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<h2>
<a name="1273372"> </a><font color="#003366" face="Verdana, Arial, Helvetica, sans-serif">mutex_lock</font>
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<p>
<a name="1273373"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">Acquire a mutex, block if not available</font>
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<h3>
<a name="1273374"> </a><font color="#003366" face="Verdana, Arial, Helvetica, sans-serif">Synopsis</font>
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<a name="1273375"> </a><font size=2 face=Courier><strong>#include <mutex.h><br></strong></font>
<a name="1273376"> </a><font size=2 face=Courier><strong>int mutex_lock(mutex_t* mutex);<br></strong></font>
<h3>
<a name="1273377"> </a><font color="#003366" face="Verdana, Arial, Helvetica, sans-serif">Arguments</font>
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<p>
<a name="1273378"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif"><b><font size=2 face=Courier><strong>mutex_t* mutex</strong></font></b></font>
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<dl><dl> <dl>
<dt> <a name="1273379"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">A pointer to a mutex</font>
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</dl></dl>
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<a name="1273380"> </a><font color="#003366" face="Verdana, Arial, Helvetica, sans-serif">Results</font>
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<a name="1273381"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">Returns 0 on success, -1 if an error occurs.</font>
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<h3>
<a name="1273786"> </a><font color="#003366" face="Verdana, Arial, Helvetica, sans-serif">Errors</font>
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<p>
<a name="1273793"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">Returns -1 if the call is unable to allocate memory for the mutex control block.</font>
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<h3>
<a name="1273784"> </a><font color="#003366" face="Verdana, Arial, Helvetica, sans-serif">Description</font>
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<p>
<a name="1273804"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif"><font size=2 face=Courier><strong>mutex_lock()</strong></font> acquires the given mutex. The exact behavior of this function depends on the mutex type. If the mutex is currently not owned, or is already owned by the task, then the task acquires the mutex, and carries on running. If the mutex is owned by another task, then the calling task is added to the queue of tasks waiting for the mutex, and deschedules. Once the task acquires the mutex it is made immortal, until it releases the mutex.</font>
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<p>
<a name="1273812"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif"><em>Note: 1 This call fails if it cannot allocate memory for the mutex control block. The first time a task tries to lock a priority mutex it allocates a mutex control block for itself, this block is cached and exists until the task is deleted. This call can only fail when a task first attempts to lock a priority mutex.</em></font>
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<p>
<a name="1273818"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif"><em> 2 FIFO mutexes do not require a mutex control block so this call cannot fail for FIFO mutexes. </em></font>
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<h3>
<a name="1273588"> </a><font color="#003366" face="Verdana, Arial, Helvetica, sans-serif">Callable from</font>
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<p>
<a name="1273589"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">Tasks only</font>
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<h3>
<a name="1273387"> </a><font color="#003366" face="Verdana, Arial, Helvetica, sans-serif">See also</font>
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<p>
<a name="1273388"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif"><a href="libs87.htm#1273397"><font color="#0000ff" face="Verdana, Arial, Helvetica, sans-serif"><i>mutex_release</i></font></a>, <a href="libs88.htm#1273432"><font color="#0000ff" face="Verdana, Arial, Helvetica, sans-serif"><i>mutex_trylock</i></font></a>, <a href="libs119.htm#1209048"><font color="#0000ff" face="Verdana, Arial, Helvetica, sans-serif"><i>task_immortal</i></font></a> </font>
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