denom = big.NewInt(1)
	ten   = big.NewInt(10)
)

func extractDigit() int64 {
	if big.CmpInt(numer, accum) > 0 {
		return -1
	}
	tmp1.Lsh(numer, 1).Add(tmp1, numer).Add(tmp1, accum)
	big.DivModInt(tmp1, tmp2, tmp1, denom)
	tmp2.Add(tmp2, numer)
	if big.CmpInt(tmp2, denom) >= 0 {
		return -1
	}
	return tmp1.Int64()
}

func nextTerm(k int64) {
	y2 := k*2 + 1
	accum.Add(accum, tmp1.Lsh(numer, 1))

	x.doinit()
	y.doinit()
	switch cmp := C.mpz_cmp(&x.i[0], &y.i[0]); {
	case cmp < 0:
		return -1
	case cmp == 0:
		return 0
	}
	return +1
}

// DivModInt sets q = x / y and r = x % y.
func DivModInt(q, r, x, y *Int) {
	q.doinit()
	r.doinit()
	x.doinit()
	y.doinit()
	C.mpz_tdiv_qr(&q.i[0], &r.i[0], &x.i[0], &y.i[0])
}