- Rank r = square_rank(s);
-
- assert(pos.piece_on(s) == piece_of_color_and_type(us, PAWN));
-
- // The file containing the pawn is not half open
- pi->halfOpenFiles[us] &= ~(1 << f);
-
- // Passed, isolated or doubled pawn?
- passed = pos.pawn_is_passed(us, s);
- isolated = pos.pawn_is_isolated(us, s);
- doubled = pos.pawn_is_doubled(us, s);
-
- // We calculate kingside and queenside pawn storm
- // scores for both colors. These are used when evaluating
- // middle game positions with opposite side castling.
- //
- // Each pawn is given a base score given by a piece square table
- // (KStormTable[] or QStormTable[]). Pawns which seem to have good
- // chances of creating an open file by exchanging itself against an
- // enemy pawn on an adjacent file gets an additional bonus.
-
- // Kingside pawn storms
- bonus = KStormTable[relative_square(us, s)];
- if (f >= FILE_F)
- {
- Bitboard b = outpost_mask(us, s) & theirPawns & (FileFBB | FileGBB | FileHBB);
- while (b)
- {
- Square s2 = pop_1st_bit(&b);
- if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2)))
- {
- // The enemy pawn has no pawn beside itself, which makes it
- // particularly vulnerable. Big bonus, especially against a
- // weakness on the rook file.
- if (square_file(s2) == FILE_H)
- bonus += 4*StormLeverBonus[f] - 8*square_distance(s, s2);
- else
- bonus += 2*StormLeverBonus[f] - 4*square_distance(s, s2);
- } else
- // There is at least one enemy pawn beside the enemy pawn we look
- // at, which means that the pawn has somewhat better chances of
- // defending itself by advancing. Smaller bonus.
- bonus += StormLeverBonus[f] - 2*square_distance(s, s2);
- }
- }
- pi->ksStormValue[us] += bonus;
-
- // Queenside pawn storms
- bonus = QStormTable[relative_square(us, s)];
- if (f <= FILE_C)
- {
- Bitboard b = outpost_mask(us, s) & theirPawns & (FileABB | FileBBB | FileCBB);
- while (b)
- {
- Square s2 = pop_1st_bit(&b);
- if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2)))
- {
- // The enemy pawn has no pawn beside itself, which makes it
- // particularly vulnerable. Big bonus, especially against a
- // weakness on the rook file.
- if (square_file(s2) == FILE_A)
- bonus += 4*StormLeverBonus[f] - 16*square_distance(s, s2);
- else
- bonus += 2*StormLeverBonus[f] - 8*square_distance(s, s2);
- } else
- // There is at least one enemy pawn beside the enemy pawn we look
- // at, which means that the pawn has somewhat better chances of
- // defending itself by advancing. Smaller bonus.
- bonus += StormLeverBonus[f] - 4*square_distance(s, s2);
- }
- }
- pi->qsStormValue[us] += bonus;
-
- // Member of a pawn chain (but not the backward one)? We could speed up
- // the test a little by introducing an array of masks indexed by color
- // and square for doing the test, but because everything is hashed,
- // it probably won't make any noticable difference.
- chain = ourPawns
- & neighboring_files_bb(f)
- & (rank_bb(r) | rank_bb(r - (us == WHITE ? 1 : -1)));
-
- // Test for backward pawn
- //
- // If the pawn is passed, isolated, or member of a pawn chain
- // it cannot be backward. If can capture an enemy pawn or if
- // there are friendly pawns behind on neighboring files it cannot
- // be backward either.
- if ( passed
- || isolated
- || chain
- || (pos.pawn_attacks(us, s) & theirPawns)
- || (ourPawns & behind_bb(us, r) & neighboring_files_bb(f)))
- backward = false;
- else
- {
- // We now know that there are no friendly pawns beside or behind this
- // pawn on neighboring files. We now check whether the pawn is
- // backward by looking in the forward direction on the neighboring
- // files, and seeing whether we meet a friendly or an enemy pawn first.
- Bitboard b;
- if (us == WHITE)
- {
- for (b = pos.pawn_attacks(us, s); !(b & (ourPawns | theirPawns)); b <<= 8);
- backward = (b | (b << 8)) & theirPawns;
- }
- else
- {
- for (b = pos.pawn_attacks(us, s); !(b & (ourPawns | theirPawns)); b >>= 8);
- backward = (b | (b >> 8)) & theirPawns;
- }
- }
-
- // Test for candidate passed pawn
- candidate = !passed
- && pos.file_is_half_open(them, f)
- && ( count_1s_max_15<false>(neighboring_files_bb(f) & (behind_bb(us, r) | rank_bb(r)) & ourPawns)
- - count_1s_max_15<false>(neighboring_files_bb(f) & in_front_bb(us, r) & theirPawns)
- >= 0);
-
- // In order to prevent doubled passed pawns from receiving a too big
- // bonus, only the frontmost passed pawn on each file is considered as
- // a true passed pawn.
- if (passed && (ourPawns & squares_in_front_of(us, s)))
- {
- // candidate = true;
- passed = false;
- }
-
- // Score this pawn
- Value mv = Value(0), ev = Value(0);
- if (isolated)
- {
- mv -= IsolatedPawnMidgamePenalty[f];
- ev -= IsolatedPawnEndgamePenalty[f];
- if (pos.file_is_half_open(them, f))
- {
- mv -= IsolatedPawnMidgamePenalty[f] / 2;
- ev -= IsolatedPawnEndgamePenalty[f] / 2;
- }
- }
- if (doubled)
- {
- mv -= DoubledPawnMidgamePenalty[f];
- ev -= DoubledPawnEndgamePenalty[f];
- }
- if (backward)
- {
- mv -= BackwardPawnMidgamePenalty[f];
- ev -= BackwardPawnEndgamePenalty[f];
- if (pos.file_is_half_open(them, f))
- {
- mv -= BackwardPawnMidgamePenalty[f] / 2;
- ev -= BackwardPawnEndgamePenalty[f] / 2;
- }
- }
- if (chain)
- {
- mv += ChainMidgameBonus[f];
- ev += ChainEndgameBonus[f];
- }
- if (candidate)
- {
- mv += CandidateMidgameBonus[relative_rank(us, s)];
- ev += CandidateEndgameBonus[relative_rank(us, s)];
- }
-
- mgValue[us] += mv;
- egValue[us] += ev;
-
- // If the pawn is passed, set the square of the pawn in the passedPawns
- // bitboard
- if (passed)
- set_bit(&(pi->passedPawns), s);
- } // while(pawns)
- } // for(colors)
-
- pi->mgValue = int16_t(mgValue[WHITE] - mgValue[BLACK]);
- pi->egValue = int16_t(egValue[WHITE] - egValue[BLACK]);
- return pi;