system76-edk2/EmbeddedPkg/Library/TimeBaseLib/TimeBaseLib.c

/** @file
*
*  Copyright (c) 2016, Hisilicon Limited. All rights reserved.
*  Copyright (c) 2016, Linaro Limited. All rights reserved.
*
*  This program and the accompanying materials
*  are licensed and made available under the terms and conditions of the BSD License
*  which accompanies this distribution.  The full text of the license may be found at
*  http://opensource.org/licenses/bsd-license.php
*
*  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
*  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
*
**/

#include <Uefi/UefiBaseType.h>
#include <Uefi/UefiSpec.h>
#include <Library/DebugLib.h>
#include <Library/TimeBaseLib.h>

/**
  Converts Epoch seconds (elapsed since 1970 JANUARY 01, 00:00:00 UTC) to EFI_TIME
 **/
VOID
EFIAPI
EpochToEfiTime (
  IN  UINTN     EpochSeconds,
  OUT EFI_TIME  *Time
  )
{
  UINTN         a;
  UINTN         b;
  UINTN         c;
  UINTN         d;
  UINTN         g;
  UINTN         j;
  UINTN         m;
  UINTN         y;
  UINTN         da;
  UINTN         db;
  UINTN         dc;
  UINTN         dg;
  UINTN         hh;
  UINTN         mm;
  UINTN         ss;
  UINTN         J;

  J  = (EpochSeconds / 86400) + 2440588;
  j  = J + 32044;
  g  = j / 146097;
  dg = j % 146097;
  c  = (((dg / 36524) + 1) * 3) / 4;
  dc = dg - (c * 36524);
  b  = dc / 1461;
  db = dc % 1461;
  a  = (((db / 365) + 1) * 3) / 4;
  da = db - (a * 365);
  y  = (g * 400) + (c * 100) + (b * 4) + a;
  m  = (((da * 5) + 308) / 153) - 2;
  d  = da - (((m + 4) * 153) / 5) + 122;

  Time->Year  = y - 4800 + ((m + 2) / 12);
  Time->Month = ((m + 2) % 12) + 1;
  Time->Day   = d + 1;

  ss = EpochSeconds % 60;
  a  = (EpochSeconds - ss) / 60;
  mm = a % 60;
  b = (a - mm) / 60;
  hh = b % 24;

  Time->Hour        = hh;
  Time->Minute      = mm;
  Time->Second      = ss;
  Time->Nanosecond  = 0;

}

/**
  Converts EFI_TIME to Epoch seconds (elapsed since 1970 JANUARY 01, 00:00:00 UTC)
 **/
UINTN
EFIAPI
EfiTimeToEpoch (
  IN  EFI_TIME  *Time
  )
{
  UINTN a;
  UINTN y;
  UINTN m;
  UINTN JulianDate;  // Absolute Julian Date representation of the supplied Time
  UINTN EpochDays;   // Number of days elapsed since EPOCH_JULIAN_DAY
  UINTN EpochSeconds;

  a = (14 - Time->Month) / 12 ;
  y = Time->Year + 4800 - a;
  m = Time->Month + (12*a) - 3;

  JulianDate = Time->Day + ((153*m + 2)/5) + (365*y) + (y/4) - (y/100) + (y/400) - 32045;

  ASSERT (JulianDate >= EPOCH_JULIAN_DATE);
  EpochDays = JulianDate - EPOCH_JULIAN_DATE;

  EpochSeconds = (EpochDays * SEC_PER_DAY) + ((UINTN)Time->Hour * SEC_PER_HOUR) + (Time->Minute * SEC_PER_MIN) + Time->Second;

  return EpochSeconds;
}

BOOLEAN
EFIAPI
IsLeapYear (
  IN EFI_TIME   *Time
  )
{
  if (Time->Year % 4 == 0) {
    if (Time->Year % 100 == 0) {
      if (Time->Year % 400 == 0) {
        return TRUE;
      } else {
        return FALSE;
      }
    } else {
      return TRUE;
    }
  } else {
    return FALSE;
  }
}

BOOLEAN
EFIAPI
IsDayValid (
  IN  EFI_TIME  *Time
  )
{
  STATIC CONST INTN DayOfMonth[12] = { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

  if (Time->Day < 1 ||
      Time->Day > DayOfMonth[Time->Month - 1] ||
      (Time->Month == 2 && (!IsLeapYear (Time) && Time->Day > 28))
     ) {
    return FALSE;
  }

  return TRUE;
}

BOOLEAN
EFIAPI
IsTimeValid(
  IN EFI_TIME *Time
  )
{
  // Check the input parameters are within the range specified by UEFI
  if ((Time->Year   < 2000) ||
     (Time->Year   > 2099) ||
     (Time->Month  < 1   ) ||
     (Time->Month  > 12  ) ||
     (!IsDayValid (Time)    ) ||
     (Time->Hour   > 23  ) ||
     (Time->Minute > 59  ) ||
     (Time->Second > 59  ) ||
     (Time->Nanosecond > 999999999) ||
     (!((Time->TimeZone == EFI_UNSPECIFIED_TIMEZONE) || ((Time->TimeZone >= -1440) && (Time->TimeZone <= 1440)))) ||
     (Time->Daylight & (~(EFI_TIME_ADJUST_DAYLIGHT | EFI_TIME_IN_DAYLIGHT)))
  ) {
    return FALSE;
  }

  return TRUE;
}