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#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include "primes-lcg64.h"
#include "primelist-lcg64.h"
#define YES 1
#define NO 0
#define NPRIMES 10000
int primes[NPRIMES];
#ifdef __STDC__
int init_prime(void)
#else
int init_prime()
#endif
{
int i, j, obtained = 0, isprime;
for(i=3; i < MINPRIME; i += 2)
{
isprime = YES;
for(j=0; j < obtained; j++)
if(i%primes[j] == 0)
{
isprime = NO;
break;
}
else if(primes[j]*primes[j] > i)
break;
if(isprime == YES)
{
primes[obtained] = i;
obtained++;
}
}
return obtained;
}
#ifdef __STDC__
int getprime(int need, unsigned int *prime_array, int offset)
#else
int getprime(need, prime_array, offset)
int need, offset;
unsigned int *prime_array;
#endif
{
static int initiallized = NO, num_prime;
unsigned int largest;
int i, isprime, index, obtained = 0;
if(need <= 0)
{
fprintf(stderr,"WARNING: Number of primes needed = %d < 1; None returned\n"
, need);
return 0;
}
if(offset < 0)
{
fprintf(stderr,"WARNING: Offset of prime = %d < 1; None returned\n"
, offset);
return 0;
}
if(offset+need-1<PRIMELISTSIZE1)
{
memcpy(prime_array,prime_list+offset,need*sizeof(unsigned int));
return need;
}
if(!initiallized)
{
num_prime = init_prime();
largest = MAXPRIME;
initiallized = YES;
}
/* int offset <=> unsigned MAXPRIMEOFFSET ??? (HAS) */
if(offset > MAXPRIMEOFFSET)
{
fprintf(stderr,"WARNING: generator has branched maximum number of times;\nindependence of generators no longer guaranteed");
offset = offset % MAXPRIMEOFFSET;
}
if(offset < PRIMELISTSIZE1) /* search table for previous prime */
{
largest = prime_list[offset] + 2;
offset = 0;
}
else
{
index = (unsigned int) ((offset-PRIMELISTSIZE1+1)/STEP) + PRIMELISTSIZE1 - 1;
largest = prime_list[index] + 2;
offset -= (index-PRIMELISTSIZE1+1)*STEP + PRIMELISTSIZE1 - 1;
}
while(need > obtained && largest > MINPRIME)
{
isprime = YES;
largest -= 2;
for(i=0; i<num_prime; i++)
if(largest%primes[i] == 0)
{
isprime = NO;
break;
}
if(isprime == YES && offset > 0)
offset--;
else if(isprime == YES)
prime_array[obtained++] = largest;
}
if(need > obtained)
fprintf(stderr,"ERROR: Insufficient number of primes: needed %d, obtained %d\n", need, obtained);
return obtained;
}
#if 0
main()
{
unsigned int newprimes[1500], np, i;
np = getprime(2,newprimes,0);
np = getprime(2,newprimes+2,9);
np = getprime(2,newprimes+4,12);
for(i=0; i<6; i++)
printf("%u. %u \n", i, newprimes[i]);
/*while(np--)
printf("New primes: %u\n", newprimes[np]);
np = getprime(5,newprimes);
printf("%d new primes obtained ...\n", np);
while(np--)
printf("New primes: %u\n", newprimes[np]);*/
}
#endif
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