X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=fd5c3c22536c62d03095f4f87fbf23c4780b7139;hp=0bf7eef91fd844206670e14ac255d4df16dae1ec;hb=HEAD;hpb=a24f28be8567c2527b154ef981090368a2bd8f76
diff --git a/src/bitboard.cpp b/src/bitboard.cpp
index 0bf7eef9..a8a10cbb 100644
--- a/src/bitboard.cpp
+++ b/src/bitboard.cpp
@@ -1,8 +1,6 @@
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
- Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2004-2023 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -18,17 +16,21 @@
along with this program. If not, see .
*/
+#include "bitboard.h"
+
#include
#include
+#include
-#include "bitboard.h"
#include "misc.h"
+namespace Stockfish {
+
uint8_t PopCnt16[1 << 16];
uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
-Bitboard SquareBB[SQUARE_NB];
Bitboard LineBB[SQUARE_NB][SQUARE_NB];
+Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
@@ -37,105 +39,113 @@ Magic BishopMagics[SQUARE_NB];
namespace {
- Bitboard RookTable[0x19000]; // To store rook attacks
- Bitboard BishopTable[0x1480]; // To store bishop attacks
+Bitboard RookTable[0x19000]; // To store rook attacks
+Bitboard BishopTable[0x1480]; // To store bishop attacks
+
+void init_magics(PieceType pt, Bitboard table[], Magic magics[]);
- void init_magics(PieceType pt, Bitboard table[], Magic magics[]);
}
+// Returns the bitboard of target square for the given step
+// from the given square. If the step is off the board, returns empty bitboard.
+inline Bitboard safe_destination(Square s, int step) {
+ Square to = Square(s + step);
+ return is_ok(to) && distance(s, to) <= 2 ? square_bb(to) : Bitboard(0);
+}
-/// Bitboards::pretty() returns an ASCII representation of a bitboard suitable
-/// to be printed to standard output. Useful for debugging.
-const std::string Bitboards::pretty(Bitboard b) {
+// Returns an ASCII representation of a bitboard suitable
+// to be printed to standard output. Useful for debugging.
+std::string Bitboards::pretty(Bitboard b) {
- std::string s = "+---+---+---+---+---+---+---+---+\n";
+ std::string s = "+---+---+---+---+---+---+---+---+\n";
- for (Rank r = RANK_8; r >= RANK_1; --r)
- {
- for (File f = FILE_A; f <= FILE_H; ++f)
- s += b & make_square(f, r) ? "| X " : "| ";
+ for (Rank r = RANK_8; r >= RANK_1; --r)
+ {
+ for (File f = FILE_A; f <= FILE_H; ++f)
+ s += b & make_square(f, r) ? "| X " : "| ";
- s += "| " + std::to_string(1 + r) + "\n+---+---+---+---+---+---+---+---+\n";
- }
- s += " a b c d e f g h\n";
+ s += "| " + std::to_string(1 + r) + "\n+---+---+---+---+---+---+---+---+\n";
+ }
+ s += " a b c d e f g h\n";
- return s;
+ return s;
}
-/// Bitboards::init() initializes various bitboard tables. It is called at
-/// startup and relies on global objects to be already zero-initialized.
-
+// 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(std::bitset<16>(i).count());
+ for (unsigned i = 0; i < (1 << 16); ++i)
+ PopCnt16[i] = uint8_t(std::bitset<16>(i).count());
- for (Square s = SQ_A1; s <= SQ_H8; ++s)
- SquareBB[s] = (1ULL << s);
+ for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
+ for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
+ SquareDistance[s1][s2] = std::max(distance(s1, s2), distance(s1, s2));
- for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
- for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
- SquareDistance[s1][s2] = std::max(distance(s1, s2), distance(s1, s2));
+ init_magics(ROOK, RookTable, RookMagics);
+ init_magics(BISHOP, BishopTable, BishopMagics);
- init_magics(ROOK, RookTable, RookMagics);
- init_magics(BISHOP, BishopTable, BishopMagics);
-
- for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
- {
- PawnAttacks[WHITE][s1] = pawn_attacks_bb(square_bb(s1));
- PawnAttacks[BLACK][s1] = pawn_attacks_bb(square_bb(s1));
+ for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
+ {
+ PawnAttacks[WHITE][s1] = pawn_attacks_bb(square_bb(s1));
+ PawnAttacks[BLACK][s1] = pawn_attacks_bb(square_bb(s1));
- for (int step : {-9, -8, -7, -1, 1, 7, 8, 9} )
- PseudoAttacks[KING][s1] |= safe_destination(s1, step);
+ for (int step : {-9, -8, -7, -1, 1, 7, 8, 9})
+ PseudoAttacks[KING][s1] |= safe_destination(s1, step);
- for (int step : {-17, -15, -10, -6, 6, 10, 15, 17} )
- PseudoAttacks[KNIGHT][s1] |= safe_destination(s1, step);
+ for (int step : {-17, -15, -10, -6, 6, 10, 15, 17})
+ PseudoAttacks[KNIGHT][s1] |= safe_destination(s1, step);
- PseudoAttacks[QUEEN][s1] = PseudoAttacks[BISHOP][s1] = attacks_bb(s1, 0);
- PseudoAttacks[QUEEN][s1] |= PseudoAttacks[ ROOK][s1] = attacks_bb< ROOK>(s1, 0);
+ PseudoAttacks[QUEEN][s1] = PseudoAttacks[BISHOP][s1] = attacks_bb(s1, 0);
+ PseudoAttacks[QUEEN][s1] |= PseudoAttacks[ROOK][s1] = attacks_bb(s1, 0);
- 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;
- }
+ 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;
+ BetweenBB[s1][s2] =
+ (attacks_bb(pt, s1, square_bb(s2)) & attacks_bb(pt, s2, square_bb(s1)));
+ }
+ BetweenBB[s1][s2] |= s2;
+ }
+ }
}
-
namespace {
- Bitboard sliding_attack(PieceType pt, Square sq, Bitboard occupied) {
+Bitboard sliding_attack(PieceType pt, Square sq, Bitboard occupied) {
- Bitboard attacks = 0;
- Direction RookDirections[4] = {NORTH, SOUTH, EAST, WEST};
+ Bitboard attacks = 0;
+ Direction RookDirections[4] = {NORTH, SOUTH, EAST, WEST};
Direction BishopDirections[4] = {NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST};
- for(Direction d : (pt == ROOK ? RookDirections : BishopDirections))
+ for (Direction d : (pt == ROOK ? RookDirections : BishopDirections))
{
Square s = sq;
- while(safe_destination(s, d) && !(occupied & s))
+ while (safe_destination(s, d) && !(occupied & s))
attacks |= (s += d);
}
return attacks;
- }
-
+}
- // 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
- // www.chessprogramming.org/Magic_Bitboards. In particular, here we use the so
- // called "fancy" approach.
- void init_magics(PieceType pt, Bitboard table[], Magic magics[]) {
+// Computes all rook and bishop attacks at startup. Magic
+// bitboards are used to look up attacks of sliding pieces. As a reference see
+// www.chessprogramming.org/Magic_Bitboards. In particular, here we use the so
+// called "fancy" approach.
+void init_magics(PieceType pt, Bitboard table[], Magic magics[]) {
// 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 } };
+ int seeds[][RANK_NB] = {{8977, 44560, 54343, 38998, 5731, 95205, 104912, 17020},
+ {728, 10316, 55013, 32803, 12281, 15100, 16645, 255}};
Bitboard occupancy[4096], reference[4096], edges, b;
- int epoch[4096] = {}, cnt = 0, size = 0;
+ int epoch[4096] = {}, cnt = 0, size = 0;
for (Square s = SQ_A1; s <= SQ_H8; ++s)
{
@@ -148,8 +158,8 @@ namespace {
// 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.
Magic& m = magics[s];
- m.mask = sliding_attack(pt, s, 0) & ~edges;
- m.shift = (Is64Bit ? 64 : 32) - popcount(m.mask);
+ m.mask = sliding_attack(pt, 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".
@@ -158,7 +168,8 @@ namespace {
// Use Carry-Rippler trick to enumerate all subsets of masks[s] and
// store the corresponding sliding attack bitboard in reference[].
b = size = 0;
- do {
+ do
+ {
occupancy[size] = b;
reference[size] = sliding_attack(pt, s, b);
@@ -176,9 +187,9 @@ namespace {
// Find a magic for square 's' picking up an (almost) random number
// until we find the one that passes the verification test.
- for (int i = 0; i < size; )
+ for (int i = 0; i < size;)
{
- for (m.magic = 0; popcount((m.magic * m.mask) >> 56) < 6; )
+ for (m.magic = 0; popcount((m.magic * m.mask) >> 56) < 6;)
m.magic = rng.sparse_rand();
// A good magic must map every possible occupancy to an index that
@@ -193,7 +204,7 @@ namespace {
if (epoch[idx] < cnt)
{
- epoch[idx] = cnt;
+ epoch[idx] = cnt;
m.attacks[idx] = reference[i];
}
else if (m.attacks[idx] != reference[i])
@@ -201,5 +212,7 @@ namespace {
}
}
}
- }
}
+}
+
+} // namespace Stockfish