posix/src/clockgetres.c

0001 /* SPDX-License-Identifier: BSD-2-Clause */
0002
0003 /**
0004  * @file
0005  *
0006  * @ingroup POSIXAPI
0007  *
0008  * @brief Function Returns the Resolution of any Clock
0009  */
0010
0011 /*
0012  *  COPYRIGHT (c) 1989-2007.
0013  *  On-Line Applications Research Corporation (OAR).
0014  *
0015  * Redistribution and use in source and binary forms, with or without
0016  * modification, are permitted provided that the following conditions
0017  * are met:
0018  * 1. Redistributions of source code must retain the above copyright
0019  *    notice, this list of conditions and the following disclaimer.
0020  * 2. Redistributions in binary form must reproduce the above copyright
0021  *    notice, this list of conditions and the following disclaimer in the
0022  *    documentation and/or other materials provided with the distribution.
0023  *
0024  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
0025  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0026  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0027  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
0028  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
0029  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
0030  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0031  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0032  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
0033  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
0034  * POSSIBILITY OF SUCH DAMAGE.
0035  */
0036
0037 #ifdef HAVE_CONFIG_H
0038 #include "config.h"
0039 #endif
0040
0041 #include <time.h>
0042 #include <errno.h>
0043
0044 #include <rtems/score/todimpl.h>
0045 #include <rtems/config.h>
0046 #include <rtems/seterr.h>
0047
0048 /*
0049  *  14.2.1 Clocks, P1003.1b-1993, p. 263
0050  */
0051
0052 int clock_getres(
0053   clockid_t        clock_id,
0054   struct timespec *res
0055 )
0056 {
0057   if ( !res )
0058     rtems_set_errno_and_return_minus_one( EINVAL );
0059
0060   switch ( clock_id ) {
0061
0062     /*
0063      *  All time in rtems is based on the same clock tick.
0064      */
0065
0066     case CLOCK_REALTIME:
0067     case CLOCK_PROCESS_CPUTIME_ID:
0068     case CLOCK_THREAD_CPUTIME_ID:
0069       if ( res ) {
0070         res->tv_sec = rtems_configuration_get_microseconds_per_tick() /
0071             TOD_MICROSECONDS_PER_SECOND;
0072         res->tv_nsec = rtems_configuration_get_nanoseconds_per_tick();
0073       }
0074       break;
0075
0076     default:
0077       rtems_set_errno_and_return_minus_one( EINVAL );
0078
0079   }
0080   return 0;
0081 }