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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libc/] [sys/] [linux/] [clock_getres.c] - Rev 258
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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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