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1 | /** @file \r | |
2 | \r | |
3 | UEFI Miscellaneous boot Services Stall service implementation\r | |
4 | \r | |
5 | Copyright (c) 2006 - 2008, Intel Corporation\r | |
6 | All rights reserved. This program and the accompanying materials\r | |
7 | are licensed and made available under the terms and conditions of the BSD License\r | |
8 | which accompanies this distribution. The full text of the license may be found at\r | |
9 | http://opensource.org/licenses/bsd-license.php\r | |
10 | \r | |
11 | THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r | |
12 | WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r | |
13 | \r | |
14 | **/\r | |
15 | \r | |
16 | //\r | |
17 | // Include statements\r | |
18 | //\r | |
19 | \r | |
20 | #include <DxeMain.h>\r | |
21 | \r | |
22 | \r | |
23 | \r | |
24 | /**\r | |
25 | Introduces a fine-grained stall.\r | |
26 | \r | |
27 | @param Microseconds The number of microseconds to stall execution.\r | |
28 | \r | |
29 | @retval EFI_SUCCESS Execution was stalled for at least the requested \r | |
30 | amount of microseconds. \r | |
31 | @retval EFI_NOT_AVAILABLE_YET gMetronome is not available yet\r | |
32 | \r | |
33 | **/\r | |
34 | EFI_STATUS\r | |
35 | EFIAPI\r | |
36 | CoreStall (\r | |
37 | IN UINTN Microseconds\r | |
38 | )\r | |
39 | {\r | |
40 | UINT32 Counter;\r | |
41 | UINT32 Remainder;\r | |
42 | \r | |
43 | if (gMetronome == NULL) {\r | |
44 | return EFI_NOT_AVAILABLE_YET;\r | |
45 | }\r | |
46 | \r | |
47 | //\r | |
48 | // Calculate the number of ticks by dividing the number of microseconds by\r | |
49 | // the TickPeriod.\r | |
50 | // Calcullation is based on 100ns unit.\r | |
51 | //\r | |
52 | Counter = (UINT32) DivU64x32Remainder (\r | |
53 | Microseconds * 10,\r | |
54 | gMetronome->TickPeriod,\r | |
55 | &Remainder\r | |
56 | );\r | |
57 | \r | |
58 | //\r | |
59 | // Call WaitForTick for Counter + 1 ticks to try to guarantee Counter tick\r | |
60 | // periods, thus attempting to ensure Microseconds of stall time.\r | |
61 | //\r | |
62 | if (Remainder != 0) {\r | |
63 | Counter++;\r | |
64 | }\r | |
65 | \r | |
66 | gMetronome->WaitForTick (gMetronome, Counter);\r | |
67 | \r | |
68 | return EFI_SUCCESS;\r | |
69 | }\r |