nuttx/libc/time/lib_gettimeofday.c

/****************************************************************************
 * libc/time/lib_gettimeofday.c
 *
 *   Copyright (C) 2009, 2015 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/time.h>
#include <errno.h>

#include <nuttx/clock.h>

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: gettimeofday
 *
 * Description:
 *   Get the current time
 *
 *   Conforming to SVr4, 4.3BSD. POSIX.1-2001 describes gettimeofday().
 *   POSIX.1-2008 marks gettimeofday() as obsolete, recommending the use of
 *   clock_gettime(2) instead.
 *
 *   NuttX implements gettimeofday() as a thin layer around clock_gettime();
 *
 * Input Parameters:
 *   tv - The location to return the current time
 *   tz - Ignored
 *
 * Returned value:
 *   Zero (OK) on success;  -1 is returned on failure with the errno variable
 *   set appropriately.
 *
 ****************************************************************************/

int gettimeofday(FAR struct timeval *tv, FAR struct timezone *tz)
{
  struct timespec ts;
  int ret;

#ifdef CONFIG_DEBUG
  if (!tv)
    {
      set_errno(EINVAL);
      return ERROR;
    }
#endif

  /* Let clock_gettime do most of the work */

  ret = clock_gettime(CLOCK_REALTIME, &ts);
  if (ret == OK)
    {
       /* Convert the struct timespec to a struct timeval */

       tv->tv_sec  = ts.tv_sec;
       tv->tv_usec = ts.tv_nsec / NSEC_PER_USEC;
    }

  return ret;
}