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/* Copyright (C) 1999, 2000, 2001 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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <errno.h>
#include <stdint.h>
#include <time.h>
#include <unistd.h>
#include <sys/param.h>
#include <libc-internal.h>
#if HP_TIMING_AVAIL
/* Clock frequency of the processor. */
static long int nsec;
#endif
/* Get resolution of clock. */
int
clock_getres (clockid_t clock_id, struct timespec *res)
{
int retval = -1;
switch (clock_id)
{
case CLOCK_REALTIME:
{
long int clk_tck = sysconf (_SC_CLK_TCK);
if (__builtin_expect (clk_tck != -1, 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;
retval = 0;
}
}
break;
#if HP_TIMING_AVAIL
case CLOCK_PROCESS_CPUTIME_ID:
case CLOCK_THREAD_CPUTIME_ID:
{
if (__builtin_expect (nsec == 0, 0))
{
hp_timing_t freq;
/* This can only happen if we haven't initialized the `freq'
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 (__builtin_expect (freq == 0, 0))
/* Something went wrong. */
break;
nsec = MAX (UINT64_C (1000000000) / freq, 1);
}
/* File in the values. The seconds are always zero (unless we
have a 1Hz machine). */
res->tv_sec = 0;
res->tv_nsec = nsec;
retval = 0;
}
break;
#endif
default:
__set_errno (EINVAL);
break;
}
return retval;
}
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