void prime_iterator_global_startup(void)
{
primary_sieve = sieve_erat30(primary_limit);
#ifdef NSMALL_PRIMES
{
UV p;
uint32_t *primes32;
UV *primes64 = sieve_to_n(NSMALL_PRIMES + 180, &num_small_primes);
New(0, primes32, num_small_primes, uint32_t);
for (p = 0; p < num_small_primes; p++) primes32[p] = primes64[p];
Safefree(primes64);
small_primes = primes32;
}
#endif
}
void prime_iterator_global_startup(void)
{
primary_sieve = sieve_erat30(primary_limit);
}
static int sieve_segment(unsigned char* mem, UV startd, UV endd,
const unsigned char* prim_sieve, UV prim_limit)
{
const unsigned char* sieve;
UV limit, p;
UV startp = 30*startd;
UV endp = (endd >= (UV_MAX/30)) ? UV_MAX-2 : 30*endd+29;
MPUassert( (mem != 0) && (endd >= startd) && (endp >= startp),
"sieve_segment bad arguments");
/* Fill buffer with marked 7, 11, and 13 */
sieve_prefill(mem, startd, endd);
limit = sqrt((double) endp);
if (limit*limit < endp) limit++; /* ceil(sqrt(endp)) */
/* printf("segment sieve from %"UVuf" to %"UVuf" (aux sieve to %"UVuf")\n", startp, endp, limit); */
if ( (prim_sieve != 0) && (prim_limit <= limit) ) {
sieve = prim_sieve;
} else {
sieve = sieve_erat30(limit);
}
MPUassert( sieve != 0, "Could not generate base sieve" );
for (p = 17; p <= prim_limit; p = next_prime_in_sieve(sieve,p))
{
/* p increments from 17 to at least sqrt(endp) */
UV p2 = p*p; /* TODO: overflow */
if (p2 > endp) break;
/* Find first multiple of p greater than p*p and larger than startp */
if (p2 < startp) {
p2 = (startp / p) * p;
if (p2 < startp) p2 += p;
}
/* Bump to next multiple that isn't divisible by 2, 3, or 5 */
while (masktab30[p2%30] == 0) { p2 += p; }
/* It is possible we've overflowed p2, so check for that */
if ( (p2 <= endp) && (p2 >= startp) ) {
/* Sieve from startd to endd starting at p2, stepping p */
UV d = (p2)/30;
UV m = (p2) - d*30;
UV dinc = (2*p)/30;
UV minc = (2*p) - dinc*30;
UV wdinc[8];
unsigned char wmask[8];
UV offset_endd = endd - startd;
/* Find the positions of the next composites we will mark */
FIND_COMPOSITE_POSITIONS(p);
d -= startd;
/* Mark composites (unrolled) */
while ( (d+p) <= offset_endd ) {
mem[d] |= wmask[0]; d += wdinc[0];
mem[d] |= wmask[1]; d += wdinc[1];
mem[d] |= wmask[2]; d += wdinc[2];
mem[d] |= wmask[3]; d += wdinc[3];
mem[d] |= wmask[4]; d += wdinc[4];
mem[d] |= wmask[5]; d += wdinc[5];
mem[d] |= wmask[6]; d += wdinc[6];
mem[d] |= wmask[7]; d += wdinc[7];
}
while (1) {
mem[d] |= wmask[0]; d += wdinc[0]; if (d > offset_endd) break;
mem[d] |= wmask[1]; d += wdinc[1]; if (d > offset_endd) break;
mem[d] |= wmask[2]; d += wdinc[2]; if (d > offset_endd) break;
mem[d] |= wmask[3]; d += wdinc[3]; if (d > offset_endd) break;
mem[d] |= wmask[4]; d += wdinc[4]; if (d > offset_endd) break;
mem[d] |= wmask[5]; d += wdinc[5]; if (d > offset_endd) break;
mem[d] |= wmask[6]; d += wdinc[6]; if (d > offset_endd) break;
mem[d] |= wmask[7]; d += wdinc[7]; if (d > offset_endd) break;
}
}
}
if (sieve != prim_sieve) Safefree(sieve);
return 1;
}
