Step to UEFI (181）GetTime 研究

//
// EFI Time Abstraction:
//  Year:       2000 - 20XX
//  Month:      1 - 12
//  Day:        1 - 31
//  Hour:       0 - 23
//  Minute:     0 - 59
//  Second:     0 - 59
//  Nanosecond: 0 - 999,999,999
//  TimeZone:   -1440 to 1440 or 2047
//
typedef struct {
  UINT16  Year;
  UINT8   Month;
  UINT8   Day;
  UINT8   Hour;
  UINT8   Minute;
  UINT8   Second;
  UINT8   Pad1;
  UINT32  Nanosecond;
  INT16   TimeZone;
  UINT8   Daylight;
  UINT8   Pad2;
} EFI_TIME;

/** @file
    A simple, basic, EDK II native, "hello" application to verify that
    we can build applications without LibC.

    Copyright (c) 2010 - 2011, Intel Corporation. All rights reserved.<BR>
    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.

    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.h>
#include  <Library/UefiLib.h>
#include  <Library/ShellCEntryLib.h>
#include  <Library/UefiBootServicesTableLib.h> //global gST gBS gImageHandle
#include  <Library/ShellLib.h>

extern EFI_RUNTIME_SERVICES      *gRT;

EFI_TIME        ET;

/***
  Print a welcoming message.

  Establishes the main structure of the application.

  @retval  0         The application exited normally.
  @retval  Other     An error occurred.
***/
INTN
EFIAPI
ShellAppMain (
  IN UINTN Argc,
  IN CHAR16 **Argv
  )
{
        gRT->GetTime(&ET,NULL);
        
        Print(L"Hour  [%d]\n",ET.Hour);
        Print(L"Minute[%d]\n",ET.Minute);
        Print(L"Second[%d]\n",ET.Second);
        Print(L"Nano  [%d]\n",ET.Nanosecond);
       
        return(0);
}

EFI_STATUS
EFIAPI
InitializeRealTimeClock (
  IN EFI_HANDLE                            ImageHandle,
  IN EFI_SYSTEM_TABLE                      *SystemTable
  )
  SystemTable->RuntimeServices->GetTime       = WinNtGetTime;
  SystemTable->RuntimeServices->SetTime       = WinNtSetTime;

EFI_STATUS
EFIAPI
WinNtGetTime (
  OUT EFI_TIME                                 *Time,
  OUT EFI_TIME_CAPABILITIES                    *Capabilities OPTIONAL
  )
/*++

Routine Description:
  Service routine for RealTimeClockInstance->GetTime 

Arguments:

  Time          - A pointer to storage that will receive a snapshot of the current time.

  Capabilities  - A pointer to storage that will receive the capabilities of the real time clock
                  in the platform. This includes the real time clock's resolution and accuracy.  
                  All reported device capabilities are rounded up.  This is an OPTIONAL argument.

Returns:

  EFI_SUCEESS   - The underlying GetSystemTime call occurred and returned
                  Note that in the NT32 emulation, the GetSystemTime call has no return value
                  thus you will always receive a EFI_SUCCESS on this.

--*/
// TODO:    EFI_INVALID_PARAMETER - add return value to function comment
{
  SYSTEMTIME            SystemTime;
  TIME_ZONE_INFORMATION TimeZone;

  //
  // Check parameter for null pointer
  //
  if (Time == NULL) {
    return EFI_INVALID_PARAMETER;

  }

  gWinNt->GetLocalTime (&SystemTime);
  gWinNt->GetTimeZoneInformation (&TimeZone);

  Time->Year        = (UINT16) SystemTime.wYear;
  Time->Month       = (UINT8) SystemTime.wMonth;
  Time->Day         = (UINT8) SystemTime.wDay;
  Time->Hour        = (UINT8) SystemTime.wHour;
  Time->Minute      = (UINT8) SystemTime.wMinute;
  Time->Second      = (UINT8) SystemTime.wSecond;
  Time->Nanosecond  = (UINT32) (SystemTime.wMilliseconds * 1000000);
  Time->TimeZone    = (INT16) TimeZone.Bias;

  if (Capabilities != NULL) {
    Capabilities->Resolution  = 1;
    Capabilities->Accuracy    = 50000000;
    Capabilities->SetsToZero  = FALSE;
  }

  Time->Daylight = 0;
  if (TimeZone.StandardDate.wMonth) {
    Time->Daylight = (UINT8) TimeZone.StandardDate.wMonth;
  }

  return EFI_SUCCESS;
}

/**
  Converts time read from RTC to EFI_TIME format defined by UEFI spec.

  This function converts raw time data read from RTC to the EFI_TIME format
  defined by UEFI spec.
  If data mode of RTC is BCD, then converts it to decimal,
  If RTC is in 12-hour format, then converts it to 24-hour format.

  @param   Time       On input, the time data read from RTC to convert
                      On output, the time converted to UEFI format
  @param   RegisterB  Value of Register B of RTC, indicating data mode
                      and hour format.

  @retval  EFI_INVALID_PARAMETER  Parameters passed in are invalid.
  @retval  EFI_SUCCESS            Convert RTC time to EFI time successfully.

**/
EFI_STATUS
ConvertRtcTimeToEfiTime (
  IN OUT EFI_TIME        *Time,
  IN     RTC_REGISTER_B  RegisterB
  )
{
  BOOLEAN IsPM;
  UINT8   Century;

  if ((Time->Hour & 0x80) != 0) {
    IsPM = TRUE;
  } else {
    IsPM = FALSE;
  }

  Time->Hour = (UINT8) (Time->Hour & 0x7f);

  if (RegisterB.Bits.Dm == 0) {
    Time->Year    = CheckAndConvertBcd8ToDecimal8 ((UINT8) Time->Year);
    Time->Month   = CheckAndConvertBcd8ToDecimal8 (Time->Month);
    Time->Day     = CheckAndConvertBcd8ToDecimal8 (Time->Day);
    Time->Hour    = CheckAndConvertBcd8ToDecimal8 (Time->Hour);
    Time->Minute  = CheckAndConvertBcd8ToDecimal8 (Time->Minute);
    Time->Second  = CheckAndConvertBcd8ToDecimal8 (Time->Second);
  }

  if (Time->Year == 0xff || Time->Month == 0xff || Time->Day == 0xff ||
      Time->Hour == 0xff || Time->Minute == 0xff || Time->Second == 0xff) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // For minimal/maximum year range [1970, 2069],
  //   Century is 19 if RTC year >= 70,
  //   Century is 20 otherwise.
  //
  Century = (UINT8) (PcdGet16 (PcdMinimalValidYear) / 100);
  if (Time->Year < PcdGet16 (PcdMinimalValidYear) % 100) {
    Century++;
  }
  Time->Year = (UINT16) (Century * 100 + Time->Year);

  //
  // If time is in 12 hour format, convert it to 24 hour format
  //
  if (RegisterB.Bits.Mil == 0) {
    if (IsPM && Time->Hour < 12) {
      Time->Hour = (UINT8) (Time->Hour + 12);
    }

    if (!IsPM && Time->Hour == 12) {
      Time->Hour = 0;
    }
  }

  Time->Nanosecond  = 0;

  return EFI_SUCCESS;
}