function generate() {
var mac = document.getElementById('mac').value.replace(/:/g, '').toUpperCase();
var pwd = document.getElementById('pwd');
if (mac.search(/^[A-F0-9]{12}$/) == -1) {
pwd.innerHTML = 'Unknown MAC';
} else {
var i;
var t;
var s = '';
for (i = 0; i < 12; i++) {
t = mac.charCodeAt(i) + add;
if (subst[t]) { t = subst[t]; }
s += String.fromCharCode(t);
}
pwd.innerHTML = 'Password: <b>2008' + s + '</b>';
}
}