S(33, 31), S(33, 31), S(29, 31), S(20, 28) }};
// Pawn chain membership bonus by file
- const Score ChainMember[FILE_NB] = {
- S(11,-1), S(13,-1), S(13,-1), S(14,-1),
- S(14,-1), S(13,-1), S(13,-1), S(11,-1)
- };
+ const Score ChainMember[FILE_NB][RANK_NB] = {
+ { S(0, 0), S(14, 0), S(16, 4), S(18, 9), S(56, 56), S(104, 208), S(236, 472) },
+ { S(0, 0), S(16, 0), S(18, 5), S(20, 10), S(60, 60), S(108, 216), S(240, 480) },
+ { S(0, 0), S(16, 0), S(18, 5), S(20, 10), S(60, 60), S(108, 216), S(240, 480) },
+ { S(0, 0), S(17, 0), S(19, 6), S(22, 11), S(66, 66), S(118, 236), S(254, 508) },
+ { S(0, 0), S(17, 0), S(19, 6), S(22, 11), S(66, 66), S(118, 236), S(254, 508) },
+ { S(0, 0), S(16, 0), S(18, 5), S(20, 10), S(60, 60), S(108, 216), S(240, 480) },
+ { S(0, 0), S(16, 0), S(18, 5), S(20, 10), S(60, 60), S(108, 216), S(240, 480) },
+ { S(0, 0), S(14, 0), S(16, 4), S(18, 9), S(56, 56), S(104, 208), S(236, 472) }
+ };
// Candidate passed pawn bonus by rank
const Score CandidatePassed[RANK_NB] = {
Bitboard b;
Square s;
File f;
+ Rank r;
bool passed, isolated, doubled, opposed, chain, backward, candidate;
Score value = SCORE_ZERO;
const Square* pl = pos.list<PAWN>(Us);
assert(pos.piece_on(s) == make_piece(Us, PAWN));
f = file_of(s);
+ r = relative_rank(Us, s);
// This file cannot be semi-open
e->semiopenFiles[Us] &= ~(1 << f);
value -= Backward[opposed][f];
if (chain)
- value += ChainMember[f] + CandidatePassed[relative_rank(Us, s)] / 2;
+ value += opposed ? ChainMember[f][r] / 2 : ChainMember[f][r];
if (candidate)
{
- value += CandidatePassed[relative_rank(Us, s)];
+ value += CandidatePassed[r];
if (!doubled)
e->candidatePawns[Us] |= s;