runtime.cpp

void timing()
{
  unsigned int len = 4096 * 4096;
  unsigned char *buf = new unsigned char[len];
  srand(12345);
  for (size_t i = 0; i < len; i++) {
    buf[i] = (uint8_t)(rand() >> 8);
  }

  auto current_timestamp = []() -> long long {
    struct timeval te;
    gettimeofday(&te, NULL);
    long long milliseconds = te.tv_sec*1000LL + te.tv_usec/1000;
    return milliseconds;
  };

  auto benchmark = [&](std::function<unsigned long(unsigned long, unsigned char *, unsigned int)> callback,
                       const std::string &name,
                       const size_t runs) ->  long long{
    long long start, end;
    unsigned long adler = 0;
    start = current_timestamp();
    for (size_t i = 0; i < runs; ++i) {
      adler = callback(adler, buf, len);
    }
    end = current_timestamp();
    std::cout << "### Function " << name
              << " took " << end - start << " ms." << std::endl;

    return end - start;
  };

  // A first execution to prime caches and warm up the CPU.
  unsigned long tmp = 0;
  tmp = adler32_z(tmp, buf, len);

  benchmark(adler32_z, "zlib reference", 30);
  benchmark(NEON_adler32, "neonized", 30);

  delete [] buf;
}