#include "bitcount.h"
#include "rkiss.h"
+CACHE_LINE_ALIGNMENT
+
Bitboard RMasks[64];
Bitboard RMagics[64];
Bitboard* RAttacks[64];
-int RShifts[64];
+unsigned RShifts[64];
Bitboard BMasks[64];
Bitboard BMagics[64];
Bitboard* BAttacks[64];
-int BShifts[64];
-
-Bitboard SetMaskBB[65];
-Bitboard ClearMaskBB[65];
+unsigned BShifts[64];
+Bitboard SquareBB[64];
Bitboard FileBB[8];
Bitboard RankBB[8];
Bitboard AdjacentFilesBB[8];
Bitboard SquaresInFrontMask[2][64];
Bitboard PassedPawnMask[2][64];
Bitboard AttackSpanMask[2][64];
-
Bitboard PseudoAttacks[6][64];
uint8_t BitCount8Bit[256];
CACHE_LINE_ALIGNMENT
int BSFTable[64];
- Bitboard RookTable[0x19000]; // Storage space for rook attacks
- Bitboard BishopTable[0x1480]; // Storage space for bishop attacks
-
- void init_magic_bitboards(PieceType pt, Bitboard* attacks[], Bitboard magics[],
- Bitboard masks[], int shifts[]);
-}
-
-
-/// print_bitboard() prints a bitboard in an easily readable format to the
-/// standard output. This is sometimes useful for debugging.
+ int MS1BTable[256];
+ Bitboard RTable[0x19000]; // Storage space for rook attacks
+ Bitboard BTable[0x1480]; // Storage space for bishop attacks
-void print_bitboard(Bitboard b) {
+ typedef unsigned (Fn)(Square, Bitboard);
- for (Rank r = RANK_8; r >= RANK_1; r--)
- {
- std::cout << "+---+---+---+---+---+---+---+---+" << '\n';
- for (File f = FILE_A; f <= FILE_H; f++)
- std::cout << "| " << (bit_is_set(b, make_square(f, r)) ? "X " : " ");
-
- std::cout << "|\n";
- }
- std::cout << "+---+---+---+---+---+---+---+---+" << std::endl;
+ void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[],
+ 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.
// Use type-punning
union b_union {
- Bitboard b;
+ Bitboard dummy;
struct {
#if defined (BIGENDIAN)
uint32_t h;
uint32_t l;
uint32_t h;
#endif
- } dw;
+ } b;
};
-Square pop_1st_bit(Bitboard* bb) {
-
- b_union u;
- Square ret;
+Square pop_1st_bit(Bitboard* b) {
- u.b = *bb;
+ const b_union u = *((b_union*)b);
- if (u.dw.l)
+ if (u.b.l)
{
- ret = Square(BSFTable[((u.dw.l ^ (u.dw.l - 1)) * 0x783A9B23) >> 26]);
- u.dw.l &= (u.dw.l - 1);
- *bb = u.b;
- return ret;
+ ((b_union*)b)->b.l = u.b.l & (u.b.l - 1);
+ return Square(BSFTable[((u.b.l ^ (u.b.l - 1)) * 0x783A9B23) >> 26]);
}
- ret = Square(BSFTable[((~(u.dw.h ^ (u.dw.h - 1))) * 0x783A9B23) >> 26]);
- u.dw.h &= (u.dw.h - 1);
- *bb = u.b;
- return ret;
+
+ ((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 last_1(Bitboard b) {
+
+ unsigned b32;
+ int result = 0;
+
+ if (b > 0xFFFFFFFF)
+ {
+ b >>= 32;
+ result = 32;
+ }
+
+ b32 = unsigned(b);
+
+ if (b32 > 0xFFFF)
+ {
+ b32 >>= 16;
+ result += 16;
+ }
+
+ if (b32 > 0xFF)
+ {
+ b32 >>= 8;
+ result += 8;
+ }
+
+ return Square(result + MS1BTable[b32]);
}
#endif // !defined(USE_BSFQ)
-/// bitboards_init() initializes various bitboard arrays. It is called during
+/// Bitboards::print() prints a bitboard in an easily readable format to the
+/// standard output. This is sometimes useful for debugging.
+
+void Bitboards::print(Bitboard b) {
+
+ for (Rank rank = RANK_8; rank >= RANK_1; rank--)
+ {
+ std::cout << "+---+---+---+---+---+---+---+---+" << '\n';
+
+ for (File file = FILE_A; file <= FILE_H; file++)
+ std::cout << "| " << ((b & make_square(file, rank)) ? "X " : " ");
+
+ std::cout << "|\n";
+ }
+ std::cout << "+---+---+---+---+---+---+---+---+" << std::endl;
+}
+
+
+/// Bitboards::init() initializes various bitboard arrays. It is called during
/// program initialization.
-void bitboards_init() {
+void Bitboards::init() {
+
+ for (int k = 0, i = 0; i < 8; i++)
+ while (k < (2 << i))
+ MS1BTable[k++] = i;
for (Bitboard b = 0; b < 256; b++)
BitCount8Bit[b] = (uint8_t)popcount<Max15>(b);
for (Square s = SQ_A1; s <= SQ_H8; s++)
- {
- SetMaskBB[s] = 1ULL << s;
- ClearMaskBB[s] = ~SetMaskBB[s];
- }
-
- ClearMaskBB[SQ_NONE] = ~0ULL;
+ SquareBB[s] = 1ULL << s;
FileBB[FILE_A] = FileABB;
RankBB[RANK_1] = Rank1BB;
{
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);
+ if (is_ok(to) && square_distance(s, to) < 3)
+ StepAttacksBB[make_piece(c, pt)][s] |= to;
}
- init_magic_bitboards(ROOK, RAttacks, RMagics, RMasks, RShifts);
- init_magic_bitboards(BISHOP, BAttacks, BMagics, BMasks, BShifts);
+ Square RDeltas[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W };
+ Square BDeltas[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW };
+
+ init_magics(RTable, RAttacks, RMagics, RMasks, RShifts, RDeltas, magic_index<ROOK>);
+ init_magics(BTable, BAttacks, BMagics, BMasks, BShifts, BDeltas, magic_index<BISHOP>);
for (Square s = SQ_A1; s <= SQ_H8; s++)
{
- PseudoAttacks[BISHOP][s] = bishop_attacks_bb(s, 0);
- PseudoAttacks[ROOK][s] = rook_attacks_bb(s, 0);
- PseudoAttacks[QUEEN][s] = queen_attacks_bb(s, 0);
+ 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];
}
for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
- if (bit_is_set(PseudoAttacks[QUEEN][s1], s2))
+ if (PseudoAttacks[QUEEN][s1] & s2)
{
Square delta = (s2 - s1) / square_distance(s1, s2);
for (Square s = s1 + delta; s != s2; s += delta)
- set_bit(&BetweenBB[s1][s2], s);
+ BetweenBB[s1][s2] |= s;
}
}
namespace {
- Bitboard sliding_attacks(PieceType pt, Square sq, Bitboard occupied) {
+ Bitboard sliding_attack(Square deltas[], Square sq, Bitboard occupied) {
- Square deltas[][4] = { { DELTA_N, DELTA_E, DELTA_S, DELTA_W },
- { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW } };
- Bitboard attacks = 0;
- Square* delta = (pt == ROOK ? deltas[0] : deltas[1]);
+ Bitboard attack = 0;
for (int i = 0; i < 4; i++)
- {
- Square s = sq + delta[i];
-
- while (square_is_ok(s) && square_distance(s, s - delta[i]) == 1)
+ for (Square s = sq + deltas[i];
+ is_ok(s) && square_distance(s, s - deltas[i]) == 1;
+ s += deltas[i])
{
- set_bit(&attacks, s);
+ attack |= s;
- if (bit_is_set(occupied, s))
+ if (occupied & s)
break;
-
- s += delta[i];
}
- }
- return attacks;
+
+ return attack;
}
}
- // init_magic_bitboards() computes all rook and bishop magics at startup.
- // Magic bitboards are used to look up attacks of sliding pieces. As reference
- // see chessprogramming.wikispaces.com/Magic+Bitboards. In particular, here we
+ // init_magics() computes all rook and bishop attacks at startup. Magic
+ // bitboards are used to look up attacks of sliding pieces. As a reference see
+ // chessprogramming.wikispaces.com/Magic+Bitboards. In particular, here we
// use the so called "fancy" approach.
- void init_magic_bitboards(PieceType pt, Bitboard* attacks[], Bitboard magics[],
- Bitboard masks[], int shifts[]) {
+ void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[],
+ Bitboard masks[], unsigned shifts[], Square deltas[], Fn index) {
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], edges, b;
- int i, size, index, booster;
+ int i, size, booster;
// attacks[s] is a pointer to the beginning of the attacks table for square 's'
- attacks[SQ_A1] = (pt == ROOK ? RookTable : BishopTable);
+ attacks[SQ_A1] = table;
for (Square s = SQ_A1; s <= SQ_H8; s++)
{
// 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.
- masks[s] = sliding_attacks(pt, s, 0) & ~edges;
+ masks[s] = sliding_attack(deltas, s, 0) & ~edges;
shifts[s] = (Is64Bit ? 64 : 32) - popcount<Max15>(masks[s]);
// Use Carry-Rippler trick to enumerate all subsets of masks[s] and
- // store the corresponding sliding attacks bitboard in reference[].
+ // store the corresponding sliding attack bitboard in reference[].
b = size = 0;
do {
occupancy[size] = b;
- reference[size++] = sliding_attacks(pt, s, b);
+ reference[size++] = sliding_attack(deltas, s, b);
b = (b - masks[s]) & masks[s];
} while (b);
// effect of verifying the magic.
for (i = 0; i < size; i++)
{
- index = (pt == ROOK ? rook_index(s, occupancy[i])
- : bishop_index(s, occupancy[i]));
-
- if (!attacks[s][index])
- attacks[s][index] = reference[i];
+ Bitboard& attack = attacks[s][index(s, occupancy[i])];
- else if (attacks[s][index] != reference[i])
+ if (attack && attack != reference[i])
break;
+
+ attack = reference[i];
}
} while (i != size);
}