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csr_time.h
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1 #ifndef CSR_TIME_H__
2 #define CSR_TIME_H__
3 /*****************************************************************************
4 
5  (c) Cambridge Silicon Radio Limited 2010
6  All rights reserved and confidential information of CSR
7 
8  Refer to LICENSE.txt included with this source for details
9  on the license terms.
10 
11 *****************************************************************************/
12 
13 #include <linux/types.h>
14 
15 #ifdef __cplusplus
16 extern "C" {
17 #endif
18 
19 /*******************************************************************************
20 
21  NAME
22  CsrTime
23 
24  DESCRIPTION
25  Type to hold a value describing the current system time, which is a
26  measure of time elapsed since some arbitrarily defined fixed time
27  reference, usually associated with system startup.
28 
29 *******************************************************************************/
30 typedef u32 CsrTime;
31 
32 
33 /*******************************************************************************
34 
35  NAME
36  CsrTimeUtc
37 
38  DESCRIPTION
39  Type to hold a value describing a UTC wallclock time expressed in
40  seconds and milliseconds elapsed since midnight January 1st 1970.
41 
42 *******************************************************************************/
43 typedef struct
44 {
45  u32 sec;
46  u16 msec;
47 } CsrTimeUtc;
48 
49 
50 /*******************************************************************************
51 
52  NAME
53  CsrTimeGet
54 
55  DESCRIPTION
56  Returns the current system time in a low and a high part. The low part
57  is expressed in microseconds. The high part is incremented when the low
58  part wraps to provide an extended range.
59 
60  The caller may provide a NULL pointer as the high parameter. In this case
61  the function just returns the low part and ignores the high parameter.
62 
63  Although the time is expressed in microseconds the actual resolution is
64  platform dependent and can be less. It is recommended that the
65  resolution is at least 10 milliseconds.
66 
67  PARAMETERS
68  high - Pointer to variable that will receive the high part of the
69  current system time. Passing NULL is valid.
70 
71  RETURNS
72  Low part of current system time in microseconds.
73 
74 *******************************************************************************/
75 CsrTime CsrTimeGet(CsrTime *high);
76 
77 
78 /*------------------------------------------------------------------*/
79 /* CsrTime Macros */
80 /*------------------------------------------------------------------*/
81 
82 /*----------------------------------------------------------------------------*
83  * NAME
84  * CsrTimeAdd
85  *
86  * DESCRIPTION
87  * Add two time values. Adding the numbers can overflow the range of a
88  * CsrTime, so the user must be cautious.
89  *
90  * RETURNS
91  * CsrTime - the sum of "t1" and "t2".
92  *
93  *----------------------------------------------------------------------------*/
94 #define CsrTimeAdd(t1, t2) ((t1) + (t2))
95 
96 /*----------------------------------------------------------------------------*
97  * NAME
98  * CsrTimeSub
99  *
100  * DESCRIPTION
101  * Subtract two time values. Subtracting the numbers can provoke an
102  * underflow, so the user must be cautious.
103  *
104  * RETURNS
105  * CsrTime - "t1" - "t2".
106  *
107  *----------------------------------------------------------------------------*/
108 #define CsrTimeSub(t1, t2) ((s32) (t1) - (s32) (t2))
109 
110 #ifdef __cplusplus
111 }
112 #endif
113 
114 #endif
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