-------------------------------------------------------------------------------
--- $Id: Gates.hs#1 2009/10/01 10:31:09 REDMOND\\satnams $
-------------------------------------------------------------------------------

module Lava.Gates
where
import Lava.Combinators
import Lava.Serial

import Lava.Classes

inv :: Combinational m bit => bit -> m bit
inv = lut1 not

and2 :: Combinational m bit => (bit, bit) -> m bit
and2 = lut2 (&&)

or2 :: Combinational m bit => (bit, bit) -> m bit
or2 = lut2 (||)

xor2 :: Combinational m bit => (bit, bit) -> m bit
xor2 = lut2 (/=)

nxor2 :: Combinational m bit => (bit, bit) -> m bit
nxor2 = lut2 (==)

-------------------------------------------------------------------------------

muxBit :: Combinational m bit => bit -> (bit, bit) -> m bit
muxBit sel (d0, d1) = lut3 muxFn (sel, d0, d1)

-------------------------------------------------------------------------------

muxBit' :: Combinational m bit => bit -> (bit, bit) -> m bit
muxBit' sel (d0, d1) = lut3 muxFn' (sel, d0, d1)

-------------------------------------------------------------------------------
-- The behaviour of a multiplexor.

muxFn :: Bool -> Bool -> Bool -> Bool
muxFn sel d0 d1
  = if sel then
      d1
    else
      d0

-------------------------------------------------------------------------------
-- A multiplexor which has an inverted control input w.r.t. muxBit

muxFn' :: Bool -> Bool -> Bool -> Bool
muxFn' sel d0 d1
  = if sel then
      d0
    else
      d1
-------------------------------------------------------------------------------

muxBus :: Combinational m a => (a, ([a], [a])) -> m [a]
muxBus (sel, (a,b)) = (ziP >->  mapM (muxBit sel)) (a, b)

-------------------------------------------------------------------------------

muxBus' :: Combinational m a => (a, ([a], [a])) -> m [a]
muxBus' (sel, (a,b)) = (ziP >->  mapM (muxBit' sel)) (a, b)

-------------------------------------------------------------------------------