1/* Implementation of the SYSTEM_CLOCK intrinsic.
2   Copyright (C) 2004-2020 Free Software Foundation, Inc.
3
4This file is part of the GNU Fortran runtime library (libgfortran).
5
6Libgfortran is free software; you can redistribute it and/or
7modify it under the terms of the GNU General Public
8License as published by the Free Software Foundation; either
9version 3 of the License, or (at your option) any later version.
10
11Libgfortran is distributed in the hope that it will be useful,
12but WITHOUT ANY WARRANTY; without even the implied warranty of
13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14GNU General Public License for more details.
15
16Under Section 7 of GPL version 3, you are granted additional
17permissions described in the GCC Runtime Library Exception, version
183.1, as published by the Free Software Foundation.
19
20You should have received a copy of the GNU General Public License and
21a copy of the GCC Runtime Library Exception along with this program;
22see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23<http://www.gnu.org/licenses/>.  */
24
25#include "libgfortran.h"
26
27#include <limits.h>
28
29#include "time_1.h"
30
31
32#if !defined(__MINGW32__)
33
34/* POSIX states that CLOCK_REALTIME must be present if clock_gettime
35   is available, others are optional.  */
36#if defined(HAVE_CLOCK_GETTIME) || defined(HAVE_CLOCK_GETTIME_LIBRT)
37#if defined(CLOCK_MONOTONIC) && defined(_POSIX_MONOTONIC_CLOCK) \
38  && _POSIX_MONOTONIC_CLOCK >= 0
39#define GF_CLOCK_MONOTONIC CLOCK_MONOTONIC
40#else
41#define GF_CLOCK_MONOTONIC CLOCK_REALTIME
42#endif
43#endif
44
45/* Weakref trickery for clock_gettime().  On Glibc <= 2.16,
46   clock_gettime() requires us to link in librt, which also pulls in
47   libpthread.  In order to avoid this by default, only call
48   clock_gettime() through a weak reference.  */
49#if SUPPORTS_WEAKREF && defined(HAVE_CLOCK_GETTIME_LIBRT)
50static int weak_gettime (clockid_t, struct timespec *)
51  __attribute__((__weakref__("clock_gettime")));
52#endif
53
54
55/* High resolution monotonic clock, falling back to the realtime clock
56   if the target does not support such a clock.
57
58   Arguments:
59   secs     - OUTPUT, seconds
60   fracsecs - OUTPUT, fractional seconds, units given by tk argument
61   tk       - OUTPUT, clock resolution [counts/sec]
62
63   If the target supports a monotonic clock, the OUTPUT arguments
64   represent a monotonically incrementing clock starting from some
65   unspecified time in the past.
66
67   If a monotonic clock is not available, falls back to the realtime
68   clock which is not monotonic.
69
70   Return value: 0 for success, -1 for error. In case of error, errno
71   is set.
72*/
73static int
74gf_gettime_mono (time_t * secs, long * fracsecs, long * tck)
75{
76  int err;
77#ifdef HAVE_CLOCK_GETTIME
78  struct timespec ts;
79  *tck = 1000000000;
80  err = clock_gettime (GF_CLOCK_MONOTONIC, &ts);
81  *secs = ts.tv_sec;
82  *fracsecs = ts.tv_nsec;
83  return err;
84#else
85#if SUPPORTS_WEAKREF && defined(HAVE_CLOCK_GETTIME_LIBRT)
86  if (weak_gettime)
87    {
88      struct timespec ts;
89      *tck = 1000000000;
90      err = weak_gettime (GF_CLOCK_MONOTONIC, &ts);
91      *secs = ts.tv_sec;
92      *fracsecs = ts.tv_nsec;
93      return err;
94    }
95#endif
96  *tck = 1000000;
97  err = gf_gettime (secs, fracsecs);
98  return err;
99#endif
100}
101
102#endif /* !__MINGW32__  */
103
104extern void
105system_clock_4 (GFC_INTEGER_4 *count, GFC_INTEGER_4 *count_rate,
106		GFC_INTEGER_4 *count_max);
107export_proto(system_clock_4);
108
109extern void
110system_clock_8 (GFC_INTEGER_8 *count, GFC_INTEGER_8 *count_rate,
111		GFC_INTEGER_8 *count_max);
112export_proto(system_clock_8);
113
114
115/* prefix(system_clock_4) is the INTEGER(4) version of the SYSTEM_CLOCK
116   intrinsic subroutine.  It returns the number of clock ticks for the current
117   system time, the number of ticks per second, and the maximum possible value
118   for COUNT.  */
119
120void
121system_clock_4 (GFC_INTEGER_4 *count, GFC_INTEGER_4 *count_rate,
122	       GFC_INTEGER_4 *count_max)
123{
124#if defined(__MINGW32__)
125  if (count)
126    {
127      /* Use GetTickCount here as the resolution and range is
128	 sufficient for the INTEGER(kind=4) version, and
129	 QueryPerformanceCounter has potential issues.  */
130      uint32_t cnt = GetTickCount ();
131      if (cnt > GFC_INTEGER_4_HUGE)
132	cnt = cnt - GFC_INTEGER_4_HUGE - 1;
133      *count = cnt;
134    }
135  if (count_rate)
136    *count_rate = 1000;
137  if (count_max)
138    *count_max = GFC_INTEGER_4_HUGE;
139#else
140  time_t secs;
141  long fracsecs, tck;
142
143  if (gf_gettime_mono (&secs, &fracsecs, &tck) == 0)
144    {
145      long tck_out = tck > 1000 ? 1000 : tck;
146      long tck_r = tck / tck_out;
147      GFC_UINTEGER_4 ucnt = (GFC_UINTEGER_4) secs * tck_out;
148      ucnt += fracsecs / tck_r;
149      if (ucnt > GFC_INTEGER_4_HUGE)
150	ucnt = ucnt - GFC_INTEGER_4_HUGE - 1;
151      if (count)
152	*count = ucnt;
153      if (count_rate)
154	*count_rate = tck_out;
155      if (count_max)
156	*count_max = GFC_INTEGER_4_HUGE;
157    }
158  else
159    {
160      if (count)
161	*count = - GFC_INTEGER_4_HUGE;
162      if (count_rate)
163	*count_rate = 0;
164      if (count_max)
165	*count_max = 0;
166    }
167#endif
168}
169
170
171/* INTEGER(8) version of the above routine.  */
172
173void
174system_clock_8 (GFC_INTEGER_8 *count, GFC_INTEGER_8 *count_rate,
175		 GFC_INTEGER_8 *count_max)
176{
177#if defined(__MINGW32__)
178  LARGE_INTEGER cnt;
179  LARGE_INTEGER freq;
180  bool fail = false;
181  if (count && !QueryPerformanceCounter (&cnt))
182    fail = true;
183  if (count_rate && !QueryPerformanceFrequency (&freq))
184    fail = true;
185  if (fail)
186    {
187      if (count)
188	*count = - GFC_INTEGER_8_HUGE;
189      if (count_rate)
190	*count_rate = 0;
191      if (count_max)
192	*count_max = 0;
193    }
194  else
195    {
196      if (count)
197	*count = cnt.QuadPart;
198      if (count_rate)
199	*count_rate = freq.QuadPart;
200      if (count_max)
201	*count_max = GFC_INTEGER_8_HUGE;
202    }
203#else
204  time_t secs;
205  long fracsecs, tck;
206
207  if (gf_gettime_mono (&secs, &fracsecs, &tck) == 0)
208    {
209      GFC_UINTEGER_8 ucnt = (GFC_UINTEGER_8) secs * tck;
210      ucnt += fracsecs;
211      if (ucnt > GFC_INTEGER_8_HUGE)
212	ucnt = ucnt - GFC_INTEGER_8_HUGE - 1;
213      if (count)
214	*count = ucnt;
215      if (count_rate)
216	*count_rate = tck;
217      if (count_max)
218	*count_max = GFC_INTEGER_8_HUGE;
219    }
220  else
221    {
222      if (count)
223	*count = - GFC_INTEGER_8_HUGE;
224      if (count_rate)
225	*count_rate = 0;
226      if (count_max)
227	*count_max = 0;
228    }
229#endif
230}
231