/*
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) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2004-2020 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
*/
#include <algorithm>
+#include <bitset>
#include "bitboard.h"
#include "misc.h"
uint8_t PopCnt16[1 << 16];
-int SquareDistance[SQUARE_NB][SQUARE_NB];
+uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
Bitboard SquareBB[SQUARE_NB];
-Bitboard FileBB[FILE_NB];
-Bitboard RankBB[RANK_NB];
-Bitboard AdjacentFilesBB[FILE_NB];
-Bitboard ForwardRanksBB[COLOR_NB][RANK_NB];
-Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
Bitboard LineBB[SQUARE_NB][SQUARE_NB];
-Bitboard DistanceRingBB[SQUARE_NB][8];
-Bitboard ForwardFileBB[COLOR_NB][SQUARE_NB];
-Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
-Bitboard PawnAttackSpan[COLOR_NB][SQUARE_NB];
Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
Bitboard RookTable[0x19000]; // To store rook attacks
Bitboard BishopTable[0x1480]; // To store bishop attacks
- void init_magics(Bitboard table[], Magic magics[], Direction directions[]);
+ void init_magics(PieceType pt, Bitboard table[], Magic magics[]);
- // popcount16() counts the non-zero bits using SWAR-Popcount algorithm
+}
- unsigned popcount16(unsigned u) {
- u -= (u >> 1) & 0x5555U;
- u = ((u >> 2) & 0x3333U) + (u & 0x3333U);
- u = ((u >> 4) + u) & 0x0F0FU;
- return (u * 0x0101U) >> 8;
- }
+
+/// safe_destination() 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);
}
for (File f = FILE_A; f <= FILE_H; ++f)
s += b & make_square(f, r) ? "| X " : "| ";
- s += "|\n+---+---+---+---+---+---+---+---+\n";
+ s += "| " + std::to_string(1 + r) + "\n+---+---+---+---+---+---+---+---+\n";
}
+ s += " a b c d e f g h\n";
return s;
}
void Bitboards::init() {
for (unsigned i = 0; i < (1 << 16); ++i)
- PopCnt16[i] = (uint8_t) popcount16(i);
+ PopCnt16[i] = uint8_t(std::bitset<16>(i).count());
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;
-
- 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)
- ForwardRanksBB[WHITE][r] = ~(ForwardRanksBB[BLACK][r + 1] = ForwardRanksBB[BLACK][r] | RankBB[r]);
-
- for (Color c = WHITE; c <= BLACK; ++c)
- for (Square s = SQ_A1; s <= SQ_H8; ++s)
- {
- ForwardFileBB [c][s] = ForwardRanksBB[c][rank_of(s)] & FileBB[file_of(s)];
- PawnAttackSpan[c][s] = ForwardRanksBB[c][rank_of(s)] & AdjacentFilesBB[file_of(s)];
- PassedPawnMask[c][s] = ForwardFileBB [c][s] | PawnAttackSpan[c][s];
- }
+ SquareBB[s] = (1ULL << s);
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[][5] = { {}, { 7, 9 }, { 6, 10, 15, 17 }, {}, {}, {}, { 1, 7, 8, 9 } };
-
- for (Color c = WHITE; c <= BLACK; ++c)
- 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 + 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;
- }
- }
-
- Direction RookDirections[] = { NORTH, EAST, SOUTH, WEST };
- Direction BishopDirections[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST };
-
- init_magics(RookTable, RookMagics, RookDirections);
- init_magics(BishopTable, BishopMagics, BishopDirections);
+ SquareDistance[s1][s2] = std::max(distance<File>(s1, s2), distance<Rank>(s1, s2));
+
+ 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<WHITE>(square_bb(s1));
+ PawnAttacks[BLACK][s1] = pawn_attacks_bb<BLACK>(square_bb(s1));
+
+ 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);
+
PseudoAttacks[QUEEN][s1] = PseudoAttacks[BISHOP][s1] = attacks_bb<BISHOP>(s1, 0);
PseudoAttacks[QUEEN][s1] |= PseudoAttacks[ ROOK][s1] = attacks_bb< ROOK>(s1, 0);
for (PieceType pt : { BISHOP, ROOK })
for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
- {
- if (!(PseudoAttacks[pt][s1] & s2))
- continue;
-
- LineBB[s1][s2] = (attacks_bb(pt, s1, 0) & attacks_bb(pt, s2, 0)) | s1 | s2;
- BetweenBB[s1][s2] = attacks_bb(pt, s1, SquareBB[s2]) & attacks_bb(pt, s2, SquareBB[s1]);
- }
+ if (PseudoAttacks[pt][s1] & s2)
+ LineBB[s1][s2] = (attacks_bb(pt, s1, 0) & attacks_bb(pt, s2, 0)) | s1 | s2;
}
}
namespace {
- Bitboard sliding_attack(Direction directions[], Square sq, Bitboard occupied) {
+ Bitboard sliding_attack(PieceType pt, Square sq, Bitboard occupied) {
- Bitboard attack = 0;
+ Bitboard attacks = 0;
+ Direction RookDirections[4] = {NORTH, SOUTH, EAST, WEST};
+ Direction BishopDirections[4] = {NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST};
- 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;
-
- if (occupied & s)
- break;
- }
+ for (Direction d : (pt == ROOK ? RookDirections : BishopDirections))
+ {
+ Square s = sq;
+ while(safe_destination(s, d) && !(occupied & s))
+ attacks |= (s += d);
+ }
- return attack;
+ 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
- // 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[], Magic magics[], Direction directions[]) {
+ 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 },
// 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(directions, s, 0) & ~edges;
+ 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
b = size = 0;
do {
occupancy[size] = b;
- reference[size] = sliding_attack(directions, s, b);
+ reference[size] = sliding_attack(pt, s, b);
if (HasPext)
m.attacks[pext(b, m.mask)] = reference[size];
projects / stockfish / blobdiff