sysdeps/unix/clock_settime.c

   1 /* Copyright (C) 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <errno.h>
  20 #include <time.h>
  21 #include <sys/time.h>
  22 #include <libc-internal.h>
  23 #include <ldsodefs.h>
  24
  25
  26 #if HP_TIMING_AVAIL
  27 /* Clock frequency of the processor.  We make it a 64-bit variable
  28    because some jokers are already playing with processors with more
  29    than 4GHz.  */
  30 static hp_timing_t freq;
  31
  32
  33 /* This function is defined in the thread library.  */
  34 extern void __pthread_clock_settime (hp_timing_t offset)
  35      __attribute__ ((__weak__));
  36 #endif
  37
  38
  39 /* Set CLOCK to value TP.  */
  40 int
  41 clock_settime (clockid_t clock_id, const struct timespec *tp)
  42 {
  43   struct timeval tv;
  44   int retval;
  45
  46   /* Make sure the time cvalue is OK.  */
  47   if (tp->tv_nsec < 0 || tp->tv_nsec >= 1000000000)
  48     {
  49       __set_errno (EINVAL);
  50       return -1;
  51     }
  52
  53   switch (clock_id)
  54     {
  55     case CLOCK_REALTIME:
  56       TIMESPEC_TO_TIMEVAL (&tv, tp);
  57
  58       retval = settimeofday (&tv, NULL);
  59       break;
  60
  61 #if HP_TIMING_AVAIL
  62     case CLOCK_PROCESS_CPUTIME_ID:
  63     case CLOCK_THREAD_CPUTIME_ID:
  64       {
  65         hp_timing_t tsc;
  66         hp_timing_t usertime;
  67
  68         /* First thing is to get the current time.  */
  69         HP_TIMING_NOW (tsc);
  70
  71         if (__builtin_expect (freq == 0, 0))
  72           {
  73             /* This can only happen if we haven't initialized the `freq'
  74                variable yet.  Do this now. We don't have to protect this
  75                code against multiple execution since all of them should
  76                lead to the same result.  */
  77             freq = __get_clockfreq ();
  78             if (__builtin_expect (freq == 0, 0))
  79               {
  80                 /* Something went wrong.  */
  81                 retval = -1;
  82                 break;
  83               }
  84           }
  85
  86         /* Convert the user-provided time into CPU ticks.  */
  87         usertime = tp->tv_sec * freq + (tp->tv_nsec * freq) / 1000000000ull;
  88
  89         /* Determine the offset and use it as the new base value.  */
  90         if (clock_id != CLOCK_THREAD_CPUTIME_ID
  91             || __pthread_clock_settime == NULL)
  92           GL(dl_cpuclock_offset) = tsc - usertime;
  93         else
  94           __pthread_clock_settime (tsc - usertime);
  95
  96         retval = 0;
  97       }
  98       break;
  99 #endif
 100
 101     default:
 102       __set_errno (EINVAL);
 103       retval = -1;
 104       break;
 105     }
 106
 107   return retval;
 108 }