+ SquaresByColorBB[DARK] = 0xAA55AA55AA55AA55ULL;
+ SquaresByColorBB[LIGHT] = ~SquaresByColorBB[DARK];
+
+ for (Square s = SQ_A1; s <= SQ_H8; s++)
+ {
+ SetMaskBB[s] = (1ULL << s);
+ ClearMaskBB[s] = ~SetMaskBB[s];
+ }
+
+ ClearMaskBB[SQ_NONE] = ~EmptyBoardBB;
+
+ FileBB[FILE_A] = FileABB;
+ RankBB[RANK_1] = Rank1BB;
+
+ for (int f = FILE_B; f <= FILE_H; f++)
+ {
+ FileBB[f] = FileBB[f - 1] << 1;
+ RankBB[f] = RankBB[f - 1] << 8;
+ }
+
+ for (int f = FILE_A; f <= FILE_H; f++)
+ {
+ NeighboringFilesBB[f] = (f > FILE_A ? FileBB[f - 1] : 0) | (f < FILE_H ? FileBB[f + 1] : 0);
+ ThisAndNeighboringFilesBB[f] = FileBB[f] | NeighboringFilesBB[f];
+ }
+
+ for (int rw = RANK_7, rb = RANK_2; rw >= RANK_1; rw--, rb++)
+ {
+ InFrontBB[WHITE][rw] = InFrontBB[WHITE][rw + 1] | RankBB[rw + 1];
+ InFrontBB[BLACK][rb] = InFrontBB[BLACK][rb - 1] | RankBB[rb - 1];
+ }
+
+ for (Color c = WHITE; c <= BLACK; c++)
+ for (Square s = SQ_A1; s <= SQ_H8; s++)
+ {
+ SquaresInFrontMask[c][s] = in_front_bb(c, s) & file_bb(s);
+ PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_neighboring_files_bb(s);
+ AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s);
+ }
+
+ for (Bitboard b = 0; b < 256; b++)
+ BitCount8Bit[b] = (uint8_t)count_1s<CNT32>(b);
+
+ for (int i = 1; i < 64; i++)
+ if (!CpuIs64Bit) // Matt Taylor's folding trick for 32 bit systems
+ {
+ Bitboard b = 1ULL << i;
+ b ^= b - 1;
+ b ^= b >> 32;
+ BSFTable[uint32_t(b * DeBruijnMagic) >> 26] = i;
+ }
+ else
+ BSFTable[((1ULL << i) * DeBruijnMagic) >> 58] = i;
+
+ int steps[][9] = {
+ {0}, {7,9,0}, {17,15,10,6,-6,-10,-15,-17,0}, {0}, {0}, {0}, {9,7,-7,-9,8,1,-1,-8,0}
+ };
+
+ for (Color c = WHITE; c <= BLACK; c++)
+ for (Square s = SQ_A1; s <= SQ_H8; s++)
+ for (PieceType pt = PAWN; pt <= KING; pt++)
+ for (int k = 0; steps[pt][k]; k++)
+ {
+ Square to = s + Square(c == WHITE ? steps[pt][k] : -steps[pt][k]);
+
+ if (square_is_ok(to) && square_distance(s, to) < 3)
+ set_bit(&StepAttacksBB[make_piece(c, pt)][s], to);
+ }
+
+ int rookDeltas[4][2] = { {0,1}, {0 ,-1}, {1, 0}, {-1, 0} };
+ int bishopDeltas[4][2] = { {1,1}, {-1, 1}, {1,-1}, {-1,-1} };