X86TimerLib.c

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#include <Base.h>
#include <Library/TimerLib.h>
#include <Library/BaseLib.h>
#include <Library/PcdLib.h>
#include <Library/DebugLib.h>
#include <Library/LocalApicLib.h>
 
UINT32
EFIAPI
InternalX86GetTimerFrequency (
  VOID
  )
{
  UINTN  Divisor;
 
  GetApicTimerState (&Divisor, NULL, NULL);
  return PcdGet32 (PcdFSBClock) / (UINT32)Divisor;
}
 
VOID
EFIAPI
InternalX86Delay (
  IN      UINT32  Delay
  )
{
  INT32   Ticks;
  UINT32  Times;
  UINT32  InitCount;
  UINT32  StartTick;
 
  //
  // In case Delay is too larger, separate it into several small delay slot.
  // Devided Delay by half value of Init Count is to avoid Delay close to
  // the Init Count, timeout maybe missing if the time consuming between 2
  // GetApicTimerCurrentCount() invoking is larger than the time gap between
  // Delay and the Init Count.
  //
  InitCount = GetApicTimerInitCount ();
  ASSERT (InitCount != 0);
  Times = Delay / (InitCount / 2);
  Delay = Delay % (InitCount / 2);
 
  //
  // Get Start Tick and do delay
  //
  StartTick = GetApicTimerCurrentCount ();
  do {
    //
    // Wait until time out by Delay value
    //
    do {
      CpuPause ();
      //
      // Get Ticks from Start to Current.
      //
      Ticks = StartTick - GetApicTimerCurrentCount ();
      //
      // Ticks < 0 means Timer wrap-arounds happens.
      //
      if (Ticks < 0) {
        Ticks += InitCount;
      }
    } while ((UINT32)Ticks < Delay);
 
    //
    // Update StartTick and Delay for next delay slot
    //
    StartTick -= (StartTick > Delay) ?  Delay : (Delay - InitCount);
    Delay      = InitCount / 2;
  } while (Times-- > 0);
}
 
UINTN
EFIAPI
MicroSecondDelay (
  IN      UINTN  MicroSeconds
  )
{
  InternalX86Delay (
    (UINT32)DivU64x32 (
              MultU64x64 (
                InternalX86GetTimerFrequency (),
                MicroSeconds
                ),
              1000000u
              )
    );
  return MicroSeconds;
}
 
UINTN
EFIAPI
NanoSecondDelay (
  IN      UINTN  NanoSeconds
  )
{
  InternalX86Delay (
    (UINT32)DivU64x32 (
              MultU64x64 (
                InternalX86GetTimerFrequency (),
                NanoSeconds
                ),
              1000000000u
              )
    );
  return NanoSeconds;
}
 
UINT64
EFIAPI
GetPerformanceCounter (
  VOID
  )
{
  return (UINT64)GetApicTimerCurrentCount ();
}
 
UINT64
EFIAPI
GetPerformanceCounterProperties (
  OUT      UINT64  *StartValue   OPTIONAL,
  OUT      UINT64  *EndValue     OPTIONAL
  )
{
  if (StartValue != NULL) {
    *StartValue = (UINT64)GetApicTimerInitCount ();
  }
 
  if (EndValue != NULL) {
    *EndValue = 0;
  }
 
  return (UINT64)InternalX86GetTimerFrequency ();
}
 
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;
}