Декодирование JSON 16bit UNICODE в PHP

function unenc_utf16_code_units($string) {
$string = preg_replace_callback(‘/\\\\U(D[89ab][0-9a-f]{2})\\\\U(D[c-f][0-9a-f]{2})/i’,
function ($matches) {
$hi_surr = hexdec($matches[1]);
$lo_surr = hexdec($matches[2]);
$scalar = (0x10000 + (($hi_surr & 0x3FF) << 10) |
($lo_surr & 0x3FF));
return «&#x» . dechex($scalar) . «;»;
}, $string);
$string = preg_replace_callback(‘/\\\\U([0-9a-f]{4})/i’,
function ($matches) {
//just to remove leading zeros
return «&#x» . dechex(hexdec($matches[1])) . «;»;
}, $string);
return $string;
}