/*
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) 2004-2021 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 "bitboard.h"
#include "misc.h"
+namespace Stockfish {
+
uint8_t PopCnt16[1 << 16];
uint8_t SquareDistance[SQUARE_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[]);
+
+}
+
+/// 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);
}
/// 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) {
+std::string Bitboards::pretty(Bitboard b) {
std::string s = "+---+---+---+---+---+---+---+---+\n";
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] = std::bitset<16>(i).count();
+ PopCnt16[i] = uint8_t(std::bitset<16>(i).count());
for (Square s = SQ_A1; s <= SQ_H8; ++s)
SquareBB[s] = (1ULL << s);
for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
SquareDistance[s1][s2] = std::max(distance<File>(s1, s2), distance<Rank>(s1, s2));
- 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);
+ init_magics(ROOK, RookTable, RookMagics);
+ init_magics(BISHOP, BishopTable, BishopMagics);
for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
{
}
}
-
namespace {
- Bitboard sliding_attack(Direction directions[], Square sq, Bitboard occupied) {
+ Bitboard sliding_attack(PieceType pt, Square sq, Bitboard occupied) {
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 (Direction d : (pt == ROOK ? RookDirections : BishopDirections))
{
Square s = sq;
- while(safe_destination(s, directions[i]) && !(occupied & s))
- attacks |= (s += directions[i]);
+ while(safe_destination(s, d) && !(occupied & s))
+ attacks |= (s += d);
}
return attacks;
// 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];
}
}
}
+
+} // namespace Stockfish