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) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2015-2018 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
Bitboard RookTable[0x19000]; // To store rook attacks
Bitboard BishopTable[0x1480]; // To store bishop attacks
- void init_magics(Bitboard table[], Magic magics[], Square deltas[]);
+ void init_magics(Bitboard table[], Magic magics[], Direction directions[]);
// 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.
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][i] : -steps[pt][i]);
+ Square to = s + Direction(c == WHITE ? steps[pt][i] : -steps[pt][i]);
if (is_ok(to) && distance(s, to) < 3)
{
}
}
- Square RookDeltas[] = { NORTH, EAST, SOUTH, WEST };
- Square BishopDeltas[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST };
+ Direction RookDirections[] = { NORTH, EAST, SOUTH, WEST };
+ Direction BishopDirections[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST };
- init_magics(RookTable, RookMagics, RookDeltas);
- init_magics(BishopTable, BishopMagics, BishopDeltas);
+ init_magics(RookTable, RookMagics, RookDirections);
+ init_magics(BishopTable, BishopMagics, BishopDirections);
for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
{
namespace {
- Bitboard sliding_attack(Square deltas[], Square sq, Bitboard occupied) {
+ Bitboard sliding_attack(Direction directions[], Square sq, Bitboard occupied) {
Bitboard attack = 0;
for (int i = 0; i < 4; ++i)
- for (Square s = sq + deltas[i];
- is_ok(s) && distance(s, s - deltas[i]) == 1;
- s += deltas[i])
+ for (Square s = sq + directions[i];
+ is_ok(s) && distance(s, s - directions[i]) == 1;
+ s += directions[i])
{
attack |= s;
// chessprogramming.wikispaces.com/Magic+Bitboards. In particular, here we
// use the so called "fancy" approach.
- void init_magics(Bitboard table[], Magic magics[], Square deltas[]) {
+ void init_magics(Bitboard table[], Magic magics[], Direction directions[]) {
+ // 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 } };
// 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(deltas, s, 0) & ~edges;
+ m.mask = sliding_attack(directions, 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(deltas, s, b);
+ reference[size] = sliding_attack(directions, s, b);
if (HasPext)
m.attacks[pext(b, m.mask)] = reference[size];