<?php
function decbin2($number, $bits, $cutoff) {
    $byte = "";
    if($cutoff == "") {
        $cutoff = false;
    }
    if(!$cutoff) {
        $disp = true;
    } else {
        $disp = false;
    }
    while($bits > 0) {
        $maxnr = pow(2,$bits-1);
        if(($number-$maxnr) >= 0) {
            $number = $number-$maxnr;
            $byte .= "1";
            $disp = true;
        } else {
            if($disp) {
                $byte .= "0";
            }
        }
        $bits--;
    }
    return $byte;
}
//voorbeeld:
$nr = 6000000001;
echo 'getal: '.$nr.'<hr>';
echo 'oude: '.decbin($nr).'<hr>';
echo 'nieuwe: '.decbin2($nr,256, true);//256 bits, met onnodige 0'en verwijderen
?> 