nsieve-bits

routine  nsieve(  bits  :  bitarray,  m=0  )
{
     bits[]  =  1;
     count  =  0;
     for(  i  =  2  :  m  ){
          if(  bits[i]  ){
               count  ++;
               for(  k  =  i+i  :  i  :  m  )  bits[k]  =  0;
          }
     }
     return  count;
}

routine  main(  n  =  2  )
{
     m  =  10000  *  (1<);
     bits  :  bitarray  =  1L  <<  (m+1);
     stdio.printf("Primes up to %8d %8d\n",  m,  nsieve(bits,  m)  );

     m  =  10000  *  (1<<(n-1));
     stdio.printf("Primes up to %8d %8d\n",  m,  nsieve(bits,  m)  );

     m  =  10000  *  (1<<(n-2));
     stdio.printf("Primes up to %8d %8d\n",  m,  nsieve(bits,  m)  );
}