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23c98c94 | 1 | /** @file\r |
504214c4 | 2 | UEFI Miscellaneous boot Services Stall service implementation\r |
28a00297 | 3 | \r |
cd5ebaa0 HT |
4 | Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>\r |
5 | This program and the accompanying materials\r | |
28a00297 | 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 | |
504214c4 | 13 | **/\r |
28a00297 | 14 | \r |
15 | //\r | |
16 | // Include statements\r | |
17 | //\r | |
18 | \r | |
9c4ac31c | 19 | #include "DxeMain.h"\r |
28a00297 | 20 | \r |
21 | \r | |
28a00297 | 22 | \r |
162ed594 | 23 | /**\r |
28a00297 | 24 | Introduces a fine-grained stall.\r |
25 | \r | |
162ed594 | 26 | @param Microseconds The number of microseconds to stall execution.\r |
28a00297 | 27 | \r |
022c6d45 | 28 | @retval EFI_SUCCESS Execution was stalled for at least the requested\r |
29 | amount of microseconds.\r | |
162ed594 | 30 | @retval EFI_NOT_AVAILABLE_YET gMetronome is not available yet\r |
28a00297 | 31 | \r |
162ed594 | 32 | **/\r |
33 | EFI_STATUS\r | |
34 | EFIAPI\r | |
35 | CoreStall (\r | |
36 | IN UINTN Microseconds\r | |
37 | )\r | |
28a00297 | 38 | {\r |
39 | UINT32 Counter;\r | |
40 | UINT32 Remainder;\r | |
41 | \r | |
42 | if (gMetronome == NULL) {\r | |
43 | return EFI_NOT_AVAILABLE_YET;\r | |
44 | }\r | |
45 | \r | |
46 | //\r | |
47 | // Calculate the number of ticks by dividing the number of microseconds by\r | |
48 | // the TickPeriod.\r | |
d7db0902 | 49 | // Calculation is based on 100ns unit.\r |
28a00297 | 50 | //\r |
51 | Counter = (UINT32) DivU64x32Remainder (\r | |
52 | Microseconds * 10,\r | |
53 | gMetronome->TickPeriod,\r | |
54 | &Remainder\r | |
55 | );\r | |
56 | \r | |
57 | //\r | |
58 | // Call WaitForTick for Counter + 1 ticks to try to guarantee Counter tick\r | |
59 | // periods, thus attempting to ensure Microseconds of stall time.\r | |
60 | //\r | |
61 | if (Remainder != 0) {\r | |
62 | Counter++;\r | |
63 | }\r | |
64 | \r | |
65 | gMetronome->WaitForTick (gMetronome, Counter);\r | |
66 | \r | |
67 | return EFI_SUCCESS;\r | |
68 | }\r |