/*

 * Check: a unit test framework for C

 * Copyright (C) 2001, 2002 Arien Malec

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, write to the

 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,

 * MA 02110-1301, USA.

 */

#include "libcompat.h"

#ifdef __APPLE__

#include <mach/clock.h>

#include <mach/mach.h>

#include <mach/mach_time.h>

#include <TargetConditionals.h>

/* CoreServices.h is only available on macOS */

# if TARGET_OS_MAC && !TARGET_OS_IPHONE

#  include <CoreServices/CoreServices.h>

# endif

#include <unistd.h>

#endif

#define NANOSECONDS_PER_SECOND 1000000000

int

clock_gettime (clockid_t clk_id CK_ATTRIBUTE_UNUSED, struct timespec *ts)

{

#ifdef __APPLE__

  /* OS X does not have clock_gettime, use mach_absolute_time */

  static mach_timebase_info_data_t sTimebaseInfo;

  uint64_t rawTime;

  uint64_t nanos;

  rawTime = mach_absolute_time ();

  /*

   * OS X has a function to convert abs time to nano seconds: AbsoluteToNanoseconds

   * However, the function may not be available as we may not have

   * access to CoreServices. Because of this, we convert the abs time

   * to nano seconds manually.

   */

  /*

   * First grab the time base used on the system, if this is the first

   * time we are being called. We can check if the value is uninitialized,

   * as the denominator will be zero. 

   */

  if (sTimebaseInfo.denom == 0) {

    (void) mach_timebase_info (&sTimebaseInfo);

  }

  /* 

   * Do the conversion. We hope that the multiplication doesn't 

   * overflow; the price you pay for working in fixed point.

   */

  nanos = rawTime * sTimebaseInfo.numer / sTimebaseInfo.denom;

  /* 

   * Fill in the timespec container 

   */

  ts->tv_sec = nanos / NANOSECONDS_PER_SECOND;

  ts->tv_nsec = nanos - (ts->tv_sec * NANOSECONDS_PER_SECOND);

#else

  /* 

   * As there is no function to fall back onto to get the current

   * time, zero out the time so the caller will have a sane value. 

   */

  ts->tv_sec = 0;

  ts->tv_nsec = 0;

#endif

  return 0;

}