/* clock_getres -- Get the resolution of a POSIX clockid_t.
   Copyright (C) 1999-2025 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, see
   <https://www.gnu.org/licenses/>.  */

#include <errno.h>
#include <stdint.h>
#include <time.h>
#include <sys/time.h>

static inline int realtime_getres(struct timespec *res)
{
	long int clk_tck = CLOCKS_PER_SEC; /* sysconf(_SC_CLK_TCK) */

	/* This implementation assumes that the realtime clock has a
	   resolution higher than 1 second.  This is the case for any
	   reasonable implementation.  */
	if (res)
	{
		res->tv_sec = 0;
		res->tv_nsec = 1000000000 / clk_tck;
	}
	return 0;
}

__typeof__(clock_getres) __clock_getres;

/* Get resolution of clock.  */
int __clock_getres(clockid_t clock_id, struct timespec *res)
{
	int retval = -1;

	switch (clock_id)
	{
	case CLOCK_MONOTONIC:
	case CLOCK_REALTIME:
		retval = realtime_getres(res);
		break;

	default:
		__set_errno(EINVAL);
		break;
	}

	return retval;
}

weak_alias (__clock_getres, clock_getres)
