/*
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) 2015-2016 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 "bitboard.h"
-#include "bitcount.h"
-#include "rkiss.h"
-
-CACHE_LINE_ALIGNMENT
-
-Bitboard RMasks[64];
-Bitboard RMagics[64];
-Bitboard* RAttacks[64];
-int RShifts[64];
-
-Bitboard BMasks[64];
-Bitboard BMagics[64];
-Bitboard* BAttacks[64];
-int 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"
+
+uint8_t PopCnt16[1 << 16];
+int SquareDistance[SQUARE_NB][SQUARE_NB];
+
+Bitboard RookMasks [SQUARE_NB];
+Bitboard RookMagics [SQUARE_NB];
+Bitboard* RookAttacks[SQUARE_NB];
+unsigned RookShifts [SQUARE_NB];
+
+Bitboard BishopMasks [SQUARE_NB];
+Bitboard BishopMagics [SQUARE_NB];
+Bitboard* BishopAttacks[SQUARE_NB];
+unsigned BishopShifts [SQUARE_NB];
+
+Bitboard SquareBB[SQUARE_NB];
+Bitboard FileBB[FILE_NB];
+Bitboard RankBB[RANK_NB];
+Bitboard AdjacentFilesBB[FILE_NB];
+Bitboard InFrontBB[COLOR_NB][RANK_NB];
+Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB];
+Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
+Bitboard LineBB[SQUARE_NB][SQUARE_NB];
+Bitboard DistanceRingBB[SQUARE_NB][8];
+Bitboard ForwardBB[COLOR_NB][SQUARE_NB];
+Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
+Bitboard PawnAttackSpan[COLOR_NB][SQUARE_NB];
+Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
namespace {
- CACHE_LINE_ALIGNMENT
+ // De Bruijn sequences. See chessprogramming.wikispaces.com/BitScan
+ const uint64_t DeBruijn64 = 0x3F79D71B4CB0A89ULL;
+ const uint32_t DeBruijn32 = 0x783A9B23;
- int BSFTable[64];
- Bitboard RTable[0x19000]; // Storage space for rook attacks
- Bitboard BTable[0x1480]; // Storage space for bishop attacks
+ int MSBTable[256]; // To implement software msb()
+ Square BSFTable[SQUARE_NB]; // To implement software bitscan
+ Bitboard RookTable[0x19000]; // To store rook attacks
+ Bitboard BishopTable[0x1480]; // To store bishop attacks
typedef unsigned (Fn)(Square, Bitboard);
void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[],
- Bitboard masks[], int shifts[], Square deltas[], Fn get_index);
-}
+ Bitboard masks[], unsigned shifts[], Square deltas[], Fn index);
+ // bsf_index() returns the index into BSFTable[] to look up the bitscan. Uses
+ // Matt Taylor's folding for 32 bit case, extended to 64 bit by Kim Walisch.
-/// print_bitboard() prints a bitboard in an easily readable format to the
-/// standard output. This is sometimes useful for debugging.
+ unsigned bsf_index(Bitboard b) {
+ b ^= b - 1;
+ return Is64Bit ? (b * DeBruijn64) >> 58
+ : ((unsigned(b) ^ unsigned(b >> 32)) * DeBruijn32) >> 26;
+ }
-void print_bitboard(Bitboard b) {
- for (Rank r = RANK_8; r >= RANK_1; r--)
- {
- std::cout << "+---+---+---+---+---+---+---+---+" << '\n';
- for (File f = FILE_A; f <= FILE_H; f++)
- std::cout << "| " << ((b & make_square(f, r)) ? "X " : " ");
+ // popcount16() counts the non-zero bits using SWAR-Popcount algorithm
- std::cout << "|\n";
+ unsigned popcount16(unsigned u) {
+ u -= (u >> 1) & 0x5555U;
+ u = ((u >> 2) & 0x3333U) + (u & 0x3333U);
+ u = ((u >> 4) + u) & 0x0F0FU;
+ return (u * 0x0101U) >> 8;
}
- std::cout << "+---+---+---+---+---+---+---+---+" << std::endl;
}
+#ifdef NO_BSF
-/// 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)
+/// Software fall-back of lsb() and msb() for CPU lacking hardware support
-Square first_1(Bitboard b) {
- return Square(BSFTable[((b & -b) * 0x218A392CD3D5DBFULL) >> 58]);
+Square lsb(Bitboard b) {
+ assert(b);
+ return BSFTable[bsf_index(b)];
}
-Square pop_1st_bit(Bitboard* b) {
- Bitboard bb = *b;
- *b &= (*b - 1);
- return Square(BSFTable[((bb & -bb) * 0x218A392CD3D5DBFULL) >> 58]);
-}
+Square msb(Bitboard b) {
-#elif !defined(USE_BSFQ)
+ assert(b);
+ unsigned b32;
+ int result = 0;
-Square first_1(Bitboard b) {
- b ^= (b - 1);
- uint32_t fold = unsigned(b) ^ unsigned(b >> 32);
- return Square(BSFTable[(fold * 0x783A9B23) >> 26]);
-}
+ if (b > 0xFFFFFFFF)
+ {
+ b >>= 32;
+ result = 32;
+ }
-// Use type-punning
-union b_union {
-
- Bitboard b;
- struct {
-#if defined (BIGENDIAN)
- uint32_t h;
- uint32_t l;
-#else
- uint32_t l;
- uint32_t h;
-#endif
- } dw;
-};
-
-Square pop_1st_bit(Bitboard* bb) {
-
- b_union u;
- Square ret;
-
- u.b = *bb;
-
- if (u.dw.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;
- }
- ret = Square(BSFTable[((~(u.dw.h ^ (u.dw.h - 1))) * 0x783A9B23) >> 26]);
- u.dw.h &= (u.dw.h - 1);
- *bb = u.b;
- return ret;
-}
+ b32 = unsigned(b);
+
+ if (b32 > 0xFFFF)
+ {
+ b32 >>= 16;
+ result += 16;
+ }
-#endif // !defined(USE_BSFQ)
+ if (b32 > 0xFF)
+ {
+ b32 >>= 8;
+ result += 8;
+ }
+ return Square(result + MSBTable[b32]);
+}
-/// bitboards_init() initializes various bitboard arrays. It is called during
-/// program initialization.
+#endif // ifdef NO_BSF
-void bitboards_init() {
- for (Bitboard b = 0; b < 256; b++)
- BitCount8Bit[b] = (uint8_t)popcount<Max15>(b);
+/// Bitboards::pretty() returns an ASCII representation of a bitboard suitable
+/// to be printed to standard output. Useful for debugging.
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- SquareBB[s] = 1ULL << s;
+const std::string Bitboards::pretty(Bitboard b) {
- FileBB[FILE_A] = FileABB;
- RankBB[RANK_1] = Rank1BB;
+ std::string s = "+---+---+---+---+---+---+---+---+\n";
- for (int f = FILE_B; f <= FILE_H; f++)
+ for (Rank r = RANK_8; r >= RANK_1; --r)
{
- FileBB[f] = FileBB[f - 1] << 1;
- RankBB[f] = RankBB[f - 1] << 8;
- }
+ for (File f = FILE_A; f <= FILE_H; ++f)
+ s += b & make_square(f, r) ? "| X " : "| ";
- 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];
+ s += "|\n+---+---+---+---+---+---+---+---+\n";
}
- for (int rw = RANK_7, rb = RANK_2; rw >= RANK_1; rw--, rb++)
+ return s;
+}
+
+
+/// 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 (unsigned i = 0; i < (1 << 16); ++i)
+ PopCnt16[i] = (uint8_t) popcount16(i);
+
+ for (Square s = SQ_A1; s <= SQ_H8; ++s)
{
- InFrontBB[WHITE][rw] = InFrontBB[WHITE][rw + 1] | RankBB[rw + 1];
- InFrontBB[BLACK][rb] = InFrontBB[BLACK][rb - 1] | RankBB[rb - 1];
+ SquareBB[s] = 1ULL << s;
+ BSFTable[bsf_index(SquareBB[s])] = s;
}
- 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 (Bitboard b = 2; b < 256; ++b)
+ MSBTable[b] = MSBTable[b - 1] + !more_than_one(b);
- 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 (File f = FILE_A; f <= FILE_H; ++f)
+ FileBB[f] = f > FILE_A ? FileBB[f - 1] << 1 : FileABB;
- for (int i = 0; i < 64; i++)
- if (!Is64Bit) // Matt Taylor's folding trick for 32 bit systems
+ for (Rank r = RANK_1; r <= RANK_8; ++r)
+ RankBB[r] = r > RANK_1 ? RankBB[r - 1] << 8 : Rank1BB;
+
+ 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);
+
+ 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)
{
- Bitboard b = 1ULL << i;
- b ^= b - 1;
- b ^= b >> 32;
- BSFTable[(uint32_t)(b * 0x783A9B23) >> 26] = i;
+ ForwardBB[c][s] = InFrontBB[c][rank_of(s)] & FileBB[file_of(s)];
+ PawnAttackSpan[c][s] = InFrontBB[c][rank_of(s)] & AdjacentFilesBB[file_of(s)];
+ PassedPawnMask[c][s] = ForwardBB[c][s] | PawnAttackSpan[c][s];
}
- else
- BSFTable[((1ULL << i) * 0x218A392CD3D5DBFULL) >> 58] = i;
+
+ for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
+ for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
+ if (s1 != s2)
+ {
+ SquareDistance[s1][s2] = std::max(distance<File>(s1, s2), distance<Rank>(s1, s2));
+ DistanceRingBB[s1][SquareDistance[s1][s2] - 1] |= s2;
+ }
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; c <= BLACK; ++c)
+ for (PieceType pt = PAWN; pt <= KING; ++pt)
+ 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]);
+ Square to = s + Square(c == WHITE ? steps[pt][i] : -steps[pt][i]);
- if (square_is_ok(to) && square_distance(s, to) < 3)
+ if (is_ok(to) && distance(s, to) < 3)
StepAttacksBB[make_piece(c, pt)][s] |= to;
}
- Square RDeltas[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W };
- Square BDeltas[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW };
+ Square RookDeltas[] = { NORTH, EAST, SOUTH, WEST };
+ Square BishopDeltas[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST };
- init_magics(RTable, RAttacks, RMagics, RMasks, RShifts, RDeltas, r_index);
- init_magics(BTable, BAttacks, BMagics, BMasks, BShifts, BDeltas, b_index);
+ init_magics(RookTable, RookAttacks, RookMagics, RookMasks, RookShifts, RookDeltas, magic_index<ROOK>);
+ init_magics(BishopTable, BishopAttacks, BishopMagics, BishopMasks, BishopShifts, BishopDeltas, magic_index<BISHOP>);
- for (Square s = SQ_A1; s <= SQ_H8; s++)
+ for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
{
- PseudoAttacks[BISHOP][s] = bishop_attacks_bb(s, 0);
- PseudoAttacks[ROOK][s] = rook_attacks_bb(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)
+ for (Piece pc = W_BISHOP; pc <= W_ROOK; ++pc)
+ for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
{
- Square delta = (s2 - s1) / square_distance(s1, s2);
+ if (!(PseudoAttacks[pc][s1] & s2))
+ continue;
- for (Square s = s1 + delta; s != s2; s += delta)
- BetweenBB[s1][s2] |= s;
+ LineBB[s1][s2] = (attacks_bb(pc, s1, 0) & attacks_bb(pc, s2, 0)) | s1 | s2;
+ BetweenBB[s1][s2] = attacks_bb(pc, s1, SquareBB[s2]) & attacks_bb(pc, s2, SquareBB[s1]);
}
+ }
}
Bitboard attack = 0;
- for (int i = 0; i < 4; i++)
+ for (int i = 0; i < 4; ++i)
for (Square s = sq + deltas[i];
- square_is_ok(s) && square_distance(s, s - deltas[i]) == 1;
+ is_ok(s) && distance(s, s - deltas[i]) == 1;
s += deltas[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.
void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[],
- Bitboard masks[], int shifts[], Square deltas[], Fn get_index) {
+ Bitboard masks[], unsigned shifts[], Square deltas[], Fn index) {
+
+ int seeds[][RANK_NB] = { { 8977, 44560, 54343, 38998, 5731, 95205, 104912, 17020 },
+ { 728, 10316, 55013, 32803, 12281, 15100, 16645, 255 } };
- 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;
+ int age[4096] = {0}, current = 0, i, size;
// attacks[s] is a pointer to the beginning of the attacks table for square 's'
attacks[SQ_A1] = table;
- 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));
// 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]);
+ shifts[s] = (Is64Bit ? 64 : 32) - popcount(masks[s]);
// 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);
+ reference[size] = sliding_attack(deltas, s, b);
+
+ if (HasPext)
+ attacks[s][pext(b, masks[s])] = reference[size];
+
+ size++;
b = (b - masks[s]) & masks[s];
} while (b);
if (s < SQ_H8)
attacks[s + 1] = attacks[s] + size;
- booster = MagicBoosters[Is64Bit][rank_of(s)];
+ if (HasPext)
+ continue;
+
+ 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));
+ do
+ magics[s] = rng.sparse_rand<Bitboard>();
+ while (popcount((magics[s] * masks[s]) >> 56) < 6);
// 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++)
+ for (++current, i = 0; i < size; ++i)
{
- Bitboard& attack = attacks[s][get_index(s, occupancy[i])];
-
- if (attack && attack != reference[i])
+ unsigned idx = index(s, occupancy[i]);
+
+ if (age[idx] < current)
+ {
+ age[idx] = current;
+ attacks[s][idx] = reference[i];
+ }
+ else if (attacks[s][idx] != reference[i])
break;
-
- attack = reference[i];
}
- } while (i != size);
+ } while (i < size);
}
}
}
projects / stockfish / blobdiff