ENCODAGE UTF16

<?php
/**
 * This File is part of APIS Framework.
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  
 * See the GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @category   APIS Tools
 * @package    None
 * @copyright  Copyright (c) 2009-2010 APIS ( VAT ID: FR74 510 367 881 000 16 )
 * @author		 Salvan Gregory <apis@apieum.com> <+33 (0) 810 200 119>
 * @license    http://www.gnu.org/licenses/gpl.txt    GPL3
 * @rev 5
 */
 
/**
 * @param int $int UTF-16 Char Code
 * @return string the corresponding char hexadecimal value in UTF-8
 * @example for UTF-16:0x4E00 return "\\xE4\\xB8\\x80"
 */
function strval16( $int ) {
	if ($int<0x80) {
		return '\\x'.dechex($int);
	} elseif ($int<0x110000) {
		$bin = strrev(decbin($int));
		$c = strlen($bin);
		if ($int>0x7FF) {
			if($int<0x10000) {
				if ($c<13)$bin.=str_repeat('0',13-$c);
			} elseif($c<19) {			
				$bin.=str_repeat('0',19-$c);
			}
		}
		$str = str_split($bin,6);
		for ($i=0;$i<count($str)-1;$i++) {
			$str[$i]='\\x'.base_convert('10'.strrev($str[$i]),2,16);
		}
		$c = 8-(strlen($str[$i])+$i+1);
		$str[$i]=str_repeat('1',$i+1).str_repeat('0',$c).strrev($str[$i]);
		$str[$i]='\\x'.base_convert($str[$i],2,16);
		$str = array_reverse($str);
		return implode('',$str);
	} else {
		throw new OutOfRangeException("UTF16 accept Chars codes under 0x10FFFF");
	}	
}

/**
 * @param int $int UTF-16 Char Code
 * @return string the corresponding char encoded in UTF-8
 * @example for UTF-16:0x4E00 return UTF-8:0xE4 0xB8 0x80 ("\xE4\xB8\x80")
 * @link http://www.ietf.org/rfc/rfc3629.txt See UTF-8 definition for more informations
 */
function chr16to8( $int ) {
	if ($int<0x80) {
		return chr($int);
	} elseif ($int<0x110000) {
		$bin = strrev(decbin($int));
		$c = strlen($bin);
		if ($int>0x7FF) {
			if($int<0x10000) {
				if($c<13)$bin.=str_repeat('0',13-$c);
			} elseif($c<19){			
				$bin.=str_repeat('0',19-$c);
			}
		}
		$str = str_split($bin,6);
		for ($i=0;$i<count($str)-1;$i++) {
			$str[$i]=chr(base_convert('10'.strrev($str[$i]),2,10));
		}
		$c = 8-(strlen($str[$i])+$i+1);
		$str[$i]=str_repeat('1',$i+1).str_repeat('0',$c).strrev($str[$i]);
		$str[$i]=chr(base_convert($str[$i],2,10));
		$str = array_reverse($str);
		return implode('',$str);
	} else {
		throw new OutOfRangeException("UTF16 accept Chars codes under 0x10FFFF");
	}
}
/**
 * @param string $str Text which contains UTF-16 Characters (Raw)
 * @return string $str with UTF-16 characters into html entities
 */
function html_entity_encode16( $str) {
	// Chars between 0xD800 and 0xDFFF aren't found
	if (preg_match_all('@[\x{80}-\x{10FFFF}]@u',$str,$res)!=false) {
		$res = array_unique($res[0]);
		foreach($res as $k=>$v) {
			$v = str_split(bin2hex($v),2);
			$c = count($v)-1;
			for ($i=$c;$i>0;$i--) {
				$v[$i]=substr(base_convert($v[$i],16,2),-6);
			}
			$v[0]=substr(base_convert($v[0],16,2),$c-6);
			$res1[$k]= '&#'.base_convert(implode('',$v),2,10).';';
		}
		return str_replace($res,$res1,$str);
	}
	return $str;
}
/**
 * @param string $str Text which contains html characters entities
 * @return string $str with UTF-16 raw characters.
 */
function html_entity_decode16( $str) {
	if (preg_match_all('@&#[0-9a-f]+;@i',$str,$res)!=false) {
		$res = array_unique($res[0]);
		foreach($res as $k=>$v) {
			$res1[$k]=chr16to8(intval(substr($v,2,strlen($v)-1)));
		}
		return str_replace($res,$res1,$str);
	}
	return $str;
}