refactor mstimer callback handling (#400)

Co-authored-by: Steve Karg <skarg@users.sourceforge.net>

ports/stm32f4xx/mstimer-init.c

@@ -34,36 +34,16 @@
 
 /* counter for the various timers */
 static volatile unsigned long Millisecond_Counter;
-static volatile struct mstimer_callback_data_t *Callback_Head;
-
-/**
- * Toggle the state of the debug LED
- */
-static void timer_debug_toggle(void)
-{
-    led_toggle(LED_LD1);
-}
 
 /**
  * Handles the interrupt from the timer
  */
 void SysTick_Handler(void)
 {
-    struct mstimer_callback_data_t *cb;
-
     /* increment the tick count */
     Millisecond_Counter++;
-    cb = (struct mstimer_callback_data_t *)Callback_Head;
-    while (cb) {
-        if (mstimer_expired(&cb->timer)) {
-            cb->callback();
-            if (mstimer_interval(&cb->timer) > 0) {
-                mstimer_reset(&cb->timer);
-            }
-        }
-        cb = cb->next;
-    }
-    timer_debug_toggle();
+    /* run any callbacks */
+    mstimer_callback_handler();
 }
 
 /**
@@ -76,40 +56,6 @@ unsigned long mstimer_now(void)
     return Millisecond_Counter;
 }
 
-/**
- * Configures and enables a repeating callback function
- *
- * @param cb - pointer to a #mstimer_callback_data_t
- * @param callback - pointer to a #timer_callback_function function
- * @param milliseconds - how often to call the function
- *
- * @return true if successfully added and enabled
- */
-void mstimer_callback(struct mstimer_callback_data_t *new_cb,
-    mstimer_callback_function callback,
-    unsigned long milliseconds)
-{
-    struct mstimer_callback_data_t *cb;
-
-    if (new_cb) {
-        new_cb->callback = callback;
-        mstimer_set(&new_cb->timer, milliseconds);
-    }
-    if (Callback_Head) {
-        cb = (struct mstimer_callback_data_t *)Callback_Head;
-        while (cb) {
-            if (!cb->next) {
-                cb->next = new_cb;
-                break;
-            } else {
-                cb = cb->next;
-            }
-        }
-    } else {
-        Callback_Head = new_cb;
-    }
-}
-
 /**
  * Timer setup for 1 millisecond timer
  */
@@ -117,9 +63,9 @@ void mstimer_init(void)
 {
     /* Setup SysTick Timer for 1ms interrupts  */
     if (SysTick_Config(SystemCoreClock / 1000)) {
-        /* Capture error */
-        while (1)
-            ;
+        while (1) {
+            /* config error? return  1 = failed, 0 = successful */
+        }
     }
     NVIC_EnableIRQ(SysTick_IRQn);
 }