/* rtcsync.c */
/* read RTC and SetLocalTime (Ver.0.01) */
/* written by linear a */
/* create: Fri Feb 11 22:19:48 JST 2000 */
/* last update: Thu Feb 17 01:42:26 JST 2000 */

/* license: GPL */
/* require: directio.zip (DDJ 1996/5) and instdrv (NT DDK) or equivalent */

#include <windows.h>
#include <stdio.h>
#include <conio.h>
#include <string.h>

#define DEBUG 0

#if DEBUG
#define dprintf(a) printf a
#else
#define dprintf(a) /* epsilon */
#endif

#define bcd2int(a) (((((a) & 0xf0) >> 4) * 10) + ((a) & 0xf))

/* These macros come from Linux kernel arch/i386/time.c */
#define CMOS_READ(addr) (_outp(0x70, (addr)), _inp(0x71))

#define RTC_SECONDS		0
#define RTC_MINUTES		2
#define RTC_HOURS		4
#define RTC_DAY_OF_WEEK		6
#define RTC_DAY_OF_MONTH	7
#define RTC_MONTH		8
#define RTC_YEAR		9

SYSTEMTIME tm;

int main(int argc, char *argv[])
{
  unsigned char sec, year;
  HANDLE h;

  h = CreateFile("\\\\.\\giveio", GENERIC_READ, 0, NULL,
		 OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
  if(h == INVALID_HANDLE_VALUE) {
    printf("Couldn't access giveio device\n");
    return -1;
  }
  CloseHandle(h);

  GetLocalTime(&tm);
  dprintf(("kernel time is %d/%d/%d %d:%d:%d\n", tm.wYear, tm.wMonth, tm.wDay, tm.wHour, tm.wMinute, tm.wSecond));

  do {
    sec = CMOS_READ(RTC_SECONDS);
    tm.wMinute = bcd2int(CMOS_READ(RTC_MINUTES));
    tm.wHour = bcd2int(CMOS_READ(RTC_HOURS));
    tm.wDay = bcd2int(CMOS_READ(RTC_DAY_OF_MONTH));
    tm.wMonth = bcd2int(CMOS_READ(RTC_MONTH));
    year = bcd2int(CMOS_READ(RTC_YEAR));
  } while (sec != CMOS_READ(RTC_SECONDS));
  tm.wSecond = bcd2int(sec);
  /* avoid patent ?! */
  if (year < 50) {
    tm.wYear = year + 2000;
  } else {
    tm.wYear = year + 1900;
  }
  dprintf(("hardware time is %d/%d/%d %d:%d:%d\n", tm.wYear, tm.wMonth, tm.wDay, tm.wHour, tm.wMinute, tm.wSecond));
  if (argc > 1 && strcmp(argv[1], "-n") == 0) {
    dprintf(("time is not set\n"));
  } else {
    SetLocalTime(&tm);
    dprintf(("time is set\n"));
  }
  return 0;
}