1 /** @file 2 ACPI Timer implements one instance of Timer Library. 3 4 Copyright (c) 2013 - 2014, Intel Corporation. All rights reserved.<BR> 5 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 #include <Base.h> 16 #include <Library/TimerLib.h> 17 #include <Library/BaseLib.h> 18 19 /** 20 Internal function to retrieves the 64-bit frequency in Hz. 21 22 Internal function to retrieves the 64-bit frequency in Hz. 23 24 @return The frequency in Hz. 25 26 **/ 27 UINT64 28 InternalGetPerformanceCounterFrequency ( 29 VOID 30 ) 31 { 32 BOOLEAN InterruptState; 33 UINT64 Count; 34 UINT64 Frequency; 35 36 InterruptState = SaveAndDisableInterrupts (); 37 Count = GetPerformanceCounter (); 38 MicroSecondDelay (100); 39 Frequency = MultU64x32 (GetPerformanceCounter () - Count, 10000); 40 SetInterruptState (InterruptState); 41 return Frequency; 42 } 43
