gettimeofday.c

/*
* gettimeofday.c
*    Win32 gettimeofday() replacement
*
* src/port/gettimeofday.c
*
* 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.
*/
#include "gettimeofday.h"
#ifdef _WIN32
#include <Windows.h>

/* FILETIME of Jan 1 1970 00:00:00. */
static const unsigned __int64 epoch = ((unsigned __int64)116444736000000000ULL);

/*
* 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;
}
#endif

int timeval_subtract(struct timeval *result, struct timeval *x, struct timeval *y)
{
  /* Perform the carry for the later subtraction by updating y. */
  if (x->tv_usec < y->tv_usec) {
    int nsec = (y->tv_usec - x->tv_usec) / 1000000 + 1;
    y->tv_usec -= 1000000 * nsec;
    y->tv_sec += nsec;
  }
  if (x->tv_usec - y->tv_usec > 1000000) {
    int nsec = (x->tv_usec - y->tv_usec) / 1000000;
    y->tv_usec += 1000000 * nsec;
    y->tv_sec -= nsec;
  }

  /* Compute the time remaining to wait.
  tv_usec is certainly positive. */
  result->tv_sec = x->tv_sec - y->tv_sec;
  result->tv_usec = x->tv_usec - y->tv_usec;

  /* Return 1 if result is negative. */
  return x->tv_sec < y->tv_sec;
}

float timeval_to_ms(struct timeval *tv) {
  double sec, usec;

  sec = (float)tv->tv_sec;
  usec = (float)tv->tv_usec;

  return (float)(sec * 1000 + usec / 1000);
}

uint64_t timeval_to_us(struct timeval *tv)
{
  return tv->tv_sec * (uint64_t)1000000 + tv->tv_usec;
}