void pushBack_N_Primes(uint64_t n, uint64_t start)
{
n_ = n;
PrimeSieve ps;
std::size_t newSize = primes_.size() + static_cast<std::size_t>(n_);
primes_.reserve(newSize);
try
{
while (n_ > 0)
{
// choose stop > nth prime
uint64_t logx = 50;
uint64_t dist = n_ * logx + 10000;
uint64_t stop = start + dist;
// fix integer overflow
if (stop < start)
stop = get_max_stop();
ps.callbackPrimes(start, stop, this);
start = stop + 1;
if (stop >= get_max_stop())
throw primesieve_error("cannot generate primes > 2^64");
}
}
catch (cancel_callback&) { }
}
void iterator::skipto(uint64_t start, uint64_t stop_hint)
{
if (start > get_max_stop())
throw primesieve_error("start must be <= " + PrimeFinder::getMaxStopString());
start_ = start;
stop_ = start;
stop_hint_ = stop_hint;
i_ = 0;
last_idx_ = 0;
tiny_cache_size_ = 1 << 11;
primes_.clear();
}
void iterator::generate_next_primes()
{
primes_.clear();
while (primes_.empty())
{
start_ = add_overflow_safe(stop_, 1);
stop_ = add_overflow_safe(start_, get_interval_size(start_));
if (start_ <= stop_hint_ && stop_ >= stop_hint_)
stop_ = add_overflow_safe(stop_hint_, max_prime_gap(stop_hint_));
primesieve::generate_primes(start_, stop_, &primes_);
if (primes_.empty() && stop_ >= get_max_stop())
throw primesieve_error("next_prime() > " + PrimeFinder::getMaxStopString());
}
last_idx_ = primes_.size() - 1;
i_ = 0;
}
uint64_t add_overflow_safe(uint64_t a, uint64_t b)
{
uint64_t max_stop = get_max_stop();
return (a < max_stop - b) ? a + b : max_stop;
}
