mb := uint32(p.RestArgs[1].Addr.Offset) & 0x3F
		o1 = AOP_RRR(c.opirr(p.As), uint32(p.From.Reg), uint32(p.To.Reg), (uint32(sh) & 0x1F))
		o1 |= (sh & 0x20) >> 4 // sh[5] is placed in bit 1.
		o1 |= (mb & 0x1F) << 6 // mb[0:4] is placed in bits 6-10.
		o1 |= (mb & 0x20)      // mb[5] is placed in bit 5

	case 10: /* sub Ra,[Rb],Rd => subf Rd,Ra,Rb */
		r := int(p.Reg)

		if r == 0 {
			r = int(p.To.Reg)
		}

    assertFailsWith<IllegalArgumentException> {
      Request.Builder().addHeader("a b", "c")
    }.also { expected ->
      assertThat(expected.message).isEqualTo("Unexpected char 0x20 at 1 in header name: a b")
    }
  }

  @Test
  fun requestHeaderNameWithTabForbidden() {
    assertFailsWith<IllegalArgumentException> {
      Request.Builder().addHeader("a\tb", "c")