DxeCoreTimerLib.c

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#include <PiPei.h>
#include <Library/BaseLib.h>
#include <Library/TimerLib.h>
#include <Library/DebugLib.h>
#include <Library/EmuThunkLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/UefiLib.h>
 
#include <Protocol/Timer.h>
 
UINTN
EFIAPI
MicroSecondDelay (
  IN      UINTN  MicroSeconds
  )
{
  return NanoSecondDelay (MicroSeconds * 1000);
}
 
UINTN
EFIAPI
NanoSecondDelay (
  IN      UINTN  NanoSeconds
  )
{
  gEmuThunk->Sleep (NanoSeconds);
  return NanoSeconds;
}
 
UINT64
EFIAPI
GetPerformanceCounter (
  VOID
  )
{
  return gEmuThunk->QueryPerformanceCounter ();
}
 
UINT64
EFIAPI
GetPerformanceCounterProperties (
  OUT      UINT64  *StartValue   OPTIONAL,
  OUT      UINT64  *EndValue     OPTIONAL
  )
{
  if (StartValue != NULL) {
    *StartValue = 0ULL;
  }
 
  if (EndValue != NULL) {
    *EndValue = (UINT64)-1LL;
  }
 
  return gEmuThunk->QueryPerformanceFrequency ();
}
 
UINT64
EFIAPI
GetTimeInNanoSecond (
  IN UINT64  Ticks
  )
{
  UINT64  Frequency;
  UINT64  NanoSeconds;
  UINT64  Remainder;
  INTN    Shift;
 
  Frequency = GetPerformanceCounterProperties (NULL, NULL);
 
  //
  //          Ticks
  // Time = --------- x 1,000,000,000
  //        Frequency
  //
  NanoSeconds = MultU64x32 (DivU64x64Remainder (Ticks, Frequency, &Remainder), 1000000000u);
 
  //
  // Ensure (Remainder * 1,000,000,000) will not overflow 64-bit.
  // Since 2^29 < 1,000,000,000 = 0x3B9ACA00 < 2^30, Remainder should < 2^(64-30) = 2^34,
  // i.e. highest bit set in Remainder should <= 33.
  //
  Shift        = MAX (0, HighBitSet64 (Remainder) - 33);
  Remainder    = RShiftU64 (Remainder, (UINTN)Shift);
  Frequency    = RShiftU64 (Frequency, (UINTN)Shift);
  NanoSeconds += DivU64x64Remainder (MultU64x32 (Remainder, 1000000000u), Frequency, NULL);
 
  return NanoSeconds;
}