Randomize-ing with PHP

random.php

<?php
/**
 * Randomize algorithm. In this case, I tried to random those bytes.
 * April 14, 2018.
 * 
 * @author KennFatt
 */
$y = ["\xff", "\x00", "\xfe", "\xf3", "\x00"];
$m = [];
$x = $y;
$n = 4;
$i = $n;
for ($i; $i > 0; $i--) { 
    $a = random_int(0, count($x) - 1);
    if (!isset($x[$a])) {
        $z = array_keys($x);
        $a = $z[random_int(0, count($z) - 1)];
        $m[] = $x[$a];
        unset($x[$a]);        
    } else {
        $m[] = $x[$a];
        unset($x[$a]);
    }
}

// m