HEX dump

function hex_dump($data, $newline="\n"){
    static $from = '';
    static $to = '';

    static $width = 16; # number of bytes per line

    static $pad = '.'; # padding for non-visible characters

    if ($from==='') {
        for ($i=0; $i<=0xFF; $i++){
            $from .= chr($i);
            $to .= ($i >= 0x20 && $i <= 0x7E) ? chr($i) : $pad;
        }
    }

    $hex = str_split(bin2hex($data), $width*2);
    $chars = str_split(strtr($data, $from, $to), $width);

    $offset = 0;
    foreach ($hex as $i => $line) {
      echo sprintf('%6X',$offset) . ' : ' .implode(' ', str_split($line,2)) .
           ' [' . $chars[$i] . ']' . $newline;
      $offset += $width;
    }
}