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1 | /** @file\r |
2 | ACPI Timer implements one instance of Timer Library.\r | |
3 | \r | |
4 | Copyright (c) 2013 - 2014, Intel Corporation. All rights reserved.<BR>\r | |
5 | This program and the accompanying materials\r | |
6 | are licensed and made available under the terms and conditions of the BSD License\r | |
7 | which accompanies this distribution. The full text of the license may be found at\r | |
8 | http://opensource.org/licenses/bsd-license.php\r | |
9 | \r | |
10 | THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r | |
11 | WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r | |
12 | \r | |
13 | **/\r | |
14 | \r | |
15 | #include <Base.h>\r | |
16 | #include <Library/TimerLib.h>\r | |
17 | #include <Library/BaseLib.h>\r | |
18 | \r | |
19 | //\r | |
20 | // Cached performance counter frequency\r | |
21 | //\r | |
22 | UINT64 mPerformanceCounterFrequency = 0;\r | |
23 | \r | |
24 | /**\r | |
25 | Internal function to retrieves the 64-bit frequency in Hz.\r | |
26 | \r | |
27 | Internal function to retrieves the 64-bit frequency in Hz.\r | |
28 | \r | |
29 | @return The frequency in Hz.\r | |
30 | \r | |
31 | **/\r | |
32 | UINT64\r | |
33 | InternalGetPerformanceCounterFrequency (\r | |
34 | VOID\r | |
35 | ) \r | |
36 | {\r | |
37 | BOOLEAN InterruptState;\r | |
38 | UINT64 Count;\r | |
39 | \r | |
40 | if (mPerformanceCounterFrequency == 0) {\r | |
41 | InterruptState = SaveAndDisableInterrupts ();\r | |
42 | Count = GetPerformanceCounter ();\r | |
43 | MicroSecondDelay (100);\r | |
44 | mPerformanceCounterFrequency = MultU64x32 (GetPerformanceCounter () - Count, 10000);\r | |
45 | SetInterruptState (InterruptState);\r | |
46 | }\r | |
47 | return mPerformanceCounterFrequency;\r | |
48 | }\r |