// including forms involving multiple registers such as R1:R2.
func (p *Parser) register(name string, prefix rune) (r1, r2 int16, scale int8, ok bool) {
	// R1 or R(1) R1:R2 R1,R2 R1+R2, or R1*scale.
	r1, ok = p.registerReference(name)
	if !ok {
		return
	}
	if prefix != 0 && prefix != '*' { // *AX is OK.

			if arch.IsARMMULA(op) {
				// All must be registers.
				p.getRegister(prog, op, &a[0])
				r1 := p.getRegister(prog, op, &a[1])
				r2 := p.getRegister(prog, op, &a[2])
				p.getRegister(prog, op, &a[3])
				prog.From = a[0]
				prog.To = a[3]
				prog.To.Type = obj.TYPE_REGREG2
				prog.To.Offset = int64(r2)
				prog.Reg = r1
				break
			}
		}
		if p.arch.Family == sys.AMD64 {
			prog.From = a[0]

func IndexRune(s []byte, r rune) int {
	switch {
	case 0 <= r && r < utf8.RuneSelf:
		return IndexByte(s, byte(r))
	case r == utf8.RuneError:
		for i := 0; i < len(s); {
			r1, n := utf8.DecodeRune(s[i:])
			if r1 == utf8.RuneError {
				return i
			}
			i += n
		}
		return -1
	case !utf8.ValidRune(r):
		return -1
	default:
		var b [utf8.UTFMax]byte
		n := utf8.EncodeRune(b[:], r)

	}

	// check not at EOF
	buf.Write(b)
	for r := rune(0); r < NRune; r++ {
		r1, size, _ := buf.ReadRune()
		if err := buf.UnreadRune(); err != nil {
			t.Fatalf("UnreadRune(%U) got error %q", r, err)
		}
		r2, nbytes, err := buf.ReadRune()
		if r1 != r2 || r1 != r || nbytes != size || err != nil {

	var __cgofn__cgo_be59f0f25121_Cfunc_puts byte
	var _cgo_be59f0f25121_Cfunc_puts = unsafe.Pointer(&__cgofn__cgo_be59f0f25121_Cfunc_puts)

	func _Cfunc_puts(p0 *_Ctype_char) (r1 _Ctype_int) {
		_cgo_runtime_cgocall(_cgo_be59f0f25121_Cfunc_puts, uintptr(unsafe.Pointer(&p0)))
		return
	}

The hexadecimal number is a hash of cgo's input, chosen to be