{ 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 file and rank (initialized by formula)
- Score Connected[FILE_NB][RANK_NB];
-
- // Candidate passed pawn bonus by rank
- const Score CandidatePassed[RANK_NB] = {
- S( 0, 0), S( 6, 13), S(6,13), S(14,29),
- S(34,68), S(83,166), S(0, 0), S( 0, 0) };
+ // Connected bonus by rank
+ const int Connected[RANK_NB] = {0, 6, 15, 10, 57, 75, 135, 258};
// Levers bonus by rank
const Score Lever[RANK_NB] = {
Bitboard b, p, doubled;
Square s;
- File f;
- bool passed, isolated, opposed, connected, backward, candidate, unsupported, lever;
+ bool passed, isolated, opposed, connected, backward, unsupported, lever;
Score value = 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] = e->candidatePawns[Us] = 0;
+ e->passedPawns[Us] = 0;
e->kingSquares[Us] = SQ_NONE;
e->semiopenFiles[Us] = 0xFF;
e->pawnAttacks[Us] = shift_bb<Right>(ourPawns) | shift_bb<Left>(ourPawns);
{
assert(pos.piece_on(s) == make_piece(Us, PAWN));
- f = file_of(s);
+ Rank r = rank_of(s), rr = relative_rank(Us, s);
+ File f = file_of(s);
// This file cannot be semi-open
e->semiopenFiles[Us] &= ~(1 << f);
assert(opposed | passed | (pawn_attack_span(Us, s) & theirPawns));
- // A not-passed pawn is a candidate to become passed, if it is free to
- // advance and if the number of friendly pawns beside or behind this
- // pawn on adjacent files is higher than or equal to the number of
- // enemy pawns in the forward direction on the adjacent files.
- candidate = !(opposed | passed | backward | isolated)
- && (b = pawn_attack_span(Them, s + pawn_push(Us)) & ourPawns) != 0
- && popcount<Max15>(b) >= popcount<Max15>(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 (backward)
value -= Backward[opposed][f];
- if (connected)
- value += Connected[f][relative_rank(Us, s)];
+ if (connected) {
+ int bonus = Connected[rr];
+ if (ourPawns & adjacent_files_bb(f) & rank_bb(r))
+ bonus += (Connected[rr+1] - Connected[rr]) / 2;
+ value += make_score(bonus / 2, bonus >> opposed);
+ }
if (lever)
- value += Lever[relative_rank(Us, s)];
-
- if (candidate)
- {
- value += CandidatePassed[relative_rank(Us, s)];
-
- if (!doubled)
- e->candidatePawns[Us] |= s;
- }
+ value += Lever[rr];
}
b = e->semiopenFiles[Us] ^ 0xFF;
namespace Pawns {
-/// init() initializes some tables by formula instead of hard-coding their values
-
-void init() {
-
- const int bonusByFile[] = { 1, 3, 3, 4, 4, 3, 3, 1 };
-
- for (Rank r = RANK_1; r < RANK_8; ++r)
- for (File f = FILE_A; f <= FILE_H; ++f)
- {
- int bonus = r * (r - 1) * (r - 2) + bonusByFile[f] * (r / 2 + 1);
- Connected[f][r] = make_score(bonus, bonus);
- }
-}
-
-
/// probe() takes a position as input, computes a Entry object, and returns a
/// pointer to it. The result is also stored in a hash table, so we don't have
/// to recompute everything when the same pawn structure occurs again.