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+<HTML
+><HEAD
+><TITLE
+>Synchronization [POSIX Section 11]</TITLE
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+TITLE="POSIX Standard Support"
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+TITLE="Data Interchange Format [POSIX Section 10]"
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+TITLE="Memory Management [POSIX Section 12]"
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+>eCos Reference Manual</TH
+></TR
+><TR
+><TD
+WIDTH="10%"
+ALIGN="left"
+VALIGN="bottom"
+><A
+HREF="posix-data-interchange-format.html"
+ACCESSKEY="P"
+>Prev</A
+></TD
+><TD
+WIDTH="80%"
+ALIGN="center"
+VALIGN="bottom"
+>Chapter 31. POSIX Standard Support</TD
+><TD
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+VALIGN="bottom"
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+HREF="posix-memory-management.html"
+ACCESSKEY="N"
+>Next</A
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+><HR
+ALIGN="LEFT"
+WIDTH="100%"></DIV
+><DIV
+CLASS="SECT1"
+><H1
+CLASS="SECT1"
+><A
+NAME="POSIX-SYNCHRONIZATION">Synchronization [POSIX Section 11]</H1
+><DIV
+CLASS="SECT2"
+><H2
+CLASS="SECT2"
+><A
+NAME="AEN13150">Functions Implemented</H2
+><TABLE
+BORDER="5"
+BGCOLOR="#E0E0F0"
+WIDTH="70%"
+><TR
+><TD
+><PRE
+CLASS="SCREEN"
+>int sem_init(sem_t *sem, int pshared, unsigned int value);
+int sem_destroy(sem_t *sem);
+int sem_wait(sem_t *sem);
+int sem_trywait(sem_t *sem);
+int sem_post(sem_t *sem);
+int sem_getvalue(sem_t *sem, int *sval);
+int pthread_mutexattr_init( pthread_mutexattr_t *attr);
+int pthread_mutexattr_destroy( pthread_mutexattr_t *attr);
+int pthread_mutex_init(pthread_mutex_t *mutex,
+ const pthread_mutexattr_t *mutex_attr);
+int pthread_mutex_destroy(pthread_mutex_t *mutex);
+int pthread_mutex_lock(pthread_mutex_t *mutex);
+int pthread_mutex_trylock(pthread_mutex_t *mutex);
+int pthread_mutex_unlock(pthread_mutex_t *mutex);
+int pthread_condattr_init(pthread_condattr_t *attr);
+int pthread_condattr_destroy(pthread_condattr_t *attr);
+int pthread_cond_init(pthread_cond_t *cond,
+ const pthread_condattr_t *attr);
+int pthread_cond_destroy(pthread_cond_t *cond);
+int pthread_cond_signal(pthread_cond_t *cond);
+int pthread_cond_broadcast(pthread_cond_t *cond);
+int pthread_cond_wait(pthread_cond_t *cond,
+ pthread_mutex_t *mutex);
+int pthread_cond_timedwait(pthread_cond_t *cond,
+ pthread_mutex_t *mutex,
+ const struct timespec *abstime);</PRE
+></TD
+></TR
+></TABLE
+></DIV
+><DIV
+CLASS="SECT2"
+><H2
+CLASS="SECT2"
+><A
+NAME="AEN13153">Functions Omitted</H2
+><TABLE
+BORDER="5"
+BGCOLOR="#E0E0F0"
+WIDTH="70%"
+><TR
+><TD
+><PRE
+CLASS="SCREEN"
+>sem_t *sem_open(const char *name, int oflag, ...); // TBA
+int sem_close(sem_t *sem); // TBA
+int sem_unlink(const char *name); // TBA
+int pthread_mutexattr_getpshared( const pthread_mutexattr_t *attr,
+ int *pshared );
+int pthread_mutexattr_setpshared( const pthread_mutexattr_t *attr,
+ int pshared );
+int pthread_condattr_getpshared( const pthread_condattr_t *attr,
+ int *pshared);
+int pthread_condattr_setpshared( const pthread_condattr_t *attr,
+ int pshared);</PRE
+></TD
+></TR
+></TABLE
+></DIV
+><DIV
+CLASS="SECT2"
+><H2
+CLASS="SECT2"
+><A
+NAME="AEN13156">Notes</H2
+><P
+></P
+><UL
+><LI
+><P
+> The presence of semaphores is controlled by the
+ CYGPKG_POSIX_SEMAPHORES option. This in turn
+ causes the _POSIX_SEMAPHORES feature test
+ macro to be defined and the semaphore API to be made
+ available.
+ </P
+></LI
+><LI
+><P
+> The <SPAN
+CLASS="strong"
+><B
+CLASS="EMPHASIS"
+>pshared</B
+></SPAN
+> argument to
+ <SPAN
+CLASS="emphasis"
+><I
+CLASS="EMPHASIS"
+>sem_init()</I
+></SPAN
+> is not implemented,
+ its value is ignored.
+ </P
+></LI
+><LI
+><P
+> Functions <SPAN
+CLASS="emphasis"
+><I
+CLASS="EMPHASIS"
+>sem_open()</I
+></SPAN
+>,
+ <SPAN
+CLASS="emphasis"
+><I
+CLASS="EMPHASIS"
+>sem_close()</I
+></SPAN
+> and
+ <SPAN
+CLASS="emphasis"
+><I
+CLASS="EMPHASIS"
+>sem_unlink()</I
+></SPAN
+> are present but
+ always return an error (ENOSYS).
+ </P
+></LI
+><LI
+><P
+> The exact priority inversion protocols supported may be
+ controlled with the
+ _POSIX_THREAD_PRIO_INHERIT and
+ _POSIX_THREAD_PRIO_PROTECT
+ configuration options.
+ </P
+></LI
+><LI
+><P
+> {_POSIX_THREAD_PROCESS_SHARED} is
+ not defined, so the
+ <SPAN
+CLASS="strong"
+><B
+CLASS="EMPHASIS"
+>process-shared</B
+></SPAN
+> mutex
+ and condition variable attributes are not supported, and
+ neither are the functions
+ <SPAN
+CLASS="emphasis"
+><I
+CLASS="EMPHASIS"
+>pthread_mutexattr_getpshared()</I
+></SPAN
+>,
+ <SPAN
+CLASS="emphasis"
+><I
+CLASS="EMPHASIS"
+>pthread_mutexattr_setpshared()</I
+></SPAN
+>,
+ <SPAN
+CLASS="emphasis"
+><I
+CLASS="EMPHASIS"
+>pthread_condattr_getpshared()</I
+></SPAN
+> and
+ <SPAN
+CLASS="emphasis"
+><I
+CLASS="EMPHASIS"
+>pthread_condattr_setpshared()</I
+></SPAN
+>.
+ </P
+></LI
+><LI
+><P
+> Condition variables do not become bound to a particular
+ mutex when
+ <SPAN
+CLASS="emphasis"
+><I
+CLASS="EMPHASIS"
+>pthread_cond_wait()</I
+></SPAN
+> is
+ called. Hence different threads may wait on a condition
+ variable with different mutexes. This is at variance with
+ the standard, which requires a condition variable to
+ become (dynamically) bound by the first waiter, and
+ unbound when the last finishes. However, this difference
+ is largely benign, and the cost of policing this feature
+ is non-trivial.
+ </P
+></LI
+></UL
+></DIV
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