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https://github.com/sockspls/badfish
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Better name and document magic botboard stuff
No functional change. Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
parent
2f6142cb9b
commit
3092f0c646
2 changed files with 44 additions and 47 deletions
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@ -194,7 +194,7 @@ const int RShift[64] = {
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CACHE_LINE_ALIGNMENT int BSFTable[64];
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void init_sliding_attacks(Bitboard attacks[], Magics m[], const int shift[],
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const Bitboard mult[], int deltas[][2]);
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const Bitboard mult[], Square deltas[]);
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}
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@ -351,11 +351,11 @@ void init_bitboards() {
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set_bit(&StepAttacksBB[make_piece(c, pt)][s], to);
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}
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int rookDeltas[4][2] = { {0,1}, {0 ,-1}, {1, 0}, {-1, 0} };
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int bishopDeltas[4][2] = { {1,1}, {-1, 1}, {1,-1}, {-1,-1} };
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Square RDeltas[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W };
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Square BDeltas[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW };
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init_sliding_attacks(RAttacks, RMagics, RShift, RMult, rookDeltas);
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init_sliding_attacks(BAttacks, BMagics, BShift, BMult, bishopDeltas);
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init_sliding_attacks(RAttacks, RMagics, RShift, RMult, RDeltas);
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init_sliding_attacks(BAttacks, BMagics, BShift, BMult, BDeltas);
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for (Square s = SQ_A1; s <= SQ_H8; s++)
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{
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@ -381,70 +381,67 @@ void init_bitboards() {
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namespace {
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Bitboard index_to_bitboard(int index, Bitboard mask) {
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Bitboard submask(Bitboard mask, int key) {
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Bitboard result = 0;
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int sq, cnt = 0;
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Bitboard subMask = 0;
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int bitNum = -1;
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while (mask)
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{
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sq = pop_1st_bit(&mask);
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// Extract an unique submask out of a mask according to the given key
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for (Square s = SQ_A1; s <= SQ_H8; s++)
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if (bit_is_set(mask, s) && bit_is_set(key, Square(++bitNum)))
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set_bit(&subMask, s);
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if (index & (1 << cnt++))
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result |= (1ULL << sq);
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}
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return result;
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return subMask;
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}
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Bitboard sliding_attacks(int sq, Bitboard occupied, int deltas[][2],
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int fmin, int fmax, int rmin, int rmax) {
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Bitboard sliding_attacks(Square sq, Bitboard occupied, Square deltas[], bool skipLast) {
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Bitboard attacks = 0;
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int dx, dy, f, r;
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int rk = sq / 8;
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int fl = sq % 8;
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for (int i = 0; i < 4; i++)
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{
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dx = deltas[i][0];
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dy = deltas[i][1];
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f = fl + dx;
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r = rk + dy;
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Square s = sq + deltas[i];
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while ( (dx == 0 || (f >= fmin && f <= fmax))
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&& (dy == 0 || (r >= rmin && r <= rmax)))
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while ( square_is_ok(s)
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&& square_distance(s, s - deltas[i]) == 1
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&& (!skipLast || !file_distance(s, sq) || (square_file(s) != FILE_A && square_file(s) != FILE_H))
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&& (!skipLast || !rank_distance(s, sq) || (square_rank(s) != RANK_1 && square_rank(s) != RANK_8)))
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{
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attacks |= (1ULL << (f + r * 8));
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attacks |= 1ULL << s;
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if (occupied & (1ULL << (f + r * 8)))
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if (occupied & (1ULL << s))
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break;
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f += dx;
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r += dy;
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s += deltas[i];
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}
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}
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return attacks;
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}
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void init_sliding_attacks(Bitboard attacks[], Magics m[], const int shift[],
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const Bitboard mult[], int deltas[][2]) {
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Bitboard b, v;
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int i, j, index;
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const Bitboard mult[], Square deltas[]) {
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Bitboard occupancy, index;
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int maxKey, offset = 0;
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for (i = index = 0; i < 64; i++)
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for (Square s = SQ_A1; s <= SQ_H8; s++)
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{
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m[i].index = index;
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m[i].mult = mult[i];
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m[i].shift = shift[i];
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m[i].mask = sliding_attacks(i, 0, deltas, 1, 6, 1, 6);
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j = 1 << ((CpuIs64Bit ? 64 : 32) - m[i].shift);
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m[s].offset = offset;
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m[s].mult = mult[s];
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m[s].shift = shift[s];
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m[s].mask = sliding_attacks(s, EmptyBoardBB, deltas, true);
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for (int k = 0; k < j; k++)
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maxKey = 1 << (CpuIs64Bit ? 64 - shift[s] : 32 - shift[s]);
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for (int key = 0; key < maxKey; key++)
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{
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b = index_to_bitboard(k, m[i].mask);
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v = CpuIs64Bit ? b * mult[i] : unsigned(b * mult[i] ^ (b >> 32) * (mult[i] >> 32));
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attacks[index + (v >> shift[i])] = sliding_attacks(i, b, deltas, 0, 7, 0, 7);
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occupancy = submask(m[s].mask, key);
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index = CpuIs64Bit ? occupancy * mult[s]
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: unsigned(occupancy * mult[s] ^ (occupancy >> 32) * (mult[s] >> 32));
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attacks[offset + (index >> shift[s])] = sliding_attacks(s, occupancy, deltas, false);
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}
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index += j;
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offset += maxKey;
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}
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}
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}
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@ -69,7 +69,7 @@ extern uint8_t BitCount8Bit[256];
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struct Magics {
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Bitboard mask;
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uint64_t mult;
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uint32_t index;
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uint32_t offset;
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uint32_t shift;
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};
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@ -189,14 +189,14 @@ inline Bitboard bishop_attacks_bb(Square s, Bitboard occ) {
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inline Bitboard rook_attacks_bb(Square s, Bitboard occ) {
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const Magics& m = RMagics[s];
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Bitboard b = occ & m.mask;
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return RAttacks[m.index +
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return RAttacks[m.offset +
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((unsigned(b) * unsigned(m.mult) ^ unsigned(b >> 32) * unsigned(m.mult >> 32)) >> m.shift)];
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}
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inline Bitboard bishop_attacks_bb(Square s, Bitboard occ) {
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const Magics& m = BMagics[s];
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Bitboard b = occ & m.mask;
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return BAttacks[m.index +
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return BAttacks[m.offset +
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((unsigned(b) * unsigned(m.mult) ^ unsigned(b >> 32) * unsigned(m.mult >> 32)) >> m.shift)];
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}
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