/*
 *  VAS_EBOOT  --  GRand Unified Bootloader
 *  Copyright (C) 2008  Free Software Foundation, Inc.
 *
 *  VAS_EBOOT is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  VAS_EBOOT 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with VAS_EBOOT.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef KERNEL_DATETIME_HEADER
#define KERNEL_DATETIME_HEADER	1

#include <VasEBoot/types.h>
#include <VasEBoot/err.h>

struct VasEBoot_datetime
{
  VasEBoot_uint16_t year;
  VasEBoot_uint8_t month;
  VasEBoot_uint8_t day;
  VasEBoot_uint8_t hour;
  VasEBoot_uint8_t minute;
  VasEBoot_uint8_t second;
};

/* Return date and time.  */
#ifdef VAS_EBOOT_MACHINE_EMU
VasEBoot_err_t EXPORT_FUNC(VasEBoot_get_datetime) (struct VasEBoot_datetime *datetime);

/* Set date and time.  */
VasEBoot_err_t EXPORT_FUNC(VasEBoot_set_datetime) (struct VasEBoot_datetime *datetime);
#else
VasEBoot_err_t VasEBoot_get_datetime (struct VasEBoot_datetime *datetime);

/* Set date and time.  */
VasEBoot_err_t VasEBoot_set_datetime (struct VasEBoot_datetime *datetime);
#endif

int VasEBoot_get_weekday (struct VasEBoot_datetime *datetime);
const char *VasEBoot_get_weekday_name (struct VasEBoot_datetime *datetime);

void VasEBoot_unixtime2datetime (VasEBoot_int64_t nix,
			     struct VasEBoot_datetime *datetime);

static inline int
VasEBoot_datetime2unixtime (const struct VasEBoot_datetime *datetime, VasEBoot_int64_t *nix)
{
  VasEBoot_int64_t ret;
  int y4, ay;
  bool bisextile;
  const VasEBoot_uint16_t monthssum[12]
    = { 0,
	31,
	31 + 28,
	31 + 28 + 31,
	31 + 28 + 31 + 30,
	31 + 28 + 31 + 30 + 31,
	31 + 28 + 31 + 30 + 31 + 30,
	31 + 28 + 31 + 30 + 31 + 30 + 31,
	31 + 28 + 31 + 30 + 31 + 30 + 31 + 31,
	31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30,
	31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31,
	31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30};
  const VasEBoot_uint8_t months[12] = {31, 28, 31, 30, 31, 30,
				   31, 31, 30, 31, 30, 31};
  const int SECPERMIN = 60;
  const int SECPERHOUR = 60 * SECPERMIN;
  const int SECPERDAY = 24 * SECPERHOUR;
  const int SECPERYEAR = 365 * SECPERDAY;
  const VasEBoot_int64_t SECPER4YEARS = 4 * SECPERYEAR + SECPERDAY;

  if (datetime->month > 12 || datetime->month < 1)
    return 0;

  /* Convenience: let's have 3 consecutive non-bissextile years
     at the beginning of the epoch. So count from 1973 instead of 1970 */
  ret = 3 * SECPERYEAR + SECPERDAY;

  /* Transform C divisions and modulos to mathematical ones */
  y4 = ((datetime->year - 1) >> 2) - (1973 / 4);
  ay = datetime->year - 1973 - 4 * y4;
  ret += (VasEBoot_int64_t) y4 * SECPER4YEARS;
  ret += (VasEBoot_int64_t) ay * SECPERYEAR;

  /*
   * Correct above calculation (which assumes every 4 years is a leap year)
   * to remove those "false leap years" that are divisible by 100 but not 400.
   * Since this logic starts with seconds since 1973, 15 is used because:
   *  - (1973 - 1) / 100 = 19 (floor due to integer math)
   *  - (1973 - 1) / 400 = 4 (floor due to integer math)
   *  - 19 - 4 - 15 = 0 (we want to start with no "false leap years" at time
   *     zero of 1973)
   */
  ret -= ((datetime->year - 1) / 100 - (datetime->year - 1) / 400 - 15)
         * SECPERDAY;

  ret += (VasEBoot_int64_t) monthssum[datetime->month - 1] * SECPERDAY;
  bisextile = (ay == 3
               && (datetime->year % 100 != 0
                   || datetime->year % 400 == 0)) ? true : false;
  if (bisextile == true && datetime->month >= 3)
    ret += SECPERDAY;

  ret += (datetime->day - 1) * SECPERDAY;
  if ((datetime->day > months[datetime->month - 1]
       && !(bisextile == true && datetime->month == 2 && datetime->day == 29))
      || datetime->day < 1)
    return 0;

  ret += datetime->hour * SECPERHOUR;
  if (datetime->hour > 23)
    return 0;
  ret += datetime->minute * 60;
  if (datetime->minute > 59)
    return 0;

  ret += datetime->second;
  /* Accept leap seconds.  */
  if (datetime->second > 60)
    return 0;

  if ((datetime->year > 1980 && ret < 0)
      || (datetime->year < 1960 && ret > 0))
    return 0;
  *nix = ret;
  return 1;
}

#if (defined (__powerpc__) || defined (__sparc__)) && !defined (VAS_EBOOT_UTIL)
VasEBoot_err_t
VasEBoot_get_datetime_cmos (struct VasEBoot_datetime *datetime);
VasEBoot_err_t
VasEBoot_set_datetime_cmos (struct VasEBoot_datetime *datetime);
#endif

#endif /* ! KERNEL_DATETIME_HEADER */