sys/transceiver: implement transceiver_unregister

sys/include/transceiver.h

@@ -228,5 +228,15 @@ int transceiver_start(void);
  */
 uint8_t transceiver_register(transceiver_type_t transceivers, int pid);
 
+/**
+ * @brief unregister a thread for events from certain transceivers
+ *
+ * @param transceivers  The transceiver types to register for
+ * @param pid           The pid of the thread to register
+ *
+ * @return              1 on success, 0 otherwise
+ */
+uint8_t transceiver_unregister(transceiver_type_t transceivers, int pid);
+
 #endif /* TRANSCEIVER_H */
 /** @} */

sys/transceiver/transceiver.c

@@ -251,6 +251,25 @@ uint8_t transceiver_register(transceiver_type_t t, int pid)
     }
 }
 
+/* Unregister an upper layer thread */
+uint8_t transceiver_unregister(transceiver_type_t t, int pid)
+{
+    uint8_t i;
+
+    /* find pid in unregistered threads or first unused space */
+    for (i = 0; ((i < TRANSCEIVER_MAX_REGISTERED) &&
+                 (reg[i].pid != pid) &&
+                 (reg[i].transceivers != TRANSCEIVER_NONE)); i++);
+
+    if (i >= TRANSCEIVER_MAX_REGISTERED) {
+        return 0;
+    }
+    else if (reg[i].pid == pid) {
+        reg[i].transceivers ^= t;
+    }
+    return 1;
+}
+
 /*------------------------------------------------------------------------------------*/
 /*                                Internal functions                                  */
 /*------------------------------------------------------------------------------------*/