Add the framework to support POSIX timers

git-svn-id: https://nuttx.svn.sourceforge.net/svnroot/nuttx/trunk@110 7fd9a85b-ad96-42d3-883c-3090e2eb8679

6 files changed, 563 insertions, 1 deletions

diff --git a/nuttx/sched/Makefile b/nuttx/sched/Makefile
index de80373901..4679a846d6 100644
--- a/nuttx/sched/Makefile
+++ b/nuttx/sched/Makefile
@@ -99,10 +99,13 @@ SEM_SRCS	= sem_initialize.c sem_init.c sem_destroy.c\
 		  sem_open.c sem_close.c sem_unlink.c \
 		  sem_wait.c sem_trywait.c sem_post.c sem_getvalue.c \
                   sem_waitirq.c sem_findnamed.c
+ifneq ($(CONFIG_DISABLE_POSIX_TIMERSA),y)
+TIMERS_SRCS	= timer_create.c timer_delete.c timer_getoverrun.c timer_gettime.c timer_settime.c
+endif
 IRQ_SRCS	= irq_initialize.c irq_attach.c irq_dispatch.c irq_unexpectedisr.c
 
 CSRCS		= $(MISC_SRCS) $(TSK_SRCS) $(SCHED_SRCS) $(WDOG_SRCS) $(TIME_SRCS) \
-		  $(SEM_SRCS) $(IRQ_SRCS)
+		  $(SEM_SRCS) $(TIMER_SRCS) $(IRQ_SRCS)
 ifneq ($(CONFIG_DISABLE_CLOCK),y)
 CSRCS		+= $(CLOCK_SRCS)
 endif
diff --git a/nuttx/sched/timer_create.c b/nuttx/sched/timer_create.c
new file mode 100644
index 0000000000..b86d38d6dd
--- /dev/null
+++ b/nuttx/sched/timer_create.c
@@ -0,0 +1,120 @@
+/********************************************************************************
+ * timer_create.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ********************************************************************************/
+
+/********************************************************************************
+ * Included Files
+ ********************************************************************************/
+
+#include <nuttx/config.h>
+#include <time.h>
+#include <errno.h>
+
+#ifdef CONFIG_POSIX_TIMERS
+
+/********************************************************************************
+ * Definitions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Data
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Data
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Function:  timer_create
+ *
+ * Description:
+ *   The  timer_create() function creates per-thread timer using the specified
+ *   clock, clock_id, as the timing base. The timer_create() function returns, in
+ *   the location referenced by timerid, a timer ID of type timer_t used to identify
+ *   the timer in timer requests. This timer ID is unique until the timer is
+ *   deleted. The particular clock, clock_id, is defined in <time.h>. The timer
+ *   whose ID is returned will be in a disarmed state upon return from
+ *   timer_create().
+ *
+ *   The evp argument, if non-NULL, points to a sigevent structure. This structure
+ *   is allocated by the called and defines the asynchronous notification to occur.
+ *   If the evp argument is NULL, the effect is as if the evp argument pointed to
+ *   a sigevent structure with the sigev_notify member having the value SIGEV_SIGNAL,
+ *   the sigev_signo having a default signal number, and the sigev_value member
+ *   having the value of the timer ID.
+ *
+ *   Each implementation defines a set of clocks that can be used as timing bases
+ *   for per-thread timers. All implementations shall support a clock_id of
+ *   CLOCK_REALTIME.
+ *
+ * Parameters:
+ *   clockid - Specifies the clock to use as the timing base.
+ *   evp - Refers to a user allocated sigevent structure that defines the
+ *     asynchronous notification.  evp may be NULL (see above).
+ *   timerid - The pre-thread timer created by the call to timer_create().
+ *
+ * Return Value:
+ *   If the call succeeds, timer_create() will return 0 (OK) and update the
+ *   location referenced by timerid to a timer_t, which can be passed to the
+ *   other per-thread timer calls.  If an error occurs, the function will return
+ *   a value of -1 (ERROR) and set errno to indicate the error.
+ *
+ *   EAGAIN - The system lacks sufficient signal queuing resources to honor the
+ *    request.
+ *   EAGAIN - The calling process has already created all of the timers it is
+ *     allowed by this implementation.
+ *   EINVAL - The specified clock ID is not defined.
+ *   ENOTSUP - The implementation does not support the creation of a timer attached
+ *     to the CPU-time clock that is specified by clock_id and associated with a
+ *     thread different thread invoking timer_create().
+ *
+ * Assumptions:
+ *
+ ********************************************************************************/
+
+int timer_create(clockid_t clockid, FAR struct sigevent *evp, FAR timer_t *timerid)
+{
+#warning "Not Implemented"
+  return ENOTSUP;
+}
+
+#endif /* CONFIG_POSIX_TIMERS */
diff --git a/nuttx/sched/timer_delete.c b/nuttx/sched/timer_delete.c
new file mode 100644
index 0000000000..4dc97a9bde
--- /dev/null
+++ b/nuttx/sched/timer_delete.c
@@ -0,0 +1,95 @@
+/********************************************************************************
+ * timer_delete.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ********************************************************************************/
+
+/********************************************************************************
+ * Included Files
+ ********************************************************************************/
+
+#include <nuttx/config.h>
+#include <time.h>
+#include <errno.h>
+
+#ifndef CONFIG_DISABLE_POSIX_TIMERS
+
+/********************************************************************************
+ * Definitions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Data
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Data
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Function:  timer_delete
+ *
+ * Description:
+ *   The timer_delete() function deletes the specified timer, timerid, previously
+ *   created by the timer_create() function. If the timer is armed when
+ *   timer_delete() is called, the timer will be automatically disarmed before
+ *   removal. The disposition of pending signals for the deleted timer is unspecified.
+ *
+ * Parameters:
+ *   timerid - The pre-thread timer, previously created by the call to
+ *   timer_create(), to be deleted.
+ *
+ * Return Value:
+ *   If the call succeeds, timer_create() will return 0 (OK).  Otherwise, the
+ *   function will return a value of -1 (ERROR) and set errno to indicate the error.
+ *
+ *   EINVAL - The timer specified timerid is not valid.
+ *
+ * Assumptions:
+ *
+ ********************************************************************************/
+
+int timer_delete(timer_t timerid)
+{
+#warning "Not Implemented"
+  return ENOTSUP;
+}
+
+#endif /* CONFIG_DISABLE_POSIX_TIMERS */
diff --git a/nuttx/sched/timer_getoverrun.c b/nuttx/sched/timer_getoverrun.c
new file mode 100644
index 0000000000..8dbd8da628
--- /dev/null
+++ b/nuttx/sched/timer_getoverrun.c
@@ -0,0 +1,108 @@
+/********************************************************************************
+ * timer_getoverrun.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ********************************************************************************/
+
+/********************************************************************************
+ * Included Files
+ ********************************************************************************/
+
+#include <nuttx/config.h>
+#include <time.h>
+#include <errno.h>
+
+#ifndef CONFIG_DISABLE_POSIX_TIMERS
+
+/********************************************************************************
+ * Definitions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Data
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Data
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Function:  timer_getoverrun
+ *
+ * Description:
+ *   Only a single signal will be queued to the process for a given timer at any
+ *   point in time.  When a timer for which a signal is still pending expires, no
+ *   signal will be queued, and a timer overrun will occur. When a timer
+ *   expiration signal is delivered to or accepted by a process, if the
+ *   implementation  supports  the  Realtime Signals Extension, the
+ *   timer_getoverrun() function will return the timer expiration overrun count for
+ *   the specified timer. The overrun count returned contains the number of extra
+ *   timer expirations that occurred between the time the signal was generated
+ *   (queued) and when it was delivered or accepted, up to but not including an 
+ *   implementation-defined  maximum of DELAYTIMER_MAX. If the number of such
+ *   extra expirations is greater than or equal to DELAYTIMER_MAX, then the
+ *   overrun count will be set to DELAYTIMER_MAX. The value returned by
+ *   timer_getoverrun() will apply to the most recent expiration signal delivery
+ *   or acceptance for the timer.  If no expiration signal has been delivered
+ *   for the timer, or if the Realtime Signals Extension is not supported, the
+ *   return value of timer_getoverrun() is unspecified.
+ *
+ * Parameters:
+ *   timerid - The pre-thread timer, previously created by the call to
+ *   timer_create(), whose overrun count will be returned..
+ *
+ * Return Value:
+ *   If the timer_getoverrun() function succeeds, it will return the timer
+ *   expiration overrun count as explained above. timer_getoverrun() will fail if:
+ *
+ *   EINVAL - The timerid argument does not correspond to an ID returned by
+ *     timer_create() but not yet deleted by timer_delete().
+ *
+ * Assumptions:
+ *
+ ********************************************************************************/
+
+int timer_getoverrun(timer_t timerid)
+{
+#warning "Not Implemented"
+  return ENOTSUP;
+}
+
+#endif /* CONFIG_DISABLE_POSIX_TIMERS */
diff --git a/nuttx/sched/timer_gettime.c b/nuttx/sched/timer_gettime.c
new file mode 100644
index 0000000000..948c6043cf
--- /dev/null
+++ b/nuttx/sched/timer_gettime.c
@@ -0,0 +1,100 @@
+/********************************************************************************
+ * timer_gettime.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ********************************************************************************/
+
+/********************************************************************************
+ * Included Files
+ ********************************************************************************/
+
+#include <nuttx/config.h>
+#include <time.h>
+#include <errno.h>
+
+#ifndef CONFIG_DISABLE_POSIX_TIMERS
+
+/********************************************************************************
+ * Definitions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Data
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Data
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Function:  timer_gettime
+ *
+ * Description:
+ *  The timer_gettime() function will store the amount of time until the
+ *  specified timer, timerid, expires and the reload value of the timer into the
+ *  space pointed to by the value argument. The it_value member of this structure
+ *  will contain the amount of time before the timer expires, or zero if the timer
+ *  is disarmed. This value is returned as the interval until timer expiration,
+ *  even if the timer was armed with absolute time. The it_interval member of
+ *  value will contain the reload value last set by timer_settime().
+ *
+ * Parameters:
+ *   timerid - The pre-thread timer, previously created by the call to
+ *   timer_create(), whose remaining time count will be returned..
+ *
+ * Return Value:
+ *   If the timer_gettime() succeeds, a value of 0 (OK) will be returned.
+ *   If an error occurs, the value -1 (ERROR) will be returned, and errno set to
+ *   indicate the error.
+ *
+ *   EINVAL - The timerid argument does not correspond to an ID returned by
+ *     timer_create() but not yet deleted by timer_delete().
+ *
+ * Assumptions:
+ *
+ ********************************************************************************/
+
+int timer_gettime(timer_t timerid, FAR struct itimerspec *value)
+{
+#warning "Not Implemented"
+  return ENOTSUP;
+}
+
+#endif /* CONFIG_DISABLE_POSIX_TIMERS */
diff --git a/nuttx/sched/timer_settime.c b/nuttx/sched/timer_settime.c
new file mode 100644
index 0000000000..8df4c7e326
--- /dev/null
+++ b/nuttx/sched/timer_settime.c
@@ -0,0 +1,136 @@
+/********************************************************************************
+ * timer_settime.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ********************************************************************************/
+
+/********************************************************************************
+ * Included Files
+ ********************************************************************************/
+
+#include <nuttx/config.h>
+#include <time.h>
+#include <errno.h>
+
+#ifndef CONFIG_DISABLE_POSIX_TIMERS
+
+/********************************************************************************
+ * Definitions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Data
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Data
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Function:  timer_settime
+ *
+ * Description:
+ *   The timer_settime() function sets the time until the next expiration of the
+ *   timer specified by timerid from the it_value member of the value argument
+ *   and arm the timer if the it_value member of value is non-zero. If the
+ *   specified timer was already armed when timer_settime() is called, this call
+ *   will reset the time until next expiration to the value specified. If the
+ *   it_value member of value is zero, the timer will be disarmed. The effect
+ *   of disarming or resetting a timer with pending expiration notifications is
+ *   unspecified.
+ *
+ *   If the flag TIMER_ABSTIME is not set in the argument flags, timer_settime()
+ *   will behave as if the time until next expiration is set to be equal to the
+ *   interval specified by the it_value member of value. That is, the timer will
+ *   expire in it_value nanoseconds from when the call is made. If the flag
+ *   TIMER_ABSTIME is set in the argument flags, timer_settime() will behave as
+ *   if the time until next expiration is set to be equal to the difference between
+ *   the absolute time specified by the it_value member of value and the current
+ *   value of the clock associated with timerid.  That is, the timer will expire
+ *   when the clock reaches the value specified by the it_value member of value.
+ *   If the specified time has already passed, the function will succeed and the
+ *   expiration notification will be made.
+ *
+ *   The reload value of the timer will be set to the value specified by the
+ *   it_interval member of value.  When a timer is armed with a non-zero
+ *   it_interval, a periodic (or repetitive) timer is specified.
+ *
+ *   Time values that are between two consecutive non-negative integer multiples
+ *   of the resolution of the specified timer will be rounded up to the larger
+ *   multiple of the resolution. Quantization error will not cause the timer to
+ *   expire earlier than the rounded time value.
+ *
+ *   If the argument ovalue is not NULL, the timer_settime() function will store,
+ *   in the location referenced by ovalue, a value representing the previous
+ *   amount of time before the timer would have expired, or zero if the timer was
+ *   disarmed, together with the previous timer reload value. Timers will not
+ *   expire before their scheduled time.
+ *
+ * Parameters:
+ *   timerid - The pre-thread timer, previously created by the call to
+ *     timer_create(), to be be set.
+ *   flags - Specifie characteristics of the timer (see above)
+ *   value - Specifies the timer value to set
+ *   ovalue - A location in which to return the time remaining from the previous
+ *     timer setting.
+ *
+ * Return Value:
+ *   If the timer_settime() succeeds, a value of 0 (OK) will be returned.
+ *   If an error occurs, the value -1 (ERROR) will be returned, and errno set to
+ *   indicate the error.
+ *
+ *   EINVAL - The timerid argument does not correspond to an ID returned by
+ *     timer_create() but not yet deleted by timer_delete().
+ *   EINVAL - A value structure specified a nanosecond value less than zero or
+ *     greater than or equal to 1000 million, and the it_value member of that
+ *     structure did not specify zero seconds and nanoseconds.
+ *
+ * Assumptions:
+ *
+ ********************************************************************************/
+
+int timer_settime(timer_t timerid, int flags, FAR const struct itimerspec *value,
+                  FAR struct itimerspec *ovalue)
+{
+#warning "Not Implemented"
+  return ENOTSUP;
+}
+
+#endif /* CONFIG_DISABLE_POSIX_TIMERS */