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+/* Provide gettimeofday for systems that don't have it or for which it's broken.
+
+ Copyright (C) 2001-2003, 2005-2007, 2009-2022 Free Software Foundation, Inc.
+
+ This file is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ This file is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+/* written by Jim Meyering */
+
+#include <config.h>
+
+/* Specification. */
+#include <sys/time.h>
+
+#include <time.h>
+
+#if defined _WIN32 && ! defined __CYGWIN__
+# define WINDOWS_NATIVE
+# include <windows.h>
+#endif
+
+#ifdef WINDOWS_NATIVE
+
+/* Don't assume that UNICODE is not defined. */
+# undef LoadLibrary
+# define LoadLibrary LoadLibraryA
+
+# if !(_WIN32_WINNT >= _WIN32_WINNT_WIN8)
+
+/* Avoid warnings from gcc -Wcast-function-type. */
+# define GetProcAddress \
+ (void *) GetProcAddress
+
+/* GetSystemTimePreciseAsFileTime was introduced only in Windows 8. */
+typedef void (WINAPI * GetSystemTimePreciseAsFileTimeFuncType) (FILETIME *lpTime);
+static GetSystemTimePreciseAsFileTimeFuncType GetSystemTimePreciseAsFileTimeFunc = NULL;
+static BOOL initialized = FALSE;
+
+static void
+initialize (void)
+{
+ HMODULE kernel32 = LoadLibrary ("kernel32.dll");
+ if (kernel32 != NULL)
+ {
+ GetSystemTimePreciseAsFileTimeFunc =
+ (GetSystemTimePreciseAsFileTimeFuncType) GetProcAddress (kernel32, "GetSystemTimePreciseAsFileTime");
+ }
+ initialized = TRUE;
+}
+
+# else
+
+# define GetSystemTimePreciseAsFileTimeFunc GetSystemTimePreciseAsFileTime
+
+# endif
+
+#endif
+
+/* This is a wrapper for gettimeofday. It is used only on systems
+ that lack this function, or whose implementation of this function
+ causes problems.
+ Work around the bug in some systems whereby gettimeofday clobbers
+ the static buffer that localtime uses for its return value. The
+ gettimeofday function from Mac OS X 10.0.4 (i.e., Darwin 1.3.7) has
+ this problem. */
+
+int
+gettimeofday (struct timeval *restrict tv, void *restrict tz)
+{
+#undef gettimeofday
+#ifdef WINDOWS_NATIVE
+
+ /* On native Windows, there are two ways to get the current time:
+ GetSystemTimeAsFileTime
+ <https://docs.microsoft.com/en-us/windows/desktop/api/sysinfoapi/nf-sysinfoapi-getsystemtimeasfiletime>
+ or
+ GetSystemTimePreciseAsFileTime
+ <https://docs.microsoft.com/en-us/windows/desktop/api/sysinfoapi/nf-sysinfoapi-getsystemtimepreciseasfiletime>.
+ GetSystemTimeAsFileTime produces values that jump by increments of
+ 15.627 milliseconds (!) on average.
+ Whereas GetSystemTimePreciseAsFileTime values usually jump by 1 or 2
+ microseconds.
+ More discussion on this topic:
+ <http://www.windowstimestamp.com/description>. */
+ FILETIME current_time;
+
+# if !(_WIN32_WINNT >= _WIN32_WINNT_WIN8)
+ if (!initialized)
+ initialize ();
+# endif
+ if (GetSystemTimePreciseAsFileTimeFunc != NULL)
+ GetSystemTimePreciseAsFileTimeFunc (&current_time);
+ else
+ GetSystemTimeAsFileTime (&current_time);
+
+ /* Convert from FILETIME to 'struct timeval'. */
+ /* FILETIME: <https://docs.microsoft.com/en-us/windows/desktop/api/minwinbase/ns-minwinbase-filetime> */
+ ULONGLONG since_1601 =
+ ((ULONGLONG) current_time.dwHighDateTime << 32)
+ | (ULONGLONG) current_time.dwLowDateTime;
+ /* Between 1601-01-01 and 1970-01-01 there were 280 normal years and 89 leap
+ years, in total 134774 days. */
+ ULONGLONG since_1970 =
+ since_1601 - (ULONGLONG) 134774 * (ULONGLONG) 86400 * (ULONGLONG) 10000000;
+ ULONGLONG microseconds_since_1970 = since_1970 / (ULONGLONG) 10;
+ tv->tv_sec = microseconds_since_1970 / (ULONGLONG) 1000000;
+ tv->tv_usec = microseconds_since_1970 % (ULONGLONG) 1000000;
+
+ return 0;
+
+#else
+
+# if HAVE_GETTIMEOFDAY
+
+# if defined timeval /* 'struct timeval' overridden by gnulib? */
+# undef timeval
+ struct timeval otv;
+ int result = gettimeofday (&otv, (struct timezone *) tz);
+ if (result == 0)
+ {
+ tv->tv_sec = otv.tv_sec;
+ tv->tv_usec = otv.tv_usec;
+ }
+# else
+ int result = gettimeofday (tv, (struct timezone *) tz);
+# endif
+
+ return result;
+
+# else
+
+# if !defined OK_TO_USE_1S_CLOCK
+# error "Only 1-second nominal clock resolution found. Is that intended?" \
+ "If so, compile with the -DOK_TO_USE_1S_CLOCK option."
+# endif
+ tv->tv_sec = time (NULL);
+ tv->tv_usec = 0;
+
+ return 0;
+
+# endif
+#endif
+}