updated the comment according to latest version of MWG.
[mirror_edk2.git] / MdePkg / Library / BaseTimerLibNullTemplate / TimerLibNull.c
1 /** @file
2 A non-functional instance of the Timer Library.
3
4 Copyright (c) 2007, Intel Corporation<BR>
5 All rights reserved. This program and the accompanying materials
6 are licensed and made available under the terms and conditions of the BSD License
7 which accompanies this distribution. The full text of the license may be found at
8 http://opensource.org/licenses/bsd-license.php
9
10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
12
13 Module Name: TimerLibNull.c
14
15 **/
16
17 /**
18 Stalls the CPU for at least the given number of microseconds.
19
20 Stalls the CPU for the number of microseconds specified by MicroSeconds.
21
22 @param MicroSeconds The minimum number of microseconds to delay.
23
24 @return MicroSeconds
25
26 **/
27 UINTN
28 EFIAPI
29 MicroSecondDelay (
30 IN UINTN MicroSeconds
31 )
32 {
33 ASSERT (FALSE);
34 return MicroSeconds;
35 }
36
37 /**
38 Stalls the CPU for at least the given number of nanoseconds.
39
40 Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
41
42 @param NanoSeconds The minimum number of nanoseconds to delay.
43
44 @return NanoSeconds
45
46 **/
47 UINTN
48 EFIAPI
49 NanoSecondDelay (
50 IN UINTN NanoSeconds
51 )
52 {
53 ASSERT (FALSE);
54 return 0;
55 }
56
57 /**
58 Retrieves the current value of a 64-bit free running performance counter.
59
60 Retrieves the current value of a 64-bit free running performance counter. The
61 counter can either count up by 1 or count down by 1. If the physical
62 performance counter counts by a larger increment, then the counter values
63 must be translated. The properties of the counter can be retrieved from
64 GetPerformanceCounterProperties().
65
66 @return The current value of the free running performance counter.
67
68 **/
69 UINT64
70 EFIAPI
71 GetPerformanceCounter (
72 VOID
73 )
74 {
75 ASSERT (FALSE);
76 return 0;
77 }
78
79 /**
80 Retrieves the 64-bit frequency in Hz and the range of performance counter
81 values.
82
83 If StartValue is not NULL, then the value that the performance counter starts
84 with immediately after is it rolls over is returned in StartValue. If
85 EndValue is not NULL, then the value that the performance counter end with
86 immediately before it rolls over is returned in EndValue. The 64-bit
87 frequency of the performance counter in Hz is always returned. If StartValue
88 is less than EndValue, then the performance counter counts up. If StartValue
89 is greater than EndValue, then the performance counter counts down. For
90 example, a 64-bit free running counter that counts up would have a StartValue
91 of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
92 that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
93
94 @param StartValue The value the performance counter starts with when it
95 rolls over.
96 @param EndValue The value that the performance counter ends with before
97 it rolls over.
98
99 @return The frequency in Hz.
100
101 **/
102 UINT64
103 EFIAPI
104 GetPerformanceCounterProperties (
105 OUT UINT64 *StartValue, OPTIONAL
106 OUT UINT64 *EndValue OPTIONAL
107 )
108 {
109 ASSERT (FALSE);
110 return 0;
111 }