b = [Low, Low, Low, High]
(s, c) = f (a, b)
+-- Not really an adder, but this is nice minimal hardware description
+wire :: Bit -> Bit
+wire a = a
+
+-- Not really an adder either, but a slightly more complex example
+inv :: Bit -> Bit
+inv a = hwnot a
+
+-- Not really an adder either, but a slightly more complex example
+invinv :: Bit -> Bit
+invinv a = hwnot (hwnot a)
+
+-- Not really an adder either, but a slightly more complex example
+dup :: Bit -> (Bit, Bit)
+dup a = (a, a)
+
-- Combinatoric stateless no-carry adder
-- A -> B -> S
no_carry_adder :: (Bit, Bit) -> Bit
full_adder :: (Bit, Bit, Bit) -> (Bit, Bit)
full_adder (a, b, cin) = (s, c)
where
- s = a `hwxor` b `hwxor` cin
- c = a `hwand` b `hwor` (cin `hwand` (a `hwxor` b))
+ x = a `hwxor` b
+ s = x `hwxor` cin
+ c = a `hwand` b `hwor` (cin `hwand` x)
-- Four bit adder
-- Explicit version