/**
* Solver::__fix
*
* Swap two last cells in a board if unsolvable
*
*/
inline void Solver::__fix()
{
int cs = __checksum();
int zx, zy = 0;
_board.getValueXY(0, zx, zy);
int size = _board.getSize() - 1;
if ( size & 1 )
{
// for boards like 2x2(3), 2x3(5), 3x2(5), ...
// add row index of zero
cs += zx;
}
if ( ! (_board.getHeight() & 1) )
{
if ( ! (_board.getWidth() & 1) )
{
// for boards like 2x2, 4x4, ...
// row index of zero numbered from 1
cs += 1;
}
else
{
// for boards like 3x2, 3x4, 5x2, ...
// add parity of zero row index
cs += (zx & 1);
}
}
// if parity odd then should swap
if ( cs & 1 )
{
_board.swap(size - 1, size - 2);
}
}
void __ip_make_header( ip_header * ip, u08 proto, u16 ident, u16 len, u32 dest )
{
ip->version = 0x45;
ip->tos = 0;
ip->length = __htons( len );
ip->fraginfo = 0;
ip->ident = ident;
ip->dest_addr = dest;
ip->src_addr = get_hostaddr();
ip->ttl = 128;
ip->proto = proto;
ip->checksum = ~__htons( __checksum( ip, sizeof(ip_header) ) );
}
static void icmp_send_reply( ip_header * reqip, icmp_header * reqping, u16 len )
{
u08 iface;
memset( &out, 0, sizeof(out) );
if (!arp_make_eth_header( &out.eth, reqip->src_addr, &iface ))
return;
__ip_make_response( &out.ip, reqip, len );
out.icmp.type = 0;
out.icmp.code = 0;
out.icmp.sequence = reqping->sequence;
out.icmp.id = reqping->id;
memcpy( &out.crap, reqping + 1, len - sizeof( ip_header ) - sizeof( icmp_header ) );
out.icmp.checksum = ~__htons(__checksum( &out.icmp, len - sizeof( ip_header ) ));
__send_packet( iface, &out, len + sizeof( eth_header ) );
}
