glibc/sysdeps/unix/sysv/aix/gettimeofday.c

/* Copyright (C) 1991,92,94,95,96,97,2001,2002 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 <time.h>
#include <sys/time.h>

#ifndef HAVE_GNU_LD
# define __daylight	daylight
# define __timezone	timezone
# define __tzname	tzname
#endif

#undef __gettimeofday

extern int rtc_upper (void);
extern int rtc_lower (void);

/* Assembler Routines to access the timer registers */
asm("\n\
.rtc_upper: mfspr   3,4         # copy RTCU to return register\n\
            blr\n\
\n\
.rtc_lower: mfspr   3,5         # copy RTCL to return register\n\
            blr\n\
");

/* Get the current time of day and timezone information,
   putting it into *TV and *TZ.  If TZ is NULL, *TZ is not filled.
   Returns 0 on success, -1 on errors.  */
int
__gettimeofday (tv, tz)
     struct timeval  *tv;
     struct timezone *tz;
{
  int ts, tl, tu;

  if (tv == NULL)
    {
      __set_errno (EINVAL);
      return -1;
    }

  ts = rtc_upper ();		/* Seconds.  */
  tl = rtc_lower ();		/* Nanoseconds.  */
  tu = rtc_upper ();		/* Check for a carry from.  */
  if (ts != tu)			/* The lower reg to the upper.  */
      tl  = rtc_lower ();	/* Recover from the race condition.  */

  tv->tv_sec  = (long int) (tu + (double) tl / 1000000000);
  tv->tv_usec = (long int) ((double) tl / 1000);

  if (tz != NULL)
    {
      const  time_t timer = tv->tv_sec;
      struct tm tm;
      const  struct tm *tmp;

      const long int save_timezone = __timezone;
      const long int save_daylight = __daylight;
      char *save_tzname[2];
      save_tzname[0] = __tzname[0];
      save_tzname[1] = __tzname[1];

      tmp = localtime_r (&timer, &tm);

      tz->tz_minuteswest = __timezone / 60;
      tz->tz_dsttime     = __daylight;

      __timezone  = save_timezone;
      __daylight  = save_daylight;
      __tzname[0] = save_tzname[0];
      __tzname[1] = save_tzname[1];

      if (tmp == NULL)
	return -1;
    }

  return 0;
}

INTDEF(__gettimeofday)
weak_alias (__gettimeofday, gettimeofday)