crc32 support for 32 bit legacy results on a 32 bit machine

// crc32 can give different results on 32 bit and 64 bit machines running PHP.
// If you have legacy stored CRC32 values to match against, this will convert them.

$crc32 = crc32($value);
if(PHP_INT_SIZE == 8) {
    // recast to 32 bit CRC on 64 bit machines...
	if($crc32 > 0x7FFFFFFF) {   // Negative bit is set
		$crc32 -= 0x100000000;
	}
}

echo $crc32;