Example7.hs

module Example7 where
import CLaSH.Prelude

--
-- Configuration
--
type Value      = Signed 16
type SizeInBits = 3
type StackDepth = 2^SizeInBits
type SP         = Unsigned SizeInBits
type SMem       = Vec StackDepth Value

data SInstr = Push Value
            | Pop
            | PopPush Value
            deriving (Show)

--
-- Logic
--
stack5 (mem, sp) instr = ((mem', sp'), o)
  where
    (mem', sp') = case instr of
      Push val    -> (replace sp val mem, sp + 1)
      Pop         -> (mem, sp - 1)
      PopPush val -> (replace (sp - 1) val mem, sp)
    o = case instr of
      Pop       -> mem !! sp'
      PopPush _ -> mem !! (sp - 1)
      _         -> 0

topEntity
  :: Signal SInstr
  -> Signal Value
topEntity instr = mealy stack5 (repeat 0 :: SMem, 0 :: SP) instr

--
-- Simulation
--
instrs_vec = (Push 3 :> Push 5 :> PopPush 6 :> Pop :> Pop :> Nil)
instrs = toList instrs_vec

-- Synchronous logic simulation
test_sync = sampleN 5 $ simulate_lazy topEntity instrs

-- Synchronous logic testbench generation

--testInput :: Signal SInstr
testInput = stimuliGenerator instrs_vec

--expectedOutput :: Signal Value -> Signal Bool
expectedOutput = outputVerifier (0 :> 0 :> 5 :> 6 :> 3 :> Nil)

test_sync_tb = sampleN 5 $ expectedOutput $ topEntity testInput

-- Combinatorial logic simulation

-- Simulation function that just stores the output
sim_o f s [] = []
sim_o f s (x:xs) = o:sim_o f s' xs
  where
    (s', o) = f s x

-- Simulation function that stores the internal state and the output
sim_full f s [] = []
sim_full f s (x:xs) = (s', o):sim_full f s' xs
  where
    (s', o) = f s x

-- Simulation function that only stores the state of the memory
sim_mem f s [] = []
sim_mem f s (x:xs) = mem:sim_mem f s' xs
  where
    (s'@(mem, sp), o) = f s x

-- Simulation function that only stores the state of the stack pointer
sim_sp f s [] = []
sim_sp f s (x:xs) = sp:sim_sp f s' xs
  where
    (s'@(_, sp), o) = f s x

-- Will contain just the output
test_o = sim_o stack5 (repeat 0 :: SMem, 0 :: SP) instrs

-- Will also contain the internal state
test_full = sim_full stack5 (repeat 0 :: SMem, 0 :: SP) instrs

-- Will only contain the memory state
test_mem = sim_mem stack5 (repeat 0 :: SMem, 0 :: SP) instrs

-- Will only contain the stack pointer state
test_sp = sim_sp stack5 (repeat 0 :: SMem, 0 :: SP) instrs