extend address helper functions

src/j1939/address.rs

@@ -2,15 +2,34 @@
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 #[repr(transparent)]
-pub struct Address(pub u8);
+pub struct Address(u8);
 
 impl Address {
     /// Address representing broadcasts for destination specific PGNs
-    pub const GLOBAL: Address = Address(0xFF);
+    pub const GLOBAL: Address = Self::BROADCAST;
     /// Alias for the global address
     pub const BROADCAST: Address = Address(0xFF);
     /// The null address is used by ECUs without an address such as during address claiming
     pub const NULL: Address = Address(0xFE);
+
+    pub fn new(raw_address: u8) -> Self {
+        Self { 0: raw_address }
+    }
+
+    #[inline]
+    pub fn is_global(&self) -> bool {
+        self.is_broadcast()
+    }
+
+    #[inline]
+    pub fn is_broadcast(&self) -> bool {
+        self == Self::BROADCAST
+    }
+
+    #[inline]
+    pub fn is_null(&self) -> bool {
+        self == Self::NULL
+    }
 }
 
 // TODO: custom Debug impl and helpers