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Avoid multiplying the block header hash with the fixed multiplier to make bignum calculations faster in CSieveOfEratosthenes::Weave().

master
mikaelh 2013-07-24 20:16:04 +03:00
parent cd6ce096d7
commit df0b09da73
2 changed files with 24 additions and 8 deletions
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26
src/prime.cpp
View File

@ -956,20 +956,18 @@ bool CSieveOfEratosthenes::Weave()
CBlockIndex* pindexPrev = this->pindexPrev;
unsigned int nSieveSize = this->nSieveSize;
const unsigned int nTotalPrimes = vPrimes.size();
mpz_class mpzHash = this->mpzHash;
mpz_class mpzFixedMultiplier = this->mpzFixedMultiplier;
// Process only a set percentage of the primes
// Most composites are still found
const unsigned int nPrimes = (uint64)nTotalPrimes * nSievePercentage / 100;
mpz_t mpzFixedFactor; // fixed factor to derive the chain
unsigned int vCunningham1AMultipliers[nPrimes][nHalfChainLength];
unsigned int vCunningham1BMultipliers[nPrimes][nHalfChainLength];
unsigned int vCunningham2AMultipliers[nPrimes][nHalfChainLength];
unsigned int vCunningham2BMultipliers[nPrimes][nHalfChainLength];
mpz_init_set(mpzFixedFactor, this->mpzFixedFactor.get_mpz_t());
memset(vCunningham1AMultipliers, 0xFF, sizeof(vCunningham1AMultipliers));
memset(vCunningham1BMultipliers, 0xFF, sizeof(vCunningham1BMultipliers));
memset(vCunningham2AMultipliers, 0xFF, sizeof(vCunningham2AMultipliers));
@ -988,12 +986,29 @@ bool CSieveOfEratosthenes::Weave()
unsigned long *vfCandidates = this->vfCandidates;
// Check whether fixed multiplier fits in an unsigned long
bool fUseLongForFixedMultiplier = mpzFixedMultiplier < ULONG_MAX;
unsigned long nFixedMultiplier;
mpz_class mpzFixedFactor;
if (fUseLongForFixedMultiplier)
nFixedMultiplier = mpzFixedMultiplier.get_ui();
else
mpzFixedFactor = mpzHash * mpzFixedMultiplier;
for (unsigned int nPrimeSeq = 1; nPrimeSeq < nPrimes; nPrimeSeq++)
{
if (pindexPrev != pindexBest)
break; // new block
unsigned int nPrime = vPrimes[nPrimeSeq];
unsigned int nFixedFactorMod = mpz_tdiv_ui(mpzFixedFactor, nPrime);
unsigned int nFixedFactorMod;
if (fUseLongForFixedMultiplier)
{
nFixedFactorMod = mpz_tdiv_ui(mpzHash.get_mpz_t(), nPrime);
nFixedFactorMod = (uint64)nFixedFactorMod * (nFixedMultiplier % nPrime) % nPrime;
}
else
nFixedFactorMod = mpz_tdiv_ui(mpzFixedFactor.get_mpz_t(), nPrime);
if (nFixedFactorMod == 0)
{
// Nothing in the sieve is divisible by this prime
@ -1094,7 +1109,6 @@ bool CSieveOfEratosthenes::Weave()
free(vfCompositeCunningham1B);
free(vfCompositeCunningham2A);
free(vfCompositeCunningham2B);
mpz_clear(mpzFixedFactor);
return false;
}

6
src/prime.h
View File

@ -105,7 +105,8 @@ class CSieveOfEratosthenes
{
unsigned int nSieveSize; // size of the sieve
unsigned int nBits; // target of the prime chain to search for
mpz_class mpzFixedFactor; // fixed factor to derive the chain
mpz_class mpzHash; // hash of the block header
mpz_class mpzFixedMultiplier; // fixed round multiplier
// final set of candidates for probable primality checking
unsigned long *vfCandidates;
@ -168,7 +169,8 @@ public:
{
this->nSieveSize = nSieveSize;
this->nBits = nBits;
this->mpzFixedFactor = mpzFixedMultiplier * mpzHash;
this->mpzHash = mpzHash;
this->mpzFixedMultiplier = mpzFixedMultiplier;
this->pindexPrev = pindexPrev;
nPrimeSeq = 0;
nCandidateCount = 0;