}
}

// Lsh sets z = x << n and returns z.
func (z *Int) Lsh(x *Int, n uint) *Int {
	z.abs = z.abs.shl(x.abs, n)
	z.neg = x.neg
	return z
}

// Rsh sets z = x >> n and returns z.
func (z *Int) Rsh(x *Int, n uint) *Int {
	if x.neg {
		// (-x) >> s == ^(x-1) >> s == ^((x-1) >> s) == -(((x-1) >> s) + 1)
		t := z.abs.sub(x.abs, natOne) // no underflow because |x| > 0
		t = t.shr(t, n)

	//	">>" == 1
	//	"->" == 2
	//	"@>" == 3
	r1, ok := p.registerReference(name)
	if !ok {
		return 0
	}
	var op int16
	switch p.next().ScanToken {
	case lex.LSH:
		op = 0
	case lex.RSH:
		op = 1
	case lex.ARR:
		op = 2
	case lex.ROT:
		// following instructions on ARM64 support rotate right
		// AND, ANDS, TST, BIC, BICS, EON, EOR, ORR, MVN, ORN
		op = 3
	}
	tok := p.next()

		}

	case intVal:
		if s == 0 {
			return x
		}
		z := newInt()
		switch op {
		case token.SHL:
			return makeInt(z.Lsh(x.val, s))
		case token.SHR:
			return makeInt(z.Rsh(x.val, s))
		}
	}

	panic(fmt.Sprintf("invalid shift %v %s %d", x, op, s))
}

func cmpZero(x int, op token.Token) bool {
	switch op {
	case token.EQL:
		return x == 0