php function array generator support seek

Butuh function php generator string A-Z+0-9  yg support seek, min n max string result, unique, fast (tidak loop dari awal), urutan / bukan random (AAA,AAB,AAC, ..... AA0,AA1,AA9,ABA,ABC.......)
misal:

function generator($resultmax, $strmin, $strmax, $curent){
  $str =   A-Z+0-9
}

$array = generator(4, 3,3, 'AAC');
result yg diharapkan:
array('AAC', 'AAD', 'AAE', 'AAF', 'AAG');