private function UpdateCastlingBitmaps()
{
$this->nCalls++;
$this->n64WhiteCastle->set_value('0x0');
$this->n64BlackCastle->set_value('0x0');
// If white king or black king are in check, then castling isn't possible;
if ($this->PlayerTurn == 0 && $this->nStatus == CHESS_BOARD_STATUS::CHECK) {
$this->n64WhiteCastle->set_value('0x0');
return;
} else {
if ($this->PlayerTurn == 1 && $this->nStatus == CHESS_BOARD_STATUS::CHECK) {
$this->n64BlackCastle->set_value('0x0');
return;
}
}
// NOTE: Limit to updating the castling bitboards to the next side to move because these bitboards
// are only valid for the next move.
// Need to check columns 2,3 and 5,6 for ranks 0 and 7 to see if they are empty and not attacked.
if ($this->fCastleWQueenside) {
if (BitBoard::_AND_($this->n64All, $this->n64WhiteCastleQFree)->is_zero()) {
$bitmap = $this->FindAttacksToTile(0, 2)->_AND($this->n64BAll);
if ($bitmap->is_zero()) {
$bitmap = $this->FindAttacksToTile(0, 3)->_AND($this->n64BAll);
if ($bitmap->is_zero()) {
$this->n64WhiteCastle->_OR($this->Tiles[2]);
}
}
}
}
if ($this->fCastleWKingside) {
if (BitBoard::_AND_($this->n64All, $this->n64WhiteCastleKFree)->is_zero()) {
$bitmap = $this->FindAttacksToTile(0, 5)->_AND($this->n64BAll);
if ($bitmap->is_zero()) {
$bitmap = $this->FindAttacksToTile(0, 6)->_AND($this->n64BAll);
if ($bitmap->is_zero()) {
$this->n64WhiteCastle->_OR($this->Tiles[6]);
}
}
}
}
if ($this->fCastleBQueenside) {
if (BitBoard::_AND_($this->n64All, $this->n64BlackCastleQFree)->is_zero()) {
$bitmap = $this->FindAttacksToTile(7, 2)->_AND($this->n64WAll);
if ($bitmap->is_zero()) {
$bitmap = $this->FindAttacksToTile(7, 3)->_AND($this->n64WAll);
if ($bitmap->is_zero()) {
$this->n64BlackCastle->_OR($this->Tiles[58]);
}
}
}
}
if ($this->fCastleBKingside) {
if (BitBoard::_AND_($this->n64All, $this->n64BlackCastleKFree)->is_zero()) {
$bitmap = $this->FindAttacksToTile(7, 5)->_AND($this->n64WAll);
if ($bitmap->is_zero()) {
$bitmap = $this->FindAttacksToTile(7, 6)->_AND($this->n64WAll);
if ($bitmap->is_zero()) {
$this->n64BlackCastle->_OR($this->Tiles[62]);
}
}
}
}
}
