<?php
/**
* Adapted from the work of Paul Haahr, http://www.webcom.com/~haahr/
* http://www.stillhq.com/cgi-bin/cvsweb/ascii85/
*
*/
/**
* @package ASCII85
* @example /ascii85example.php Example usage of this class.
* @category Numbers
* @author Sam Shull <samshull@samshull.com>
* @copyright Copyright (c) 2007, Sam Shull
* @license http://www.samshull.com/bsdlicense.txt BSD License
* @link http://samshull.com/ascii85example.php
* @version 0.9
* @access public
*/
class ASCII85{
/**
* Line width for splitting
*
* @var integer
* @access protected
*/
var $width = 72;
/**
* Position within the line
*
* @var integer
* @access protected
*/
var $pos = 0;
/**
* Unsigned long being manipulated
*
* @var string
* @access protected
*/
var $tuple = "0";
/**
* Number of bytes being manipulated
*
* @var integer
* @access protected
*/
var $count = 0;
/**
* Output
*
* @var string
* @access protected
*/
var $out = "";
/**
* Power of 85 multiplier
*
* @var array
* @access protected
*/
var $pow85;
/**
* Error
*
* @var string
* @access public
*/
var $error;
/**
* For storing unpacked bytes
*
* @var array
* @access protected
*/
var $array = array();
/**
* Position within byte array
*
* @var integer
* @access protected
*/
var $i = 1;
/**
* Method: encode
* Primary encoding method, one argument, the string that is to be encoded
* @param string $string
* @return string
**/
function encode($string){
$this->error = "";
$this->out = "<~";
$this->pos = 2;
$array = unpack("C*",$string);
//print_r($array);
for($i=1;$i<=count($array);$i++){
$this->put85($array[$i]);
}
if ($this->count > 0)
$this->encode85(false);
if ($this->pos + 2 > $this->width)
$this->out.="\n";
$this->out.="~>\n";
if($this->error){
return $this->error;
}else{
return $this->out;
}
}
/**
* Method: encode85 - if PHP5 mark as private or protected
* Method used to convert an unsigned long to ASCII characters
* One parameter bool increase the count by one when adding
* encoded characters to output string
* @param bool $tru default:true
**/
function encode85($tru=true) {
$s = array();
$i = 5;
while (--$i >= 0){
$s[$i] = (int)bcmod($this->tuple,"85");
$this->tuple = bcdiv($this->tuple,"85");
}
//print_r($s);
$f = $tru ? 1 : 0;
for($i=0;$i<=$this->count+$f;$i++){
$this->out .= chr(($s[$i] + ord('!')));
if ($this->pos++ >= $this->width) {
$this->pos = 0;
$this->out.="\n";
}
}
}
/**
* Method: put85 - if PHP5 mark as private or protected
* Method is passed each char of the string to be encoded and adds it
* to an unsigned long for conversion by encode85
* @param decimal $c
**/
function put85($c) {
switch ($this->count) {
case 0: $this->tuple = bcadd($this->lshift($c,24),$this->tuple);
$this->count++;
break;
case 1: $this->tuple = bcadd($this->tuple,((string)($c << 16)));
$this->count++;
break;
case 2: $this->tuple = bcadd($this->tuple,((string)($c << 8)));
$this->count++;
break;
case 3:
$this->tuple = bcadd($this->tuple,((string)$c));
if ($this->tuple == 0) {
$this->out.='z';
if ($this->pos++ >= $this->width) {
$this->pos = 0;
$this->out.="\n";
}
} else {
$this->encode85();
}
$this->tuple = "0";
$this->count = 0;
break;
}
}
/**
* Method: decode
* Primary method used to decode an encoded string, one parameter an encoded string
* Breaks apart string for encoding and returns
* @param string $string
* @return string
**/
function decode($string){
$this->error = "";
$this->out = "";
$this->count = 0;
$this->pow85 = array((85*85*85*85), (85*85*85), (85*85), 85, 1);
$string=preg_replace("/^<~/isx","",$string);
$this->array = str_split($string);
while($this->i < count($this->array)){
$this->decode85(current($this->array));
next($this->array);
$this->i++;
}
if($this->error){
return $this->error;
}else{
return $this->out;
}
}
/**
* Method: wput - if PHP5 mark as private or protected
* Used to pack the output codes, one parameter number of bytes to output
* @param int $bytes
**/
function wput($bytes) {
switch ($bytes) {
case 4:
$this->out.=pack("C",$this->rshift($this->tuple,24));
$this->out.=pack("C",$this->rshift($this->tuple,16));
$this->out.=pack("C",$this->rshift($this->tuple,8));
$this->out.=pack("C",((float)$this->tuple));
break;
case 3:
$this->out.=pack("C",$this->rshift($this->tuple,24));
$this->out.=pack("C",$this->rshift($this->tuple,16));
$this->out.=pack("C",$this->rshift($this->tuple,8));
break;
case 2:
$this->out.=pack("C",$this->rshift($this->tuple,24));
$this->out.=pack("C",$this->rshift($this->tuple,16));
break;
case 1:
$this->out.=pack("C",$this->rshift($this->tuple,24));
break;
}
//$this->tuple = "0";
}
/**
* Method: decode85 - if PHP5 mark as private or protected
* Used to decode the chars and add them up in an unsigned long
* to be encoded, one paramater char to be added
* @param char $c
**/
function decode85($c) {
switch ($c) {
case 'z':
if ($this->count != 0) {
$this->error.="\n: z inside ascii85 5-tuple";
return;
}
$this->out.=pack("C",0x00);
$this->out.=pack("C",0x00);
$this->out.=pack("C",0x00);
$this->out.=pack("C",0x00);
break;
case '~':
$c = next($this->array);
if ($c == '>') {
if ($this->count > 0) {
$this->count--;
$this->tuple = bcadd($this->tuple,$this->pow85[$this->count]);
$this->wput($this->count);
}
return;
}
$this->error.="\n: ~ without > in ascii85 section";
return;
case "\n": case "\r": case "\t": case " ":
case "\0": case "\f": case "\b": case 0177:
break;
default:
//echo (ord($c)-ord('!'))."\n";
if (ord($c) < ord('!') || ord($c) > ord('u')) {
$this->error.="\nBad character in ascii85 region: ".current($this->array)." ".$this->i;
//return;
}
$this->tuple = bcadd($this->tuple,bcmul((ord($c)-ord('!')),$this->pow85[$this->count]));
$this->count++;
if ($this->count == 5) {
$this->wput(4);
$this->count = 0;
$this->tuple = "0";
}
break;
}
}
/**
* Method: lshift - if PHP5 mark as private or protected
* Used to allow class to deal with unsigned longs, bitwise left shift
* Two parameters, number to be shifted, and how much to shift
* @param int|string $n
* @param int $b
* @return string
**/
function lshift($n,$b){
for($t=0;$t<$b;$t++){
$n = bcmul($n,"2");
}
return ((string)$n);
}
/**
* Method: rshift - if PHP5 mark as private or protected
* Used to allow class to deal with unsigned longs, bitwise right shift
* Two parameters, number to be shifted, and how much to shift
* @param int $n
* @param int $b
* @return int
*/
function rshift($n,$b){
for($t=0;$t<$b;$t++){
$n = bcdiv($n,"2");
}
return ((int)$n);
}
}
?>
|
ReTweet
Stumble It!
Bookmark in del.icio.us
Advertise on this site
Site map
Statistics
Site tips
Privacy policy
Contact