X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=82608eab4f1ba1e937dc4dd56b29a73b5b2a6e20;hp=40cdbb21ff956601238b0db0dc72176e5cb081cb;hb=c2cd75843eb0b6a29ce291fc3ac041b5a082afbc;hpb=797c960d2004eacbbd19c656f483f070130bb358 diff --git a/src/bitboard.cpp b/src/bitboard.cpp index 40cdbb21..82608eab 100644 --- a/src/bitboard.cpp +++ b/src/bitboard.cpp @@ -23,6 +23,7 @@ #include "bitboard.h" #include "bitcount.h" +#include "misc.h" #include "rkiss.h" CACHE_LINE_ALIGNMENT @@ -45,63 +46,57 @@ Bitboard ThisAndAdjacentFilesBB[8]; 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 = 0x3F79D71B4CB0A89ULL; + const uint32_t DeBruijn_32 = 0x783A9B23; + CACHE_LINE_ALIGNMENT - int BSFTable[64]; int MS1BTable[256]; + Square BSFTable[64]; 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); 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. -#if defined(IS_64BIT) && !defined(USE_BSFQ) + FORCE_INLINE unsigned bsf_index(Bitboard b) { -Square first_1(Bitboard b) { - return Square(BSFTable[((b & -b) * 0x218A392CD3D5DBFULL) >> 58]); + // Matt Taylor's folding for 32 bit systems, extended to 64 bits by Kim Walisch + b ^= (b - 1); + return Is64Bit ? (b * DeBruijn_64) >> 58 + : ((unsigned(b) ^ unsigned(b >> 32)) * DeBruijn_32) >> 26; + } } -Square pop_1st_bit(Bitboard* b) { - Bitboard bb = *b; - *b &= (*b - 1); - return Square(BSFTable[((bb & -bb) * 0x218A392CD3D5DBFULL) >> 58]); -} +/// 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. -#elif !defined(USE_BSFQ) +#if !defined(USE_BSFQ) -Square first_1(Bitboard b) { - b ^= (b - 1); - uint32_t fold = unsigned(b) ^ unsigned(b >> 32); - return Square(BSFTable[(fold * 0x783A9B23) >> 26]); -} +Square lsb(Bitboard b) { return BSFTable[bsf_index(b)]; } -Square pop_1st_bit(Bitboard* b) { +Square pop_lsb(Bitboard* b) { Bitboard bb = *b; *b = bb & (bb - 1); - bb ^= (bb - 1); - uint32_t fold = unsigned(bb) ^ unsigned(bb >> 32); - return Square(BSFTable[(fold * 0x783A9B23) >> 26]); + return BSFTable[bsf_index(bb)]; } -Square last_1(Bitboard b) { +Square msb(Bitboard b) { unsigned b32; int result = 0; @@ -126,7 +121,7 @@ Square last_1(Bitboard b) { result += 8; } - return Square(result + MS1BTable[b32]); + return (Square)(result + MS1BTable[b32]); } #endif // !defined(USE_BSFQ) @@ -137,16 +132,18 @@ Square last_1(Bitboard b) { void Bitboards::print(Bitboard b) { + sync_cout; + 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 << "| " << (b & (file | rank) ? "X " : " "); std::cout << "|\n"; } - std::cout << "+---+---+---+---+---+---+---+---+" << std::endl; + std::cout << "+---+---+---+---+---+---+---+---+" << sync_endl; } @@ -159,6 +156,9 @@ void Bitboards::init() { while (k < (2 << i)) MS1BTable[k++] = i; + for (int i = 0; i < 64; i++) + BSFTable[bsf_index(1ULL << i)] = Square(i); + for (Bitboard b = 0; b < 256; b++) BitCount8Bit[b] = (uint8_t)popcount(b); @@ -168,46 +168,38 @@ void Bitboards::init() { 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 (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; - } - else - BSFTable[((1ULL << i) * 0x218A392CD3D5DBFULL) >> 58] = i; + 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; int steps[][9] = { {}, { 7, 9 }, { 17, 15, 10, 6, -6, -10, -15, -17 }, {}, {}, {}, { 9, 7, -7, -9, 8, 1, -1, -8 } }; @@ -231,9 +223,8 @@ void Bitboards::init() { for (Square s = SQ_A1; s <= SQ_H8; s++) { - PseudoAttacks[BISHOP][s] = attacks_bb(s, 0); - PseudoAttacks[ROOK][s] = attacks_bb(s, 0); - PseudoAttacks[QUEEN][s] = PseudoAttacks[BISHOP][s] | PseudoAttacks[ROOK][s]; + PseudoAttacks[QUEEN][s] = PseudoAttacks[BISHOP][s] = attacks_bb(s, 0); + PseudoAttacks[QUEEN][s] |= PseudoAttacks[ ROOK][s] = attacks_bb< ROOK>(s, 0); } for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++) @@ -269,25 +260,17 @@ namespace { } - 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(); - magic = (magic >> s1) | (magic << (64 - s1)); - magic &= rk.rand(); - magic = (magic >> s2) | (magic << (64 - s2)); - magic &= rk.rand(); - - if (BitCount8Bit[(mask * magic) >> 56] >= 6) - return magic; - } + Bitboard m = rk.rand(); + m = (m >> s1) | (m << (64 - s1)); + m &= rk.rand(); + m = (m >> s2) | (m << (64 - s2)); + return m & rk.rand(); } @@ -340,7 +323,9 @@ namespace { // 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 @@ -354,6 +339,8 @@ namespace { if (attack && attack != reference[i]) break; + assert(reference[i] != 0); + attack = reference[i]; } } while (i != size);