lib/timespec_getres.c

   1 /* Get resolution of a time base.
   2    Copyright 2021-2024 Free Software Foundation, Inc.
   3
   4    This file is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU Lesser General Public License as
   6    published by the Free Software Foundation, either version 3 of the
   7    License, or (at your option) any later version.
   8
   9    This file is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18
  19 #include <time.h>
  20
  21 #include "timespec.h"
  22
  23 /* Set TS to resolution of time base BASE.
  24    Return BASE if successful, 0 otherwise.  */
  25 int
  26 timespec_getres (struct timespec *ts, int base)
  27 {
  28   if (base == TIME_UTC)
  29     {
  30 #if defined CLOCK_REALTIME && HAVE_CLOCK_GETRES
  31       clock_getres (CLOCK_REALTIME, ts);
  32 #else
  33       long int res = gettime_res ();
  34       *ts = (struct timespec) { .tv_sec  = res / TIMESPEC_HZ,
  35                                 .tv_nsec = res % TIMESPEC_HZ };
  36 #endif
  37       return base;
  38     }
  39   return 0;
  40 }