/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
*/
#include <algorithm>
-#include <cstring>
-#include <iostream>
+#include <bitset>
#include "bitboard.h"
-#include "bitcount.h"
-#include "rkiss.h"
-
-CACHE_LINE_ALIGNMENT
-
-Bitboard RMasks[64];
-Bitboard RMagics[64];
-Bitboard* RAttacks[64];
-unsigned RShifts[64];
-
-Bitboard BMasks[64];
-Bitboard BMagics[64];
-Bitboard* BAttacks[64];
-unsigned BShifts[64];
-
-Bitboard SquareBB[64];
-Bitboard FileBB[8];
-Bitboard RankBB[8];
-Bitboard AdjacentFilesBB[8];
-Bitboard ThisAndAdjacentFilesBB[8];
-Bitboard InFrontBB[2][8];
-Bitboard StepAttacksBB[16][64];
-Bitboard BetweenBB[64][64];
-Bitboard SquaresInFrontMask[2][64];
-Bitboard PassedPawnMask[2][64];
-Bitboard AttackSpanMask[2][64];
-Bitboard PseudoAttacks[6][64];
-
-uint8_t BitCount8Bit[256];
-int SquareDistance[64][64];
+#include "misc.h"
-namespace {
-
- 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
-
- typedef unsigned (Fn)(Square, Bitboard);
+uint8_t PopCnt16[1 << 16];
+uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
- 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.
+Bitboard SquareBB[SQUARE_NB];
+Bitboard LineBB[SQUARE_NB][SQUARE_NB];
+Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
+Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
-#if defined(IS_64BIT) && !defined(USE_BSFQ)
-
-Square first_1(Bitboard b) {
- return Square(BSFTable[((b & -b) * 0x218A392CD3D5DBFULL) >> 58]);
-}
+Magic RookMagics[SQUARE_NB];
+Magic BishopMagics[SQUARE_NB];
-Square pop_1st_bit(Bitboard* b) {
- Bitboard bb = *b;
- *b &= (*b - 1);
- return Square(BSFTable[((bb & -bb) * 0x218A392CD3D5DBFULL) >> 58]);
-}
-
-#elif !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]);
-}
+namespace {
-Square pop_1st_bit(Bitboard* b) {
+ Bitboard RookTable[0x19000]; // To store rook attacks
+ Bitboard BishopTable[0x1480]; // To store bishop attacks
- Bitboard bb = *b;
- *b = bb & (bb - 1);
- bb ^= (bb - 1);
- uint32_t fold = unsigned(bb) ^ unsigned(bb >> 32);
- return Square(BSFTable[(fold * 0x783A9B23) >> 26]);
+ void init_magics(Bitboard table[], Magic magics[], Direction directions[]);
}
-Square last_1(Bitboard b) {
- unsigned b32;
- int result = 0;
+/// Bitboards::pretty() returns an ASCII representation of a bitboard suitable
+/// to be printed to standard output. Useful for debugging.
- if (b > 0xFFFFFFFF)
- {
- b >>= 32;
- result = 32;
- }
+const std::string Bitboards::pretty(Bitboard b) {
- b32 = unsigned(b);
+ std::string s = "+---+---+---+---+---+---+---+---+\n";
- if (b32 > 0xFFFF)
+ for (Rank r = RANK_8; r >= RANK_1; --r)
{
- b32 >>= 16;
- result += 16;
- }
+ for (File f = FILE_A; f <= FILE_H; ++f)
+ s += b & make_square(f, r) ? "| X " : "| ";
- if (b32 > 0xFF)
- {
- b32 >>= 8;
- result += 8;
+ s += "|\n+---+---+---+---+---+---+---+---+\n";
}
- return Square(result + MS1BTable[b32]);
+ return s;
}
-#endif // !defined(USE_BSFQ)
-
-
-/// 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.
+/// Bitboards::init() initializes various bitboard tables. It is called at
+/// startup and relies on global objects to be already zero-initialized.
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++)
- SquareBB[s] = 1ULL << s;
-
- FileBB[FILE_A] = FileABB;
- RankBB[RANK_1] = Rank1BB;
+ for (unsigned i = 0; i < (1 << 16); ++i)
+ PopCnt16[i] = std::bitset<16>(i).count();
- for (int f = FILE_B; f <= FILE_H; f++)
- {
- FileBB[f] = FileBB[f - 1] << 1;
- RankBB[f] = RankBB[f - 1] << 8;
- }
+ for (Square s = SQ_A1; s <= SQ_H8; ++s)
+ SquareBB[s] = (1ULL << s);
- for (int 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 (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
+ for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
+ SquareDistance[s1][s2] = std::max(distance<File>(s1, s2), distance<Rank>(s1, s2));
- 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];
- }
+ int steps[][5] = { {}, { 7, 9 }, { 6, 10, 15, 17 }, {}, {}, {}, { 1, 7, 8, 9 } };
- 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));
- }
-
- 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;
-
- int steps[][9] = { {}, { 7, 9 }, { 17, 15, 10, 6, -6, -10, -15, -17 },
- {}, {}, {}, { 9, 7, -7, -9, 8, 1, -1, -8 } };
-
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- for (int k = 0; steps[pt][k]; k++)
+ for (Color c : { WHITE, BLACK })
+ for (PieceType pt : { PAWN, KNIGHT, KING })
+ for (Square s = SQ_A1; s <= SQ_H8; ++s)
+ for (int i = 0; steps[pt][i]; ++i)
{
- Square to = s + Square(c == WHITE ? steps[pt][k] : -steps[pt][k]);
-
- if (is_ok(to) && square_distance(s, to) < 3)
- StepAttacksBB[make_piece(c, pt)][s] |= to;
+ Square to = s + Direction(c == WHITE ? steps[pt][i] : -steps[pt][i]);
+
+ if (is_ok(to) && distance(s, to) < 3)
+ {
+ if (pt == PAWN)
+ PawnAttacks[c][s] |= to;
+ else
+ PseudoAttacks[pt][s] |= to;
+ }
}
- Square RDeltas[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W };
- Square BDeltas[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW };
+ Direction RookDirections[] = { NORTH, EAST, SOUTH, WEST };
+ Direction BishopDirections[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST };
- init_magics(RTable, RAttacks, RMagics, RMasks, RShifts, RDeltas, magic_index<ROOK>);
- init_magics(BTable, BAttacks, BMagics, BMasks, BShifts, BDeltas, magic_index<BISHOP>);
+ init_magics(RookTable, RookMagics, RookDirections);
+ init_magics(BishopTable, BishopMagics, BishopDirections);
- for (Square s = SQ_A1; s <= SQ_H8; s++)
+ for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
{
- 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][s1] = PseudoAttacks[BISHOP][s1] = attacks_bb<BISHOP>(s1, 0);
+ PseudoAttacks[QUEEN][s1] |= PseudoAttacks[ ROOK][s1] = attacks_bb< ROOK>(s1, 0);
- for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
- for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
- if (PseudoAttacks[QUEEN][s1] & s2)
- {
- Square delta = (s2 - s1) / square_distance(s1, s2);
-
- for (Square s = s1 + delta; s != s2; s += delta)
- BetweenBB[s1][s2] |= s;
- }
+ for (PieceType pt : { BISHOP, ROOK })
+ for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
+ if (PseudoAttacks[pt][s1] & s2)
+ LineBB[s1][s2] = (attacks_bb(pt, s1, 0) & attacks_bb(pt, s2, 0)) | s1 | s2;
+ }
}
namespace {
- Bitboard sliding_attack(Square deltas[], Square sq, Bitboard occupied) {
+ Bitboard sliding_attack(Direction directions[], Square sq, Bitboard occupied) {
Bitboard attack = 0;
- for (int i = 0; i < 4; i++)
- for (Square s = sq + deltas[i];
- is_ok(s) && square_distance(s, s - deltas[i]) == 1;
- s += deltas[i])
+ for (int i = 0; i < 4; ++i)
+ for (Square s = sq + directions[i];
+ is_ok(s) && distance(s, s - directions[i]) == 1;
+ s += directions[i])
{
attack |= s;
}
- Bitboard pick_random(Bitboard mask, RKISS& rk, int booster) {
-
- Bitboard magic;
-
- // 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;
- }
- }
-
-
// 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.
+ // www.chessprogramming.org/Magic_Bitboards. In particular, here we use the so
+ // called "fancy" approach.
- void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[],
- Bitboard masks[], unsigned shifts[], Square deltas[], Fn index) {
+ void init_magics(Bitboard table[], Magic magics[], Direction directions[]) {
- 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, booster;
+ // Optimal PRNG seeds to pick the correct magics in the shortest time
+ int seeds[][RANK_NB] = { { 8977, 44560, 54343, 38998, 5731, 95205, 104912, 17020 },
+ { 728, 10316, 55013, 32803, 12281, 15100, 16645, 255 } };
- // attacks[s] is a pointer to the beginning of the attacks table for square 's'
- attacks[SQ_A1] = table;
+ Bitboard occupancy[4096], reference[4096], edges, b;
+ int epoch[4096] = {}, cnt = 0, size = 0;
- for (Square s = SQ_A1; s <= SQ_H8; s++)
+ for (Square s = SQ_A1; s <= SQ_H8; ++s)
{
// Board edges are not considered in the relevant occupancies
edges = ((Rank1BB | Rank8BB) & ~rank_bb(s)) | ((FileABB | FileHBB) & ~file_bb(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_attack(deltas, s, 0) & ~edges;
- shifts[s] = (Is64Bit ? 64 : 32) - popcount<Max15>(masks[s]);
+ Magic& m = magics[s];
+ m.mask = sliding_attack(directions, s, 0) & ~edges;
+ m.shift = (Is64Bit ? 64 : 32) - popcount(m.mask);
+
+ // Set the offset for the attacks table of the square. We have individual
+ // table sizes for each square with "Fancy Magic Bitboards".
+ m.attacks = s == SQ_A1 ? table : magics[s - 1].attacks + size;
// Use Carry-Rippler trick to enumerate all subsets of masks[s] and
// store the corresponding sliding attack bitboard in reference[].
b = size = 0;
do {
occupancy[size] = b;
- reference[size++] = sliding_attack(deltas, s, b);
- b = (b - masks[s]) & masks[s];
+ reference[size] = sliding_attack(directions, s, b);
+
+ if (HasPext)
+ m.attacks[pext(b, m.mask)] = reference[size];
+
+ size++;
+ b = (b - m.mask) & m.mask;
} while (b);
- // Set the offset for the table of the next square. We have individual
- // table sizes for each square with "Fancy Magic Bitboards".
- if (s < SQ_H8)
- attacks[s + 1] = attacks[s] + size;
+ if (HasPext)
+ continue;
- booster = MagicBoosters[Is64Bit][rank_of(s)];
+ PRNG rng(seeds[Is64Bit][rank_of(s)]);
// 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);
- memset(attacks[s], 0, size * sizeof(Bitboard));
+ for (int i = 0; i < size; )
+ {
+ for (m.magic = 0; popcount((m.magic * m.mask) >> 56) < 6; )
+ m.magic = rng.sparse_rand<Bitboard>();
// A good magic must map every possible occupancy to an index that
// looks up the correct sliding attack in the attacks[s] database.
// Note that we build up the database for square 's' as a side
- // effect of verifying the magic.
- for (i = 0; i < size; i++)
+ // effect of verifying the magic. Keep track of the attempt count
+ // and save it in epoch[], little speed-up trick to avoid resetting
+ // m.attacks[] after every failed attempt.
+ for (++cnt, i = 0; i < size; ++i)
{
- Bitboard& attack = attacks[s][index(s, occupancy[i])];
-
- if (attack && attack != reference[i])
+ unsigned idx = m.index(occupancy[i]);
+
+ if (epoch[idx] < cnt)
+ {
+ epoch[idx] = cnt;
+ m.attacks[idx] = reference[i];
+ }
+ else if (m.attacks[idx] != reference[i])
break;
-
- attack = reference[i];
}
- } while (i != size);
+ }
}
}
}
projects / stockfish / blobdiff