tesseract/vs2008/port/gettimeofday.cpp

/*
 * gettimeofday.c
 *    Win32 gettimeofday() replacement
 *
 * $PostgreSQL: pgsql/src/port/gettimeofday.c,v 1.9 2006/03/04 04:44:07 momjian Exp $
 *
 * Copyright (c) 2003 SRA, Inc.
 * Copyright (c) 2003 SKC, Inc.
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation for any purpose, without fee, and without a
 * written agreement is hereby granted, provided that the above
 * copyright notice and this paragraph and the following two
 * paragraphs appear in all copies.
 *
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT,
 * INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
 * LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
 * DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS
 * IS" BASIS, AND THE AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
 * SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 */

#ifdef _WIN32
#include          <winsock.h>    // timeval is defined in here.
#endif

/* FILETIME of Jan 1 1970 00:00:00. */
static const unsigned __int64 epoch = 11644473600000000Ui64;

struct timezone {
  int  tz_minuteswest; /* minutes W of Greenwich */
  int  tz_dsttime;     /* type of dst correction */
};

/*
 * timezone information is stored outside the kernel so tzp isn't used anymore.
 *
 * Note: this function is not for Win32 high precision timing purpose. See
 * elapsed_time().
 */
int
gettimeofday(struct timeval * tp, struct timezone * tzp) {
  FILETIME file_time;
  SYSTEMTIME system_time;
  ULARGE_INTEGER ularge;

  GetSystemTime(&system_time);
  SystemTimeToFileTime(&system_time, &file_time);
  ularge.LowPart = file_time.dwLowDateTime;
  ularge.HighPart = file_time.dwHighDateTime;

  tp->tv_sec = (long)((ularge.QuadPart - epoch) / 10000000L);
  tp->tv_usec = (long)(system_time.wMilliseconds * 1000);

  return 0;
}