basepointNafTable := basepointNafTable()
	var aTable nafLookupTable5
	aTable.FromP3(A)
	// Because the basepoint is fixed, we can use a wider NAF
	// corresponding to a bigger table.
	aNaf := a.nonAdjacentForm(5)
	bNaf := b.nonAdjacentForm(8)

	// Find the first nonzero coefficient.
	i := 255
	for j := i; j >= 0; j-- {
		if aNaf[j] != 0 || bNaf[j] != 0 {
			break
		}
	}

	multA := &projCached{}

	nonzero |= nonzero >> 4
	nonzero |= nonzero >> 2
	nonzero |= nonzero >> 1
	return int(^nonzero) & 1
}

// nonAdjacentForm computes a width-w non-adjacent form for this scalar.
//
// w must be between 2 and 8, or nonAdjacentForm will panic.
func (s *Scalar) nonAdjacentForm(w uint) [256]int8 {
	// This implementation is adapted from the one
	// in curve25519-dalek and is documented there:

		0, 0, 0, 11, 0, 0, 0, 0, 0, 15, 0, 0, 0, 0, 0, -9, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 7,
		0, 0, 0, 0, 0, -15, 0, 0, 0, 0, 0, 15, 0, 0, 0, 0, 15, 0, 0, 0, 0, 15, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0,
	}

	sNaf := s.nonAdjacentForm(5)

	for i := 0; i < 256; i++ {
		if expectedNaf[i] != sNaf[i] {
			t.Errorf("Wrong digit at position %d, got %d, expected %d", i, sNaf[i], expectedNaf[i])
		}
	}
}

type notZeroScalar Scalar