Diff: main.cpp

Revision:

7:985db97e8ae0

Parent:

4:40078e697304

--- a/main.cpp	Mon Oct 15 17:25:24 2018 -0500
+++ b/main.cpp	Mon Oct 15 17:26:47 2018 -0500
@@ -1,32 +1,73 @@
 #include "mbed.h"
 
+Ticker ticker;
 Thread thread;
-Ticker ticker;
-Queue<uint32_t, 5> queue;
-DigitalOut myled(LED1);
+Queue<const char*, 5> trail;
+
+// Since we're printing from multiple threads, we need a mutex
+Mutex print_lock;
+
+enum ExecutionTypes {
+    IDLE,
+    USER,
+    ISR
+};
 
-void queue_isr() {
-    queue.put((uint32_t*)2);
-    myled = !myled;
-}
+const char* ExecutionMessages[] = {
+    "the idle thread",
+    "a user thread",
+    "interrupt context"
+};
 
-void queue_thread() {
-    while (true) {
-        queue.put((uint32_t*)1);
-        wait(1);
+void handler() {
+    // Check to see if we're in interrupt context
+    if (core_util_is_isr_active()) {
+        // Do not print since we're in interrupt context
+        trail.put(&(ExecutionMessages[ISR]));
+    } else {
+        // Safe to print since we're in a user thread
+        print_lock.lock();
+        printf("Starting user thread\r\n");
+        print_lock.unlock();
+        while(true) {
+            trail.put(&(ExecutionMessages[USER]));
+            wait(5);
+        }
     }
 }
 
-int main (void) {
-    thread.start(callback(queue_thread));
-    ticker.attach(queue_isr, 1.0);
+void custom_idle_function() {
+    // Custom idle behavior would go here
+    // We won't print here since the default idle thread's stack is too small
+    trail.put(&(ExecutionMessages[IDLE]));
+
+    // Switch back to the default idle behavior
+    Kernel::attach_idle_hook(NULL);
+}
 
+int main() {
+    printf("Starting execution example\r\n");
+
+    // Attach the custom idle thread function
+    Kernel::attach_idle_hook(custom_idle_function);
+
+    // Trigger the interrupt every 3 seconds
+    ticker.attach(handler, 3);
+
+    // Start the user thread
+    thread.start(handler);
+
+    // Get the past exectuion trail
     while (true) {
-        osEvent evt = queue.get();
+        osEvent evt = trail.get();
         if (evt.status != osEventMessage) {
-            printf("queue->get() returned %02x status\n\r", evt.status);
+            print_lock.lock();
+            printf("Failed to retrieve the execution trail (returned %02x)\r\n", evt.status);
+            print_lock.unlock();
         } else {
-            printf("queue->get() returned %d\n\r", evt.value.v);
+            print_lock.lock();
+            printf("Execution was in %s\r\n", *(const char**)evt.value.v);
+            print_lock.unlock();
         }
     }
 }