func (d *decoder) fill() error {
	if d.bytes.i != d.bytes.j {
		panic("jpeg: fill called when unread bytes exist")
	}
	// Move the last 2 bytes to the start of the buffer, in case we need
	// to call unreadByteStuffedByte.
	if d.bytes.j > 2 {
		d.bytes.buf[0] = d.bytes.buf[d.bytes.j-2]
		d.bytes.buf[1] = d.bytes.buf[d.bytes.j-1]
		d.bytes.i, d.bytes.j = 2, 2
	}
	// Fill in the rest of the buffer.

			// be able to read the next symbol out of the previously read bits.
			// First, undo the readByte that the ensureNBits call made.
			if d.bytes.nUnreadable != 0 {
				d.unreadByteStuffedByte()
			}
			goto slowPath
		}
	}
	if v := h.lut[(d.bits.a>>uint32(d.bits.n-lutSize))&0xff]; v != 0 {
		n := (v & 0xff) - 1
		d.bits.n -= int32(n)
		d.bits.m >>= n
		return uint8(v >> 8), nil

	// in issue 10413. It is only 504 bytes, and shouldn't take long for Decode
	// to return an error. The Start Of Frame marker gives the image dimensions
	// as 8192 wide and 8192 high, so even if an unreadByteStuffedByte bug
	// doesn't technically lead to an infinite loop, such a bug can still cause
	// an unreasonably long loop for such a short input.
	const input = "" +