Merge pull request #3991 from geky/fix-events-non-rtos-wait

events: Fix zero wait condition in non-rtos semaphore

Author: sg-

events/equeue/equeue_mbed.cpp

@@ -131,7 +131,9 @@ static void equeue_sema_timeout(equeue_sema_t *s) {
 bool equeue_sema_wait(equeue_sema_t *s, int ms) {
     int signal = 0;
     Timeout timeout;
-    if (ms > 0) {
+    if (ms == 0) {
+        return false;
+    } else if (ms > 0) {
         timeout.attach_us(callback(equeue_sema_timeout, s), ms*1000);
     }
 

events/equeue/equeue_platform.h

@@ -129,7 +129,8 @@ typedef volatile int equeue_sema_t;
 // The equeue_sema_wait waits for a semaphore to be signalled or returns
 // immediately if equeue_sema_signal had been called since the last
 // equeue_sema_wait. The equeue_sema_wait returns true if it detected that
-// equeue_sema_signal had been called.
+// equeue_sema_signal had been called. If ms is negative, equeue_sema_wait
+// will wait for a signal indefinitely.
 int equeue_sema_create(equeue_sema_t *sema);
 void equeue_sema_destroy(equeue_sema_t *sema);
 void equeue_sema_signal(equeue_sema_t *sema);