+ // Initialize pawn storm scores by giving bonuses for open files
+ if (EvaluatePawnStorms)
+ 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) == pawn_of_color(us));
+
+ // 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);
+
+ if (EvaluatePawnStorms)
+ {
+ // 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[]). This score is increased if
+ // there are enemy pawns on adjacent files in front of the pawn.
+ // This is because we want to be able to open files against the
+ // enemy king, and to avoid blocking the pawn structure (e.g. white
+ // pawns on h6, g5, black pawns on h7, g6, f7).
+
+ // Kingside and queenside pawn storms
+ int KBonus = KStormTable[relative_square(us, s)];
+ int QBonus = QStormTable[relative_square(us, s)];
+ bool outPost = (KBonus > 0 && (outpost_mask(us, s) & theirPawns));
+ bool passed = (QBonus > 0 && (passed_pawn_mask(us, s) & theirPawns));
+
+ switch (f) {
+
+ case FILE_A:
+ QBonus += passed * QBonus / 2;
+ break;
+
+ case FILE_B:
+ QBonus += passed * (QBonus / 2 + QBonus / 4);
+ break;
+
+ case FILE_C:
+ QBonus += passed * QBonus / 2;
+ break;
+
+ case FILE_F:
+ KBonus += outPost * KBonus / 4;
+ break;
+
+ case FILE_G:
+ KBonus += outPost * (KBonus / 2 + KBonus / 4);
+ break;
+
+ case FILE_H:
+ KBonus += outPost * KBonus / 2;
+ break;
+
+ default:
+ break;
+ }
+ pi->ksStormValue[us] += KBonus;
+ pi->qsStormValue[us] += QBonus;