Bitboard QueenPseudoAttacks[64];
uint8_t BitCount8Bit[256];
+int SquareDistance[64][64];
namespace {
void init_bitboards() {
+ for (Bitboard b = 0; b < 256; b++)
+ BitCount8Bit[b] = (uint8_t)count_1s<CNT32_MAX15>(b);
+
+ for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
+ for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
+ SquareDistance[s1][s2] = Max(file_distance(s1, s2), rank_distance(s1, s2));
+
SquaresByColorBB[DARK] = 0xAA55AA55AA55AA55ULL;
SquaresByColorBB[LIGHT] = ~SquaresByColorBB[DARK];
for (Square s = SQ_A1; s <= SQ_H8; s++)
{
- SetMaskBB[s] = (1ULL << s);
+ SetMaskBB[s] = 1ULL << s;
ClearMaskBB[s] = ~SetMaskBB[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++)
+ for (int i = 0; i < 64; i++)
if (!CpuIs64Bit) // Matt Taylor's folding trick for 32 bit systems
{
Bitboard b = 1ULL << i;
else
BSFTable[((1ULL << i) * 0x218A392CD3D5DBFULL) >> 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}
- };
+ int steps[][9] = { {}, { 7, 9 }, { 17, 15, 10, 6, -6, -10, -15, -17 },
+ {}, {}, {}, { 9, 7, -7, -9, 8, 1, -1, -8 } };
for (Color c = WHITE; c <= BLACK; c++)
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
+ for (PieceType pt = PAWN; pt <= KING; pt++)
+ for (Square s = SQ_A1; s <= SQ_H8; s++)
for (int k = 0; steps[pt][k]; k++)
{
Square to = s + Square(c == WHITE ? steps[pt][k] : -steps[pt][k]);
set_bit(&StepAttacksBB[make_piece(c, pt)][s], to);
}
- Square RDeltas[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W };
- Square BDeltas[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW };
+ Square RDelta[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W };
+ Square BDelta[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW };
- init_sliding_attacks(BMult, BAttacks, BAttacksTable, BMask, BShift, BDeltas);
- init_sliding_attacks(RMult, RAttacks, RAttacksTable, RMask, RShift, RDeltas);
+ init_sliding_attacks(BMult, BAttacks, BAttacksTable, BMask, BShift, BDelta);
+ init_sliding_attacks(RMult, RAttacks, RAttacksTable, RMask, RShift, RDelta);
for (Square s = SQ_A1; s <= SQ_H8; s++)
{
namespace {
- Bitboard submask(Bitboard mask, int key) {
-
- Bitboard b, subMask = 0;
- int bitProbe = 1;
-
- // Extract an unique submask out of a mask according to the given key
- while (mask)
- {
- b = mask & -mask;
- mask ^= b;
-
- if (key & bitProbe)
- subMask |= b;
-
- bitProbe <<= 1;
- }
-
- return subMask;
- }
-
- Bitboard sliding_attacks(Square sq, Bitboard occupied, Square deltas[], Bitboard excluded) {
+ Bitboard sliding_attacks(Square sq, Bitboard occupied, Square delta[]) {
Bitboard attacks = 0;
for (int i = 0; i < 4; i++)
{
- Square s = sq + deltas[i];
+ Square s = sq + delta[i];
- while ( square_is_ok(s)
- && square_distance(s, s - deltas[i]) == 1
- && !bit_is_set(excluded, s))
+ while (square_is_ok(s) && square_distance(s, s - delta[i]) == 1)
{
set_bit(&attacks, s);
if (bit_is_set(occupied, s))
break;
- s += deltas[i];
+ s += delta[i];
}
}
return attacks;
Bitboard magic;
- // Values s1 and s2 are used to rotate the candidate magic of
- // a quantity known to be the optimal to quickly find the magics.
+ // Values s1 and s2 are used to rotate the candidate magic of a
+ // quantity known to be the optimal to quickly find the magics.
int s1 = booster & 63, s2 = (booster >> 6) & 63;
while (true)
const int MagicBoosters[][8] = { { 3191, 2184, 1310, 3618, 2091, 1308, 2452, 3996 },
{ 1059, 3608, 605, 3234, 3326, 38, 2029, 3043 } };
RKISS rk;
- Bitboard occupancy[4096], reference[4096], excluded;
+ Bitboard occupancy[4096], reference[4096], edges, b;
int key, maxKey, index, booster, offset = 0;
for (Square s = SQ_A1; s <= SQ_H8; s++)
{
- excluded = ((Rank1BB | Rank8BB) & ~rank_bb(s)) | ((FileABB | FileHBB) & ~file_bb(s));
+ edges = ((Rank1BB | Rank8BB) & ~rank_bb(s)) | ((FileABB | FileHBB) & ~file_bb(s));
attack[s] = &attTable[offset];
- mask[s] = sliding_attacks(s, EmptyBoardBB, delta, excluded);
+ mask[s] = sliding_attacks(s, EmptyBoardBB, delta) & ~edges;
shift[s] = (CpuIs64Bit ? 64 : 32) - count_1s<CNT32_MAX15>(mask[s]);
- maxKey = 1 << count_1s<CNT32_MAX15>(mask[s]);
+ // Use Carry-Rippler trick to enumerate all subsets of mask[s]
+ b = maxKey = 0;
+ do {
+ occupancy[maxKey] = b;
+ reference[maxKey++] = sliding_attacks(s, b, delta);
+ b = (b - mask[s]) & mask[s];
+ } while (b);
+
offset += maxKey;
booster = MagicBoosters[CpuIs64Bit][square_rank(s)];
- // First compute occupancy and attacks for square 's'
- for (key = 0; key < maxKey; key++)
- {
- occupancy[key] = submask(mask[s], key);
- reference[key] = sliding_attacks(s, occupancy[key], delta, EmptyBoardBB);
- }
-
// Then find a possible magic and the corresponding attacks
do {
magic[s] = pick_magic(mask[s], rk, booster);