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    tk       - OUTPUT, clock resolution [counts/sec]
  68
  69    If the target supports a monotonic clock, the OUTPUT arguments
  70    represent a monotonically incrementing clock starting from some
  71    unspecified time in the past.
  72
  73    If a monotonic clock is not available, falls back to the realtime
  74    clock which is not monotonic.
  75
  76    Return value: 0 for success, -1 for error. In case of error, errno
  77    is set.
  78 */
  79 static int
  80 gf_gettime_mono (time_t * secs, long * nanosecs, long * tck)
  81 {
  82   int err;
  83 #ifdef HAVE_CLOCK_GETTIME
  84   struct timespec ts;
  85   *tck = 1000000000;
  86   err = clock_gettime (GF_CLOCK_MONOTONIC, &ts);
  87   *secs = ts.tv_sec;
  88   *nanosecs = ts.tv_nsec;
  89   return err;
  90 #else
  91 #if defined(HAVE_CLOCK_GETTIME_LIBRT) && SUPPORTS_WEAK && GTHREAD_USE_WEAK
  92   if (weak_gettime)
  93     {
  94       struct timespec ts;
  95       *tck = 1000000000;
  96       err = weak_gettime (GF_CLOCK_MONOTONIC, &ts);
  97       *secs = ts.tv_sec;
  98       *nanosecs = ts.tv_nsec;
  99       return err;
 100     }
 101 #endif
 102   *tck = 1000000;
 103   err = gf_gettime (secs, nanosecs);
 104   *nanosecs *= 1000;
 105   return err;
 106 #endif
 107 }
 108
 109 extern void system_clock_4 (GFC_INTEGER_4 *, GFC_INTEGER_4 *, GFC_INTEGER_4 *);
 110 export_proto(system_clock_4);
 111
 112 extern void system_clock_8 (GFC_INTEGER_8 *, GFC_INTEGER_8 *, GFC_INTEGER_8 *);
 113 export_proto(system_clock_8);
 114
 115
 116 /* prefix(system_clock_4) is the INTEGER(4) version of the SYSTEM_CLOCK
 117    intrinsic subroutine.  It returns the number of clock ticks for the current
 118    system time, the number of ticks per second, and the maximum possible value
 119    for COUNT.  On the first call to SYSTEM_CLOCK, COUNT is set to zero. */
 120
 121 void
 122 system_clock_4(GFC_INTEGER_4 *count, GFC_INTEGER_4 *count_rate,
 123                GFC_INTEGER_4 *count_max)
 124 {
 125   GFC_INTEGER_4 cnt;
 126   GFC_INTEGER_4 mx;
 127
 128   time_t secs;
 129   long nanosecs, tck;
 130
 131   if (sizeof (secs) < sizeof (GFC_INTEGER_4))
 132     internal_error (NULL, "secs too small");
 133
 134   if (gf_gettime_mono (&secs, &nanosecs, &tck) == 0)
 135     {
 136       tck = tck>1000 ? 1000 : tck;
 137       GFC_UINTEGER_4 ucnt = (GFC_UINTEGER_4) secs * tck;
 138       ucnt += (nanosecs + 500000000 / tck) / (1000000000 / tck);
 139       if (ucnt > GFC_INTEGER_4_HUGE)
 140         cnt = ucnt - GFC_INTEGER_4_HUGE - 1;
 141       else
 142         cnt = ucnt;
 143       mx = GFC_INTEGER_4_HUGE;
 144     }
 145   else
 146     {
 147       if (count != NULL)
 148         *count = - GFC_INTEGER_4_HUGE;
 149       if (count_rate != NULL)
 150         *count_rate = 0;
 151       if (count_max != NULL)
 152         *count_max = 0;
 153       return;
 154     }
 155
 156   if (count != NULL)
 157     *count = cnt;
 158   if (count_rate != NULL)
 159     *count_rate = tck;
 160   if (count_max != NULL)
 161     *count_max = mx;
 162 }
 163
 164
 165 /* INTEGER(8) version of the above routine.  */
 166
 167 void
 168 system_clock_8 (GFC_INTEGER_8 *count, GFC_INTEGER_8 *count_rate,
 169                 GFC_INTEGER_8 *count_max)
 170 {
 171   GFC_INTEGER_8 cnt;
 172   GFC_INTEGER_8 mx;
 173
 174   time_t secs;
 175   long nanosecs, tck;
 176
 177   if (sizeof (secs) < sizeof (GFC_INTEGER_4))
 178     internal_error (NULL, "secs too small");
 179
 180   if (gf_gettime_mono (&secs, &nanosecs, &tck) == 0)
 181     {
 182       GFC_UINTEGER_8 ucnt = (GFC_UINTEGER_8) secs * tck;
 183       ucnt += (nanosecs + 500000000 / tck) / (1000000000 / tck);
 184       if (ucnt > GFC_INTEGER_8_HUGE)
 185         cnt = ucnt - GFC_INTEGER_8_HUGE - 1;
 186       else
 187         cnt = ucnt;
 188       mx = GFC_INTEGER_8_HUGE;
 189     }
 190   else
 191     {
 192       if (count != NULL)
 193         *count = - GFC_INTEGER_8_HUGE;
 194       if (count_rate != NULL)
 195         *count_rate = 0;
 196       if (count_max != NULL)
 197         *count_max = 0;
 198
 199       return;
 200     }
 201
 202   if (count != NULL)
 203     *count = cnt;
 204   if (count_rate != NULL)
 205     *count_rate = tck;
 206   if (count_max != NULL)
 207     *count_max = mx;
 208 }