_11111111 = _1111 + _11110000 // x16 = _11111111 << 8 + _11111111 // x32 = x16 << 16 + x16 // x64 = x32 << 32 + x32 // x65 = 2*x64 + 1 // x129 = x65 << 64 + x64 // x130 = 2*x129 + 1 // x259 = x130 << 129 + x129 // x260 = 2*x259 + 1 // x519 = x260 << 259 + x259 // return x519 << 2 + 1 // var z = new(P521Element).Set(e) var t0 = new(P521Element) z.Square(x) z.Mul(x, z) t0.Square(z) for s := 1; s < 2; s++ { t0.Square(t0) } z.Mul(z, t0) t0.Square(z) for s := 1; s < 4; s++ { t0.Square(t0) } z.Mul(z, t0)...