MdePkg/Include/Library/TimerLib.h

   1 /** @file
   2   Provides calibrated delay and performance counter services.
   3
   4 Copyright (c) 2006 - 2008, Intel Corporation
   5 All rights reserved. This program and the accompanying materials
   6 are licensed and made available under the terms and conditions of the BSD License
   7 which accompanies this distribution.  The full text of the license may be found at
   8 http://opensource.org/licenses/bsd-license.php
   9
  10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15 #ifndef __TIMER_LIB__
  16 #define __TIMER_LIB__
  17
  18 /**
  19   Stalls the CPU for the number of microseconds specified by MicroSeconds.
  20
  21   @param  MicroSeconds  The minimum number of microseconds to delay.
  22
  23   @return The value of MicroSeconds inputted.
  24
  25 **/
  26 UINTN
  27 EFIAPI
  28 MicroSecondDelay (
  29   IN      UINTN                     MicroSeconds
  30   );
  31
  32 /**
  33   Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
  34
  35   @param  NanoSeconds The minimum number of nanoseconds to delay.
  36
  37   @return The value of NanoSeconds inputted.
  38
  39 **/
  40 UINTN
  41 EFIAPI
  42 NanoSecondDelay (
  43   IN      UINTN                     NanoSeconds
  44   );
  45
  46 /**
  47   Retrieves the current value of a 64-bit free running performance counter.
  48   The counter can either count up by 1 or count down by 1. If the physical
  49   performance counter counts by a larger increment, then the counter values
  50   must be translated. The properties of the counter can be retrieved from
  51   GetPerformanceCounterProperties().
  52
  53   @return The current value of the free running performance counter.
  54
  55 **/
  56 UINT64
  57 EFIAPI
  58 GetPerformanceCounter (
  59   VOID
  60   );
  61
  62 /**
  63   Retrieves the 64-bit frequency in Hz and the range of performance counter
  64   values.
  65
  66   If StartValue is not NULL, then the value that the performance counter starts
  67   with immediately after is it rolls over is returned in StartValue. If
  68   EndValue is not NULL, then the value that the performance counter end with
  69   immediately before it rolls over is returned in EndValue. The 64-bit
  70   frequency of the performance counter in Hz is always returned. If StartValue
  71   is less than EndValue, then the performance counter counts up. If StartValue
  72   is greater than EndValue, then the performance counter counts down. For
  73   example, a 64-bit free running counter that counts up would have a StartValue
  74   of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
  75   that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
  76
  77   @param  StartValue  The value the performance counter starts with when it
  78                       rolls over.
  79   @param  EndValue    The value that the performance counter ends with before
  80                       it rolls over.
  81
  82   @return The frequency in Hz.
  83
  84 **/
  85 UINT64
  86 EFIAPI
  87 GetPerformanceCounterProperties (
  88   OUT      UINT64                    *StartValue,  OPTIONAL
  89   OUT      UINT64                    *EndValue     OPTIONAL
  90   );
  91
  92 #endif