MdePkg/Include/Library/TimerLib.h

   1 /** @file
   2   Provides calibrated delay and performance counter services.
   3
   4 Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
   5 SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #ifndef __TIMER_LIB__
  10 #define __TIMER_LIB__
  11
  12 /**
  13   Stalls the CPU for at least the given number of microseconds.
  14
  15   Stalls the CPU for the number of microseconds specified by MicroSeconds.
  16
  17   @param  MicroSeconds  The minimum number of microseconds to delay.
  18
  19   @return The value of MicroSeconds inputted.
  20
  21 **/
  22 UINTN
  23 EFIAPI
  24 MicroSecondDelay (
  25   IN      UINTN                     MicroSeconds
  26   );
  27
  28 /**
  29   Stalls the CPU for at least the given number of nanoseconds.
  30
  31   Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
  32
  33   @param  NanoSeconds The minimum number of nanoseconds to delay.
  34
  35   @return The value of NanoSeconds inputted.
  36
  37 **/
  38 UINTN
  39 EFIAPI
  40 NanoSecondDelay (
  41   IN      UINTN                     NanoSeconds
  42   );
  43
  44 /**
  45   Retrieves the current value of a 64-bit free running performance counter.
  46
  47   The counter can either count up by 1 or count down by 1. If the physical
  48   performance counter counts by a larger increment, then the counter values
  49   must be translated. The properties of the counter can be retrieved from
  50   GetPerformanceCounterProperties().
  51
  52   @return The current value of the free running performance counter.
  53
  54 **/
  55 UINT64
  56 EFIAPI
  57 GetPerformanceCounter (
  58   VOID
  59   );
  60
  61 /**
  62   Retrieves the 64-bit frequency in Hz and the range of performance counter
  63   values.
  64
  65   If StartValue is not NULL, then the value that the performance counter starts
  66   with immediately after is it rolls over is returned in StartValue. If
  67   EndValue is not NULL, then the value that the performance counter end with
  68   immediately before it rolls over is returned in EndValue. The 64-bit
  69   frequency of the performance counter in Hz is always returned. If StartValue
  70   is less than EndValue, then the performance counter counts up. If StartValue
  71   is greater than EndValue, then the performance counter counts down. For
  72   example, a 64-bit free running counter that counts up would have a StartValue
  73   of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
  74   that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
  75
  76   @param  StartValue  The value the performance counter starts with when it
  77                       rolls over.
  78   @param  EndValue    The value that the performance counter ends with before
  79                       it rolls over.
  80
  81   @return The frequency in Hz.
  82
  83 **/
  84 UINT64
  85 EFIAPI
  86 GetPerformanceCounterProperties (
  87   OUT      UINT64                    *StartValue,  OPTIONAL
  88   OUT      UINT64                    *EndValue     OPTIONAL
  89   );
  90
  91 /**
  92   Converts elapsed ticks of performance counter to time in nanoseconds.
  93
  94   This function converts the elapsed ticks of running performance counter to
  95   time value in unit of nanoseconds.
  96
  97   @param  Ticks     The number of elapsed ticks of running performance counter.
  98
  99   @return The elapsed time in nanoseconds.
 100
 101 **/
 102 UINT64
 103 EFIAPI
 104 GetTimeInNanoSecond (
 105   IN      UINT64                     Ticks
 106   );
 107
 108 #endif