1 /* clock_getres -- Get the resolution of a POSIX clockid_t.
2 Copyright (C) 1999-2020 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library 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 GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
23 #include <sys/param.h>
24 #include <libc-internal.h>
25 #include <shlib-compat.h>
28 realtime_getres (struct timespec
*res
)
30 long int clk_tck
= __sysconf (_SC_CLK_TCK
);
32 if (__glibc_likely (clk_tck
!= -1))
34 /* This implementation assumes that the realtime clock has a
35 resolution higher than 1 second. This is the case for any
36 reasonable implementation. */
38 res
->tv_nsec
= 1000000000 / clk_tck
;
46 /* Get resolution of clock. */
48 __clock_getres (clockid_t clock_id
, struct timespec
*res
)
55 retval
= realtime_getres (res
);
66 versioned_symbol (libc
, __clock_getres
, clock_getres
, GLIBC_2_17
);
67 /* clock_getres moved to libc in version 2.17;
68 old binaries may expect the symbol version it had in librt. */
69 #if SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_17)
70 strong_alias (__clock_getres
, __clock_getres_2
);
71 compat_symbol (libc
, __clock_getres_2
, clock_getres
, GLIBC_2_2
);