atomkernel: Support thread entry points running to completion. Ports which use a thread_shell() can allow the entry point to finish and return back to the thread_shell(), which sets the terminated flag and calls the scheduler to force another thread to be scheduled in. Currently implemented in the ARM and AVR ports.

kernel/atom.h

@@ -77,6 +77,7 @@ typedef struct atom_tcb
     uint8_t suspended;            /* TRUE if task is currently suspended */
     uint8_t suspend_wake_status;  /* Status returned to woken suspend calls */
     ATOM_TIMER *suspend_timo_cb;  /* Callback registered for suspension timeouts */
+    uint8_t terminated;           /* TRUE if task is being terminated (run to completion) */
 
     /* Details used if thread stack-checking is required */
 #ifdef ATOM_STACK_CHECKING

kernel/atomkernel.c

@@ -241,10 +241,11 @@ void atomSched (uint8_t timer_tick)
     CRITICAL_START ();
 
     /**
-     * If the current thread is going into suspension, then
-     * unconditionally dequeue the next thread for execution.
+     * If the current thread is going into suspension or is being
+     * terminated (run to completion), then unconditionally dequeue
+     * the next thread for execution.
      */
-    if (curr_tcb->suspended == TRUE)
+    if ((curr_tcb->suspended == TRUE) || (curr_tcb->terminated == TRUE))
     {
         /**
          * Dequeue the next ready to run thread. There will always be