Please email me back
yehia.shouman@gmail.com

thanks

You may need some extra libraries (for mb_* calls)

Here are the tricky parts to porting to PHP:
1. ord/chr in php don’t handle unicode (I’ve included two functions thanks to the community on php.net)
2. after preg_splitting with //g (to split unicode), there is a blank item in the beginning and end of the array (which i pop and shift off)
3. I give this code without any warranty of its validity — check everything before you use in production

function encode_lzw($str)
{
$dico = array();

for ($i = 0; $i < 256; $i++)
{
$dico[unichr($i)] = $i;
}

$res = “”;
$len = strlen($str);
$nbChar = 256;
$buffer = “”;

for ($i = 0; $i <= $len; $i++)
{
$current = $str[$i];
if ($i < strlen($str) && $dico[$buffer . $current] !== null)
{
$buffer .= $current;
}
else
{
$res .= unichr($dico[$buffer]);
$dico[$buffer . $current] = $nbChar;
$nbChar++;
$buffer = $current;
}
}

return $res;
}

function decode_lzw($str)
{
$dico = array();

for ($i = 0; $i < 256; $i++)
{
$c = unichr($i);
$dico[$i] = $c;
}

$nbChar = 256;
$buffer = “”;
$chaine = “”;
$result = “”;
$strSplit = preg_split(’//u’, $str);
array_pop($strSplit);
array_shift($strSplit);

$length = count($strSplit);

for ($i = 0; $i < $length; $i++)
{
$code = uniord($strSplit[$i]);
$current = $dico[$code];
if ($buffer == “”)
{
$buffer = $current;
$result .= $current;
}
else
{
if ($code <= 255)
{
$result .= $current;
$chaine = $buffer . $current;
$dico[$nbChar] = $chaine;
$nbChar++;
$buffer = $current;
}
else
{
$chaine = $dico[$code];
if ($chaine == “”) $chaine = $buffer . $buffer[0];
$result .= $chaine;
$dico[$nbChar] = $buffer . $chaine[0];
$nbChar++;
$buffer = $chaine;
}
}
}

return $result;
}

function unichr($u)
{
$str = html_entity_decode(’&#’.$u.’;',ENT_NOQUOTES,’UTF-8′);
return $str;
}

function uniord($u) {
$k = mb_convert_encoding($u, ‘UCS-2LE’, ‘UTF-8′);
$k1 = ord(substr($k, 0, 1));
$k2 = ord(substr($k, 1, 1));
return $k2 * 256 + $k1;
}

If i compress and decompress in same environment(Flash to Flash or Java to Java ) then it is going ok.

Any help is appreciated.

~Amit