re-factored thread_mcast_should_register_address. (ARMmbed#1887)

Author: deepakvenugopal

source/6LoWPAN/Thread/thread_common.c

@@ -2060,24 +2060,25 @@ static bool thread_mcast_should_register_address(struct protocol_interface_info_
 {
     uint8_t thread_realm_local_mcast_addr[16];
     uint8_t thread_ll_unicast_prefix_based_mcast_addr[16];
+    if (addr_ipv6_multicast_scope(addr) < IPV6_SCOPE_LINK_LOCAL) {
+        return false;
+    }
+    if (memcmp(addr, ADDR_MULTICAST_SOLICITED, 13) == 0) {
+        return false;
+    }
+    if (memcmp(addr, ADDR_LINK_LOCAL_ALL_NODES, 16) == 0) {
+        return false;
+    }
+    if (memcmp(addr, ADDR_LINK_LOCAL_ALL_ROUTERS, 16) == 0) {
+        return false;
+    }
     thread_bootstrap_all_nodes_address_generate(thread_realm_local_mcast_addr, cur->thread_info->threadPrivatePrefixInfo.ulaPrefix, IPV6_SCOPE_REALM_LOCAL);
+    if (memcmp(addr, thread_realm_local_mcast_addr, 16) == 0) {
+        return false;
+    }
     thread_bootstrap_all_nodes_address_generate(thread_ll_unicast_prefix_based_mcast_addr, cur->thread_info->threadPrivatePrefixInfo.ulaPrefix, IPV6_SCOPE_LINK_LOCAL);
-    if (addr_ipv6_multicast_scope(addr) >= IPV6_SCOPE_LINK_LOCAL) {
-        if (memcmp(addr, ADDR_MULTICAST_SOLICITED, 13) == 0) {
-            return false;
-        }
-        if (memcmp(addr, thread_realm_local_mcast_addr, 16) == 0) {
-            return false;
-        }
-        if (memcmp(addr, thread_ll_unicast_prefix_based_mcast_addr, 16) == 0) {
-            return false;
-        }
-        if (memcmp(addr, ADDR_LINK_LOCAL_ALL_NODES, 16) == 0) {
-            return false;
-        }
-        if (memcmp(addr, ADDR_LINK_LOCAL_ALL_ROUTERS, 16) == 0) {
-            return false;
-        }
+    if (memcmp(addr, thread_ll_unicast_prefix_based_mcast_addr, 16) == 0) {
+        return false;
     }
     return true;
 }