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23c98c94 | 1 | /** @file\r |
504214c4 | 2 | UEFI Miscellaneous boot Services Stall service implementation\r |
28a00297 | 3 | \r |
d1102dba | 4 | Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>\r |
9d510e61 | 5 | SPDX-License-Identifier: BSD-2-Clause-Patent\r |
28a00297 | 6 | \r |
504214c4 | 7 | **/\r |
28a00297 | 8 | \r |
9 | //\r | |
10 | // Include statements\r | |
11 | //\r | |
12 | \r | |
9c4ac31c | 13 | #include "DxeMain.h"\r |
28a00297 | 14 | \r |
a62da87e | 15 | /**\r |
d1102dba LG |
16 | Internal worker function to call the Metronome Architectural Protocol for\r |
17 | the number of ticks specified by the UINT64 Counter value. WaitForTick()\r | |
a62da87e | 18 | service of the Metronome Architectural Protocol uses a UINT32 for the number\r |
19 | of ticks to wait, so this function loops when Counter is larger than 0xffffffff.\r | |
28a00297 | 20 | \r |
a62da87e | 21 | @param Counter Number of ticks to wait.\r |
22 | \r | |
23 | **/\r | |
24 | VOID\r | |
25 | CoreInternalWaitForTick (\r | |
26 | IN UINT64 Counter\r | |
27 | )\r | |
28 | {\r | |
769e4531 | 29 | while (RShiftU64 (Counter, 32) > 0) {\r |
a62da87e | 30 | gMetronome->WaitForTick (gMetronome, 0xffffffff);\r |
31 | Counter -= 0xffffffff;\r | |
32 | }\r | |
1436aea4 | 33 | \r |
a62da87e | 34 | gMetronome->WaitForTick (gMetronome, (UINT32)Counter);\r |
35 | }\r | |
28a00297 | 36 | \r |
162ed594 | 37 | /**\r |
28a00297 | 38 | Introduces a fine-grained stall.\r |
39 | \r | |
162ed594 | 40 | @param Microseconds The number of microseconds to stall execution.\r |
28a00297 | 41 | \r |
022c6d45 | 42 | @retval EFI_SUCCESS Execution was stalled for at least the requested\r |
43 | amount of microseconds.\r | |
162ed594 | 44 | @retval EFI_NOT_AVAILABLE_YET gMetronome is not available yet\r |
28a00297 | 45 | \r |
162ed594 | 46 | **/\r |
47 | EFI_STATUS\r | |
48 | EFIAPI\r | |
49 | CoreStall (\r | |
1436aea4 | 50 | IN UINTN Microseconds\r |
162ed594 | 51 | )\r |
28a00297 | 52 | {\r |
a62da87e | 53 | UINT64 Counter;\r |
28a00297 | 54 | UINT32 Remainder;\r |
a62da87e | 55 | UINTN Index;\r |
28a00297 | 56 | \r |
57 | if (gMetronome == NULL) {\r | |
58 | return EFI_NOT_AVAILABLE_YET;\r | |
59 | }\r | |
60 | \r | |
61 | //\r | |
a62da87e | 62 | // Counter = Microseconds * 10 / gMetronome->TickPeriod\r |
63 | // 0x1999999999999999 = (2^64 - 1) / 10\r | |
28a00297 | 64 | //\r |
1436aea4 | 65 | if ((UINT64)Microseconds > 0x1999999999999999ULL) {\r |
a62da87e | 66 | //\r |
d1102dba | 67 | // Microseconds is too large to multiple by 10 first. Perform the divide\r |
a62da87e | 68 | // operation first and loop 10 times to avoid 64-bit math overflow.\r |
69 | //\r | |
70 | Counter = DivU64x32Remainder (\r | |
71 | Microseconds,\r | |
72 | gMetronome->TickPeriod,\r | |
73 | &Remainder\r | |
74 | );\r | |
75 | for (Index = 0; Index < 10; Index++) {\r | |
76 | CoreInternalWaitForTick (Counter);\r | |
d1102dba | 77 | }\r |
a62da87e | 78 | \r |
79 | if (Remainder != 0) {\r | |
80 | //\r | |
d1102dba | 81 | // If Remainder was not zero, then normally, Counter would be rounded\r |
a62da87e | 82 | // up by 1 tick. In this case, since a loop for 10 counts was used\r |
83 | // to emulate the multiply by 10 operation, Counter needs to be rounded\r | |
84 | // up by 10 counts.\r | |
85 | //\r | |
86 | CoreInternalWaitForTick (10);\r | |
87 | }\r | |
88 | } else {\r | |
89 | //\r | |
90 | // Calculate the number of ticks by dividing the number of microseconds by\r | |
91 | // the TickPeriod. Calculation is based on 100ns unit.\r | |
92 | //\r | |
93 | Counter = DivU64x32Remainder (\r | |
94 | MultU64x32 (Microseconds, 10),\r | |
95 | gMetronome->TickPeriod,\r | |
96 | &Remainder\r | |
97 | );\r | |
98 | if (Remainder != 0) {\r | |
99 | //\r | |
100 | // If Remainder is not zero, then round Counter up by one tick.\r | |
101 | //\r | |
102 | Counter++;\r | |
103 | }\r | |
1436aea4 | 104 | \r |
a62da87e | 105 | CoreInternalWaitForTick (Counter);\r |
28a00297 | 106 | }\r |
107 | \r | |
28a00297 | 108 | return EFI_SUCCESS;\r |
109 | }\r |