source: rtems-central/spec/rtems/event/if/receive.yml @ bb2a124

Last change on this file since bb2a124 was bb2a124, checked in by Sebastian Huber <sebastian.huber@…>, on Nov 9, 2020 at 12:16:40 PM

spec: Review Event Manager API

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File size: 4.7 KB
Line 
1SPDX-License-Identifier: CC-BY-SA-4.0 OR BSD-2-Clause
2brief: |
3  Receives or gets an event set from the calling task.
4copyrights:
5- Copyright (C) 2020 embedded brains GmbH (http://www.embedded-brains.de)
6- Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR)
7definition:
8  default:
9    attributes: null
10    body: null
11    params:
12    - ${set:/name} ${.:/params[0]/name}
13    - ${../../option/if/option:/name} ${.:/params[1]/name}
14    - ${../../type/if/interval:/name} ${.:/params[2]/name}
15    - ${set:/name} *${.:/params[3]/name}
16    return: ${../../status/if/code:/name}
17  variants: []
18description: |
19  This directive can be used to
20
21  * get the pending events of the calling task, or
22
23  * receive events.
24
25  To **get the pending events** use the constant ${pending-events:/name} for
26  the ``${.:/params[0]/name}`` parameter.  The pending events are returned to
27  the calling task but the event set of the task is left unaltered.  The
28  ``${.:/params[1]/name}`` and ``${.:params[2]/name}`` parameters are ignored
29  in this case.  The directive returns immediately and does not block.
30
31  To **receive events** you have to define an input event condition and some
32  options.  The **option set** specified in ``${.:/params[1]/name}`` defines
33
34  * if the task will wait or poll for the events, and
35
36  * if the task wants to receive all or any of the input events.
37
38  The option set is built through a *bitwise or* of the option constants
39  described below.
40
41  The task can **wait** or **poll** for the events.
42
43  * **Waiting** for events is the default and can be emphasized through the use
44    of the ${../../option/if/wait:/name} option.  The ``${.:/params[2]/name}``
45    parameter defines how long the task is willing to wait.  Use
46    ${../../type/if/no-timeout:/name} to wait potentially forever, otherwise
47    set a timeout interval in clock ticks.
48
49  * Not waiting for events (**polling**) is selected by the
50    ${../../option/if/no-wait:/name} option.  If this option is defined, then
51    the ``${.:/params[2]/name}`` parameter is ignored.
52
53  The task can receive **all** or **any** of the input events specified in
54  ``${.:/params[0]/name}``.
55
56  * Receiving **all** input events is the default and can be emphasized through
57    the use of the ${../../option/if/event-all:/name} option.
58
59  * Receiving **any** of the input events is selected by the
60    ${../../option/if/event-any:/name} option.
61enabled-by: true
62index-entries: []
63interface-type: function
64links:
65- role: interface-placement
66  uid: header
67- role: interface-ingroup
68  uid: group
69name: rtems_event_receive
70notes: |
71  This directive shall be called by a task.  Calling this directive from
72  interrupt context is undefined behaviour.
73
74  This directive only affects the events specified in ``${.:/params[0]/name}``.
75  Any pending events that do not correspond to any of the events specified in
76  ``${.:/params[0]/name}`` will be left pending.
77
78  To receive all events use the event set constant ${all-events:/name} for the
79  ``${.:/params[0]/name}`` parameter.  Do not confuse this event set constant
80  with the directive option ${../../option/if/event-all:/name}.
81
82  A task can **receive all of the pending events** by calling the directive
83  with a value of ${all-events:/name} for the ``${.:/params[0]/name}``
84  parameter and the bitwise or of the ${../../option/if/no-wait:/name} and
85  ${../../option/if/event-any:/name} options for the ``${.:/params[1]/name}``
86  parameter.  The pending events are returned and the event set of the task is
87  cleared.  If no events are pending then the
88  ${../../status/if/unsatisfied:/name} status code will be returned.
89params:
90- description: |
91    is the event set of interest.  Use ${pending-events:/name} to get the
92    pending events.
93  dir: null
94  name: event_in
95- description: is the option set.
96  dir: null
97  name: option_set
98- description: |
99    is the timeout in clock ticks if the ${../../option/if/wait:/name} option
100    is set.  Use ${../../type/if/no-timeout:/name} to wait potentially
101    forever.
102  dir: null
103  name: ticks
104- description: |
105    is the pointer to an event set.  The received or pending events are stored
106    in the referenced event set if the operation was successful.
107  dir: null
108  name: event_out
109return:
110  return: null
111  return-values:
112  - description: |
113      The requested operation was successful.
114    value: ${../../status/if/successful:/name}
115  - description: |
116      The ``${.:/params[3]/name}`` parameter was ${/c/if/null:/name}.
117    value: ${../../status/if/invalid-address:/name}
118  - description: |
119      The events of interest were not immediately available.
120    value: ${../../status/if/unsatisfied:/name}
121  - description: |
122      The events of interest were not available within the specified timeout
123      interval.
124    value: ${../../status/if/timeout:/name}
125type: interface
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