+ // Board edges are not considered in the relevant occupancies
+ edges = ((Rank1BB | Rank8BB) & ~rank_bb(s)) | ((FileABB | FileHBB) & ~file_bb(s));
+
+ // Given a square 's', the mask is the bitboard of sliding attacks from
+ // 's' computed on an empty board. The index must be big enough to contain
+ // all the attacks for each possible subset of the mask and so is 2 power
+ // the number of 1s of the mask. Hence we deduce the size of the shift to
+ // apply to the 64 or 32 bits word to get the index.
+ Magic& m = magics[s];
+ m.mask = sliding_attack(directions, s, 0) & ~edges;
+ m.shift = (Is64Bit ? 64 : 32) - popcount(m.mask);
+
+ // Set the offset for the attacks table of the square. We have individual
+ // table sizes for each square with "Fancy Magic Bitboards".
+ m.attacks = s == SQ_A1 ? table : magics[s - 1].attacks + size;
+
+ // Use Carry-Rippler trick to enumerate all subsets of masks[s] and
+ // store the corresponding sliding attack bitboard in reference[].
+ b = size = 0;
+ do {
+ occupancy[size] = b;
+ reference[size] = sliding_attack(directions, s, b);