libgfortran/intrinsics/system_clock.c

   1 /* Implementation of the SYSTEM_CLOCK intrinsic.
   2    Copyright (C) 2004, 2005, 2007, 2009, 2010, 2011 Free Software
   3    Foundation, Inc.
   4
   5 This file is part of the GNU Fortran runtime library (libgfortran).
   6
   7 Libgfortran is free software; you can redistribute it and/or
   8 modify it under the terms of the GNU General Public
   9 License as published by the Free Software Foundation; either
  10 version 3 of the License, or (at your option) any later version.
  11
  12 Libgfortran is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 Under Section 7 of GPL version 3, you are granted additional
  18 permissions described in the GCC Runtime Library Exception, version
  19 3.1, as published by the Free Software Foundation.
  20
  21 You should have received a copy of the GNU General Public License and
  22 a copy of the GCC Runtime Library Exception along with this program;
  23 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 <http://www.gnu.org/licenses/>.  */
  25
  26 #include "libgfortran.h"
  27
  28 #include <limits.h>
  29
  30 #include "time_1.h"
  31
  32
  33 /* POSIX states that CLOCK_REALTIME must be present if clock_gettime
  34    is available, others are optional.  */
  35 #if defined(HAVE_CLOCK_GETTIME) || defined(HAVE_CLOCK_GETTIME_LIBRT)
  36 #ifdef CLOCK_MONOTONIC
  37 #define GF_CLOCK_MONOTONIC CLOCK_MONOTONIC
  38 #else
  39 #define GF_CLOCK_MONOTONIC CLOCK_REALTIME
  40 #endif
  41 #endif
  42
  43 /* Weakref trickery for clock_gettime().  On Glibc, clock_gettime()
  44    requires us to link in librt, which also pulls in libpthread.  In
  45    order to avoid this by default, only call clock_gettime() through a
  46    weak reference.
  47
  48    Some targets don't support weak undefined references; on these
  49    GTHREAD_USE_WEAK is 0. So we need to define it to 1 on other
  50    targets.  */
  51 #ifndef GTHREAD_USE_WEAK
  52 #define GTHREAD_USE_WEAK 1
  53 #endif
  54
  55 #if SUPPORTS_WEAK && GTHREAD_USE_WEAK && defined(HAVE_CLOCK_GETTIME_LIBRT)
  56 static int weak_gettime (clockid_t, struct timespec *)
  57   __attribute__((__weakref__("clock_gettime")));
  58 #endif
  59
  60
  61 /* High resolution monotonic clock, falling back to the realtime clock
  62    if the target does not support such a clock.
  63
  64    Arguments:
  65    secs     - OUTPUT, seconds
  66    nanosecs - OUTPUT, nanoseconds
  67
  68    If the target supports a monotonic clock, the OUTPUT arguments
  69    represent a monotonically incrementing clock starting from some
  70    unspecified time in the past.
  71
  72    If a monotonic clock is not available, falls back to the realtime
  73    clock which is not monotonic.
  74
  75    Return value: 0 for success, -1 for error. In case of error, errno
  76    is set.
  77 */
  78 static int
  79 gf_gettime_mono (time_t * secs, long * nanosecs)
  80 {
  81   int err;
  82 #ifdef HAVE_CLOCK_GETTIME
  83   struct timespec ts;
  84   err = clock_gettime (GF_CLOCK_MONOTONIC, &ts);
  85   *secs = ts.tv_sec;
  86   *nanosecs = ts.tv_nsec;
  87   return err;
  88 #else
  89 #if defined(HAVE_CLOCK_GETTIME_LIBRT) && SUPPORTS_WEAK && GTHREAD_USE_WEAK
  90   if (weak_gettime)
  91     {
  92       struct timespec ts;
  93       err = weak_gettime (GF_CLOCK_MONOTONIC, &ts);
  94       *secs = ts.tv_sec;
  95       *nanosecs = ts.tv_nsec;
  96       return err;
  97     }
  98 #endif
  99   err = gf_gettime (secs, nanosecs);
 100   *nanosecs *= 1000;
 101   return err;
 102 #endif
 103 }
 104
 105 extern void system_clock_4 (GFC_INTEGER_4 *, GFC_INTEGER_4 *, GFC_INTEGER_4 *);
 106 export_proto(system_clock_4);
 107
 108 extern void system_clock_8 (GFC_INTEGER_8 *, GFC_INTEGER_8 *, GFC_INTEGER_8 *);
 109 export_proto(system_clock_8);
 110
 111
 112 /* prefix(system_clock_4) is the INTEGER(4) version of the SYSTEM_CLOCK
 113    intrinsic subroutine.  It returns the number of clock ticks for the current
 114    system time, the number of ticks per second, and the maximum possible value
 115    for COUNT.  On the first call to SYSTEM_CLOCK, COUNT is set to zero. */
 116
 117 void
 118 system_clock_4(GFC_INTEGER_4 *count, GFC_INTEGER_4 *count_rate,
 119                GFC_INTEGER_4 *count_max)
 120 {
 121 #undef TCK
 122 #define TCK 1000
 123   GFC_INTEGER_4 cnt;
 124   GFC_INTEGER_4 mx;
 125
 126   time_t secs;
 127   long nanosecs;
 128
 129   if (sizeof (secs) < sizeof (GFC_INTEGER_4))
 130     internal_error (NULL, "secs too small");
 131
 132   if (gf_gettime_mono (&secs, &nanosecs) == 0)
 133     {
 134       GFC_UINTEGER_4 ucnt = (GFC_UINTEGER_4) secs * TCK;
 135       ucnt += (nanosecs + 500000000 / TCK) / (1000000000 / TCK);
 136       if (ucnt > GFC_INTEGER_4_HUGE)
 137         cnt = ucnt - GFC_INTEGER_4_HUGE - 1;
 138       else
 139         cnt = ucnt;
 140       mx = GFC_INTEGER_4_HUGE;
 141     }
 142   else
 143     {
 144       if (count != NULL)
 145         *count = - GFC_INTEGER_4_HUGE;
 146       if (count_rate != NULL)
 147         *count_rate = 0;
 148       if (count_max != NULL)
 149         *count_max = 0;
 150       return;
 151     }
 152
 153   if (count != NULL)
 154     *count = cnt;
 155   if (count_rate != NULL)
 156     *count_rate = TCK;
 157   if (count_max != NULL)
 158     *count_max = mx;
 159 }
 160
 161
 162 /* INTEGER(8) version of the above routine.  */
 163
 164 void
 165 system_clock_8 (GFC_INTEGER_8 *count, GFC_INTEGER_8 *count_rate,
 166                 GFC_INTEGER_8 *count_max)
 167 {
 168 #undef TCK
 169 #define TCK 1000000000
 170   GFC_INTEGER_8 cnt;
 171   GFC_INTEGER_8 mx;
 172
 173   time_t secs;
 174   long nanosecs;
 175
 176   if (sizeof (secs) < sizeof (GFC_INTEGER_4))
 177     internal_error (NULL, "secs too small");
 178
 179   if (gf_gettime_mono (&secs, &nanosecs) == 0)
 180     {
 181       GFC_UINTEGER_8 ucnt = (GFC_UINTEGER_8) secs * TCK;
 182       ucnt += (nanosecs + 500000000 / TCK) / (1000000000 / TCK);
 183       if (ucnt > GFC_INTEGER_8_HUGE)
 184         cnt = ucnt - GFC_INTEGER_8_HUGE - 1;
 185       else
 186         cnt = ucnt;
 187       mx = GFC_INTEGER_8_HUGE;
 188     }
 189   else
 190     {
 191       if (count != NULL)
 192         *count = - GFC_INTEGER_8_HUGE;
 193       if (count_rate != NULL)
 194         *count_rate = 0;
 195       if (count_max != NULL)
 196         *count_max = 0;
 197
 198       return;
 199     }
 200
 201   if (count != NULL)
 202     *count = cnt;
 203   if (count_rate != NULL)
 204     *count_rate = TCK;
 205   if (count_max != NULL)
 206     *count_max = mx;
 207 }