X86TimerLib.c revision 4fd606d1f5abe38e1f42c38de1d2e895166bd0f4
/** @file
Copyright (c) 2006 - 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
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 <Base.h>
#include <Library/TimerLib.h>
#include <Library/DebugLib.h>
#define APIC_LVTERR 0x370
#define APIC_TMICT 0x380
#define APIC_TMCCT 0x390
#define APIC_TDCR 0x3e0
//
// The following array is used in calculating the frequency of local APIC
// timer. Refer to IA-32 developers' manual for more details.
//
0x02, 0x04, 0x08, 0x10,
0x02, 0x04, 0x08, 0x10,
0x20, 0x40, 0x80, 0x01,
0x20, 0x40, 0x80, 0x01
};
/**
Internal function to retrieve the base address of local APIC.
@return The base address of local APIC
**/
)
{
}
/**
Internal function to return the frequency of the local APIC timer.
@param ApicBase The base address of memory mapped registers of local APIC.
@return The frequency of the timer in Hz.
**/
)
{
return
}
/**
Internal function to read the current tick counter of local APIC.
@param ApicBase The base address of memory mapped registers of local APIC.
@return The tick counter read.
**/
)
{
}
/**
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 ApicBase The base address of memory mapped registers of local APIC.
@param Delay A period of time to delay in ticks.
**/
)
{
//
// The target timer count is calculated here
//
//
// Wait until time out
// Delay > 2^31 could not be handled by this function
// Timer wrap-arounds are handled correctly by this function
//
CpuPause ();
}
}
/**
Stalls the CPU for at least the given number of microseconds.
Stalls the CPU for the number of microseconds specified by MicroSeconds.
@param MicroSeconds The minimum number of microseconds to delay.
@return The value of MicroSeconds inputted.
**/
)
{
),
1000000u
)
);
return MicroSeconds;
}
/**
Stalls the CPU for at least the given number of nanoseconds.
Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
@param NanoSeconds The minimum number of nanoseconds to delay.
@return The value of NanoSeconds inputted.
**/
)
{
),
1000000000u
)
);
return NanoSeconds;
}
/**
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.
**/
)
{
}
/**
Retrieves the 64-bit frequency in Hz and the range of performance counter
values.
If StartValue is not NULL, then the value that the performance counter starts
with immediately after is it rolls over is returned in StartValue. If
EndValue is not NULL, then the value that the performance counter end with
immediately before it rolls over is returned in EndValue. The 64-bit
frequency of the performance counter in Hz is always returned. If StartValue
is less than EndValue, then the performance counter counts up. If StartValue
is greater than EndValue, then the performance counter counts down. For
example, a 64-bit free running counter that counts up would have a StartValue
of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
@param StartValue The value the performance counter starts with when it
rolls over.
@param EndValue The value that the performance counter ends with before
it rolls over.
@return The frequency in Hz.
**/
)
{
if (StartValue != NULL) {
//
// make sure StartValue is all 1s from High Bit
//
}
*EndValue = 0;
}
}
/**
Converts elapsed ticks of performance counter to time in nanoseconds.
This function converts the elapsed ticks of running performance counter to
time value in unit of nanoseconds.
@param Ticks The number of elapsed ticks of running performance counter.
@return The elapsed time in nanoseconds.
**/
)
{
//
// Ticks
// Time = --------- x 1,000,000,000
// Frequency
//
//
// 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.
//
return NanoSeconds;
}