t, and returns e. func (e *P521Element) Square(t *P521Element) *P521Element { p521Square(&e.x, &t.x) return e } // Select sets v to a if cond == 1, and to b if cond == 0. func (v *P521Element) Select(a, b *P521Element, cond int) *P521Element { p521Selectznz((*p521UntypedFieldElem)(&v.x), p521Uint1(cond), (*p521UntypedFieldElem)(&b.x), (*p521UntypedFieldElem)(&a.x)) return v } func p521InvertEndianness(v []byte) { for i := 0; i < len(v)/2; i++ { v[i], v[len(v)-1-i] = v[len(v)-1-i], v[i] } } golang...