#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <time.h>
#include <stdint.h>

#ifdef __x86_64__
# define HP_TIMING_NOW(Var) \
  ({ unsigned int _hi, _lo; \
     asm volatile ("rdtsc" : "=a" (_lo), "=d" (_hi)); \
     (Var) = ((unsigned long long int) _hi << 32) | _lo; })
#else
# define HP_TIMING_NOW(Var)      __asm__ __volatile__ ("rdtsc" : "=A" (Var))
#endif

/* Compute the difference between START and END, storing into DIFF.  */
#define HP_TIMING_DIFF(Diff, Start, End)        ((Diff) = (End) - (Start))

/* Accumulate ADD into SUM.  No attempt is made to be thread-safe.  */
#define HP_TIMING_ACCUM_NT(Sum, Diff)           ((Sum) += (Diff))

/* We use 64bit values for the times.  */
typedef unsigned long long int hp_timing_t;

#define NITER 10000000UL

int main ()
{
  const clockid_t id = CLOCK_REALTIME;
  uint64_t i;
  hp_timing_t start, end, diff;
  int ret = 0;
  
  HP_TIMING_NOW (start);
  for (i=0; i<NITER; ++i)
    {
      struct timespec ts;
      ret += clock_gettime (id, &ts);
    }
  HP_TIMING_NOW (end);
  HP_TIMING_DIFF (diff, start, end);
  double callcyc = (double)diff / (double)NITER;
  printf ("%2.2lf cycles\n", callcyc);

  return ret;
}