/// Position::init() initializes at startup the various arrays used to compute
/// hash keys.
internal static void init()
{
var rng = new PRNG(1070372);
foreach (var c in Color.AllColors)
{
foreach (var pt in PieceType.AllPieceTypes)
{
for (var s = Square.SQ_A1; s <= Square.SQ_H8; ++s)
{
Zobrist.psq[c, pt, s] = rng.rand();
}
}
}
foreach (var f in File.AllFiles)
{
Zobrist.enpassant[f] = rng.rand();
}
for (var cr = (int) CastlingRight.NO_CASTLING; cr <= (int) CastlingRight.ANY_CASTLING; ++cr)
{
Zobrist.castling[cr] = 0;
var b = Bitboard.Create((ulong) cr);
while (b != 0)
{
var k = Zobrist.castling[1 << Utils.pop_lsb(ref b)];
Zobrist.castling[cr] ^= (k != 0 ? k : rng.rand());
}
}
Zobrist.side = rng.rand();
Zobrist.exclusion = rng.rand();
}