/**
Stalls the CPU for at least the given number of ticks.
Stalls the CPU for at least the given number of ticks. It's invoked by
MicroSecondDelay() and NanoSecondDelay().
@param Delay A period of time to delay in ticks.
**/
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 ();
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);
}
/**
Stalls the CPU for at least the given number of ticks.
Stalls the CPU for at least the given number of ticks. It's invoked by
MicroSecondDelay() and NanoSecondDelay().
@param Delay A period of time to delay in ticks.
**/
VOID
EFIAPI
InternalX86Delay (
IN UINT32 Delay
)
{
INT32 Ticks;
UINT32 Times;
UINT32 InitCount;
UINT32 StartTick;
BOOLEAN IsOverTurn;
//
// The target timer count is calculated here
//
InitCount = GetApicTimerInitCount ();
Times = Delay / InitCount;
Delay = Delay % InitCount;
do {
//
// Get Start Tick
//
IsOverTurn = FALSE;
StartTick = GetApicTimerCurrentCount ();
//
// Wait until time out
//
do {
CpuPause ();
//
// Get Ticks from Start to Current.
//
Ticks = StartTick - GetApicTimerCurrentCount ();
//
// Ticks < 0 means OverTurn happens.
//
if (Ticks < 0 || IsOverTurn) {
Ticks += InitCount;
IsOverTurn = TRUE;
}
} while ((UINT32) Ticks <= Delay);
//
// Wait next round Delay
//
Delay = InitCount;
} while (Times-- > 0);
}
/**
Check if the timer is time out.
@param[in] TimerCycle Timer initial count.
@param[in] Timer The start timer from the begin.
@param[in] TimeoutTicker Ticker number need time out.
@return TRUE Timer time out occurs.
@retval FALSE Timer does not time out.
**/
BOOLEAN
IsDebugTimerTimeout (
IN UINT32 TimerCycle,
IN UINT32 Timer,
IN UINT32 TimeoutTicker
)
{
UINT64 CurrentTimer;
UINT64 Delta;
CurrentTimer = GetApicTimerCurrentCount ();
//
// This timer counter counts down. Check for roll over condition.
// If CurrentTimer is equal to Timer, it does not mean that roll over
// happened.
//
if (CurrentTimer <= Timer) {
Delta = Timer - CurrentTimer;
} else {
//
// Handle one roll-over.
//
Delta = TimerCycle - (CurrentTimer - Timer) + 1;
}
return (BOOLEAN) (Delta >= TimeoutTicker);
}
/**
Check if the timer is time out.
@param[in] TimerCycle Timer total count.
@param[in] Timer The start timer from the begin.
@param[in] TimeoutTicker Ticker number need time out.
@return TRUE Timer time out occurs.
@retval FALSE Timer does not time out.
**/
BOOLEAN
IsDebugTimerTimeout (
IN UINT32 TimerCycle,
IN UINT32 Timer,
IN UINT32 TimeoutTicker
)
{
UINT64 CurrentTimer;
UINT64 Delta;
CurrentTimer = GetApicTimerCurrentCount ();
//
// This timer counter counts down. Check for roll over condition.
//
if (CurrentTimer < Timer) {
Delta = Timer - CurrentTimer;
} else {
//
// Handle one roll-over.
//
Delta = TimerCycle - (CurrentTimer - Timer);
}
return (BOOLEAN) (Delta >= TimeoutTicker);
}
/**
Retrieves the current value of a 64-bit free running performance counter.
The counter can either count up by 1 or count down by 1. If the physical
performance counter counts by a larger increment, then the counter values
must be translated. The properties of the counter can be retrieved from
GetPerformanceCounterProperties().
@return The current value of the free running performance counter.
**/
UINT64
EFIAPI
GetPerformanceCounter (
VOID
)
{
return (UINT64)GetApicTimerCurrentCount ();
}
