X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=639ef3f06e968d7249c55ff45748577a9e6cfefa;hp=1bae6843df5303d3d7379e335debd7c02946b898;hb=6008f6538e9c3912c88e89d77ef3e3d3351a6e55;hpb=2f47844c7cb34c7de5b5d41cda10b7d8736a20bc diff --git a/src/bitboard.cpp b/src/bitboard.cpp index 1bae6843..639ef3f0 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 @@ -45,22 +46,27 @@ Bitboard ThisAndAdjacentFilesBB[8]; 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 { + // 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); @@ -68,40 +74,35 @@ namespace { 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]); } -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) * DeBruijn_64) >> 58]); + bb ^= (bb - 1); uint32_t fold = unsigned(bb) ^ unsigned(bb >> 32); - return Square(BSFTable[(fold * 0x783A9B23) >> 26]); + return Square(BSFTable[(fold * DeBruijn_32) >> 26]); } -Square last_1(Bitboard b) { +Square msb(Bitboard b) { unsigned b32; int result = 0; @@ -137,16 +138,18 @@ 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; } @@ -195,16 +198,22 @@ void Bitboards::init() { 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 } }; @@ -265,25 +274,17 @@ 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(); } @@ -336,7 +337,9 @@ 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 @@ -350,6 +353,8 @@ namespace { if (attack && attack != reference[i]) break; + assert(reference[i] != 0); + attack = reference[i]; } } while (i != size);