let top = (bits.read_bits(br, 4)? as usize) << 8;
let offs = top + (br.read_byte()? as usize);
if (subtag != 0) || (offs <= 0xF80) {
let top = (bits.read_bits(br, 4)? as usize) << 8;
let offs = top + (br.read_byte()? as usize);
if (subtag != 0) || (offs <= 0xF80) {