// Just like Split, but return an error when receiving a kill signal from t.
func splitOrQuit(z *big.Int, quit <-chan time.Time) (p, q *big.Int, err error) {
q, r := big.NewInt(0), big.NewInt(0)
if z.Sign() == 0 {
return
}
max := roughSqrt(z)
primes := sieve.BigSieve()
for {
select {
case <-quit:
err = ErrTimeout
return
case p = <-primes:
if q.DivMod(z, p, r); r.Sign() == 0 {
return
}
if max.Cmp(p) == -1 {
q.SetInt64(1)
p.Set(z)
return
}
}
}
return
}
