PrefLib/support/algorithm.cpp at master · PREF/PrefLib · GitHub

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#include "algorithm.h"

#define logn(n, base) (log(n) / log(base))

namespace PrefLib {

namespace Support {

Algorithm::Algorithm()

{

}

Algorithm::~Algorithm()

{

}

uint64_t Algorithm::rebase(uint64_t address, uint64_t oldbaseaddress, uint64_t newbaseaddress)

{

return (address - oldbaseaddress) + newbaseaddress;

}

double Algorithm::entropy(const ByteElaborator::CountResult& cr, uint64_t size)

{

double e = 0.0;

uint64_t base = std::min(size, uint64_t(256));

for(uint64_t i = 0; i < cr.Counts.size(); i++)

{

const uintmax_t& c = cr.Counts.at(i);

if(!c)

continue;

double freq = static_cast<double>(c) / static_cast<double>(size);

e += freq * logn(freq, base);

}

return -e;

}

double Algorithm::entropy(IO::DataBuffer *databuffer, uint64_t startoffset, uint64_t size, volatile bool *cancontinue)

{

ByteElaborator::CountResult cr;

ByteElaborator::countBytes(cr, databuffer, startoffset, startoffset + size, cancontinue);

return Algorithm::entropy(cr, size);

}

double Algorithm::entropy(IO::DataBuffer *databuffer, uint64_t size, volatile bool *cancontinue)

{

return Algorithm::entropy(databuffer, 0, size, cancontinue);

}

double Algorithm::entropy(IO::DataBuffer *databuffer, volatile bool *cancontinue)

{

return Algorithm::entropy(databuffer, databuffer->size(), cancontinue);

}

} // namespace Support

} // namespace PrefLib

PrefLib/support/algorithm.cpp at master · PREF/PrefLib · GitHub

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