sample code of mach_absolute_time

sample_time.cpp

#include <chrono>
#include <cstdio>
#include <cinttypes>
#include <mach/mach_time.h>

namespace {

void mach_ver() {
  mach_timebase_info_data_t timebase_info;
  mach_timebase_info(&timebase_info);

  int64_t base = mach_absolute_time() * timebase_info.numer / timebase_info.denom;
  int64_t diffs[10];
  for (int i = 0; i < 10; ++i) {
    int64_t now = mach_absolute_time() * timebase_info.numer / timebase_info.denom;
    diffs[i] = now - base;
    base = now;
  }

  for (int i = 0; i < 10; ++i) {
    printf("mach[%2d] = %" PRId64 "\n", i, diffs[i]);
  }
}

void chrono_ver() {
  auto base = std::chrono::system_clock::now();
  int64_t diffs[10];
	
  for (int i = 0; i < 10; ++i) {
    auto now = std::chrono::system_clock::now();
    diffs[i] = std::chrono::duration_cast<std::chrono::nanoseconds>(now - base).count();
    base = now;
  }
  for (int i = 0; i < 10; ++i) {
    printf("chrono[%2d] = %" PRId64 "\n", i, diffs[i]);
  }
}
  
} // namespace

int main() {
  mach_ver();
  chrono_ver();
  return 0;
}