Timer¶

/******************************************************************************
* Copyright (c) Intel Corporation - All rights reserved.                      *
* This file is part of the LIBXS library.                                     *
*                                                                             *
* For information on the license, see the LICENSE file.                       *
* Further information: https://github.com/hfp/libxs/                          *
* SPDX-License-Identifier: BSD-3-Clause                                       *
******************************************************************************/
#include <libxs_timer.h>
#include <libxs_rng.h>

#if !defined(USE_NOINIT)
# define USE_NOINIT
#endif

#if !defined(MAX_NSECONDS)
# define MAX_NSECONDS 16
#endif
#if !defined(MAX_TOLPERC)
# define MAX_TOLPERC 12
#endif


LIBXS_INLINE int timer_sleep(unsigned int seconds)
{
  int result;
#if defined(_WIN32)
  Sleep((DWORD)(1000 * seconds));
  result = EXIT_SUCCESS;
#else
  result = (0 == sleep(seconds) ? EXIT_SUCCESS : EXIT_FAILURE);
#endif
  return result;
}


int main(int argc, char* argv[])
{
  const int max_nseconds_input = (1 < argc ? atoi(argv[1]) : MAX_NSECONDS);
  const unsigned int max_nseconds = (unsigned int)LIBXS_UP2POT(LIBXS_MAX(max_nseconds_input, 1));
  const char *const env_delta = getenv("TIMER_DELTA");
  const int max_delta = (NULL == env_delta || 0 == *env_delta)
#if defined(_DEBUG)
    ? -1
#else
    ? 0
#endif
    : atoi(env_delta);
  unsigned int n = max_nseconds, ninterrupts = 0;
  libxs_timer_tick_t begin, start;
  double total = 0, delta = 0, d, t;
  libxs_timer_info_t info;
  int result;

#if !defined(USE_NOINIT)
  libxs_init();
#endif

  start = begin = libxs_timer_tick();
  for (n >>= 1; 0 < n; n >>= 1) {
    if (EXIT_SUCCESS == timer_sleep(n)) {
      t = libxs_timer_duration(start, libxs_timer_tick());
      d = 100.0 * LIBXS_DELTA(t, (double)n) / n;
      if (delta < d) delta = d;
      total += t;
    }
    else {
      total += (double)n;
      ++ninterrupts;
    }
    start = libxs_timer_tick();
  }

  start = libxs_timer_tick();
  if (EXIT_SUCCESS == timer_sleep(1)) {
    t = libxs_timer_duration(start, libxs_timer_tick());
    d = 100.0 * LIBXS_DELTA(t, 1.0);
    if (delta < d) delta = d;
    total += t;
  }
  else {
    ++ninterrupts;
    total += 1.0;
  }
  start = libxs_timer_tick();

  d = 100.0 * LIBXS_DELTA(total, (double)max_nseconds) / max_nseconds;
  if (delta < d) delta = d;

  result = libxs_timer_info(&info);
  if (EXIT_SUCCESS == result) {
    result = (int)LIBXS_ROUND(delta);
    if ((0 != max_delta || 0 == info.tsc) && (0 > max_delta || result <= max_delta)) {
      d = libxs_timer_duration(begin, start);
      fprintf(stderr, "seconds=%f delta=%s%i%% interrupted=%u tsc=%s\n",
        d, 0 == result ? "" : (total <= d ? "+" : "-"), result,
        ninterrupts, 0 != info.tsc ? "true" : "false");
      result = EXIT_SUCCESS;
    }
    else if ((MAX_TOLPERC) >= result) {
      result = EXIT_SUCCESS;
    }
  }

  return result;
}