function BaseBSearch($x, $t) {
    if (!is_array($x)) return -1;
    $n = sizeof($x);
    $l = 0;
    $u = $n - 1;
    $p = 0;
    $m = 0;
 
    while (true) {
        if ($l > $u) {
            $p = -1;
            break;
        }
 
        $m = ceil(($l + $u) / 2);
 
        if ($x[$m] <  $t) {
            $l = $m + 1;
        } else if ($x[$m] == $t) {
            $p = $m;
            break;
        } else if ($x[$m] > $t) {
            $u = $m - 1;
        }
    }
 
    return $p;
}