projects / mirror_edk2.git / blame
| Commit | Line | Data |
|---|---|---|
| 83d1ffb9 LG |
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 |