/*
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) 2008-2014 Marco Costalba, Joona Kiiski, 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 <sstream>
#include "bitboard.h"
#include "bitcount.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];
+Bitboard RMasks[SQUARE_NB];
+Bitboard RMagics[SQUARE_NB];
+Bitboard* RAttacks[SQUARE_NB];
+unsigned RShifts[SQUARE_NB];
+
+Bitboard BMasks[SQUARE_NB];
+Bitboard BMagics[SQUARE_NB];
+Bitboard* BAttacks[SQUARE_NB];
+unsigned BShifts[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 DistanceRingsBB[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];
+
+int SquareDistance[SQUARE_NB][SQUARE_NB];
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[SQUARE_NB];
Bitboard RTable[0x19000]; // Storage space for rook attacks
Bitboard BTable[0x1480]; // Storage space for bishop attacks
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 non-zero bitboard.
+/// pop_lsb() finds and clears the least significant bit in a non-zero bitboard.
-#elif !defined(USE_BSFQ)
+#ifndef 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_lsb(Bitboard* b) {
-// Use type-punning
-union b_union {
-
- Bitboard dummy;
- struct {
-#if defined (BIGENDIAN)
- uint32_t h;
- uint32_t l;
-#else
- uint32_t l;
- uint32_t h;
-#endif
- } b;
-};
-
-Square pop_1st_bit(Bitboard* b) {
-
- const b_union u = *((b_union*)b);
-
- if (u.b.l)
- {
- ((b_union*)b)->b.l = u.b.l & (u.b.l - 1);
- return Square(BSFTable[((u.b.l ^ (u.b.l - 1)) * 0x783A9B23) >> 26]);
- }
-
- ((b_union*)b)->b.h = u.b.h & (u.b.h - 1);
- return Square(BSFTable[((~(u.b.h ^ (u.b.h - 1))) * 0x783A9B23) >> 26]);
+ Bitboard bb = *b;
+ *b = bb & (bb - 1);
+ return BSFTable[bsf_index(bb)];
}
-Square last_1(Bitboard b) {
+Square msb(Bitboard b) {
unsigned b32;
int result = 0;
return Square(result + MS1BTable[b32]);
}
-#endif // !defined(USE_BSFQ)
+#endif // ifndef USE_BSFQ
+
+/// Bitboards::pretty() returns an ASCII representation of a bitboard to be
+/// printed to standard output. This is sometimes useful for debugging.
-/// Bitboards::print() prints a bitboard in an easily readable format to the
-/// standard output. This is sometimes useful for debugging.
+const std::string Bitboards::pretty(Bitboard b) {
-void Bitboards::print(Bitboard b) {
+ std::ostringstream ss;
- for (Rank rank = RANK_8; rank >= RANK_1; rank--)
+ for (Rank rank = RANK_8; rank >= RANK_1; --rank)
{
- std::cout << "+---+---+---+---+---+---+---+---+" << '\n';
+ ss << "+---+---+---+---+---+---+---+---+" << '\n';
- for (File file = FILE_A; file <= FILE_H; file++)
- std::cout << "| " << ((b & make_square(file, rank)) ? "X " : " ");
+ for (File file = FILE_A; file <= FILE_H; ++file)
+ ss << "| " << (b & (file | rank) ? "X " : " ");
- std::cout << "|\n";
+ ss << "|\n";
}
- std::cout << "+---+---+---+---+---+---+---+---+" << std::endl;
+ ss << "+---+---+---+---+---+---+---+---+";
+ return ss.str();
}
-/// 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 (Square s = SQ_A1; s <= SQ_H8; ++s)
+ BSFTable[bsf_index(SquareBB[s] = 1ULL << s)] = s;
- for (Bitboard b = 0; b < 256; b++)
- BitCount8Bit[b] = (uint8_t)popcount<Max15>(b);
+ for (Bitboard b = 1; b < 256; ++b)
+ MS1BTable[b] = more_than_one(b) ? MS1BTable[b - 1] : lsb(b);
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- SquareBB[s] = 1ULL << s;
+ for (File f = FILE_A; f <= FILE_H; ++f)
+ FileBB[f] = f > FILE_A ? FileBB[f - 1] << 1 : FileABB;
- FileBB[FILE_A] = FileABB;
- RankBB[RANK_1] = Rank1BB;
+ for (Rank r = RANK_1; r <= RANK_8; ++r)
+ RankBB[r] = r > RANK_1 ? RankBB[r - 1] << 8 : Rank1BB;
- for (int f = FILE_B; f <= FILE_H; f++)
- {
- FileBB[f] = FileBB[f - 1] << 1;
- RankBB[f] = RankBB[f - 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++)
+ 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)];
+ PawnAttackSpan[c][s] = InFrontBB[c][rank_of(s)] & AdjacentFilesBB[file_of(s)];
+ PassedPawnMask[c][s] = ForwardBB[c][s] | PawnAttackSpan[c][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 (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
+ if (s1 != s2)
+ {
+ SquareDistance[s1][s2] = std::max(file_distance(s1, s2), rank_distance(s1, s2));
+ DistanceRingsBB[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 (is_ok(to) && square_distance(s, to) < 3)
StepAttacksBB[make_piece(c, pt)][s] |= to;
init_magics(RTable, RAttacks, RMagics, RMasks, RShifts, RDeltas, magic_index<ROOK>);
init_magics(BTable, BAttacks, BMagics, BMasks, BShifts, BDeltas, magic_index<BISHOP>);
- 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 s2 = SQ_A1; s2 <= SQ_H8; ++s2)
+ {
+ Piece pc = (PseudoAttacks[BISHOP][s1] & s2) ? W_BISHOP :
+ (PseudoAttacks[ROOK][s1] & s2) ? W_ROOK : NO_PIECE;
- for (Square s = s1 + delta; s != s2; s += delta)
- BetweenBB[s1][s2] |= s;
- }
+ if (pc == NO_PIECE)
+ continue;
+
+ 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];
is_ok(s) && square_distance(s, s - deltas[i]) == 1;
s += deltas[i])
}
- 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
void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[],
Bitboard masks[], unsigned shifts[], Square deltas[], Fn index) {
- int MagicBoosters[][8] = { { 3191, 2184, 1310, 3618, 2091, 1308, 2452, 3996 },
- { 1059, 3608, 605, 3234, 3326, 38, 2029, 3043 } };
+ int MagicBoosters[][8] = { { 969, 1976, 2850, 542, 2069, 2852, 1708, 164 },
+ { 3101, 552, 3555, 926, 834, 4122, 2131, 1117 } };
+
RKISS rk;
Bitboard occupancy[4096], reference[4096], edges, b;
int i, size, booster;
// 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));
// 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] = rk.magic_rand<Bitboard>(booster);
+ while (popcount<Max15>((magics[s] * masks[s]) >> 56) < 6);
+
+ std::memset(attacks[s], 0, size * sizeof(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++)
+ for (i = 0; i < size; ++i)
{
Bitboard& attack = attacks[s][index(s, occupancy[i])];
if (attack && attack != reference[i])
break;
+ assert(reference[i]);
+
attack = reference[i];
}
- } while (i != size);
+ } while (i < size);
}
}
}
projects / stockfish / blobdiff