Dealing with 32 bit unsigned values overflowing 32 bit php signed values can be done by adding 0x10000000 to any unexpected negative result, rather than using sprintf.
$i = crc32('1');
printf("%u\n", $i);
if (0 > $i)
{
// Implicitly casts i as float, and corrects this sign.
$i += 0x100000000;
}
var_dump($i);
Outputs:
2212294583
float(2212294583)