{1, 9, "123456789", nil},
		{11, 10, "", io.EOF},
		{0, 0, "", nil},
		{-1, 0, "", "bytes.Reader.ReadAt: negative offset"},
	}
	for i, tt := range tests {
		b := make([]byte, tt.n)
		rn, err := r.ReadAt(b, tt.off)
		got := string(b[:rn])
		if got != tt.want {
			t.Errorf("%d. got %q; want %q", i, got, tt.want)
		}
		if fmt.Sprintf("%v", err) != fmt.Sprintf("%v", tt.wanterr) {

		return
	}

	isIndex := false
	num := int16(0)
	isAmount := true // Amount is zero by default
	ext := ""
	if p.peek() == lex.LSH {
		// (Rn)(Rm<<2), the shifted offset register.
		ext = "LSL"
	} else {
		// (Rn)(Rm.UXTW<1), the extended offset register.
		// Rm.UXTW<<3, the extended register.
		p.get('.')
		tok := p.next()
		ext = tok.String()
	}
	if p.peek() == lex.LSH {

		}

		// While not recommended, it is valid to append to a shifted buffer.
		// This forces Write to copy the input.
		if rn.Intn(8) == 0 && cap(b) > 0 {
			b = b[1:1:cap(b)]
		}

		// Append a random integer of varying width.
		n := int64(rn.Intn(1 << rn.Intn(30)))
		want = append(strconv.AppendInt(want, n, 10), ' ')
		b = append(strconv.AppendInt(b, n, 10), ' ')
		w.Write(b)
	}
	w.Flush()