static casts performance test

#include <iostream>
#include <time.h>

timespec elapsed(timespec start, timespec end)
{
   timespec result;
   if ((end.tv_nsec - start.tv_nsec) < 0) {
       result.tv_sec = end.tv_sec - start.tv_sec - 1;
       result.tv_nsec = 1e9 + end.tv_nsec - start.tv_nsec;
   } else {
       result.tv_sec = end.tv_sec - start.tv_sec;
       result.tv_nsec = end.tv_nsec - start.tv_nsec;
   }
   return result;
}

void addTo(timespec* spec1, const timespec& spec2)
{
   spec1->tv_sec += spec2.tv_sec;
   spec1->tv_nsec += spec2.tv_nsec;
}

timespec wrapAndRoundTime()
{
   double d = 123.5;
   unsigned char c = 0;
   timespec start;
   timespec end;
   clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start);
   for (unsigned i = 0; i < 4e9; ++i) {
       // uncomment ONE of the following only
       // OPTION 1
       c = static_cast<unsigned char>(d+i);
       // OPTION 2
       //c = static_cast<unsigned char>(static_cast<long long>(d+i));
   }
   clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end);
   return elapsed(start, end);
}

int main()
{
   const int ITERATIONS = 5;
   timespec totalTime = {0, 0};
   for (int j = 0; j < ITERATIONS; ++j) {
       std::cout << "Started iteration " << j + 1 << "..." << std::flush;
       timespec iterationTime = wrapAndRoundTime();
       addTo(&totalTime, iterationTime);
       std::cout << " Took " << (iterationTime.tv_sec * 1e9 + iterationTime.tv_nsec) / 1e6
                 << "ms" << std::endl;
   }
   double totalMilliseconds = (totalTime.tv_sec * 1e9 + totalTime.tv_nsec) / 1e6;
   std::cout << "Total time: " << totalMilliseconds << "ms" << std::endl
             << "Average iteration time: " << totalMilliseconds / ITERATIONS << "ms" << std::endl;
   return 0;
}