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| |
| <section id="events"> |
| <h1>Events<a class="headerlink" href="#events" title="Permalink to this heading"></a></h1> |
| <p>Events groups are synchronization primitives that allow tasks to wait |
| for multiple conditions to be met before proceeding. They are particularly |
| useful in scenarios where a task needs to wait for several events to occur |
| simultaneously. |
| This concept can be particularly powerful in real-time operating systems (RTOS).</p> |
| <section id="overview"> |
| <h2>Overview<a class="headerlink" href="#overview" title="Permalink to this heading"></a></h2> |
| <p>An event group consists of a set of binary flags, each representing a |
| specific event. Tasks can set, clear, and wait on these flags. When a |
| task waits on an event group, it can specify which flags it is interested |
| in and whether it wants to wait for all specified flags to be set or just |
| any one of them.</p> |
| </section> |
| <section id="configuration-options"> |
| <h2>Configuration Options<a class="headerlink" href="#configuration-options" title="Permalink to this heading"></a></h2> |
| <dl class="simple"> |
| <dt><code class="docutils literal notranslate"><span class="pre">CONFIG_SCHED_EVENTS</span></code></dt><dd><p>This option enables event objects. Threads may wait on event |
| objects for specific events, but both threads and ISRs may deliver |
| events to event objects.</p> |
| </dd> |
| </dl> |
| </section> |
| <section id="common-events-interfaces"> |
| <h2>Common Events Interfaces<a class="headerlink" href="#common-events-interfaces" title="Permalink to this heading"></a></h2> |
| <section id="events-types"> |
| <h3>Events Types<a class="headerlink" href="#events-types" title="Permalink to this heading"></a></h3> |
| <ul class="simple"> |
| <li><p><code class="docutils literal notranslate"><span class="pre">nxevent_t</span></code>. Defines one event group entry.</p></li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">nxevent_mask_t</span></code>. Defines one events mask value.</p></li> |
| </ul> |
| </section> |
| <section id="notifier-chain-interfaces"> |
| <h3>Notifier Chain Interfaces<a class="headerlink" href="#notifier-chain-interfaces" title="Permalink to this heading"></a></h3> |
| <dl class="c function"> |
| <dt class="sig sig-object c" id="c.nxevent_init"> |
| <span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">nxevent_init</span></span></span><span class="sig-paren">(</span><span class="pre">FAR</span><span class="w"> </span><span class="n"><span class="pre">nxevent_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">event</span></span>, <span class="n"><span class="pre">nxevent_mask_t</span></span><span class="w"> </span><span class="n"><span class="pre">events</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.nxevent_init" title="Permalink to this definition"></a><br /></dt> |
| <dd><p>Initializes an event object, Set of default events to post |
| to event.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters<span class="colon">:</span></dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>event</strong> – Address of the event object</p></li> |
| <li><p><strong>events</strong> – Set of events to post to event</p></li> |
| </ul> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt class="sig sig-object c" id="c.nxevent_destroy"> |
| <span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">nxevent_destroy</span></span></span><span class="sig-paren">(</span><span class="pre">FAR</span><span class="w"> </span><span class="n"><span class="pre">nxevent_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">event</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.nxevent_destroy" title="Permalink to this definition"></a><br /></dt> |
| <dd><p>This function is used to destroy the event.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters<span class="colon">:</span></dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>event</strong> – Address of the event object</p></li> |
| </ul> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt class="sig sig-object c" id="c.nxevent_reset"> |
| <span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">nxevent_reset</span></span></span><span class="sig-paren">(</span><span class="pre">FAR</span><span class="w"> </span><span class="n"><span class="pre">nxevent_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">event</span></span>, <span class="n"><span class="pre">nxevent_mask_t</span></span><span class="w"> </span><span class="n"><span class="pre">events</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.nxevent_reset" title="Permalink to this definition"></a><br /></dt> |
| <dd><p>Reset events mask to a specific value.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters<span class="colon">:</span></dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>event</strong> – Address of the event object</p></li> |
| <li><p><strong>events</strong> – Set of events to post to event</p></li> |
| </ul> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt class="sig sig-object c" id="c.nxevent_post"> |
| <span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">nxevent_post</span></span></span><span class="sig-paren">(</span><span class="pre">FAR</span><span class="w"> </span><span class="n"><span class="pre">nxevent_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">event</span></span>, <span class="n"><span class="pre">nxevent_mask_t</span></span><span class="w"> </span><span class="n"><span class="pre">events</span></span>, <span class="n"><span class="pre">nxevent_flags_t</span></span><span class="w"> </span><span class="n"><span class="pre">eflags</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.nxevent_post" title="Permalink to this definition"></a><br /></dt> |
| <dd><p>Post one or more events to an event object.</p> |
| <p>This routine posts one or more events to an event object. All tasks |
| waiting on the event object event whose waiting conditions become |
| met by this posting immediately unpend.</p> |
| <p>Posting differs from setting in that posted events are merged together |
| with the current set of events tracked by the event object.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters<span class="colon">:</span></dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>event</strong> – Address of the event object</p></li> |
| <li><p><strong>events</strong> – Set of events to post to event |
| Set events to 0 will be considered as any, |
| waking up the waiting thread immediately.</p></li> |
| <li><p><strong>eflags</strong> – Events flags</p></li> |
| </ul> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt class="sig sig-object c" id="c.nxevent_wait"> |
| <span class="n"><span class="pre">nxevent_mask_t</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">nxevent_wait</span></span></span><span class="sig-paren">(</span><span class="pre">FAR</span><span class="w"> </span><span class="n"><span class="pre">nxevent_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">event</span></span>, <span class="n"><span class="pre">nxevent_mask_t</span></span><span class="w"> </span><span class="n"><span class="pre">events</span></span>, <span class="n"><span class="pre">nxevent_flags_t</span></span><span class="w"> </span><span class="n"><span class="pre">eflags</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.nxevent_wait" title="Permalink to this definition"></a><br /></dt> |
| <dd><p>Wait for all of the specified events.</p> |
| <p>This routine waits on event object event until all of the specified |
| events have been delivered to the event object. A thread may wait on |
| up to 32 distinctly numbered events that are expressed as bits in a |
| single 32-bit word.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters<span class="colon">:</span></dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>event</strong> – Address of the event object</p></li> |
| <li><p><strong>events</strong> – Set of events to wait, 0 will indicate wait from any events</p></li> |
| <li><p><strong>eflags</strong> – Events flags</p></li> |
| </ul> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt class="sig sig-object c" id="c.nxevent_tickwait"> |
| <span class="n"><span class="pre">nxevent_mask_t</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">nxevent_tickwait</span></span></span><span class="sig-paren">(</span><span class="pre">FAR</span><span class="w"> </span><span class="n"><span class="pre">nxevent_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">event</span></span>, <span class="n"><span class="pre">nxevent_mask_t</span></span><span class="w"> </span><span class="n"><span class="pre">events</span></span>, <span class="n"><span class="pre">nxevent_flags_t</span></span><span class="w"> </span><span class="n"><span class="pre">eflags</span></span>, <span class="n"><span class="pre">uint32_t</span></span><span class="w"> </span><span class="n"><span class="pre">delay</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.nxevent_tickwait" title="Permalink to this definition"></a><br /></dt> |
| <dd><p>Wait for all of the specified events for the specified tick time.</p> |
| <p>This routine waits on event object event until all of the specified |
| events have been delivered to the event object, or the maximum wait time |
| timeout has expired. A thread may wait on up to 32 distinctly numbered |
| events that are expressed as bits in a single 32-bit word.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters<span class="colon">:</span></dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>event</strong> – Address of the event object.</p></li> |
| <li><p><strong>events</strong> – Set of events to wait, 0 will indicate wait from any events</p></li> |
| <li><p><strong>eflags</strong> – Events flags</p></li> |
| <li><p><strong>delay</strong> – Ticks to wait from the start time until the event is posted, |
| If ticks is zero, then this function is equivalent to nxevent_trywait().</p></li> |
| </ul> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt class="sig sig-object c" id="c.nxevent_trywait"> |
| <span class="n"><span class="pre">nxevent_mask_t</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">nxevent_trywait</span></span></span><span class="sig-paren">(</span><span class="pre">FAR</span><span class="w"> </span><span class="n"><span class="pre">nxevent_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">event</span></span>, <span class="n"><span class="pre">nxevent_mask_t</span></span><span class="w"> </span><span class="n"><span class="pre">events</span></span>, <span class="n"><span class="pre">nxevent_flags_t</span></span><span class="w"> </span><span class="n"><span class="pre">eflags</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.nxevent_trywait" title="Permalink to this definition"></a><br /></dt> |
| <dd><p>Try wait for all of the specified events.</p> |
| <p>This routine try to waits on event object event if any of the specified |
| events have been delivered to the event object. A thread may wait on |
| up to 32 distinctly numbered events that are expressed as bits in a |
| single 32-bit word.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters<span class="colon">:</span></dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>event</strong> – Address of the event object</p></li> |
| <li><p><strong>events</strong> – Set of events to wait, 0 will indicate wait from any events</p></li> |
| <li><p><strong>eflags</strong> – Events flags</p></li> |
| </ul> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt class="sig sig-object c" id="c.nxevent_open"> |
| <span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">nxevent_open</span></span></span><span class="sig-paren">(</span><span class="pre">FAR</span><span class="w"> </span><span class="n"><span class="pre">nxevent_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">event</span></span>, <span class="pre">FAR</span><span class="w"> </span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">name</span></span>, <span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="n"><span class="pre">oflags</span></span>, <span class="p"><span class="pre">...</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.nxevent_open" title="Permalink to this definition"></a><br /></dt> |
| <dd><p>This function establishes a connection between named event groups and a |
| task. the task may reference the event group associated with name using |
| the address returned by this call. The event group may be used in a |
| subsequent calls to nxevent_wait(), or nxevent_post(). And the event |
| group remains usable until the event group is closed by a successful |
| call to nxevent_close().</p> |
| <p>If a task makes multiple calls to event_open() with the same name, then |
| the same event group address is returned.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters<span class="colon">:</span></dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>event</strong> – Location to return the event group reference.</p></li> |
| <li><p><strong>name</strong> – Event group name.</p></li> |
| <li><p><strong>oflags</strong> – <p>Event group creation options. This may the following settings:</p> |
| <ul> |
| <li><p><code class="docutils literal notranslate"><span class="pre">oflags</span></code> = 0: Connect to the event group only if it already exists.</p></li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">oflags</span></code> = O_CREAT: Connect to the event group if it exists, otherwise create the event group.</p></li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">oflags</span></code> = O_CREAT|O_EXCL: Create a new event group unless already exists.</p></li> |
| </ul> |
| </p></li> |
| <li><p><strong>...</strong> – <dl class="simple"> |
| <dt>Optional parameters. When the O_CREAT flag is specified,</dt><dd><p>the two optional parameters are expected:</p> |
| </dd> |
| </dl> |
| <ul> |
| <li><dl class="simple"> |
| <dt><code class="docutils literal notranslate"><span class="pre">mode</span></code>: The mode parameter is of type mode_t. This parameter is</dt><dd><p>required but not used in the present implementation.</p> |
| </dd> |
| </dl> |
| </li> |
| <li><dl class="simple"> |
| <dt><code class="docutils literal notranslate"><span class="pre">events</span></code>: The events parameter is type unsigned. The event group</dt><dd><p>is created with an initial value of <code class="docutils literal notranslate"><span class="pre">events</span></code>.</p> |
| </dd> |
| </dl> |
| </li> |
| </ul> |
| </p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns<span class="colon">:</span></dt> |
| <dd class="field-even"><p>0 (OK), or negated errno if unsuccessful.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt class="sig sig-object c" id="c.nxevent_close"> |
| <span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">nxevent_close</span></span></span><span class="sig-paren">(</span><span class="pre">FAR</span><span class="w"> </span><span class="n"><span class="pre">nxevent_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">event</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.nxevent_close" title="Permalink to this definition"></a><br /></dt> |
| <dd><blockquote> |
| <div><p>This function is called to indicate that the calling task is finished |
| with the specified named event group. The event_close() deallocates |
| any system resources allocated by the system for this named event group.</p> |
| </div></blockquote> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters<span class="colon">:</span></dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>event</strong> – event descriptor</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns<span class="colon">:</span></dt> |
| <dd class="field-even"><p>0 (OK), or negated errno if unsuccessful.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| </section> |
| </section> |
| </section> |
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