1 /* Provide gettimeofday for systems that don't have it or for which it's broken.
3 Copyright (C) 2001-2003, 2005-2007, 2009-2018 Free Software Foundation, Inc.
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2, or (at your option)
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, see <https://www.gnu.org/licenses/>. */
18 /* written by Jim Meyering */
27 #if defined _WIN32 && ! defined __CYGWIN__
28 # define WINDOWS_NATIVE
32 #include "localtime-buffer.h"
36 /* Avoid warnings from gcc -Wcast-function-type. */
37 # define GetProcAddress \
38 (void *) GetProcAddress
40 /* GetSystemTimePreciseAsFileTime was introduced only in Windows 8. */
41 typedef void (WINAPI
* GetSystemTimePreciseAsFileTimeFuncType
) (FILETIME
*lpTime
);
42 static GetSystemTimePreciseAsFileTimeFuncType GetSystemTimePreciseAsFileTimeFunc
= NULL
;
43 static BOOL initialized
= FALSE
;
48 HMODULE kernel32
= LoadLibrary ("kernel32.dll");
51 GetSystemTimePreciseAsFileTimeFunc
=
52 (GetSystemTimePreciseAsFileTimeFuncType
) GetProcAddress (kernel32
, "GetSystemTimePreciseAsFileTime");
59 /* This is a wrapper for gettimeofday. It is used only on systems
60 that lack this function, or whose implementation of this function
62 Work around the bug in some systems whereby gettimeofday clobbers
63 the static buffer that localtime uses for its return value. The
64 gettimeofday function from Mac OS X 10.0.4 (i.e., Darwin 1.3.7) has
68 gettimeofday (struct timeval
*restrict tv
, void *restrict tz
)
73 /* On native Windows, there are two ways to get the current time:
74 GetSystemTimeAsFileTime
75 <https://msdn.microsoft.com/en-us/library/ms724397.aspx>
77 GetSystemTimePreciseAsFileTime
78 <https://msdn.microsoft.com/en-us/library/hh706895.aspx>.
79 GetSystemTimeAsFileTime produces values that jump by increments of
80 15.627 milliseconds (!) on average.
81 Whereas GetSystemTimePreciseAsFileTime values usually jump by 1 or 2
83 More discussion on this topic:
84 <http://www.windowstimestamp.com/description>. */
85 FILETIME current_time
;
89 if (GetSystemTimePreciseAsFileTimeFunc
!= NULL
)
90 GetSystemTimePreciseAsFileTimeFunc (¤t_time
);
92 GetSystemTimeAsFileTime (¤t_time
);
94 /* Convert from FILETIME to 'struct timeval'. */
95 /* FILETIME: <https://msdn.microsoft.com/en-us/library/ms724284.aspx> */
96 ULONGLONG since_1601
=
97 ((ULONGLONG
) current_time
.dwHighDateTime
<< 32)
98 | (ULONGLONG
) current_time
.dwLowDateTime
;
99 /* Between 1601-01-01 and 1970-01-01 there were 280 normal years and 89 leap
100 years, in total 134774 days. */
101 ULONGLONG since_1970
=
102 since_1601
- (ULONGLONG
) 134774 * (ULONGLONG
) 86400 * (ULONGLONG
) 10000000;
103 ULONGLONG microseconds_since_1970
= since_1970
/ (ULONGLONG
) 10;
104 tv
->tv_sec
= microseconds_since_1970
/ (ULONGLONG
) 1000000;
105 tv
->tv_usec
= microseconds_since_1970
% (ULONGLONG
) 1000000;
111 # if HAVE_GETTIMEOFDAY
112 # if GETTIMEOFDAY_CLOBBERS_LOCALTIME
113 /* Save and restore the contents of the buffer used for localtime's
114 result around the call to gettimeofday. */
115 struct tm save
= *localtime_buffer_addr
;
118 # if defined timeval /* 'struct timeval' overridden by gnulib? */
121 int result
= gettimeofday (&otv
, (struct timezone
*) tz
);
124 tv
->tv_sec
= otv
.tv_sec
;
125 tv
->tv_usec
= otv
.tv_usec
;
128 int result
= gettimeofday (tv
, (struct timezone
*) tz
);
131 # if GETTIMEOFDAY_CLOBBERS_LOCALTIME
132 *localtime_buffer_addr
= save
;
139 # if !defined OK_TO_USE_1S_CLOCK
140 # error "Only 1-second nominal clock resolution found. Is that intended?" \
141 "If so, compile with the -DOK_TO_USE_1S_CLOCK option."
143 tv
->tv_sec
= time (NULL
);