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119 lines
2.9 KiB
C
119 lines
2.9 KiB
C
/* clock_getres -- Get the resolution of a POSIX clockid_t.
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Copyright (C) 1999-2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <stdint.h>
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#include <time.h>
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#include <unistd.h>
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#include <sys/param.h>
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#include <libc-internal.h>
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#if HP_TIMING_AVAIL
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static long int nsec; /* Clock frequency of the processor. */
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static int
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hp_timing_getres (struct timespec *res)
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{
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if (__glibc_unlikely (nsec == 0))
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{
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hp_timing_t freq;
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/* This can only happen if we haven't initialized the `nsec'
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variable yet. Do this now. We don't have to protect this
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code against multiple execution since all of them should
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lead to the same result. */
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freq = __get_clockfreq ();
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if (__glibc_unlikely (freq == 0))
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/* Something went wrong. */
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return -1;
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nsec = MAX (UINT64_C (1000000000) / freq, 1);
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}
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/* Fill in the values.
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The seconds are always zero (unless we have a 1Hz machine). */
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res->tv_sec = 0;
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res->tv_nsec = nsec;
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return 0;
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}
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#endif
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static inline int
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realtime_getres (struct timespec *res)
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{
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long int clk_tck = sysconf (_SC_CLK_TCK);
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if (__glibc_likely (clk_tck != -1))
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{
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/* This implementation assumes that the realtime clock has a
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resolution higher than 1 second. This is the case for any
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reasonable implementation. */
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res->tv_sec = 0;
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res->tv_nsec = 1000000000 / clk_tck;
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return 0;
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}
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return -1;
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}
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/* Get resolution of clock. */
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int
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__clock_getres (clockid_t clock_id, struct timespec *res)
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{
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int retval = -1;
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switch (clock_id)
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{
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#ifdef SYSDEP_GETRES
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SYSDEP_GETRES;
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#endif
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#ifndef HANDLED_REALTIME
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case CLOCK_REALTIME:
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retval = realtime_getres (res);
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break;
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#endif /* handled REALTIME */
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default:
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#ifdef SYSDEP_GETRES_CPU
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SYSDEP_GETRES_CPU;
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#endif
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#if HP_TIMING_AVAIL
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if ((clock_id & ((1 << CLOCK_IDFIELD_SIZE) - 1))
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== CLOCK_THREAD_CPUTIME_ID)
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retval = hp_timing_getres (res);
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else
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#endif
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__set_errno (EINVAL);
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break;
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#if HP_TIMING_AVAIL && !defined HANDLED_CPUTIME
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case CLOCK_PROCESS_CPUTIME_ID:
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case CLOCK_THREAD_CPUTIME_ID:
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retval = hp_timing_getres (res);
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break;
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#endif
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}
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return retval;
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}
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weak_alias (__clock_getres, clock_getres)
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