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 #ifdef HAVE_CLOCK_GETTIME
  33 /* POSIX states that CLOCK_REALTIME must be present if clock_gettime
  34    is available, others are optional.  */
  35 #ifdef CLOCK_MONOTONIC
  36 #define GF_CLOCK_MONOTONIC CLOCK_MONOTONIC
  37 #else
  38 #define GF_CLOCK_MONOTONIC CLOCK_REALTIME
  39 #endif
  40
  41 /* Weakref trickery for clock_gettime().  On Glibc, clock_gettime()
  42    requires us to link in librt, which also pulls in libpthread.  In
  43    order to avoid this by default, only call clock_gettime() through a
  44    weak reference.
  45
  46    Some targets don't support weak undefined references; on these
  47    GTHREAD_USE_WEAK is 0. So we need to define it to 1 on other
  48    targets.  */
  49 #ifndef GTHREAD_USE_WEAK
  50 #define GTHREAD_USE_WEAK 1
  51 #endif
  52
  53 #if SUPPORTS_WEAK && GTHREAD_USE_WEAK
  54 static int weak_gettime (clockid_t, struct timespec *)
  55   __attribute__((__weakref__("clock_gettime")));
  56 #else
  57 static inline int weak_gettime (clockid_t clk_id, struct timespec *res)
  58 {
  59   return clock_gettime (clk_id, res);
  60 }
  61 #endif
  62 #endif
  63
  64
  65 /* High resolution monotonic clock, falling back to the realtime clock
  66    if the target does not support such a clock.
  67
  68    Arguments:
  69    secs     - OUTPUT, seconds
  70    nanosecs - OUTPUT, nanoseconds
  71
  72    If the target supports a monotonic clock, the OUTPUT arguments
  73    represent a monotonically incrementing clock starting from some
  74    unspecified time in the past.
  75
  76    If a monotonic clock is not available, falls back to the realtime
  77    clock which is not monotonic.
  78
  79    Return value: 0 for success, -1 for error. In case of error, errno
  80    is set.
  81 */
  82 static inline int
  83 gf_gettime_mono (time_t * secs, long * nanosecs)
  84 {
  85   int err;
  86 #ifdef HAVE_CLOCK_GETTIME
  87   if (weak_gettime)
  88     {
  89       struct timespec ts;
  90       err = weak_gettime (GF_CLOCK_MONOTONIC, &ts);
  91       *secs = ts.tv_sec;
  92       *nanosecs = ts.tv_nsec;
  93       return err;
  94     }
  95 #endif
  96   err = gf_gettime (secs, nanosecs);
  97   *nanosecs *= 1000;
  98   return err;
  99 }
 100
 101 extern void system_clock_4 (GFC_INTEGER_4 *, GFC_INTEGER_4 *, GFC_INTEGER_4 *);
 102 export_proto(system_clock_4);
 103
 104 extern void system_clock_8 (GFC_INTEGER_8 *, GFC_INTEGER_8 *, GFC_INTEGER_8 *);
 105 export_proto(system_clock_8);
 106
 107
 108 /* prefix(system_clock_4) is the INTEGER(4) version of the SYSTEM_CLOCK
 109    intrinsic subroutine.  It returns the number of clock ticks for the current
 110    system time, the number of ticks per second, and the maximum possible value
 111    for COUNT.  On the first call to SYSTEM_CLOCK, COUNT is set to zero. */
 112
 113 void
 114 system_clock_4(GFC_INTEGER_4 *count, GFC_INTEGER_4 *count_rate,
 115                GFC_INTEGER_4 *count_max)
 116 {
 117 #undef TCK
 118 #define TCK 1000
 119   GFC_INTEGER_4 cnt;
 120   GFC_INTEGER_4 mx;
 121
 122   time_t secs;
 123   long nanosecs;
 124
 125   if (sizeof (secs) < sizeof (GFC_INTEGER_4))
 126     internal_error (NULL, "secs too small");
 127
 128   if (gf_gettime_mono (&secs, &nanosecs) == 0)
 129     {
 130       GFC_UINTEGER_4 ucnt = (GFC_UINTEGER_4) secs * TCK;
 131       ucnt += (nanosecs + 500000000 / TCK) / (1000000000 / TCK);
 132       if (ucnt > GFC_INTEGER_4_HUGE)
 133         cnt = ucnt - GFC_INTEGER_4_HUGE - 1;
 134       else
 135         cnt = ucnt;
 136       mx = GFC_INTEGER_4_HUGE;
 137     }
 138   else
 139     {
 140       if (count != NULL)
 141         *count = - GFC_INTEGER_4_HUGE;
 142       if (count_rate != NULL)
 143         *count_rate = 0;
 144       if (count_max != NULL)
 145         *count_max = 0;
 146       return;
 147     }
 148
 149   if (count != NULL)
 150     *count = cnt;
 151   if (count_rate != NULL)
 152     *count_rate = TCK;
 153   if (count_max != NULL)
 154     *count_max = mx;
 155 }
 156
 157
 158 /* INTEGER(8) version of the above routine.  */
 159
 160 void
 161 system_clock_8 (GFC_INTEGER_8 *count, GFC_INTEGER_8 *count_rate,
 162                 GFC_INTEGER_8 *count_max)
 163 {
 164 #undef TCK
 165 #define TCK 1000000000
 166   GFC_INTEGER_8 cnt;
 167   GFC_INTEGER_8 mx;
 168
 169   time_t secs;
 170   long nanosecs;
 171
 172   if (sizeof (secs) < sizeof (GFC_INTEGER_4))
 173     internal_error (NULL, "secs too small");
 174
 175   if (gf_gettime_mono (&secs, &nanosecs) == 0)
 176     {
 177       GFC_UINTEGER_8 ucnt = (GFC_UINTEGER_8) secs * TCK;
 178       ucnt += (nanosecs + 500000000 / TCK) / (1000000000 / TCK);
 179       if (ucnt > GFC_INTEGER_8_HUGE)
 180         cnt = ucnt - GFC_INTEGER_8_HUGE - 1;
 181       else
 182         cnt = ucnt;
 183       mx = GFC_INTEGER_8_HUGE;
 184     }
 185   else
 186     {
 187       if (count != NULL)
 188         *count = - GFC_INTEGER_8_HUGE;
 189       if (count_rate != NULL)
 190         *count_rate = 0;
 191       if (count_max != NULL)
 192         *count_max = 0;
 193
 194       return;
 195     }
 196
 197   if (count != NULL)
 198     *count = cnt;
 199   if (count_rate != NULL)
 200     *count_rate = TCK;
 201   if (count_max != NULL)
 202     *count_max = mx;
 203 }