src/port/gettimeofday.c

   1 /*
   2  * gettimeofday.c
   3  *        Win32 gettimeofday() replacement
   4  *
   5  * $PostgreSQL$
   6  *
   7  * Copyright (c) 2003 SRA, Inc.
   8  * Copyright (c) 2003 SKC, Inc.
   9  *
  10  * Permission to use, copy, modify, and distribute this software and
  11  * its documentation for any purpose, without fee, and without a
  12  * written agreement is hereby granted, provided that the above
  13  * copyright notice and this paragraph and the following two
  14  * paragraphs appear in all copies.
  15  *
  16  * IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT,
  17  * INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
  18  * LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
  19  * DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED
  20  * OF THE POSSIBILITY OF SUCH DAMAGE.
  21  *
  22  * THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  24  * A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS
  25  * IS" BASIS, AND THE AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
  26  * SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  27  */
  28
  29 #include "c.h"
  30
  31 #include <sys/time.h>
  32
  33
  34 /* FILETIME of Jan 1 1970 00:00:00. */
  35 static const unsigned __int64 epoch = UINT64CONST(116444736000000000);
  36
  37 /*
  38  * timezone information is stored outside the kernel so tzp isn't used anymore.
  39  *
  40  * Note: this function is not for Win32 high precision timing purpose. See
  41  * elapsed_time().
  42  */
  43 int
  44 gettimeofday(struct timeval * tp, struct timezone * tzp)
  45 {
  46         FILETIME        file_time;
  47         SYSTEMTIME      system_time;
  48         ULARGE_INTEGER ularge;
  49
  50         GetSystemTime(&system_time);
  51         SystemTimeToFileTime(&system_time, &file_time);
  52         ularge.LowPart = file_time.dwLowDateTime;
  53         ularge.HighPart = file_time.dwHighDateTime;
  54
  55         tp->tv_sec = (long) ((ularge.QuadPart - epoch) / 10000000L);
  56         tp->tv_usec = (long) (system_time.wMilliseconds * 1000);
  57
  58         return 0;
  59 }