Add synchronous timer scheduler.

[bertos.git] / bertos / drv / timer.c

diff --git a/bertos/drv/timer.c b/bertos/drv/timer.c
index 9e2a1173011d053f1baebc60c0634cfad837abf7..60494413276918af234d3a802dbb8177c6fd413d 100644 (file)
--- a/bertos/drv/timer.c
+++ b/bertos/drv/timer.c
@@ -32,8 +32,8 @@
  *
  * \brief Hardware independent timer driver (implementation)
  *
- * \version $Id$
  * \author Bernie Innocenti <bernie@codewiz.org>
+ * \author Francesco Sacchi <batt@develer.com>
  */
 
 #include "timer.h"
@@ -115,25 +115,16 @@ volatile ticks_t _clock;
  */
 REGISTER static List timers_queue;
 
-
 /**
- * Add the specified timer to the software timer service queue.
- * When the delay indicated by the timer expires, the timer
- * device will execute the event associated with it.
- *
- * \note Interrupt safe
+ * This function really does the job. It adds \a timer to \a queue.
+ * \see timer_add for details.
  */
-void timer_add(Timer *timer)
+INLINE void timer_addToList(Timer *timer, List *queue)
 {
-       Timer *node;
-       cpu_flags_t flags;
-
-
        /* Inserting timers twice causes mayhem. */
        ASSERT(timer->magic != TIMER_MAGIC_ACTIVE);
        DB(timer->magic = TIMER_MAGIC_ACTIVE;)
 
-       IRQ_SAVE_DISABLE(flags);
 
        /* Calculate expiration time for this timer */
        timer->tick = _clock + timer->_delay;
@@ -142,7 +133,7 @@ void timer_add(Timer *timer)
         * Search for the first node whose expiration time is
         * greater than the timer we want to add.
         */
-       node = (Timer *)LIST_HEAD(&timers_queue);
+       Timer *node = (Timer *)LIST_HEAD(queue);
        while (node->link.succ)
        {
                /*
@@ -158,10 +149,19 @@ void timer_add(Timer *timer)
 
        /* Enqueue timer request into the list */
        INSERT_BEFORE(&timer->link, &node->link);
-
-       IRQ_RESTORE(flags);
 }
 
+/**
+ * Add the specified timer to the software timer service queue.
+ * When the delay indicated by the timer expires, the timer
+ * device will execute the event associated with it.
+ *
+ * \note Interrupt safe
+ */
+void timer_add(Timer *timer)
+{
+       ATOMIC(timer_addToList(timer, &timers_queue));
+}
 
 /**
  * Remove a timer from the timers queue before it has expired.
@@ -177,6 +177,64 @@ Timer *timer_abort(Timer *timer)
        return timer;
 }
 
+
+INLINE void timer_poll(List *queue)
+{
+       Timer *timer;
+
+       /*
+        * Check the first timer request in the list and process
+        * it when it has expired. Repeat this check until the
+        * first node has not yet expired. Since the list is sorted
+        * by expiry time, all the following requests are guaranteed
+        * to expire later.
+        */
+       while ((timer = (Timer *)LIST_HEAD(queue))->link.succ)
+       {
+               /* This request in list has not yet expired? */
+               if (timer_clock() - timer->tick < 0)
+                       break;
+
+               /* Retreat the expired timer */
+               REMOVE(&timer->link);
+               DB(timer->magic = TIMER_MAGIC_INACTIVE;)
+
+               /* Execute the associated event */
+               event_do(&timer->expire);
+       }
+}
+
+/**
+ * Add \a timer to \a queue.
+ * \see synctimer_poll() for details.
+ */
+void synctimer_add(Timer *timer, List *queue)
+{
+       timer_addToList(timer, queue);
+}
+
+/**
+ * Simple synchronous timer based scheduler polling routine.
+ *
+ * Sometimes you would like to have a proper scheduler,
+ * but you can't afford it due to memory constraints.
+ *
+ * This is a simple replacement: you can create events and call
+ * them periodically at specific time intervals.
+ * All you have to do is to set up normal timers, and call synctimer_add()
+ * instead of timer_add() to add the events to your specific queue.
+ * Then, in the main loop or wherever you want, you can call
+ * synctimer_poll() to process expired events. The associated callbacks will be
+ * executed.
+ * As this is done synchronously you don't have to worry about race conditions.
+ * You can kill an event by simply calling synctimer_abort().
+ *
+ */
+void synctimer_poll(List *queue)
+{
+       timer_poll(queue);
+}
+
 #endif /* CONFIG_TIMER_EVENTS */
 
 
@@ -273,10 +331,6 @@ DEFINE_TIMER_ISR
        #pragma interrupt saveall
        #endif
 
-#if CONFIG_TIMER_EVENTS
-       Timer *timer;
-#endif
-
        /*
         * On systems sharing IRQ line and vector, this check is needed
         * to ensure that IRQ is generated by timer source.
@@ -292,28 +346,9 @@ DEFINE_TIMER_ISR
        /* Update the master ms counter */
        ++_clock;
 
-#if CONFIG_TIMER_EVENTS
-       /*
-        * Check the first timer request in the list and process
-        * it when it has expired. Repeat this check until the
-        * first node has not yet expired. Since the list is sorted
-        * by expiry time, all the following requests are guaranteed
-        * to expire later.
-        */
-       while ((timer = (Timer *)LIST_HEAD(&timers_queue))->link.succ)
-       {
-               /* This request in list has not yet expired? */
-               if (_clock - timer->tick < 0)
-                       break;
-
-               /* Retreat the expired timer */
-               REMOVE(&timer->link);
-               DB(timer->magic = TIMER_MAGIC_INACTIVE;)
-
-               /* Execute the associated event */
-               event_do(&timer->expire);
-       }
-#endif /* CONFIG_TIMER_EVENTS */
+       #if CONFIG_TIMER_EVENTS
+               timer_poll(&timers_queue);
+       #endif
 
        TIMER_STROBE_OFF;
 }