compat/clock_getres.c

   1 /*****************************************************************************
   2  * clock_getres.c: POSIX clock_getres() replacement
   3  *****************************************************************************
   4  * Copyright © 2020 VLC authors and VideoLAN
   5  *
   6  * Author: Marvin Scholz <epirat07 at gmail dot com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  21  *****************************************************************************/
  22
  23 #ifdef __APPLE__
  24
  25 #ifdef HAVE_CONFIG_H
  26 # include <config.h>
  27 #endif
  28
  29 #include <sys/errno.h>
  30 #include <sys/types.h>
  31 #include <sys/time.h>
  32 #include <mach/clock_types.h>
  33
  34 int clock_getres(clockid_t clock_id, struct timespec *tp)
  35 {
  36     switch (clock_id) {
  37         case CLOCK_MONOTONIC:
  38         case CLOCK_REALTIME:
  39             // For realtime, it is using gettimeofday and for
  40             // the monotonic time it is relative to the system
  41             // boot time. Both of these use timeval, which has
  42             // at best microsecond precision.
  43             tp->tv_sec = 0;
  44             tp->tv_nsec = NSEC_PER_USEC;
  45             break;
  46         default:
  47             errno = EINVAL;
  48             return -1;
  49     }
  50
  51     return 0;
  52 }
  53
  54 #endif