95 lines
2.4 KiB
C
95 lines
2.4 KiB
C
/* Copyright (C) 1999, 2000, 2001 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, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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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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/* Clock frequency of the processor. */
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static long int nsec;
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#endif
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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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case CLOCK_REALTIME:
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{
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long int clk_tck = sysconf (_SC_CLK_TCK);
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if (__builtin_expect (clk_tck != -1, 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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retval = 0;
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}
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}
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break;
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#if HP_TIMING_AVAIL
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case CLOCK_PROCESS_CPUTIME_ID:
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case CLOCK_THREAD_CPUTIME_ID:
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{
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if (__builtin_expect (nsec == 0, 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 `freq'
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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 (__builtin_expect (freq == 0, 0))
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/* Something went wrong. */
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break;
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nsec = MAX (UINT64_C (1000000000) / freq, 1);
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}
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/* File in the values. The seconds are always zero (unless we
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have a 1Hz machine). */
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res->tv_sec = 0;
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res->tv_nsec = nsec;
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retval = 0;
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}
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break;
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#endif
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default:
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__set_errno (EINVAL);
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break;
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}
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return retval;
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}
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