I noticed that the utf-8 to html functions below are only for 2 byte long codes. Well I wanted 3 byte support (sorry haven't done 4, 5 or 6). Also I noticed the concatination of the character codes did have the hex prefix 0x and so failed with the large 2 byte codes)

<?
  public function utf2html (&$str) {
    
    $ret = "";
    $max = strlen($str);
    $last = 0;  // keeps the index of the last regular character
    for ($i=0; $i<$max; $i++) {
        $c = $str{$i};
        $c1 = ord($c);
        if ($c1>>5 == 6) {  // 110x xxxx, 110 prefix for 2 bytes unicode
            $ret .= substr($str, $last, $i-$last); // append all the regular characters we've passed
            $c1 &= 31; // remove the 3 bit two bytes prefix
            $c2 = ord($str{++$i}); // the next byte
            $c2 &= 63;  // remove the 2 bit trailing byte prefix
            $c2 |= (($c1 & 3) << 6); // last 2 bits of c1 become first 2 of c2
            $c1 >>= 2; // c1 shifts 2 to the right
            $ret .= "&#" . ($c1 * 0x100 + $c2) . ";"; // this is the fastest string concatenation
            $last = $i+1;       
        }
        elseif ($c1>>4 == 14) {  // 1110 xxxx, 110 prefix for 3 bytes unicode
            $ret .= substr($str, $last, $i-$last); // append all the regular characters we've passed
            $c2 = ord($str{++$i}); // the next byte
            $c3 = ord($str{++$i}); // the third byte
            $c1 &= 15; // remove the 4 bit three bytes prefix
            $c2 &= 63;  // remove the 2 bit trailing byte prefix
            $c3 &= 63;  // remove the 2 bit trailing byte prefix
            $c3 |= (($c2 & 3) << 6); // last 2 bits of c2 become first 2 of c3
            $c2 >>=2; //c2 shifts 2 to the right
            $c2 |= (($c1 & 15) << 4); // last 4 bits of c1 become first 4 of c2
            $c1 >>= 4; // c1 shifts 4 to the right
            $ret .= '&#' . (($c1 * 0x10000) + ($c2 * 0x100) + $c3) . ';'; // this is the fastest string concatenation
            $last = $i+1;       
        }
    }
    $str=$ret . substr($str, $last, $i); // append the last batch of regular characters
} 
?>