From b0afc266d19cdc8399f17573d0632850cfc3194d Mon Sep 17 00:00:00 2001
From: Kelvin Lawson <kelvinl@users.sf.net>
Date: Mon, 23 May 2016 20:50:51 +0100
Subject: [PATCH] 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        | 1 +
 kernel/atomkernel.c  | 7 ++++---
 ports/arm/atomport.c | 2 +-
 ports/avr/atomport.c | 5 +++--
 4 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/kernel/atom.h b/kernel/atom.h
index 2ee75a5..164c968 100755
--- a/kernel/atom.h
+++ b/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
diff --git a/kernel/atomkernel.c b/kernel/atomkernel.c
index db9273f..06ab2cc 100755
--- a/kernel/atomkernel.c
+++ b/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
diff --git a/ports/arm/atomport.c b/ports/arm/atomport.c
index 1383a8a..fc057ff 100644
--- a/ports/arm/atomport.c
+++ b/ports/arm/atomport.c
@@ -97,7 +97,7 @@ static void thread_shell (void)
     _reclaim_reent (&(curr_tcb->port_priv.reent));
 
     /* Thread has run to completion: remove it from the ready list */
-    curr_tcb->suspended = TRUE;
+    curr_tcb->terminated = TRUE;
     atomSched (FALSE);
 }
 
diff --git a/ports/avr/atomport.c b/ports/avr/atomport.c
index 9ae5555..362e66d 100644
--- a/ports/avr/atomport.c
+++ b/ports/avr/atomport.c
@@ -111,8 +111,9 @@ static void thread_shell (void)
         curr_tcb->entry_point(curr_tcb->entry_param);
     }
 
-    /* Not reached - threads should never return from the entry point */
-
+    /* Thread has run to completion: remove it from the ready list */
+    curr_tcb->terminated = TRUE;
+    atomSched (FALSE);
 }