dist/demos/primes.c

1 /* List and count primes.
26  * Do not fill primes[] with real primes when the range [fr,to] is small,
27    when fr,to are relatively large.  Fill primes[] with odd numbers instead.
28    [Probably a bad idea, since the primes[] array would become very large.]
29  * Separate small primes and large primes when sieving.  Either the Montgomery
31    separate loops for primes <= S and primes > S.  The latter primes do not
34    then omit 3 from primes array.  (May require similar special handling of 3
37    to the sieving array in make_primelist, but also because of the primes[]
39    to build primes[].  Make report() a function pointer, as part of achieving
41  * Store primes[] as two arrays, one array with primes represented as delta
42    values using just 8 bits (if gaps are too big, store bogus primes!)
45  * Improve command line syntax and versatility.  "primes -f FROM -t TO",
47    "primes -c -f FROM" since that would be infinity.)  Allow printing a
48    limited *number* of primes using syntax like "primes -f FROM -n NUMBER".
55 struct primes
61 struct primes *primes;
194   primes = malloc (est_n_primes * sizeof primes[0]);
201 	  n_primes, primes[n_primes - 1].prime);
237 /* Find primes in region [fr,fr+rsize).  Requires that fr is odd and that
265       prime = primes[i].prime;
267       if (primes[i].rem >= 0)
269 	  start2 = primes[i].rem;
294       primes[i].rem = ii - ssize;
301 	primes[i].rem = k;
308 /* Find primes in region [fr,fr+rsize), using the previously sieved s[].  */
339 /* Generate a list of primes and store in the global array primes[].  */
356 	continue;				/* only sieve with primes */
365 	  primes[n_primes].prime = j * 2 + 3;
366 	  primes[n_primes].rem = -1;
371   if (primes[n_primes - 1].prime > maxprime)
381 	  primes[n_primes].prime = i;
382 	  primes[n_primes].rem = -1;