119 lines
2.9 KiB
C
119 lines
2.9 KiB
C
/* clock_getres -- Get the resolution of a POSIX clockid_t.
|
|
Copyright (C) 1999-2014 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
#include <errno.h>
|
|
#include <stdint.h>
|
|
#include <time.h>
|
|
#include <unistd.h>
|
|
#include <sys/param.h>
|
|
#include <libc-internal.h>
|
|
|
|
|
|
#if HP_TIMING_AVAIL
|
|
static long int nsec; /* Clock frequency of the processor. */
|
|
|
|
static int
|
|
hp_timing_getres (struct timespec *res)
|
|
{
|
|
if (__glibc_unlikely (nsec == 0))
|
|
{
|
|
hp_timing_t freq;
|
|
|
|
/* This can only happen if we haven't initialized the `nsec'
|
|
variable yet. Do this now. We don't have to protect this
|
|
code against multiple execution since all of them should
|
|
lead to the same result. */
|
|
freq = __get_clockfreq ();
|
|
if (__glibc_unlikely (freq == 0))
|
|
/* Something went wrong. */
|
|
return -1;
|
|
|
|
nsec = MAX (UINT64_C (1000000000) / freq, 1);
|
|
}
|
|
|
|
/* Fill in the values.
|
|
The seconds are always zero (unless we have a 1Hz machine). */
|
|
res->tv_sec = 0;
|
|
res->tv_nsec = nsec;
|
|
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
static inline int
|
|
realtime_getres (struct timespec *res)
|
|
{
|
|
long int clk_tck = sysconf (_SC_CLK_TCK);
|
|
|
|
if (__glibc_likely (clk_tck != -1))
|
|
{
|
|
/* This implementation assumes that the realtime clock has a
|
|
resolution higher than 1 second. This is the case for any
|
|
reasonable implementation. */
|
|
res->tv_sec = 0;
|
|
res->tv_nsec = 1000000000 / clk_tck;
|
|
return 0;
|
|
}
|
|
|
|
return -1;
|
|
}
|
|
|
|
|
|
/* Get resolution of clock. */
|
|
int
|
|
__clock_getres (clockid_t clock_id, struct timespec *res)
|
|
{
|
|
int retval = -1;
|
|
|
|
switch (clock_id)
|
|
{
|
|
#ifdef SYSDEP_GETRES
|
|
SYSDEP_GETRES;
|
|
#endif
|
|
|
|
#ifndef HANDLED_REALTIME
|
|
case CLOCK_REALTIME:
|
|
retval = realtime_getres (res);
|
|
break;
|
|
#endif /* handled REALTIME */
|
|
|
|
default:
|
|
#ifdef SYSDEP_GETRES_CPU
|
|
SYSDEP_GETRES_CPU;
|
|
#endif
|
|
#if HP_TIMING_AVAIL
|
|
if ((clock_id & ((1 << CLOCK_IDFIELD_SIZE) - 1))
|
|
== CLOCK_THREAD_CPUTIME_ID)
|
|
retval = hp_timing_getres (res);
|
|
else
|
|
#endif
|
|
__set_errno (EINVAL);
|
|
break;
|
|
|
|
#if HP_TIMING_AVAIL && !defined HANDLED_CPUTIME
|
|
case CLOCK_PROCESS_CPUTIME_ID:
|
|
case CLOCK_THREAD_CPUTIME_ID:
|
|
retval = hp_timing_getres (res);
|
|
break;
|
|
#endif
|
|
}
|
|
|
|
return retval;
|
|
}
|
|
weak_alias (__clock_getres, clock_getres)
|