Bitboard InFrontBB[2][8];
Bitboard StepAttacksBB[16][64];
Bitboard BetweenBB[64][64];
+Bitboard DistanceRingsBB[64][8];
Bitboard ForwardBB[2][64];
Bitboard PassedPawnMask[2][64];
Bitboard AttackSpanMask[2][64];
Bitboard PseudoAttacks[6][64];
-uint8_t BitCount8Bit[256];
int SquareDistance[64][64];
namespace {
int MS1BTable[256];
Bitboard RTable[0x19000]; // Storage space for rook attacks
Bitboard BTable[0x1480]; // Storage space for bishop attacks
+ uint8_t BitCount8Bit[256];
typedef unsigned (Fn)(Square, Bitboard);
Bitboard masks[], unsigned shifts[], Square deltas[], Fn index);
}
-/// first_1() finds the least significant nonzero bit in a nonzero bitboard.
-/// pop_1st_bit() finds and clears the least significant nonzero bit in a
-/// nonzero bitboard.
+/// lsb()/msb() finds the least/most significant bit in a nonzero bitboard.
+/// pop_lsb() finds and clears the least significant bit in a nonzero bitboard.
-#if defined(IS_64BIT) && !defined(USE_BSFQ)
+#if !defined(USE_BSFQ)
-Square first_1(Bitboard b) {
- return Square(BSFTable[((b & -b) * 0x218A392CD3D5DBFULL) >> 58]);
-}
-
-Square pop_1st_bit(Bitboard* b) {
- Bitboard bb = *b;
- *b &= (*b - 1);
- return Square(BSFTable[((bb & -bb) * 0x218A392CD3D5DBFULL) >> 58]);
-}
+Square lsb(Bitboard b) {
-#elif !defined(USE_BSFQ)
+ if (Is64Bit)
+ return Square(BSFTable[((b & -b) * 0x218A392CD3D5DBFULL) >> 58]);
-Square first_1(Bitboard b) {
b ^= (b - 1);
uint32_t fold = unsigned(b) ^ unsigned(b >> 32);
return Square(BSFTable[(fold * 0x783A9B23) >> 26]);
}
-Square pop_1st_bit(Bitboard* b) {
+Square pop_lsb(Bitboard* b) {
Bitboard bb = *b;
*b = bb & (bb - 1);
+
+ if (Is64Bit)
+ return Square(BSFTable[((bb & -bb) * 0x218A392CD3D5DBFULL) >> 58]);
+
bb ^= (bb - 1);
uint32_t fold = unsigned(bb) ^ unsigned(bb >> 32);
return Square(BSFTable[(fold * 0x783A9B23) >> 26]);
}
-Square last_1(Bitboard b) {
+Square msb(Bitboard b) {
unsigned b32;
int result = 0;
std::cout << "+---+---+---+---+---+---+---+---+" << '\n';
for (File file = FILE_A; file <= FILE_H; file++)
- std::cout << "| " << ((b & make_square(file, rank)) ? "X " : " ");
+ std::cout << "| " << (b & (file | rank) ? "X " : " ");
std::cout << "|\n";
}
for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
SquareDistance[s1][s2] = std::max(file_distance(s1, s2), rank_distance(s1, s2));
+ for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
+ for (int d = 1; d < 8; d++)
+ for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
+ if (SquareDistance[s1][s2] == d)
+ DistanceRingsBB[s1][d - 1] |= s2;
+
for (int i = 0; i < 64; i++)
if (!Is64Bit) // Matt Taylor's folding trick for 32 bit systems
{
}
- Bitboard pick_random(Bitboard mask, RKISS& rk, int booster) {
-
- Bitboard magic;
+ Bitboard pick_random(RKISS& rk, int booster) {
// 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)
- {
- magic = rk.rand<Bitboard>();
- magic = (magic >> s1) | (magic << (64 - s1));
- magic &= rk.rand<Bitboard>();
- magic = (magic >> s2) | (magic << (64 - s2));
- magic &= rk.rand<Bitboard>();
-
- if (BitCount8Bit[(mask * magic) >> 56] >= 6)
- return magic;
- }
+ Bitboard m = rk.rand<Bitboard>();
+ m = (m >> s1) | (m << (64 - s1));
+ m &= rk.rand<Bitboard>();
+ m = (m >> s2) | (m << (64 - s2));
+ return m & rk.rand<Bitboard>();
}
// Find a magic for square 's' picking up an (almost) random number
// until we find the one that passes the verification test.
do {
- magics[s] = pick_random(masks[s], rk, booster);
+ do magics[s] = pick_random(rk, booster);
+ while (BitCount8Bit[(magics[s] * masks[s]) >> 56] < 6);
+
memset(attacks[s], 0, size * sizeof(Bitboard));
// A good magic must map every possible occupancy to an index that
if (attack && attack != reference[i])
break;
+ assert(reference[i] != 0);
+
attack = reference[i];
}
} while (i != size);