hashtest.php

<?php
$algo = 'sha512';
$algo_iter = 100;
$rand = ord(openssl_random_pseudo_bytes(1));
$pass = 'password';
$salt = openssl_random_pseudo_bytes(16);
$salt_hex = bin2hex($salt);
$finished = false;
$val = hash($algo, hash($algo, $pass) . $salt);
for ($i = 0; $i <= 255; $i++) {
    $val2 = hash($algo, $val . $i);
    for ($j = 0; $j < $algo_iter; $j++) {
        $val2 = hash($algo, $val2);
    }
    if (!$finished) {
        echo "$salt_hex $val2\n";
    }
    if ($i == $rand) {
        echo "End at $i\n";
        $finished = true;
        //exit;
    }
}