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#include <stdio.h>
#include <math.h>
#include <time.h>
#include <stc/cbits.h>
#include <stc/algo/filter.h>
#include <stc/algo/crange.h>
cbits sieveOfEratosthenes(size_t n)
{
cbits bits = cbits_with_size(n/2 + 1, true);
size_t q = (size_t) sqrt((double) n) + 1;
for (size_t i = 3; i < q; i += 2) {
size_t j = i;
for (; j < n; j += 2) {
if (cbits_test(&bits, j>>1)) {
i = j;
break;
}
}
for (size_t j = i*i; j < n; j += i*2)
cbits_reset(&bits, j>>1);
}
return bits;
}
int main(void)
{
size_t n = 1000000000;
printf("computing prime numbers up to %" c_ZU "\n", n);
clock_t t1 = clock();
c_WITH (cbits primes = sieveOfEratosthenes(n + 1), cbits_drop(&primes)) {
puts("done");
size_t np = cbits_count(&primes);
clock_t t2 = clock();
printf("number of primes: %" c_ZU ", time: %f\n", np, (t2 - t1) / (float)CLOCKS_PER_SEC);
puts("Show all the primes in the range [2, 1000):");
printf("2");
c_FORRANGE (i, 3, 1000, 2)
if (cbits_test(&primes, i>>1)) printf(" %lld", i);
puts("");
puts("Show the last 50 primes using a temporary crange generator:");
c_FORFILTER (i, crange, crange_object(n - 1, 0, -2)
, cbits_test(&primes, *i.ref>>1)
, c_FLT_TAKE(i, 50)) {
printf("%lld ", *i.ref);
if (i.count % 10 == 0) puts("");
}
}
}
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