Prime number generator. First 5gb's worth.

prime.c

/* This code is in public domain. Use for whatever purpose at your own risk. */
#include <stdio.h>
#include <string.h>
#include <stdint.h>

#define MAXN  10000000000ll  /* maximum value of N */
#define P1    156250100ll    /* = ceil(MAXN/64) */
#define P2    5000000000ll   /* = ceil(MAXN/2) */
#define P3    50000ll       /* = ceil(ceil(sqrt(MAXN))/2) */

uint64_t sieve[P1];

#define GET(b) ((sieve[(b)>>5ll]>>((b)&31ll))&1ll)

void make()
{
    uint64_t i, j, k;
    memset(sieve, 0ll, sizeof(sieve));
    printf("Mems have been allocated\n");
    for (k = 1ll; k <= P3; k++) {
        if (GET(k)==0ll) {
			for(j=2ll*k+1ll, i=2ll*k*(k+1ll); i<P2; i+=j) {
				sieve[i>>5ll]|=1ll<<(i&31ll);
			}
		}
		if (k % 1000ll == 0) {
			printf("%lu / %d\n", k, P3);
		}
	}
}

int isprime(uint64_t p) { return p==2ll || (p>2ll && (p&1ll)==1ll && (GET((p-1ll)>>1ll)==0ll)); }

int main(void)
{    
	printf("%ld ", MAXN);
	printf("%ld ", P1);
	printf("%ld ", P2);
	printf("%ld ", P3);

	uint64_t i, n;
	FILE *file = fopen("tehprimes", "w");
	uint64_t total = 0ll;
	uint64_t logval, idown;
    make();
	printf("OMG Start\n");
    for (n = 0ll, i = 0ll; i <= MAXN; i++) {
        if (isprime(i)) {
			logval = 2ll;
			idown  = i;
			fprintf(file, "%d\n", i);
			while (idown > 10ll) {
				logval++;
				idown /= 10ll;
			}
			total += logval;
			n++;
			if (n % 5000000ll == 0ll) {
				printf("%ld / 100\n", n/5000000l);
			}
		}
	}
    printf("The number of primes below 10^ is %llu.\nFile size in bytes: %llu\nDon't push anything, just close window", n, total);
    return 0;
}