function gb2utf8($gbstr) {
global $CODETABLE;
if(trim($gbstr)=="") return $gbstr;
if(empty($CODETABLE)){
$filename = dirname(__FILE__)."/gb2312-utf8.table";
$fp = fopen($filename,"r");
while ($l = fgets($fp,15))
{ $CODETABLE[hexdec(substr($l, 0, 6))] = substr($l, 7, 6); }
fclose($fp);
}
$ret = "";
$utf8 = "";
while ($gbstr) {
if (ord(substr($gbstr, 0, 1)) > 0x80) {
$thisW = substr($gbstr, 0, 2);
$gbstr = substr($gbstr, 2, strlen($gbstr));
$utf8 = "";
@$utf8 = u2utf8(hexdec($CODETABLE[hexdec(bin2hex($thisW)) - 0x8080]));
if($utf8!=""){
for ($i = 0;$i < strlen($utf;$i += 3)
$ret .= chr(substr($utf8, $i, 3));
}
}
else
{
$ret .= substr($gbstr, 0, 1);
$gbstr = substr($gbstr, 1, strlen($gbstr));
}
}
return $ret;
}

function u2utf8($c)
{
for($i=0;$i<count($c);$i++)
$str="";
if ($c < 0x80) {
$str.=$c;
}
else if ($c < 0x800) {
$str.=(0xC0 | $c>>6);
$str.=(0x80 | $c & 0x3F);
}
else if ($c < 0x10000) {
$str.=(0xE0 | $c>>12);
$str.=(0x80 | $c>>6 & 0x3F);
$str.=(0x80 | $c & 0x3F);
}
else if ($c < 0x200000) {
$str.=(0xF0 | $c>>1;
$str.=(0x80 | $c>>12 & 0x3F);
$str.=(0x80 | $c>>6 & 0x3F);
$str.=(0x80 | $c & 0x3F);
}
return $str;
}