adece55dee24776f0115c279bc15a03ce139b628
[babeltrace.git] / include / babeltrace2 / util.h
1 /*
2 * SPDX-License-Identifier: MIT
3 *
4 * Copyright (C) 2010-2019 EfficiOS Inc. and Linux Foundation
5 */
6
7 #ifndef BABELTRACE2_UTIL_H
8 #define BABELTRACE2_UTIL_H
9
10 /* IWYU pragma: private, include <babeltrace2/babeltrace.h> */
11
12 #ifndef __BT_IN_BABELTRACE_H
13 # error "Please include <babeltrace2/babeltrace.h> instead."
14 #endif
15
16 #include <stdint.h>
17
18 #ifdef __cplusplus
19 extern "C" {
20 #endif
21
22 /*!
23 @defgroup api-util General purpose utilities
24
25 @brief
26 General purpose utilities.
27
28 This module contains general purpose utilities.
29 */
30
31 /*! @{ */
32
33 /*!
34 @brief
35 Status codes for bt_util_clock_cycles_to_ns_from_origin().
36 */
37 typedef enum bt_util_clock_cycles_to_ns_from_origin_status {
38 /*!
39 @brief
40 Success.
41 */
42 BT_UTIL_CLOCK_CYCLES_TO_NS_FROM_ORIGIN_STATUS_OK = __BT_FUNC_STATUS_OK,
43
44 /*!
45 @brief
46 Integer overflow while computing the result.
47 */
48 BT_UTIL_CLOCK_CYCLES_TO_NS_FROM_ORIGIN_STATUS_OVERFLOW_ERROR = __BT_FUNC_STATUS_OVERFLOW_ERROR,
49 } bt_util_clock_cycles_to_ns_from_origin_status;
50
51 /*!
52 @brief
53 Converts the clock value \bt_p{cycles} from cycles to nanoseconds
54 from the clock's origin and sets \bt_p{*ns_from_origin} to the
55 result.
56
57 This function considers the clock's frequency in Hz (\bt_p{frequency}),
58 an offset from its origin in seconds (\bt_p{offset_seconds}) which
59 can be negative, and an additional offset in cycles
60 (\bt_p{offset_cycles}).
61
62 This function:
63
64 -# Converts the \bt_p{offset_cycles} value to seconds using
65 \bt_p{frequency}.
66 -# Converts the \bt_p{cycles} value to seconds using \bt_p{frequency}.
67 -# Adds the values of 1., 2., and \bt_p{offset_seconds}.
68 -# Converts the value of 3. to nanoseconds and sets
69 \bt_p{*ns_from_origin} to this result.
70
71 The following illustration shows the possible scenarios:
72
73 @image html clock-terminology.png
74
75 \bt_p{offset_seconds} can be negative. For example, considering:
76
77 - A 1000&nbsp;Hz clock.
78 - \bt_p{offset_seconds} set to −10&nbsp;seconds.
79 - \bt_p{offset_cycles} set to 500&nbsp;cycles
80 (that is, 0.5&nbsp;seconds).
81 - \bt_p{cycles} set to 2000&nbsp;cycles (that is, 2&nbsp;seconds).
82
83 The computed value is −7.5&nbsp;seconds, so this function sets
84 \bt_p{*ns_from_origin} to −7,500,000,000.
85
86 This function can fail and return the
87 #BT_UTIL_CLOCK_CYCLES_TO_NS_FROM_ORIGIN_STATUS_OVERFLOW_ERROR status
88 code if any step of the computation process causes an integer overflow.
89
90 @param[in] cycles
91 Clock's value (cycles).
92 @param[in] frequency
93 Clock's frequency (Hz, or cycles/second).
94 @param[in] offset_seconds
95 Offset, in seconds, from the clock's origin to add to
96 \bt_p{cycles} (once converted to seconds).
97 @param[in] offset_cycles
98 Offset, in cycles, to add to \bt_p{cycles}.
99 @param[out] ns_from_origin
100 <strong>On success</strong>, \bt_p{*ns_from_origin} is \bt_p{cycles}
101 converted to nanoseconds from origin considering the clock's
102 properties.
103
104 @retval #BT_UTIL_CLOCK_CYCLES_TO_NS_FROM_ORIGIN_STATUS_OK
105 Success.
106 @retval #BT_UTIL_CLOCK_CYCLES_TO_NS_FROM_ORIGIN_STATUS_OVERFLOW_ERROR
107 Integer overflow while computing the result.
108
109 @pre
110 \bt_p{frequency} is not 0.
111 @pre
112 \bt_p{frequency} is not <code>UINT64_C(-1)</code>.
113 @pre
114 \bt_p{frequency} is greater than \bt_p{offset_cycles}.
115 @pre
116 \bt_p{offset_cycles} is less than \bt_p{frequency}.
117 @bt_pre_not_null{ns_from_origin}
118
119 @sa bt_clock_class_cycles_to_ns_from_origin() &mdash;
120 Converts a stream clock value from cycles to nanoseconds from the
121 origin of a given clock class.
122 */
123 bt_util_clock_cycles_to_ns_from_origin_status
124 bt_util_clock_cycles_to_ns_from_origin(uint64_t cycles,
125 uint64_t frequency, int64_t offset_seconds,
126 uint64_t offset_cycles, int64_t *ns_from_origin);
127
128 /*! @} */
129
130 #ifdef __cplusplus
131 }
132 #endif
133
134 #endif /* BABELTRACE2_UTIL_H */
This page took 0.031818 seconds and 3 git commands to generate.