module DdrController where 
   {-
    - DDR controller implements top function drive of original
    - list of commands . Assuming data is random . 
    - The first version will drive commands from original command list
    - and adding to each command delta time , corresponding to minimum time
    - possible to execute 
    -}
 
 -- Each command has it's set of attributes
 type Time = Int

 
 data DdrCmd = 
    READ { bank :: Int, col :: Int } |
    READ_PCH { bank :: Int, col :: Int} |
    WRITE { bank :: Int, col :: Int} |
    WRITE_PCH { bank :: Int, col :: Int} |
    PCH_CMD {bank :: Int} |
    ACTIVATE {bank :: Int,row :: Int} |
    PCH_ALL |
    BST

 type DdrCommand = (Time,DdrCmd) -- Type of command containing offset 


 -- Using tree to search for bank info 
 data BankStateSingle = Single { bank_id :: Int , last_ras :: Time , last_cas :: Time , last_pch :: Time }; 

 type BankEntry = (Int,BankStateSingle);
 type BankState = [BankEntry];
 


 -- Check point events
 data TimingCheckPoint = RAS | CAS | PCH | NONE deriving Show

 

 type TimingCondition = (Int,TimingCheckPoint,TimingCheckPoint)
 -- All possible timing constraints
 data (Num a,Show a) => TimingParams a = TRP a | TRCD a | TRAS a 
 
 -- Function to initialize timing params
 -- Randomly generates
   
 -- Create list of entries
 init_bank_set :: [BankStateSingle] -> BankState
 init_bank_set ba_list = zip [0..((length ba_list)-1)] ba_list
 
 timing_configuration :: [(Int,TimingCheckPoint,TimingCheckPoint)] 
 timing_configuration = [ {-tRCD-}(4,RAS,CAS) , {-tRC-} (10,RAS,RAS),{-tRP-} (2,PCH,RAS)]
  

 -- Translation of timing check point
 cmd2timing_checkpoint :: DdrCmd -> TimingCheckPoint
 cmd2timing_checkpoint cmd = case cmd of 
    READ _ _ -> CAS
    READ_PCH _ _ -> CAS
    WRITE _ _ -> CAS
    WRITE_PCH  _  _-> CAS
    PCH_CMD _-> PCH
    ACTIVATE _ _ ->  RAS
    PCH_ALL ->  PCH
    BST -> NONE
    
 -- Return method from bank Id to bank selector func

 bank_timing_update :: Time -> TimingCheckPoint -> BankStateSingle -> BankStateSingle
 bank_timing_update time chk_point bank_state = new_bank_state
  where
    new_bank_state = 
      case  chk_point of
          RAS -> bank_state { last_ras = time }
          CAS -> bank_state { last_cas = time }
          PCH -> bank_state { last_pch = time }


-- Change entry in list with other one if condition is met
--upd_list :: (a -> Bool)->a->[a]->[a]
--upd_list = ()

 -- Calculate cmd delay and update bank state
 -- For each cmd define whether this is RAS,CAS or PCH command
 -- For each cmd , find bank it refers to 
 -- For bank calculate new timing offset based on last occurrence beginning of arc
 -- and longest arc to satisfy
 
 updateCmdDelay :: DdrCommand  -> BankState -> [TimingCondition] -> (DdrCommand,BankState)
 -- There are separate cases for commands
 -- PCH_ALL works on all banks and thus could not be issued before precharge
 -- timing ark is met for all cases
 updateCmdDelay (time,PCH_ALL) state timing = undefined
 updateCmdDelay (time,BST) state timing = ((time,BST),state)

 updateCmdDelay (time,(WRITE wr_bank wr_col)) state timing =

    -- Get all timing arcs to 'cmd2timing_checkpoint

     -- Find maximum by folding of delays and 
     
     -- 
    
     ((new_time,(WRITE wr_bank wr_col)),new_state)
     
     where {
        --new_state = num2bank wr_bank

        new_time = if (earliest_time > time ) then earliest_timeelse time


        new_state = (take ( wr_bank ) state) ++ [(wr_bank,curr_bank_state)]  ++ (drop (wr_bank + 2) state)

        where {

          earliest_time = last_event_occur + (foldl max 0 delays) 

          delays = [ time | (time,_,endpoint) <- timing ]

          last_event_occur = case endpoint of
            RAS -> last_ras curr_bank_state
            CAS -> last_cas curr_bank_state
            PCH -> last_pch curr_bank_state

        -- Blabla
          endpoint = cmd2timing_checkpoint (WRITE wr_bank wr_col)
        

          curr_bank_state =  head . filter (\y -> y == (wr_bank,_) state
      
        -- Update one of mields : last_ras,last_cas,last_pch
        -- For each bank 
        }
     
      }