Bitboard InFrontBB[2][8];
Bitboard StepAttacksBB[16][64];
Bitboard BetweenBB[64][64];
-Bitboard SquaresInFrontMask[2][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 {
+ // De Bruijn sequences. See chessprogramming.wikispaces.com/BitScan
+ const uint64_t DeBruijn_64 = 0x218A392CD3D5DBFULL;
+ const uint32_t DeBruijn_32 = 0x783A9B23;
+
CACHE_LINE_ALIGNMENT
int BSFTable[64];
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.
-
-#if defined(IS_64BIT) && !defined(USE_BSFQ)
+/// 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.
-Square first_1(Bitboard b) {
- return Square(BSFTable[((b & -b) * 0x218A392CD3D5DBFULL) >> 58]);
-}
+#if !defined(USE_BSFQ)
-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) * DeBruijn_64) >> 58]);
-Square first_1(Bitboard b) {
b ^= (b - 1);
uint32_t fold = unsigned(b) ^ unsigned(b >> 32);
- return Square(BSFTable[(fold * 0x783A9B23) >> 26]);
+ return Square(BSFTable[(fold * DeBruijn_32) >> 26]);
}
-// Use type-punning
-union b_union {
-
- Bitboard dummy;
- struct {
-#if defined (BIGENDIAN)
- uint32_t h;
- uint32_t l;
-#else
- uint32_t l;
- uint32_t h;
-#endif
- } b;
-};
-
-Square pop_1st_bit(Bitboard* b) {
-
- const b_union u = *((b_union*)b);
-
- if (u.b.l)
- {
- ((b_union*)b)->b.l = u.b.l & (u.b.l - 1);
- return Square(BSFTable[((u.b.l ^ (u.b.l - 1)) * 0x783A9B23) >> 26]);
- }
-
- ((b_union*)b)->b.h = u.b.h & (u.b.h - 1);
- return Square(BSFTable[((~(u.b.h ^ (u.b.h - 1))) * 0x783A9B23) >> 26]);
+Square pop_lsb(Bitboard* b) {
+
+ Bitboard bb = *b;
+ *b = bb & (bb - 1);
+
+ if (Is64Bit)
+ return Square(BSFTable[((bb & -bb) * DeBruijn_64) >> 58]);
+
+ bb ^= (bb - 1);
+ uint32_t fold = unsigned(bb) ^ unsigned(bb >> 32);
+ return Square(BSFTable[(fold * DeBruijn_32) >> 26]);
}
-Square last_1(Bitboard b) {
+Square msb(Bitboard b) {
+ unsigned b32;
int result = 0;
if (b > 0xFFFFFFFF)
result = 32;
}
- if (b > 0xFFFF)
+ b32 = unsigned(b);
+
+ if (b32 > 0xFFFF)
{
- b >>= 16;
+ b32 >>= 16;
result += 16;
}
- if (b > 0xFF)
+ if (b32 > 0xFF)
{
- b >>= 8;
+ b32 >>= 8;
result += 8;
}
- return Square(result + MS1BTable[b]);
+ return Square(result + MS1BTable[b32]);
}
#endif // !defined(USE_BSFQ)
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";
}
FileBB[FILE_A] = FileABB;
RankBB[RANK_1] = Rank1BB;
- for (int f = FILE_B; f <= FILE_H; f++)
+ for (int i = 1; i < 8; i++)
{
- FileBB[f] = FileBB[f - 1] << 1;
- RankBB[f] = RankBB[f - 1] << 8;
+ FileBB[i] = FileBB[i - 1] << 1;
+ RankBB[i] = RankBB[i - 1] << 8;
}
- for (int f = FILE_A; f <= FILE_H; f++)
+ for (File f = FILE_A; f <= FILE_H; f++)
{
AdjacentFilesBB[f] = (f > FILE_A ? FileBB[f - 1] : 0) | (f < FILE_H ? FileBB[f + 1] : 0);
ThisAndAdjacentFilesBB[f] = FileBB[f] | AdjacentFilesBB[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 (Rank r = RANK_1; r < RANK_8; r++)
+ InFrontBB[WHITE][r] = ~(InFrontBB[BLACK][r + 1] = InFrontBB[BLACK][r] | RankBB[r]);
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_adjacent_files_bb(file_of(s));
- AttackSpanMask[c][s] = in_front_bb(c, s) & adjacent_files_bb(file_of(s));
+ ForwardBB[c][s] = InFrontBB[c][rank_of(s)] & FileBB[file_of(s)];
+ PassedPawnMask[c][s] = InFrontBB[c][rank_of(s)] & ThisAndAdjacentFilesBB[file_of(s)];
+ AttackSpanMask[c][s] = InFrontBB[c][rank_of(s)] & AdjacentFilesBB[file_of(s)];
}
for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
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 b = 1ULL << i;
b ^= b - 1;
b ^= b >> 32;
- BSFTable[(uint32_t)(b * 0x783A9B23) >> 26] = i;
+ BSFTable[(uint32_t)(b * DeBruijn_32) >> 26] = i;
}
else
- BSFTable[((1ULL << i) * 0x218A392CD3D5DBFULL) >> 58] = i;
+ BSFTable[((1ULL << i) * DeBruijn_64) >> 58] = i;
int steps[][9] = { {}, { 7, 9 }, { 17, 15, 10, 6, -6, -10, -15, -17 },
{}, {}, {}, { 9, 7, -7, -9, 8, 1, -1, -8 } };
for (Square s = SQ_A1; s <= SQ_H8; s++)
{
- PseudoAttacks[BISHOP][s] = attacks_bb<BISHOP>(s, 0);
- PseudoAttacks[ROOK][s] = attacks_bb<ROOK>(s, 0);
- PseudoAttacks[QUEEN][s] = PseudoAttacks[BISHOP][s] | PseudoAttacks[ROOK][s];
+ PseudoAttacks[QUEEN][s] = PseudoAttacks[BISHOP][s] = attacks_bb<BISHOP>(s, 0);
+ PseudoAttacks[QUEEN][s] |= PseudoAttacks[ ROOK][s] = attacks_bb< ROOK>(s, 0);
}
for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
}
- 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);
projects / stockfish / blobdiff