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--  $Id: Primitives.hs#1 2009/10/01 10:31:09 REDMOND\\satnams $
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module Lava.Primitives
where 

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data CombinationalGateBehaviour
  = DriverBehaviour Bool
  | UnaryGate (Bool -> Bool)
  | BinaryGate (Bool -> Bool -> Bool)
  | Gate3 (Bool -> Bool -> Bool -> Bool)
  | Gate4 (Bool -> Bool -> Bool -> Bool -> Bool)
  | ListToListBehaviour ([Bool] -> [Bool])
  | UnspecifiedCombinationalGateBehaviour
 
 
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instance Show CombinationalGateBehaviour where
  showsPrec _ f = showString (showGateBehaviour f)

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data Primitive
   = Gate {gateKind :: GateKind, 
           gateName :: String,
           gatePos :: Position, gateSize :: (Int, Int),
           gateBehaviour :: CombinationalGateBehaviour}
   | Input String
     deriving Show


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data GateKind
  = Lut1 | Lut2 | Lut3 | Lut4 
   | LeafGate {inputPorts, outputPorts :: [String]}
     deriving Show

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data Position
  = NoPlacement
  | Unplaced
  | At (Int, Int)
    deriving (Eq, Show)

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placed :: Position -> Bool
placed (At _) = True
placed _ = False

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showGateBehaviour :: CombinationalGateBehaviour -> String
showGateBehaviour (UnaryGate f)
  = [boolToChar (f i) | i <- [True, False]]
showGateBehaviour (BinaryGate f)
  = reverse [boolToChar (f i0 i1) | [i0, i1] <- boolVecs 2]
showGateBehaviour (Gate3 f)
  = reverse [boolToChar (f i0 i1 i2) | [i0, i1, i2] <- boolVecs 3]
showGateBehaviour (Gate4 f)
  = reverse [boolToChar (f i0 i1 i2 i3) | [i0, i1, i2, i3] <- boolVecs 4]
showGateBehaviour _ = error "unknown gate behaviour"

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boolVecs :: Int -> [[Bool]]
boolVecs n
  = [numToBoolVec n i | i <- [0..2^n-1]]

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numToBoolVec 0 0 = []
numToBoolVec n i
  = lsb : numToBoolVec (n-1) (i `div` 2)
    where
    lsb = if i `mod` 2 == 0 then
            False
          else
            True

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boolToChar :: Bool -> Char
boolToChar False = '0'
boolToChar True = '1'

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