| 1 |
<?php |
| 2 |
// |
| 3 |
// FPDI - Version 1.2 |
| 4 |
// |
| 5 |
// Copyright 2004-2007 Setasign - Jan Slabon |
| 6 |
// |
| 7 |
// Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 |
// you may not use this file except in compliance with the License. |
| 9 |
// You may obtain a copy of the License at |
| 10 |
// |
| 11 |
// http://www.apache.org/licenses/LICENSE-2.0 |
| 12 |
// |
| 13 |
// Unless required by applicable law or agreed to in writing, software |
| 14 |
// distributed under the License is distributed on an "AS IS" BASIS, |
| 15 |
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 |
// See the License for the specific language governing permissions and |
| 17 |
// limitations under the License. |
| 18 |
// |
| 19 |
|
| 20 |
class LZWDecode { |
| 21 |
|
| 22 |
var $sTable = array(); |
| 23 |
var $data = null; |
| 24 |
var $tIdx; |
| 25 |
var $bitsToGet = 9; |
| 26 |
var $bytePointer; |
| 27 |
var $bitPointer; |
| 28 |
var $nextData = 0; |
| 29 |
var $nextBits = 0; |
| 30 |
var $andTable = array(511, 1023, 2047, 4095); |
| 31 |
|
| 32 |
function LZWDecode(&$fpdi) { |
| 33 |
$this->fpdi =& $fpdi; |
| 34 |
} |
| 35 |
|
| 36 |
/** |
| 37 |
* Method to decode LZW compressed data. |
| 38 |
* |
| 39 |
* @param string data The compressed data. |
| 40 |
*/ |
| 41 |
function decode(&$data) { |
| 42 |
|
| 43 |
if($data[0] == 0x00 && $data[1] == 0x01) { |
| 44 |
$this->fpdi->error("LZW flavour not supported."); |
| 45 |
} |
| 46 |
|
| 47 |
$this->initsTable(); |
| 48 |
|
| 49 |
$this->data =& $data; |
| 50 |
|
| 51 |
// Initialize pointers |
| 52 |
$this->bytePointer = 0; |
| 53 |
$this->bitPointer = 0; |
| 54 |
|
| 55 |
$this->nextData = 0; |
| 56 |
$this->nextBits = 0; |
| 57 |
|
| 58 |
$oldCode = 0; |
| 59 |
|
| 60 |
$string = ""; |
| 61 |
$uncompData = ""; |
| 62 |
|
| 63 |
while (($code = $this->getNextCode()) != 257) { |
| 64 |
if ($code == 256) { |
| 65 |
$this->initsTable(); |
| 66 |
$code = $this->getNextCode(); |
| 67 |
|
| 68 |
if ($code == 257) { |
| 69 |
break; |
| 70 |
} |
| 71 |
|
| 72 |
$uncompData .= $this->sTable[$code]; |
| 73 |
$oldCode = $code; |
| 74 |
|
| 75 |
} else { |
| 76 |
|
| 77 |
if ($code < $this->tIdx) { |
| 78 |
$string = $this->sTable[$code]; |
| 79 |
$uncompData .= $string; |
| 80 |
|
| 81 |
$this->addStringToTable($this->sTable[$oldCode], $string[0]); |
| 82 |
$oldCode = $code; |
| 83 |
} else { |
| 84 |
$string = $this->sTable[$oldCode]; |
| 85 |
$string = $string.$string[0]; |
| 86 |
$uncompData .= $string; |
| 87 |
|
| 88 |
$this->addStringToTable($string); |
| 89 |
$oldCode = $code; |
| 90 |
} |
| 91 |
} |
| 92 |
} |
| 93 |
|
| 94 |
return $uncompData; |
| 95 |
} |
| 96 |
|
| 97 |
|
| 98 |
/** |
| 99 |
* Initialize the string table. |
| 100 |
*/ |
| 101 |
function initsTable() { |
| 102 |
$this->sTable = array(); |
| 103 |
|
| 104 |
for ($i = 0; $i < 256; $i++) |
| 105 |
$this->sTable[$i] = chr($i); |
| 106 |
|
| 107 |
$this->tIdx = 258; |
| 108 |
$this->bitsToGet = 9; |
| 109 |
} |
| 110 |
|
| 111 |
/** |
| 112 |
* Add a new string to the string table. |
| 113 |
*/ |
| 114 |
function addStringToTable ($oldString, $newString="") { |
| 115 |
$string = $oldString.$newString; |
| 116 |
|
| 117 |
// Add this new String to the table |
| 118 |
$this->sTable[$this->tIdx++] = $string; |
| 119 |
|
| 120 |
if ($this->tIdx == 511) { |
| 121 |
$this->bitsToGet = 10; |
| 122 |
} else if ($this->tIdx == 1023) { |
| 123 |
$this->bitsToGet = 11; |
| 124 |
} else if ($this->tIdx == 2047) { |
| 125 |
$this->bitsToGet = 12; |
| 126 |
} |
| 127 |
} |
| 128 |
|
| 129 |
// Returns the next 9, 10, 11 or 12 bits |
| 130 |
function getNextCode() { |
| 131 |
if ($this->bytePointer == strlen($this->data)) |
| 132 |
return 257; |
| 133 |
|
| 134 |
$this->nextData = ($this->nextData << 8) | (ord($this->data[$this->bytePointer++]) & 0xff); |
| 135 |
$this->nextBits += 8; |
| 136 |
|
| 137 |
if ($this->nextBits < $this->bitsToGet) { |
| 138 |
$this->nextData = ($this->nextData << 8) | (ord($this->data[$this->bytePointer++]) & 0xff); |
| 139 |
$this->nextBits += 8; |
| 140 |
} |
| 141 |
|
| 142 |
$code = ($this->nextData >> ($this->nextBits - $this->bitsToGet)) & $this->andTable[$this->bitsToGet-9]; |
| 143 |
$this->nextBits -= $this->bitsToGet; |
| 144 |
|
| 145 |
return $code; |
| 146 |
} |
| 147 |
} |
| 148 |
|
| 149 |
|
| 150 |
|
| 151 |
?> |
