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| |
| <section id="os-data-structures"> |
| <h1>OS Data Structures<a class="headerlink" href="#os-data-structures" title="Permalink to this heading"></a></h1> |
| <section id="scalar-types"> |
| <h2>Scalar Types<a class="headerlink" href="#scalar-types" title="Permalink to this heading"></a></h2> |
| <p>Many of the types used to communicate with NuttX are simple scalar |
| types. These types are used to provide architecture independence of the |
| OS from the application. The scalar types used at the NuttX interface |
| include:</p> |
| <dl class="c type"> |
| <dt class="sig sig-object c" id="c.pid_t"> |
| <span class="k"><span class="pre">type</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">pid_t</span></span></span><a class="headerlink" href="#c.pid_t" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| <dl class="c type"> |
| <dt class="sig sig-object c" id="c.size_t"> |
| <span class="k"><span class="pre">type</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">size_t</span></span></span><a class="headerlink" href="#c.size_t" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| <dl class="c type"> |
| <dt class="sig sig-object c" id="c.sigset_t"> |
| <span class="k"><span class="pre">type</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">sigset_t</span></span></span><a class="headerlink" href="#c.sigset_t" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| <dl class="c type"> |
| <dt class="sig sig-object c" id="c.time_t"> |
| <span class="k"><span class="pre">type</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">time_t</span></span></span><a class="headerlink" href="#c.time_t" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| </section> |
| <section id="hidden-interface-structures"> |
| <h2>Hidden Interface Structures<a class="headerlink" href="#hidden-interface-structures" title="Permalink to this heading"></a></h2> |
| <p>Several of the types used to interface with NuttX are structures that |
| are intended to be hidden from the application. From the standpoint of |
| the application, these structures (and structure pointers) should be |
| treated as simple handles to reference OS resources. These hidden |
| structures include:</p> |
| <dl class="c struct"> |
| <dt class="sig sig-object c" id="c.tcb_s"> |
| <span class="k"><span class="pre">struct</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">tcb_s</span></span></span><a class="headerlink" href="#c.tcb_s" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| <dl class="c type"> |
| <dt class="sig sig-object c" id="c.mqd_t"> |
| <span class="k"><span class="pre">type</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">mqd_t</span></span></span><a class="headerlink" href="#c.mqd_t" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| <dl class="c type"> |
| <dt class="sig sig-object c" id="c.sem_t"> |
| <span class="k"><span class="pre">type</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">sem_t</span></span></span><a class="headerlink" href="#c.sem_t" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| <dl class="c type"> |
| <dt class="sig sig-object c" id="c.pthread_key_t"> |
| <span class="k"><span class="pre">type</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">pthread_key_t</span></span></span><a class="headerlink" href="#c.pthread_key_t" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| <p>In order to maintain portability, applications should not reference |
| specific elements within these hidden structures. These hidden |
| structures will not be described further in this user’s manual.</p> |
| </section> |
| <section id="access-to-the-errno-variable"> |
| <h2>Access to the <code class="docutils literal notranslate"><span class="pre">errno</span></code> Variable<a class="headerlink" href="#access-to-the-errno-variable" title="Permalink to this heading"></a></h2> |
| <p>A pointer to the thread-specific <code class="docutils literal notranslate"><span class="pre">errno</span></code> value is available through a |
| function call:</p> |
| <dl class="c function"> |
| <dt class="sig sig-object c" id="c.__errno"> |
| <span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">__errno</span></span></span><span class="sig-paren">(</span><span class="kt"><span class="pre">void</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.__errno" title="Permalink to this definition"></a><br /></dt> |
| <dd><p><code class="docutils literal notranslate"><span class="pre">__errno()</span></code> returns a pointer to the thread-specific |
| <code class="docutils literal notranslate"><span class="pre">errno</span></code> value. Note that the symbol <code class="docutils literal notranslate"><span class="pre">errno</span></code> is defined to be |
| <code class="docutils literal notranslate"><span class="pre">__errno()</span></code> so that the usual access by referencing the symbol |
| <code class="docutils literal notranslate"><span class="pre">errno</span></code> will work as expected.</p> |
| <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><errno.h></span> |
| <span class="cp">#define errno *__errno()</span> |
| <span class="kt">int</span><span class="w"> </span><span class="o">*</span><span class="nf">__errno</span><span class="p">(</span><span class="kt">void</span><span class="p">);</span> |
| </pre></div> |
| </div> |
| <p>There is a unique, private <code class="docutils literal notranslate"><span class="pre">errno</span></code> value for each NuttX task. However, |
| the implementation of <code class="docutils literal notranslate"><span class="pre">errno</span></code> differs somewhat from the use of |
| <code class="docutils literal notranslate"><span class="pre">errno</span></code> in most multi-threaded process environments: In NuttX, each |
| pthread will also have its own private copy of <code class="docutils literal notranslate"><span class="pre">errno</span></code> and the |
| <code class="docutils literal notranslate"><span class="pre">errno</span></code> will not be shared between pthreads. This is, perhaps, |
| non-standard but promotes better thread independence.</p> |
| <blockquote> |
| <div><dl class="field-list simple"> |
| <dt class="field-odd">return<span class="colon">:</span></dt> |
| <dd class="field-odd"><p>A pointer to the thread-specific <code class="docutils literal notranslate"><span class="pre">errno</span></code> value.</p> |
| </dd> |
| </dl> |
| </div></blockquote> |
| </dd></dl> |
| |
| </section> |
| <section id="user-interface-structures"> |
| <h2>User Interface Structures<a class="headerlink" href="#user-interface-structures" title="Permalink to this heading"></a></h2> |
| <dl class="c type"> |
| <dt class="sig sig-object c" id="c.main_t"> |
| <span class="k"><span class="pre">typedef</span></span><span class="w"> </span><span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="p"><span class="pre">(</span></span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">main_t</span></span></span><span class="p"><span class="pre">)</span></span><span class="p"><span class="pre">(</span></span><span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="n"><span class="pre">argc</span></span><span class="p"><span class="pre">,</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">argv</span></span><span class="p"><span class="pre">[</span></span><span class="p"><span class="pre">]</span></span><span class="p"><span class="pre">)</span></span><a class="headerlink" href="#c.main_t" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| <p><a class="reference internal" href="#c.main_t" title="main_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">main_t</span></code></a> defines the type of a task entry point. <a class="reference internal" href="#c.main_t" title="main_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">main_t</span></code></a> is declared in |
| <code class="docutils literal notranslate"><span class="pre">sys/types.h</span></code>.</p> |
| <dl class="c struct"> |
| <dt class="sig sig-object c" id="c.sched_param"> |
| <span class="k"><span class="pre">struct</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">sched_param</span></span></span><a class="headerlink" href="#c.sched_param" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| <p>This structure is used to pass scheduling priorities to and from NuttX:</p> |
| <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">struct</span><span class="w"> </span><span class="nc">sched_param</span> |
| <span class="p">{</span> |
| <span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">sched_priority</span><span class="p">;</span> |
| <span class="p">};</span> |
| </pre></div> |
| </div> |
| <dl class="c struct"> |
| <dt class="sig sig-object c" id="c.timespec"> |
| <span class="k"><span class="pre">struct</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">timespec</span></span></span><a class="headerlink" href="#c.timespec" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| <p>This structure is used to pass timing information between the NuttX and |
| a user application:</p> |
| <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">struct</span><span class="w"> </span><span class="nc">timespec</span> |
| <span class="p">{</span> |
| <span class="w"> </span><span class="kt">time_t</span><span class="w"> </span><span class="n">tv_sec</span><span class="p">;</span><span class="w"> </span><span class="cm">/* Seconds */</span> |
| <span class="w"> </span><span class="kt">long</span><span class="w"> </span><span class="n">tv_nsec</span><span class="p">;</span><span class="w"> </span><span class="cm">/* Nanoseconds */</span> |
| <span class="p">};</span> |
| </pre></div> |
| </div> |
| <dl class="c struct"> |
| <dt class="sig sig-object c" id="c.mq_attr"> |
| <span class="k"><span class="pre">struct</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">mq_attr</span></span></span><a class="headerlink" href="#c.mq_attr" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| <p>This structure is used to communicate message queue attributes between |
| NuttX and a MoBY application:</p> |
| <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">struct</span><span class="w"> </span><span class="nc">mq_attr</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="kt">size_t</span><span class="w"> </span><span class="n">mq_maxmsg</span><span class="p">;</span><span class="w"> </span><span class="cm">/* Max number of messages in queue */</span> |
| <span class="w"> </span><span class="kt">size_t</span><span class="w"> </span><span class="n">mq_msgsize</span><span class="p">;</span><span class="w"> </span><span class="cm">/* Max message size */</span> |
| <span class="w"> </span><span class="kt">unsigned</span><span class="w"> </span><span class="n">mq_flags</span><span class="p">;</span><span class="w"> </span><span class="cm">/* Queue flags */</span> |
| <span class="w"> </span><span class="kt">size_t</span><span class="w"> </span><span class="n">mq_curmsgs</span><span class="p">;</span><span class="w"> </span><span class="cm">/* Number of messages currently in queue */</span> |
| <span class="p">};</span> |
| </pre></div> |
| </div> |
| <dl class="c struct"> |
| <dt class="sig sig-object c" id="c.sigaction"> |
| <span class="k"><span class="pre">struct</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">sigaction</span></span></span><br /></dt> |
| <dd></dd></dl> |
| |
| <p>The following structure defines the action to take for given signal:</p> |
| <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">struct</span><span class="w"> </span><span class="nc">sigaction</span> |
| <span class="p">{</span> |
| <span class="w"> </span><span class="k">union</span> |
| <span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="kt">void</span><span class="w"> </span><span class="p">(</span><span class="o">*</span><span class="n">_sa_handler</span><span class="p">)(</span><span class="kt">int</span><span class="p">);</span> |
| <span class="w"> </span><span class="kt">void</span><span class="w"> </span><span class="p">(</span><span class="o">*</span><span class="n">_sa_sigaction</span><span class="p">)(</span><span class="kt">int</span><span class="p">,</span><span class="w"> </span><span class="kt">siginfo_t</span><span class="w"> </span><span class="o">*</span><span class="p">,</span><span class="w"> </span><span class="kt">void</span><span class="w"> </span><span class="o">*</span><span class="p">);</span> |
| <span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="n">sa_u</span><span class="p">;</span> |
| <span class="w"> </span><span class="kt">sigset_t</span><span class="w"> </span><span class="n">sa_mask</span><span class="p">;</span> |
| <span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">sa_flags</span><span class="p">;</span> |
| <span class="p">};</span> |
| <span class="cp">#define sa_handler sa_u._sa_handler</span> |
| <span class="cp">#define sa_sigaction sa_u._sa_sigaction</span> |
| </pre></div> |
| </div> |
| <dl class="c struct"> |
| <dt class="sig sig-object c" id="c.siginfo"> |
| <span class="k"><span class="pre">struct</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">siginfo</span></span></span><a class="headerlink" href="#c.siginfo" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| <dl class="c type"> |
| <dt class="sig sig-object c" id="c.siginfo_t"> |
| <span class="k"><span class="pre">type</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">siginfo_t</span></span></span><a class="headerlink" href="#c.siginfo_t" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| <p>The following types is used to pass parameters to/from signal handlers:</p> |
| <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">typedef</span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">siginfo</span> |
| <span class="p">{</span> |
| <span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">si_signo</span><span class="p">;</span> |
| <span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">si_code</span><span class="p">;</span> |
| <span class="w"> </span><span class="k">union</span><span class="w"> </span><span class="nc">sigval</span><span class="w"> </span><span class="n">si_value</span><span class="p">;</span> |
| <span class="p">}</span><span class="w"> </span><span class="kt">siginfo_t</span><span class="p">;</span> |
| </pre></div> |
| </div> |
| <dl class="c union"> |
| <dt class="sig sig-object c" id="c.sigval"> |
| <span class="k"><span class="pre">union</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">sigval</span></span></span><a class="headerlink" href="#c.sigval" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| <p>This defines the type of the struct siginfo si_value field and is used |
| to pass parameters with signals.</p> |
| <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">union</span><span class="w"> </span><span class="nc">sigval</span> |
| <span class="p">{</span> |
| <span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">sival_int</span><span class="p">;</span> |
| <span class="w"> </span><span class="kt">void</span><span class="w"> </span><span class="o">*</span><span class="n">sival_ptr</span><span class="p">;</span> |
| <span class="p">};</span> |
| </pre></div> |
| </div> |
| <dl class="c struct"> |
| <dt class="sig sig-object c" id="c.sigevent"> |
| <span class="k"><span class="pre">struct</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">sigevent</span></span></span><a class="headerlink" href="#c.sigevent" title="Permalink to this definition"></a><br /></dt> |
| <dd></dd></dl> |
| |
| <p>The following is used to attach a signal to a message queue to notify a |
| task when a message is available on a queue.</p> |
| <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">struct</span><span class="w"> </span><span class="nc">sigevent</span> |
| <span class="p">{</span> |
| <span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">sigev_signo</span><span class="p">;</span> |
| <span class="w"> </span><span class="k">union</span><span class="w"> </span><span class="nc">sigval</span><span class="w"> </span><span class="n">sigev_value</span><span class="p">;</span> |
| <span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">sigev_notify</span><span class="p">;</span> |
| <span class="p">};</span> |
| </pre></div> |
| </div> |
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