+ #define V Value
+ #define S(mg, eg) make_score(mg, eg)
+
+ // Doubled pawn penalty by file
+ const Score Doubled[FILE_NB] = {
+ S(13, 43), S(20, 48), S(23, 48), S(23, 48),
+ S(23, 48), S(23, 48), S(20, 48), S(13, 43) };
+
+ // Isolated pawn penalty by opposed flag and file
+ const Score Isolated[2][FILE_NB] = {
+ { S(37, 45), S(54, 52), S(60, 52), S(60, 52),
+ S(60, 52), S(60, 52), S(54, 52), S(37, 45) },
+ { S(25, 30), S(36, 35), S(40, 35), S(40, 35),
+ S(40, 35), S(40, 35), S(36, 35), S(25, 30) } };
+
+ // Backward pawn penalty by opposed flag and file
+ const Score Backward[2][FILE_NB] = {
+ { S(30, 42), S(43, 46), S(49, 46), S(49, 46),
+ S(49, 46), S(49, 46), S(43, 46), S(30, 42) },
+ { S(20, 28), S(29, 31), S(33, 31), S(33, 31),
+ S(33, 31), S(33, 31), S(29, 31), S(20, 28) } };
+
+ // Connected pawn bonus by opposed, phalanx flags and rank
+ Score Connected[2][2][RANK_NB];
+
+ // Levers bonus by rank
+ const Score Lever[RANK_NB] = {
+ S( 0, 0), S( 0, 0), S(0, 0), S(0, 0),
+ S(20,20), S(40,40), S(0, 0), S(0, 0) };
+
+ // Unsupported pawn penalty
+ const Score UnsupportedPawnPenalty = S(20, 10);
+
+ // Weakness of our pawn shelter in front of the king by [distance from edge][rank]
+ const Value ShelterWeakness[][RANK_NB] = {
+ { V( 99), V(23), V(24), V(54), V(85), V( 93), V(107) },
+ { V(119), V( 2), V(28), V(72), V(96), V(104), V(114) },
+ { V(103), V( 6), V(47), V(74), V(84), V(103), V( 94) },
+ { V( 78), V(10), V(41), V(64), V(88), V( 92), V(115) } };
+
+ // Danger of enemy pawns moving toward our king by [type][distance from edge][rank]
+ const Value StormDanger[][4][RANK_NB] = {
+ { { V( 0), V( 65), V( 125), V(37), V(30) },
+ { V( 0), V( 57), V( 136), V(39), V(24) },
+ { V( 0), V( 50), V( 114), V(45), V(29) },
+ { V( 0), V( 58), V( 129), V(56), V(34) } },
+ { { V(20), V( 45), V( 91), V(47), V(20) },
+ { V(25), V( 23), V( 105), V(38), V(14) },
+ { V(21), V( 37), V( 99), V(35), V(21) },
+ { V(30), V( 18), V( 105), V(38), V(28) } },
+ { { V( 0), V( 0), V( 81), V(13), V( 4) },
+ { V( 0), V( 0), V( 169), V(30), V( 4) },
+ { V( 0), V( 0), V( 166), V(24), V( 6) },
+ { V( 0), V( 0), V( 164), V(24), V(11) } },
+ { { V( 0), V(-289), V(-297), V(57), V(29) },
+ { V( 0), V( 66), V( 136), V(43), V(16) },
+ { V( 0), V( 66), V( 141), V(50), V(31) },
+ { V( 0), V( 63), V( 126), V(52), V(23) } } };
+
+ // Max bonus for king safety. Corresponds to start position with all the pawns
+ // in front of the king and no enemy pawn on the horizon.
+ const Value MaxSafetyBonus = V(252);
+
+ #undef S
+ #undef V
+
+ template<Color Us>
+ Score evaluate(const Position& pos, Pawns::Entry* e) {
+
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Square Up = (Us == WHITE ? DELTA_N : DELTA_S);
+ const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW);
+ const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE);
+
+ Bitboard b, p, doubled, connected;
+ Square s;
+ bool passed, isolated, opposed, phalanx, backward, unsupported, lever;
+ Score score = SCORE_ZERO;
+ const Square* pl = pos.list<PAWN>(Us);
+ const Bitboard* pawnAttacksBB = StepAttacksBB[make_piece(Us, PAWN)];
+
+ Bitboard ourPawns = pos.pieces(Us , PAWN);
+ Bitboard theirPawns = pos.pieces(Them, PAWN);
+
+ e->passedPawns[Us] = 0;
+ e->kingSquares[Us] = SQ_NONE;
+ e->semiopenFiles[Us] = 0xFF;
+ e->pawnAttacks[Us] = shift_bb<Right>(ourPawns) | shift_bb<Left>(ourPawns);
+ e->pawnsOnSquares[Us][BLACK] = popcount<Max15>(ourPawns & DarkSquares);
+ e->pawnsOnSquares[Us][WHITE] = pos.count<PAWN>(Us) - e->pawnsOnSquares[Us][BLACK];
+
+ // Loop through all pawns of the current color and score each pawn
+ while ((s = *pl++) != SQ_NONE)
+ {
+ assert(pos.piece_on(s) == make_piece(Us, PAWN));
+
+ File f = file_of(s);
+
+ // This file cannot be semi-open
+ e->semiopenFiles[Us] &= ~(1 << f);
+
+ // Previous rank
+ p = rank_bb(s - pawn_push(Us));
+
+ // Flag the pawn as passed, isolated, doubled,
+ // unsupported or connected (but not the backward one).
+ connected = ourPawns & adjacent_files_bb(f) & (rank_bb(s) | p);
+ phalanx = connected & rank_bb(s);
+ unsupported = !(ourPawns & adjacent_files_bb(f) & p);
+ isolated = !(ourPawns & adjacent_files_bb(f));
+ doubled = ourPawns & forward_bb(Us, s);
+ opposed = theirPawns & forward_bb(Us, s);
+ passed = !(theirPawns & passed_pawn_mask(Us, s));
+ lever = theirPawns & pawnAttacksBB[s];
+
+ // Test for backward pawn.
+ // If the pawn is passed, isolated, or connected it cannot be
+ // backward. If there are friendly pawns behind on adjacent files
+ // or if it can capture an enemy pawn it cannot be backward either.
+ if ( (passed | isolated | connected)
+ || (ourPawns & pawn_attack_span(Them, s))
+ || (pos.attacks_from<PAWN>(s, Us) & theirPawns))
+ backward = false;
+ else
+ {
+ // We now know that 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.
+ b = pawn_attack_span(Us, s) & (ourPawns | theirPawns);
+ b = pawn_attack_span(Us, s) & rank_bb(backmost_sq(Us, b));
+
+ // If we have an enemy pawn in the same or next rank, the pawn is
+ // backward because it cannot advance without being captured.
+ backward = (b | shift_bb<Up>(b)) & theirPawns;
+ }
+
+ assert(opposed | passed | (pawn_attack_span(Us, s) & theirPawns));
+
+ // Passed pawns will be properly scored in evaluation because we need
+ // full attack info to evaluate passed pawns. Only the frontmost passed
+ // pawn on each file is considered a true passed pawn.
+ if (passed && !doubled)
+ e->passedPawns[Us] |= s;
+
+ // Score this pawn
+ if (isolated)
+ score -= Isolated[opposed][f];
+
+ if (unsupported && !isolated)
+ score -= UnsupportedPawnPenalty;
+
+ if (doubled)
+ score -= Doubled[f] / distance<Rank>(s, frontmost_sq(Us, doubled));
+
+ if (backward)
+ score -= Backward[opposed][f];
+
+ if (connected)
+ score += Connected[opposed][phalanx][relative_rank(Us, s)];
+
+ if (lever)
+ score += Lever[relative_rank(Us, s)];
+ }
+
+ b = e->semiopenFiles[Us] ^ 0xFF;
+ e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0;
+
+ return score;
+ }