python: define _BaseObject._ptr property
[babeltrace.git] / include / babeltrace2 / util.h
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0f2d58c9 1/*
0235b0db 2 * SPDX-License-Identifier: MIT
0f2d58c9 3 *
0235b0db 4 * Copyright (C) 2010-2019 EfficiOS Inc. and Linux Foundation
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5 */
6
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7#ifndef BABELTRACE2_UTIL_H
8#define BABELTRACE2_UTIL_H
9
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10/* IWYU pragma: private, include <babeltrace2/babeltrace.h> */
11
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12#ifndef __BT_IN_BABELTRACE_H
13# error "Please include <babeltrace2/babeltrace.h> instead."
14#endif
15
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16#include <stdint.h>
17
18#ifdef __cplusplus
19extern "C" {
20#endif
21
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22/*!
23@defgroup api-util General purpose utilities
24
25@brief
26 General purpose utilities.
27
0e0c04cf 28This API offers general purpose utilities.
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29*/
30
31/*! @{ */
32
33/*!
34@brief
35 Status codes for bt_util_clock_cycles_to_ns_from_origin().
36*/
c4c4586d 37typedef enum bt_util_clock_cycles_to_ns_from_origin_status {
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38 /*!
39 @brief
40 Success.
41 */
c4c4586d 42 BT_UTIL_CLOCK_CYCLES_TO_NS_FROM_ORIGIN_STATUS_OK = __BT_FUNC_STATUS_OK,
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43
44 /*!
45 @brief
46 Integer overflow while computing the result.
47 */
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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;
0f2d58c9 50
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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
57This function considers the clock's frequency in Hz (\bt_p{frequency}),
58an offset from its origin in seconds (\bt_p{offset_seconds}) which
59can be negative, and an additional offset in cycles
60(\bt_p{offset_cycles}).
61
62This 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
71The 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.
1eca514c 78- \bt_p{offset_seconds} set to −10&nbsp;seconds.
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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
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83The computed value is −7.5&nbsp;seconds, so this function sets
84\bt_p{*ns_from_origin} to −7,500,000,000.
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85
86This function can fail and return the
87#BT_UTIL_CLOCK_CYCLES_TO_NS_FROM_ORIGIN_STATUS_OVERFLOW_ERROR status
88code 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*/
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123bt_util_clock_cycles_to_ns_from_origin_status
124bt_util_clock_cycles_to_ns_from_origin(uint64_t cycles,
0f2d58c9 125 uint64_t frequency, int64_t offset_seconds,
4c81a2b7 126 uint64_t offset_cycles, int64_t *ns_from_origin) __BT_NOEXCEPT;
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127
128/*! @} */
0f2d58c9 129
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130#ifdef __cplusplus
131}
132#endif
133
924dc299 134#endif /* BABELTRACE2_UTIL_H */
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