feat(timer): implementation of adaptive call timer handler cycle method (#4236)

docs/porting/timer_handler.rst

@@ -32,6 +32,16 @@ the porting:
       ...
    }
 
+Or use the sleep time automatically calculated by LVGL:
+
+.. code:: c
+
+   while(1) {
+     ...
+     lv_timer_periodic_handler();
+     ...
+   }
+
 In an OS environment, you can use it together with the **delay** or
 **sleep** provided by OS to release CPU whenever possible:
 

src/misc/lv_timer.c

@@ -29,6 +29,7 @@
  **********************/
 static bool lv_timer_exec(lv_timer_t * timer);
 static uint32_t lv_timer_time_remaining(lv_timer_t * timer);
+static void lv_timer_handler_resume(void);
 
 /**********************
  *  STATIC VARIABLES
@@ -37,6 +38,7 @@ static bool lv_timer_run = false;
 static uint8_t idle_last = 0;
 static bool timer_deleted;
 static bool timer_created;
+static uint32_t timer_time_until_next;
 
 /**********************
  *      MACROS
@@ -121,13 +123,13 @@ LV_ATTRIBUTE_TIMER_HANDLER uint32_t lv_timer_handler(void)
         }
     } while(LV_GC_ROOT(_lv_timer_act));
 
-    uint32_t time_till_next = LV_NO_TIMER_READY;
+    uint32_t time_until_next = LV_NO_TIMER_READY;
     next = _lv_ll_get_head(&LV_GC_ROOT(_lv_timer_ll));
     while(next) {
         if(!next->paused) {
             uint32_t delay = lv_timer_time_remaining(next);
-            if(delay < time_till_next)
-                time_till_next = delay;
+            if(delay < time_until_next)
+                time_until_next = delay;
         }
 
         next = _lv_ll_get_next(&LV_GC_ROOT(_lv_timer_ll), next); /*Find the next timer*/
@@ -142,11 +144,23 @@ LV_ATTRIBUTE_TIMER_HANDLER uint32_t lv_timer_handler(void)
         idle_period_start = lv_tick_get();
     }
 
+    timer_time_until_next = time_until_next;
     already_running = false; /*Release the mutex*/
 
-    TIMER_TRACE("finished (%" LV_PRIu32 " ms until the next timer call)", time_till_next);
+    TIMER_TRACE("finished (%" LV_PRIu32 " ms until the next timer call)", time_until_next);
     LV_PROFILER_END;
-    return time_till_next;
+    return time_until_next;
+}
+
+LV_ATTRIBUTE_TIMER_HANDLER void lv_timer_periodic_handler(void)
+{
+    static uint32_t last_tick = 0;
+
+    if(lv_tick_elaps(last_tick) >= timer_time_until_next) {
+        TIMER_TRACE("calling lv_timer_handler()");
+        lv_timer_handler();
+        last_tick = lv_tick_get();
+    }
 }
 
 /**
@@ -185,6 +199,8 @@ lv_timer_t * lv_timer_create(lv_timer_cb_t timer_xcb, uint32_t period, void * us
 
     timer_created = true;
 
+    lv_timer_handler_resume();
+
     return new_timer;
 }
 
@@ -222,6 +238,7 @@ void lv_timer_pause(lv_timer_t * timer)
 void lv_timer_resume(lv_timer_t * timer)
 {
     timer->paused = false;
+    lv_timer_handler_resume();
 }
 
 /**
@@ -261,6 +278,7 @@ void lv_timer_set_repeat_count(lv_timer_t * timer, int32_t repeat_count)
 void lv_timer_reset(lv_timer_t * timer)
 {
     timer->last_run = lv_tick_get();
+    lv_timer_handler_resume();
 }
 
 /**
@@ -270,6 +288,7 @@ void lv_timer_reset(lv_timer_t * timer)
 void lv_timer_enable(bool en)
 {
     lv_timer_run = en;
+    if(en) lv_timer_handler_resume();
 }
 
 /**
@@ -281,6 +300,15 @@ uint8_t lv_timer_get_idle(void)
     return idle_last;
 }
 
+/**
+ * Get idle period start tick
+ * @return the lv_timer idle period start tick
+ */
+uint32_t lv_timer_get_time_until_next(void)
+{
+    return timer_time_until_next;
+}
+
 /**
  * Iterate through the timers
  * @param timer NULL to start iteration or the previous return value to get the next timer
@@ -351,3 +379,12 @@ static uint32_t lv_timer_time_remaining(lv_timer_t * timer)
         return 0;
     return timer->period - elp;
 }
+
+/**
+ * Call the ready lv_timer
+ */
+static void lv_timer_handler_resume(void)
+{
+    /*If there is a timer which is ready to run then resume the timer loop*/
+    timer_time_until_next = 0;
+}

src/misc/lv_timer.h

@@ -87,6 +87,12 @@ static inline LV_ATTRIBUTE_TIMER_HANDLER uint32_t lv_timer_handler_run_in_period
     return 1;
 }
 
+/**
+ * Call it in the super-loop of main() or threads. It will automatically call lv_timer_handler() at the right time.
+ * This function is used to simplify the porting.
+ */
+LV_ATTRIBUTE_TIMER_HANDLER void lv_timer_periodic_handler(void);
+
 /**
  * Create an "empty" timer. It needs to be initialized with at least
  * `lv_timer_set_cb` and `lv_timer_set_period`
@@ -165,6 +171,12 @@ void lv_timer_enable(bool en);
  */
 uint8_t lv_timer_get_idle(void);
 
+/**
+ * Get the time remaining until the next timer will run
+ * @return the time remaining in ms
+ */
+uint32_t lv_timer_get_time_until_next(void);
+
 /**
  * Iterate through the timers
  * @param timer NULL to start iteration or the previous return value to get the next timer