tests/test-gettime-res.c

   1 /*
   2  * Copyright 2022-2024 Free Software Foundation, Inc.
   3  * Written by Paul Eggert.
   4  *
   5  * This program is free software: you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation, either version 3 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #include <config.h>
  19
  20 #include <timespec.h>
  21
  22 #include <stdio.h>
  23
  24 int
  25 main (void)
  26 {
  27   long int res = gettime_res ();
  28   printf ("gettime_res returned %ld ns\n", res);
  29
  30   if (res <= 0)
  31     {
  32       fprintf (stderr, "gettime_res value %ld not positive\n", res);
  33       return 1;
  34     }
  35
  36   if (res < TIMESPEC_HZ)
  37     {
  38       if (TIMESPEC_HZ % res != 0)
  39         {
  40           fprintf (stderr,
  41                    ("gettime_res value %ld ns is smaller than %d"
  42                     " but does not divide it\n"),
  43                    res, TIMESPEC_HZ);
  44           return 1;
  45         }
  46     }
  47   else
  48     {
  49       if (res % TIMESPEC_HZ != 0)
  50         {
  51           fprintf (stderr,
  52                    ("gettime_res value %ld ns is larger than %d"
  53                     " but is not a multiple of it\n"),
  54                    res, TIMESPEC_HZ);
  55           return 1;
  56         }
  57     }
  58
  59   int saw_res = 0;
  60
  61   for (int i = 0; i < 100000; i++)
  62     {
  63       struct timespec t = current_timespec ();
  64       if (res < TIMESPEC_HZ
  65           ? t.tv_nsec % res != 0
  66           : t.tv_nsec != 0 || t.tv_sec % (res / TIMESPEC_HZ) != 0)
  67         {
  68           fprintf (stderr,
  69                    ("current_timespec returned %lld.%09ld which is not"
  70                     " a multiple of the resolution, %ld ns\n"),
  71                    (long long) t.tv_sec, t.tv_nsec, res);
  72           return 1;
  73         }
  74       if (res < TIMESPEC_HZ
  75           ? (t.tv_nsec / res % 2 != 0
  76              || t.tv_nsec / res % 5 != 0)
  77           : (t.tv_sec / (res / TIMESPEC_HZ) % 2 != 0
  78              || t.tv_sec / (res / TIMESPEC_HZ) % 5 != 0))
  79         saw_res = 1;
  80     }
  81
  82   if (saw_res == 0)
  83     fprintf (stderr,
  84              ("warning: all timestamps had coarser"
  85               " resolution than %ld ns\n"),
  86              res);
  87
  88   return 0;
  89 }