PHP HexDump Function

function hexdump($string) {
    $data = array();
    foreach (str_split($string, 16) as $line) {
        $data[] = str_split($line);
    }

    $output = "00 01 02 03 04 05 06 07   08 09 0A 0B 0C 0D 0E 0F   0123456789ABCDEF";
    $linecount = 0;
    foreach ($data as $datum) {
        ++$linecount;
        $line = str_repeat(" ", 68);
        for ($i = 0; $i < count($datum); ++$i) {
            if (empty($datum[$i])) {
                break 2;
            }

            $chr = $datum[$i];
            $pos = $i * 3 + ( $i > 7 ? 2 : 0 );
            $hex = sprintf('%02X', ord($chr));

            $line[$pos] = $hex[0];
            $line[$pos + 1] = $hex[1];

            $line[68 - 16 + $i] = ($chr >= ' ' && $chr <= 'z' ? $chr : '.');
        }
        $output .= "\n$line";
    }

    $maxlen = max(2, strlen($linecount - 1));

    $output = explode("\n", $output);
    for ($i = 1; $i < count($output); ++$i) {
        $output[$i] = sprintf("%0{$maxlen}X %s", $i - 1, $output[$i]);
    }

    return "-- " . implode("\n", $output);
}