- // Isolated pawn penalty by file
- const Score IsolatedPawnPenalty[8] = {
- 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 file
- const Score BackwardPawnPenalty[8] = {
- S(20, 28), S(29, 31), S(33, 31), S(33, 31),
- S(33, 31), S(33, 31), S(29, 31), S(20, 28)
- };
-
- // Pawn chain membership bonus by file
- const Score ChainBonus[8] = {
- S(11,-1), S(13,-1), S(13,-1), S(14,-1),
- S(14,-1), S(13,-1), S(13,-1), S(11,-1)
- };
-
- // Candidate passed pawn bonus by rank
- const Score CandidateBonus[8] = {
- S( 0, 0), S( 6, 13), S(6,13), S(14,29),
- S(34,68), S(83,166), S(0, 0), S( 0, 0)
- };
-
- // Pawn storm tables for positions with opposite castling
- const int QStormTable[64] = {
- 0, 0, 0, 0, 0, 0, 0, 0,
- -22,-22,-22,-14,-6, 0, 0, 0,
- -6,-10,-10,-10,-6, 0, 0, 0,
- 4, 12, 16, 12, 4, 0, 0, 0,
- 16, 23, 23, 16, 0, 0, 0, 0,
- 23, 31, 31, 23, 0, 0, 0, 0,
- 23, 31, 31, 23, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0
- };
-
- const int KStormTable[64] = {
- 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0,-10,-19,-28,-33,-33,
- 0, 0, 0,-10,-15,-19,-24,-24,
- 0, 0, 0, 0, 1, 1, 1, 1,
- 0, 0, 0, 0, 1, 10, 19, 19,
- 0, 0, 0, 0, 1, 19, 31, 27,
- 0, 0, 0, 0, 0, 22, 31, 22,
- 0, 0, 0, 0, 0, 0, 0, 0
- };
-
- // Pawn storm open file bonuses by file
- const int16_t KStormOpenFileBonus[8] = { 31, 31, 18, 0, 0, 0, 0, 0 };
- const int16_t QStormOpenFileBonus[8] = { 0, 0, 0, 0, 0, 26, 42, 26 };
-
- // Pawn storm lever bonuses by file
- const int StormLeverBonus[8] = { -8, -8, -13, 0, 0, -13, -8, -8 };
-
-}
+ const Score CenterBind = S(16, 0);
+
+ // Weakness of our pawn shelter in front of the king by [distance from edge][rank]
+ const Value ShelterWeakness[][RANK_NB] = {
+ { V( 99), V(20), V(26), V(54), V(85), V( 92), V(108) },
+ { V(117), V( 1), V(27), V(71), V(94), V(104), V(118) },
+ { V(104), V( 4), V(51), V(76), V(82), V(102), V( 97) },
+ { V( 80), V(12), V(43), V(65), V(88), V( 91), 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( 126), V(36), V(30) },
+ { V( 0), V( 55), V( 135), V(36), V(23) },
+ { V( 0), V( 47), V( 116), V(45), V(26) },
+ { V( 0), V( 62), V( 127), V(57), V(34) } },
+ { { V(21), V( 45), V( 93), V(50), V(19) },
+ { V(23), V( 24), V( 105), V(41), V(13) },
+ { V(23), V( 36), V( 101), V(38), V(20) },
+ { V(30), V( 19), V( 110), V(41), V(27) } },
+ { { V( 0), V( 0), V( 81), V(14), V( 4) },
+ { V( 0), V( 0), V( 169), V(30), V( 3) },
+ { V( 0), V( 0), V( 168), V(24), V( 5) },
+ { V( 0), V( 0), V( 162), V(26), V(10) } },
+ { { V( 0), V(-283), V(-298), V(57), V(29) },
+ { V( 0), V( 63), V( 137), V(42), V(18) },
+ { V( 0), V( 67), V( 145), V(49), V(33) },
+ { V( 0), V( 62), V( 126), V(53), V(21) } } };
+
+ // 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(258);
+
+ #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, neighbours, doubled, supported, phalanx;
+ Square s;
+ bool passed, isolated, opposed, backward, lever, connected;
+ 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);
+
+ // Flag the pawn
+ neighbours = 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];
+ phalanx = neighbours & rank_bb(s);
+ supported = neighbours & rank_bb(s - Up);
+ connected = supported | phalanx;
+ isolated = !neighbours;
+
+ // Test for backward pawn.
+ // If the pawn is passed, isolated, lever or connected it cannot be
+ // backward. If there are friendly pawns behind on adjacent files
+ // it cannot be backward either.
+ if ( (passed | isolated | lever | connected)
+ || (ourPawns & pawn_attack_span(Them, s)))
+ backward = false;
+ else
+ {
+ // 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.
+ 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];
+
+ else if (backward)
+ score -= Backward[opposed][f];
+
+ else if (!supported)
+ score -= UnsupportedPawnPenalty;
+
+ if (connected)
+ score += Connected[opposed][!!phalanx][more_than_one(supported)][relative_rank(Us, s)];
+
+ if (doubled)
+ score -= Doubled[f] / distance<Rank>(s, frontmost_sq(Us, doubled));
+
+ if (lever)
+ score += Lever[relative_rank(Us, s)];
+ }
+
+ b = e->semiopenFiles[Us] ^ 0xFF;
+ e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0;
+
+ // Center binds: Two pawns controlling the same central square
+ b = shift_bb<Right>(ourPawns) & shift_bb<Left>(ourPawns) & CenterBindMask[Us];
+ score += popcount<Max15>(b) * CenterBind;
+
+ return score;
+ }