MdePkg/Include/Library/TimerLib.h

   1 /** @file
   2   Timer Library Functions
   3
   4   Copyright (c) 2006, 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   Module Name:  TimerLib.h
  14
  15 **/
  16
  17 #ifndef __TIMER_LIB__
  18 #define __TIMER_LIB__
  19
  20 /**
  21   Stalls the CPU for at least the given number of microseconds.
  22
  23   Stalls the CPU for the number of microseconds specified by MicroSeconds.
  24
  25   @param  MicroSeconds  The minimum number of microseconds to delay.
  26
  27   @return MicroSeconds
  28
  29 **/
  30 UINTN
  31 EFIAPI
  32 MicroSecondDelay (
  33   IN      UINTN                     MicroSeconds
  34   );
  35
  36 /**
  37   Stalls the CPU for at least the given number of nanoseconds.
  38
  39   Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
  40
  41   @param  NanoSeconds The minimum number of nanoseconds to delay.
  42
  43   @return NanoSeconds
  44
  45 **/
  46 UINTN
  47 EFIAPI
  48 NanoSecondDelay (
  49   IN      UINTN                     NanoSeconds
  50   );
  51
  52 /**
  53   Retrieves the current value of a 64-bit free running performance counter.
  54
  55   Retrieves the current value of a 64-bit free running performance counter. The
  56   counter can either count up by 1 or count down by 1. If the physical
  57   performance counter counts by a larger increment, then the counter values
  58   must be translated. The properties of the counter can be retrieved from
  59   GetPerformanceCounterProperties().
  60
  61   @return The current value of the free running performance counter.
  62
  63 **/
  64 UINT64
  65 EFIAPI
  66 GetPerformanceCounter (
  67   VOID
  68   );
  69
  70 /**
  71   Retrieves the 64-bit frequency in Hz and the range of performance counter
  72   values.
  73
  74   If StartValue is not NULL, then the value that the performance counter starts
  75   with immediately after is it rolls over is returned in StartValue. If
  76   EndValue is not NULL, then the value that the performance counter end with
  77   immediately before it rolls over is returned in EndValue. The 64-bit
  78   frequency of the performance counter in Hz is always returned. If StartValue
  79   is less than EndValue, then the performance counter counts up. If StartValue
  80   is greater than EndValue, then the performance counter counts down. For
  81   example, a 64-bit free running counter that counts up would have a StartValue
  82   of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
  83   that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
  84
  85   @param  StartValue  The value the performance counter starts with when it
  86                       rolls over.
  87   @param  EndValue    The value that the performance counter ends with before
  88                       it rolls over.
  89
  90   @return The frequency in Hz.
  91
  92 **/
  93 UINT64
  94 EFIAPI
  95 GetPerformanceCounterProperties (
  96   OUT      UINT64                    *StartValue,  OPTIONAL
  97   OUT      UINT64                    *EndValue     OPTIONAL
  98   );
  99
 100 #endif