void Primes_filterStartStep(cncTag_t i, cncTag_t keep, cncTag_t base, cncTag_t count, PrimeFactor *factors, PrimesCtx *ctx) {
// Filter first batch, using the entire range starting from `base'
uIntPrime end = base + CANDIDATE_BATCH_COUNT;
// Fix base so it's not a multiple of 2 or 3
base |= 1; // add 1 if even
if (base % 3 == 0) base += 2; // skip multiples of 3
// Set up memory for storing prime candidate that pass this filter
uIntPrime *candidates = cncItemCreateVector_candidates(CANDIDATE_BATCH_COUNT);
CandidatesInfo *info = cncItemCreate_candidatesInfo();
info->baseValue = base;
// Start with inc=4 if base%3 is 1, or inc=2 if base%3=2
uIntPrime startInc = 6-(base%3)*2;
assert((base+startInc)%3 > 0 && "Increment should skip all multiples of 3");
// Filter all candidate by the given batch of prime factor
// Skip primes and multiples of 3 by alternating inc between 2 and 4
u32 checkedCount = 0, confirmedCount = 0;
for (uIntPrime n=base, inc=startInc; n<end; n+=inc, inc=6-inc) {
bool belowBound = false;
uIntPrime factorBound = ZSQRT(n); // Only need to check factor thru sqrt(n)
for (u32 i=0; i<FACTOR_BATCH_COUNT && (belowBound = factors[i].prime<factorBound); i++) {
// If you find a prime factor then n isn't prime
if (DIVIDES(factors[i], n)) goto lbl_next_candidate;
}
// Completely confirmed that n is prime (checked all possible factors)
if (!belowBound) confirmedCount++;
// No prime factor, so this candidate passes
candidates[checkedCount++] = n;
lbl_next_candidate:; // labeled continue (semi-colon needed to avoid empty block)
}
// Results out
info->count = checkedCount;
info->confirmedCount = confirmedCount;
info->summarizeFlag = keep;
scheduleNextFilter(i, 1, info, candidates, factors, ctx);
}
int main() {
int y = 2;
int z = 3;
printf("%d %d\n", y, z);
SWAP(y,z);
printf("%d %d\n", y, z);
int x = 15;
if (DIVIDES(y + z, x)) {
printf("%d divides %d\n", y + z, x);
} else {
printf("%d does not divide %d\n", y + z, x);
}
printf("%d %d\n", x, y);
z = MAX(x++, y++);
printf("%d %d %d -- oops!\n", x, y, z);
}
/**
* Step function defintion for "filterContinueStep"
*/
void Primes_filterContinueStep(cncTag_t i, cncTag_t j, PrimeFactor *factors, CandidatesInfo *info, uIntPrime *candidates, PrimesCtx *ctx) {
// Filter all candidate by the given batch of prime factor
// Skip primes and multiples of 3 by alternating inc between 2 and 4
u32 confirmedCount = info->confirmedCount;
u32 checkedCount = confirmedCount;
for (u32 j=info->confirmedCount; j<info->count; j++) {
bool belowBound = false;
uIntPrime n = candidates[j];
uIntPrime factorBound = ZSQRT(n); // Only need to check factor thru sqrt(n)
for (u32 i=0; i<FACTOR_BATCH_COUNT && (belowBound = factors[i].prime<factorBound); i++) {
// If you find a prime factor then n isn't prime
if (DIVIDES(factors[i], n)) goto lbl_next_candidate;
}
// No prime factor, so this candidate passes
candidates[checkedCount++] = n;
// Completely confirmed that n is prime (checked all possible factors)
if (!belowBound) confirmedCount++;
lbl_next_candidate:; // labeled continue (semi-colon needed to avoid empty block)
}
// Results out
info->count = checkedCount;
info->confirmedCount = confirmedCount;
scheduleNextFilter(i, j+1, info, candidates, factors, ctx);
}
