Current Directory: /home/astoriaah/www/old15/plugins/system/admintools/admintools/gaphp
Viewing File: /home/astoriaah/www/old15/plugins/system/admintools/admintools/gaphp/fixedbytenotation.php
<?php
/**
* @package AdminTools
* @copyright Copyright (c)2010-2014 Nicholas K. Dionysopoulos
* @license GNU General Public License version 3, or later
*/
defined('_JEXEC') or die;
/**
* FixedBitNotation
*
* @author Andre DeMarre
* @package FixedBitNotation
*/
/**
* The FixedBitNotation class is for binary to text conversion. It
* can handle many encoding schemes, formally defined or not, that
* use a fixed number of bits to encode each character.
*
* @package FixedBitNotation
*/
class FixedBitNotation
{
protected $_chars;
protected $_bitsPerCharacter;
protected $_radix;
protected $_rightPadFinalBits;
protected $_padFinalGroup;
protected $_padCharacter;
protected $_charmap;
/**
* Constructor
*
* @param integer $bitsPerCharacter Bits to use for each encoded
* character
* @param string $chars Base character alphabet
* @param boolean $rightPadFinalBits How to encode last character
* @param boolean $padFinalGroup Add padding to end of encoded
* output
* @param string $padCharacter Character to use for padding
*/
public function __construct(
$bitsPerCharacter, $chars = null, $rightPadFinalBits = false,
$padFinalGroup = false, $padCharacter = '=')
{
// Ensure validity of $chars
if (!is_string($chars) || ($charLength = strlen($chars)) < 2)
{
$chars =
'0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-,';
$charLength = 64;
}
// Ensure validity of $bitsPerCharacter
if ($bitsPerCharacter < 1)
{
// $bitsPerCharacter must be at least 1
$bitsPerCharacter = 1;
$radix = 2;
}
elseif ($charLength < 1 << $bitsPerCharacter)
{
// Character length of $chars is too small for $bitsPerCharacter
// Set $bitsPerCharacter to greatest acceptable value
$bitsPerCharacter = 1;
$radix = 2;
while ($charLength >= ($radix <<= 1) && $bitsPerCharacter < 8)
{
$bitsPerCharacter++;
}
$radix >>= 1;
}
elseif ($bitsPerCharacter > 8)
{
// $bitsPerCharacter must not be greater than 8
$bitsPerCharacter = 8;
$radix = 256;
}
else
{
$radix = 1 << $bitsPerCharacter;
}
$this->_chars = $chars;
$this->_bitsPerCharacter = $bitsPerCharacter;
$this->_radix = $radix;
$this->_rightPadFinalBits = $rightPadFinalBits;
$this->_padFinalGroup = $padFinalGroup;
$this->_padCharacter = $padCharacter[0];
}
/**
* Encode a string
*
* @param string $rawString Binary data to encode
*
* @return string
*/
public function encode($rawString)
{
// Unpack string into an array of bytes
$bytes = unpack('C*', $rawString);
$byteCount = count($bytes);
$encodedString = '';
$byte = array_shift($bytes);
$bitsRead = 0;
$chars = $this->_chars;
$bitsPerCharacter = $this->_bitsPerCharacter;
$rightPadFinalBits = $this->_rightPadFinalBits;
$padFinalGroup = $this->_padFinalGroup;
$padCharacter = $this->_padCharacter;
// Generate encoded output;
// each loop produces one encoded character
for ($c = 0; $c < $byteCount * 8 / $bitsPerCharacter; $c++)
{
// Get the bits needed for this encoded character
if ($bitsRead + $bitsPerCharacter > 8)
{
// Not enough bits remain in this byte for the current
// character
// Save the remaining bits before getting the next byte
$oldBitCount = 8 - $bitsRead;
$oldBits = $byte ^ ($byte >> $oldBitCount << $oldBitCount);
$newBitCount = $bitsPerCharacter - $oldBitCount;
if (!$bytes)
{
// Last bits; match final character and exit loop
if ($rightPadFinalBits)
{
$oldBits <<= $newBitCount;
}
$encodedString .= $chars[$oldBits];
if ($padFinalGroup)
{
// Array of the lowest common multiples of
// $bitsPerCharacter and 8, divided by 8
$lcmMap = array(
1 => 1, 2 => 1, 3 => 3, 4 => 1,
5 => 5, 6 => 3, 7 => 7, 8 => 1
);
$bytesPerGroup = $lcmMap[$bitsPerCharacter];
$pads = $bytesPerGroup * 8 / $bitsPerCharacter
- ceil((strlen($rawString) % $bytesPerGroup)
* 8 / $bitsPerCharacter);
$encodedString .= str_repeat($padCharacter[0], $pads);
}
break;
}
// Get next byte
$byte = array_shift($bytes);
$bitsRead = 0;
}
else
{
$oldBitCount = 0;
$newBitCount = $bitsPerCharacter;
}
// Read only the needed bits from this byte
$bits = $byte >> 8 - ($bitsRead + ($newBitCount));
$bits ^= $bits >> $newBitCount << $newBitCount;
$bitsRead += $newBitCount;
if ($oldBitCount)
{
// Bits come from seperate bytes, add $oldBits to $bits
$bits = ($oldBits << $newBitCount) | $bits;
}
$encodedString .= $chars[$bits];
}
return $encodedString;
}
/**
* Decode a string
*
* @param string $encodedString Data to decode
* @param boolean $caseSensitive
* @param boolean $strict Returns NULL if $encodedString contains
* an undecodable character
*
* @return string|NULL
*/
public function decode($encodedString, $caseSensitive = true,
$strict = false)
{
if (!$encodedString || !is_string($encodedString))
{
// Empty string, nothing to decode
return '';
}
$chars = $this->_chars;
$bitsPerCharacter = $this->_bitsPerCharacter;
$radix = $this->_radix;
$rightPadFinalBits = $this->_rightPadFinalBits;
$padFinalGroup = $this->_padFinalGroup;
$padCharacter = $this->_padCharacter;
// Get index of encoded characters
if ($this->_charmap)
{
$charmap = $this->_charmap;
}
else
{
$charmap = array();
for ($i = 0; $i < $radix; $i++)
{
$charmap[$chars[$i]] = $i;
}
$this->_charmap = $charmap;
}
// The last encoded character is $encodedString[$lastNotatedIndex]
$lastNotatedIndex = strlen($encodedString) - 1;
// Remove trailing padding characters
while ($encodedString[$lastNotatedIndex] == $padCharacter[0])
{
$encodedString = substr($encodedString, 0, $lastNotatedIndex);
$lastNotatedIndex--;
}
$rawString = '';
$byte = 0;
$bitsWritten = 0;
// Convert each encoded character to a series of unencoded bits
for ($c = 0; $c <= $lastNotatedIndex; $c++)
{
if (!isset($charmap[$encodedString[$c]]) && !$caseSensitive)
{
// Encoded character was not found; try other case
if (isset($charmap[$cUpper
= strtoupper($encodedString[$c])])
)
{
$charmap[$encodedString[$c]] = $charmap[$cUpper];
}
elseif (isset($charmap[$cLower
= strtolower($encodedString[$c])])
)
{
$charmap[$encodedString[$c]] = $charmap[$cLower];
}
}
if (isset($charmap[$encodedString[$c]]))
{
$bitsNeeded = 8 - $bitsWritten;
$unusedBitCount = $bitsPerCharacter - $bitsNeeded;
// Get the new bits ready
if ($bitsNeeded > $bitsPerCharacter)
{
// New bits aren't enough to complete a byte; shift them
// left into position
$newBits = $charmap[$encodedString[$c]] << $bitsNeeded
- $bitsPerCharacter;
$bitsWritten += $bitsPerCharacter;
}
elseif ($c != $lastNotatedIndex || $rightPadFinalBits)
{
// Zero or more too many bits to complete a byte;
// shift right
$newBits = $charmap[$encodedString[$c]] >> $unusedBitCount;
$bitsWritten = 8; //$bitsWritten += $bitsNeeded;
}
else
{
// Final bits don't need to be shifted
$newBits = $charmap[$encodedString[$c]];
$bitsWritten = 8;
}
$byte |= $newBits;
if ($bitsWritten == 8 || $c == $lastNotatedIndex)
{
// Byte is ready to be written
$rawString .= pack('C', $byte);
if ($c != $lastNotatedIndex)
{
// Start the next byte
$bitsWritten = $unusedBitCount;
$byte = ($charmap[$encodedString[$c]]
^ ($newBits << $unusedBitCount)) << 8 - $bitsWritten;
}
}
}
elseif ($strict)
{
// Unable to decode character; abort
return null;
}
}
return $rawString;
}
}