A simple, tested, PHP implementation of all fisrt bits logic, with generic SQL and PDO drivers for PHP.
$firstbits = new firstbits($pdo);
// store an address, firstbits are generated, duplicates ignored
$firstbits->storeAndReturn($address);
// get the firstbits for an address if it exists
$firstbits->get($address);
To test, ensure you have apt-get install php5-cli php5-sqlite sqlite and then
php -f test-firstbits.php
A new sqlite database will be created, populated with random addresses, tested, then destroyed