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<?php
namespace Mpdf\Gif;
/**
* GIF Util - (C) 2003 Yamasoft (S/C)
*
* All Rights Reserved
*
* This file can be freely copied, distributed, modified, updated by anyone under the only
* condition to leave the original address (Yamasoft, http://www.yamasoft.com) and this header.
*
* @link http://www.yamasoft.com
*/
class Lzw
{
var $MAX_LZW_BITS;
var $Fresh;
var $CodeSize;
var $SetCodeSize;
var $MaxCode;
var $MaxCodeSize;
var $FirstCode;
var $OldCode;
var $ClearCode;
var $EndCode;
var $Next;
var $Vals;
var $Stack;
var $sp;
var $Buf;
var $CurBit;
var $LastBit;
var $Done;
var $LastByte;
public function __construct()
{
$this->MAX_LZW_BITS = 12;
unset($this->Next);
unset($this->Vals);
unset($this->Stack);
unset($this->Buf);
$this->Next = range(0, (1 << $this->MAX_LZW_BITS) - 1);
$this->Vals = range(0, (1 << $this->MAX_LZW_BITS) - 1);
$this->Stack = range(0, (1 << ($this->MAX_LZW_BITS + 1)) - 1);
$this->Buf = range(0, 279);
}
function deCompress($data, &$datLen)
{
$stLen = strlen($data);
$datLen = 0;
$ret = "";
$dp = 0; // data pointer
// INITIALIZATION
$this->LZWCommandInit($data, $dp);
while (($iIndex = $this->LZWCommand($data, $dp)) >= 0) {
$ret .= chr($iIndex);
}
$datLen = $dp;
if ($iIndex != -2) {
return false;
}
return $ret;
}
function LZWCommandInit(&$data, &$dp)
{
$this->SetCodeSize = ord($data[0]);
$dp += 1;
$this->CodeSize = $this->SetCodeSize + 1;
$this->ClearCode = 1 << $this->SetCodeSize;
$this->EndCode = $this->ClearCode + 1;
$this->MaxCode = $this->ClearCode + 2;
$this->MaxCodeSize = $this->ClearCode << 1;
$this->GetCodeInit($data, $dp);
$this->Fresh = 1;
for ($i = 0; $i < $this->ClearCode; $i++) {
$this->Next[$i] = 0;
$this->Vals[$i] = $i;
}
for (; $i < (1 << $this->MAX_LZW_BITS); $i++) {
$this->Next[$i] = 0;
$this->Vals[$i] = 0;
}
$this->sp = 0;
return 1;
}
function LZWCommand(&$data, &$dp)
{
if ($this->Fresh) {
$this->Fresh = 0;
do {
$this->FirstCode = $this->GetCode($data, $dp);
$this->OldCode = $this->FirstCode;
} while ($this->FirstCode == $this->ClearCode);
return $this->FirstCode;
}
if ($this->sp > 0) {
$this->sp--;
return $this->Stack[$this->sp];
}
while (($Code = $this->GetCode($data, $dp)) >= 0) {
if ($Code == $this->ClearCode) {
for ($i = 0; $i < $this->ClearCode; $i++) {
$this->Next[$i] = 0;
$this->Vals[$i] = $i;
}
for (; $i < (1 << $this->MAX_LZW_BITS); $i++) {
$this->Next[$i] = 0;
$this->Vals[$i] = 0;
}
$this->CodeSize = $this->SetCodeSize + 1;
$this->MaxCodeSize = $this->ClearCode << 1;
$this->MaxCode = $this->ClearCode + 2;
$this->sp = 0;
$this->FirstCode = $this->GetCode($data, $dp);
$this->OldCode = $this->FirstCode;
return $this->FirstCode;
}
if ($Code == $this->EndCode) {
return -2;
}
$InCode = $Code;
if ($Code >= $this->MaxCode) {
$this->Stack[$this->sp++] = $this->FirstCode;
$Code = $this->OldCode;
}
while ($Code >= $this->ClearCode) {
$this->Stack[$this->sp++] = $this->Vals[$Code];
if ($Code == $this->Next[$Code]) { // Circular table entry, big GIF Error!
return -1;
}
$Code = $this->Next[$Code];
}
$this->FirstCode = $this->Vals[$Code];
$this->Stack[$this->sp++] = $this->FirstCode;
if (($Code = $this->MaxCode) < (1 << $this->MAX_LZW_BITS)) {
$this->Next[$Code] = $this->OldCode;
$this->Vals[$Code] = $this->FirstCode;
$this->MaxCode++;
if (($this->MaxCode >= $this->MaxCodeSize) && ($this->MaxCodeSize < (1 << $this->MAX_LZW_BITS))) {
$this->MaxCodeSize *= 2;
$this->CodeSize++;
}
}
$this->OldCode = $InCode;
if ($this->sp > 0) {
$this->sp--;
return $this->Stack[$this->sp];
}
}
return $Code;
}
function GetCodeInit(&$data, &$dp)
{
$this->CurBit = 0;
$this->LastBit = 0;
$this->Done = 0;
$this->LastByte = 2;
return 1;
}
function GetCode(&$data, &$dp)
{
if (($this->CurBit + $this->CodeSize) >= $this->LastBit) {
if ($this->Done) {
if ($this->CurBit >= $this->LastBit) {
// Ran off the end of my bits
return 0;
}
return -1;
}
$this->Buf[0] = $this->Buf[$this->LastByte - 2];
$this->Buf[1] = $this->Buf[$this->LastByte - 1];
$Count = ord($data[$dp]);
$dp += 1;
if ($Count) {
for ($i = 0; $i < $Count; $i++) {
$this->Buf[2 + $i] = ord($data[$dp + $i]);
}
$dp += $Count;
} else {
$this->Done = 1;
}
$this->LastByte = 2 + $Count;
$this->CurBit = ($this->CurBit - $this->LastBit) + 16;
$this->LastBit = (2 + $Count) << 3;
}
$iRet = 0;
for ($i = $this->CurBit, $j = 0; $j < $this->CodeSize; $i++, $j++) {
$iRet |= (($this->Buf[intval($i / 8)] & (1 << ($i % 8))) != 0) << $j;
}
$this->CurBit += $this->CodeSize;
return $iRet;
}
}
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