php implementation of hexdump on $argv[1] supplied file

hexdump.php

<?php
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;
        }
}
$file = $argv[1];
$image = file_get_contents($file);
hex_dump($image);
?>