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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;

}