/*
 * boolean utf8_validate( string $s ) :
 *
 * Check that $s string is a valid UTF-8 string.
 * Return TRUE on success, FALSE on error.
 * It does NOT check for overlong UTF-8 sequences ! 
 * 
 * Copyright 2007 (c) LiNuCe, GCoiNCoin Inc LTD Gmbh
 * Under GPL Licence v2 or later.
 */


	function utf8_validate( $s )
	{
		$iLen = strlen( $s );
		for( $i=0 ; $i<$iLen ; $i++ )
		{
			$iByte = ord( $s[$i] );

			if( $iByte < 128 ) continue ;
			
			if    ( ( $iByte & 0xC0 ) == 0xC0 ) $iCharLen = 2 ;
			elseif( ( $iByte & 0xE0 ) == 0xE0 ) $iCharLen = 3 ;
			elseif( ( $iByte & 0xF0 ) == 0xF0 ) $iCharLen = 4 ;
			else return FALSE ;

			$iCharLen -- ;
			while( $iCharLen )
			{
					  if( ( ord($s[$i]) & 0x80 ) != 0x80 ) return FALSE ;
					  $iCharLen -- ;
					  $i++ ;
			}
		}
		return TRUE ;
	}