X-Git-Url: https://git.stderr.nl/gitweb?a=blobdiff_plain;f=Adders.hs;h=ce261668e48eb7a9afd5a8e05ddb4bd31f65edf0;hb=89dda45ec76981b8f3b84cac1537b776df479efa;hp=2e8cf35c98e3fe622e31cc76c3043149ae27067a;hpb=0b54fb07697815cb343e7f217b1bd8362365f22d;p=matthijs%2Fmaster-project%2Fc%CE%BBash.git

diff --git a/Adders.hs b/Adders.hs
index 2e8cf35..ce26166 100644
--- a/Adders.hs
+++ b/Adders.hs
@@ -1,8 +1,14 @@
-module Adders (main, no_carry_adder) where
+module Adders where
 import Bits
+import qualified Sim
 import Language.Haskell.Syntax
 
-main = do show_add exp_adder; show_add rec_adder;
+mainIO f = Sim.simulateIO (Sim.stateless f) ()
+
+-- This function is from Sim.hs, but we redefine it here so it can get inlined
+-- by default.
+stateless :: (i -> o) -> (i -> () -> ((), o))
+stateless f = \i s -> (s, f i)
 
 show_add f = do print ("Sum:   " ++ (displaysigs s)); print ("Carry: " ++ (displaysig c))
   where
@@ -10,24 +16,50 @@ show_add f = do print ("Sum:   " ++ (displaysigs s)); print ("Carry: " ++ (displ
     b = [Low, Low, Low, High]
     (s, c) = f (a, b)
 
--- Combinatoric no-carry adder
+-- 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)
+
+-- Not really an adder either, but a simple stateful example (D-flipflop)
+dff :: Bit -> Bit -> (Bit, Bit)
+dff d s = (s', q)
+  where
+    q = s
+    s' = d
+
+-- Combinatoric stateless no-carry adder
 -- A -> B -> S
 no_carry_adder :: (Bit, Bit) -> Bit
 no_carry_adder (a, b) = a `hwxor` b
 
--- Combinatoric half adder
+-- Combinatoric stateless half adder
 -- A -> B -> (S, C)
 half_adder :: (Bit, Bit) -> (Bit, Bit)
 half_adder (a, b) = 
   ( a `hwxor` b, a `hwand` b )
 
--- Combinatoric (one-bit) full adder
+-- Combinatoric stateless full adder
 -- (A, B, C) -> (S, C)
 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))
+    (s1, c1) = half_adder(a, b)
+    (s, c2)  = half_adder(s1, cin)
+    c        = c1 `hwor` c2
+
+sfull_adder = stateless full_adder
 
 -- Four bit adder
 -- Explicit version