valid_unicode( int $i ): bool

2266function valid_unicode( $i ) {2267	$i = (int) $i;2268 2269	return (2270		0x9 === $i || // U+0009 HORIZONTAL TABULATION (HT)2271		0xA === $i || // U+000A LINE FEED (LF)2272		0xD === $i || // U+000D CARRIAGE RETURN (CR)2273		/*2274		 * The valid Unicode characters according to the XML specification:2275		 *2276		 * > any Unicode character, excluding the surrogate blocks, FFFE, and FFFF.2277		 */2278		( 0x20 <= $i && $i <= 0xD7FF ) ||2279		( 0xE000 <= $i && $i <= 0xFFFD ) ||2280		( 0x10000 <= $i && $i <= 0x10FFFF )2281	);2282}