Improved and fixed tickless mode.

git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@7842 35acf78f-673a-0410-8e92-d51de3d6d3f4

1 files changed, 55 insertions, 37 deletions

diff --git a/os/rt/include/chvt.h b/os/rt/include/chvt.h
index b2118df07..01dc38ac6 100644
--- a/os/rt/include/chvt.h
+++ b/os/rt/include/chvt.h
@@ -340,6 +340,26 @@ static inline bool chVTIsArmedI(virtual_timer_t *vtp) {
 }

 

 /**

+ * @brief   Returns @p true if the specified timer is armed.

+ * @pre     The timer must have been initialized using @p chVTObjectInit()

+ *          or @p chVTDoSetI().

+ *

+ * @param[in] vtp       the @p virtual_timer_t structure pointer

+ * @return              true if the timer is armed.

+ *

+ * @api

+ */

+static inline bool chVTIsArmed(virtual_timer_t *vtp) {

+  bool b;

+

+  chSysLock();

+  b = chVTIsArmedI(vtp);

+  chSysUnlock();

+

+  return b;

+}

+

+/**

  * @brief   Disables a Virtual Timer.

  * @note    The timer is first checked and disabled only if armed.

  * @pre     The timer must have been initialized using @p chVTObjectInit()

@@ -466,35 +486,43 @@ static inline void chVTDoTickI(void) {
   }

 #else /* CH_CFG_ST_TIMEDELTA > 0 */

   virtual_timer_t *vtp;

+  systime_t now, delta;

+

+  /* First timer to be processed.*/

+  vtp = ch.vtlist.vt_next;

+  now = chVTGetSystemTimeX();

 

   /* The list is assumed to be non-empty because an tick interrupt just

      occurred.*/

-  chDbgAssert(&ch.vtlist != (virtual_timers_list_t *)ch.vtlist.vt_next,

+  chDbgAssert(&ch.vtlist != (virtual_timers_list_t *)vtp,

               "timers list empty");

 

-  /* First timer to be processed, its time is assumed to be between

-     "vt_lasttime" and "now".*/

-  vtp = ch.vtlist.vt_next;

-

+  /* The timer time is assumed to be between "vt_lasttime" and "now".*/

   chDbgAssert(chVTIsTimeWithinX(ch.vtlist.vt_lasttime + vtp->vt_delta,

                                 ch.vtlist.vt_lasttime,

-                                chVTGetSystemTimeX() + 1),

+                                now + 1),

               "out of time window");

 

-  /* Timers processing loop.*/

-  while (true) {

-    systime_t now;

+  /* All timers within the time window are triggered and removed,

+     note that the loop is stopped by the timers header having

+     "ch.vtlist.vt_delta == (systime_t)-1" which is greater than

+     all deltas.*/

+  while (vtp->vt_delta <= now - ch.vtlist.vt_lasttime) {

     vtfunc_t fn;

 

     /* The "last time" becomes this timer's expiration time.*/

     ch.vtlist.vt_lasttime += vtp->vt_delta;

 

-    /* The timer is removed from the list and marked as non-armed.*/

     vtp->vt_next->vt_prev = (virtual_timer_t *)&ch.vtlist;

     ch.vtlist.vt_next = vtp->vt_next;

     fn = vtp->vt_func;

     vtp->vt_func = NULL;

 

+    /* if the list becomes empty then the timer is stopped.*/

+    if (ch.vtlist.vt_next == (virtual_timer_t *)&ch.vtlist) {

+      port_timer_stop_alarm();

+    }

+

     /* Leaving the system critical zone in order to execute the callback

        and in order to give a preemption chance to higher priority

        interrupts.*/

@@ -507,37 +535,27 @@ static inline void chVTDoTickI(void) {
        of the list.*/

     chSysLockFromISR();

 

-    /* If the list is empty then ending the loop, the list has to be

-       re-checked because new timers could have been added/removed from

-       within the callback or other ISRs.*/

+    /* Next element in the list, the current time could have advanced so

+       recalculating the time window.*/

     vtp = ch.vtlist.vt_next;

-    if (&ch.vtlist == (virtual_timers_list_t *)vtp) {

-      /* Timers list empty, stopping alarms.*/

-      port_timer_stop_alarm();

-      return;

-    }

-

-    /* Getting the current system time and calculating the time window since

-       the last time has expired.*/

     now = chVTGetSystemTimeX();

+  }

 

-    /* The next element is outside the current time window, the loop

-       is stopped here.*/

-    if (vtp->vt_delta > now - ch.vtlist.vt_lasttime) {

-      /* Updating the alarm to the next deadline, deadline that must not be

-         closer in time than the minimum time delta.*/

-      systime_t delta = ch.vtlist.vt_lasttime + vtp->vt_delta - now;

-      if (delta < (systime_t)CH_CFG_ST_TIMEDELTA) {

-        delta = (systime_t)CH_CFG_ST_TIMEDELTA;

-      }

-      port_timer_set_alarm(now + delta);

-

-      chDbgAssert((chVTGetSystemTimeX() - ch.vtlist.vt_lasttime) < delta,

-                  "exceeding delta");

-

-      return;

-    }

+  /* if the list is empty, nothing else to do.*/

+  if (ch.vtlist.vt_next == (virtual_timer_t *)&ch.vtlist) {

+    return;

   }

+

+  /* Recalculating the next alarm time.*/

+  delta = ch.vtlist.vt_lasttime + vtp->vt_delta - now;

+  if (delta < (systime_t)CH_CFG_ST_TIMEDELTA) {

+    delta = (systime_t)CH_CFG_ST_TIMEDELTA;

+  }

+  port_timer_set_alarm(now + delta);

+

+  chDbgAssert((chVTGetSystemTimeX() - ch.vtlist.vt_lasttime) <=

+              (now + delta - ch.vtlist.vt_lasttime),

+              "exceeding delta");

 #endif /* CH_CFG_ST_TIMEDELTA > 0 */

 }