{-|
Copyright  :  (C) 2013-2016, University of Twente
License    :  BSD2 (see the file LICENSE)
Maintainer :  Christiaan Baaij <christiaan.baaij@gmail.com>
-}

{-# LANGUAGE DataKinds                  #-}
{-# LANGUAGE DeriveDataTypeable         #-}
{-# LANGUAGE FlexibleContexts           #-}
{-# LANGUAGE MagicHash                  #-}
{-# LANGUAGE MultiParamTypeClasses      #-}
{-# LANGUAGE ScopedTypeVariables        #-}
{-# LANGUAGE TemplateHaskell            #-}
{-# LANGUAGE TypeFamilies               #-}
{-# LANGUAGE TypeOperators              #-}
{-# LANGUAGE UndecidableInstances       #-}

{-# LANGUAGE Unsafe #-}

{-# OPTIONS_HADDOCK show-extensions #-}

module CLaSH.Sized.Internal.Unsigned
  ( -- * Datatypes
    Unsigned (..)
    -- * Accessors
    -- ** Length information
  , size#
    -- * Type classes
    -- ** BitConvert
  , pack#
  , unpack#
    -- ** Eq
  , eq#
  , neq#
    -- ** Ord
  , lt#
  , ge#
  , gt#
  , le#
    -- ** Enum (not synthesisable)
  , enumFrom#
  , enumFromThen#
  , enumFromTo#
  , enumFromThenTo#
    -- ** Bounded
  , minBound#
  , maxBound#
    -- ** Num
  , (+#)
  , (-#)
  , (*#)
  , negate#
  , fromInteger#
    -- ** ExtendingNum
  , plus#
  , minus#
  , times#
    -- ** Integral
  , quot#
  , rem#
  , toInteger#
    -- ** Bits
  , and#
  , or#
  , xor#
  , complement#
  , shiftL#
  , shiftR#
  , rotateL#
  , rotateR#
    -- ** Resize
  , resize#
  )
where

import Control.DeepSeq                (NFData (..))
import Control.Lens                   (Index, Ixed (..), IxValue)
import Data.Bits                      (Bits (..), FiniteBits (..))
import Data.Data                      (Data)
import Data.Default                   (Default (..))
import Data.Proxy                     (Proxy (..))
import Text.Read                      (Read (..), ReadPrec)
import GHC.TypeLits                   (KnownNat, Nat, type (+), natVal)
import Language.Haskell.TH            (TypeQ, appT, conT, litT, numTyLit, sigE)
import Language.Haskell.TH.Syntax     (Lift(..))
import Test.QuickCheck.Arbitrary      (Arbitrary (..), CoArbitrary (..),
                                       arbitraryBoundedIntegral,
                                       coarbitraryIntegral)

import CLaSH.Class.BitPack            (BitPack (..))
import CLaSH.Class.Num                (ExtendingNum (..), SaturatingNum (..),
                                       SaturationMode (..))
import CLaSH.Class.Resize             (Resize (..))
import CLaSH.Prelude.BitIndex         ((!), msb, replaceBit, split)
import CLaSH.Prelude.BitReduction     (reduceOr)
import CLaSH.Promoted.Ord             (Max)
import CLaSH.Sized.Internal.BitVector (BitVector (BV), Bit, high, low)
import qualified CLaSH.Sized.Internal.BitVector as BV

-- | Arbitrary-width unsigned integer represented by @n@ bits
--
-- Given @n@ bits, an 'Unsigned' @n@ number has a range of: [0 .. 2^@n@-1]
--
-- __NB__: The 'Num' operators perform @wrap-around@ on overflow. If you want
-- saturation on overflow, check out the 'SaturatingNum' class.
--
-- >>> maxBound :: Unsigned 3
-- 7
-- >>> minBound :: Unsigned 3
-- 0
-- >>> read (show (maxBound :: Unsigned 3)) :: Unsigned 3
-- 7
-- >>> 1 + 2 :: Unsigned 3
-- 3
-- >>> 2 + 6 :: Unsigned 3
-- 0
-- >>> 1 - 3 :: Unsigned 3
-- 6
-- >>> 2 * 3 :: Unsigned 3
-- 6
-- >>> 2 * 4 :: Unsigned 3
-- 0
-- >>> (2 :: Unsigned 3) `times` (4 :: Unsigned 3) :: Unsigned 6
-- 8
-- >>> (2 :: Unsigned 3) `plus` (6 :: Unsigned 3) :: Unsigned 4
-- 8
-- >>> satPlus SatSymmetric 2 6 :: Unsigned 3
-- 7
-- >>> satMin SatSymmetric 2 3 :: Unsigned 3
-- 0
newtype Unsigned (n :: Nat) =
    -- | The constructor, 'U', and the field, 'unsafeToInteger', are not
    -- synthesisable.
    U { unsafeToInteger :: Integer }
  deriving Data

{-# NOINLINE size# #-}
size# :: KnownNat n => Unsigned n -> Int
size# u = fromInteger (natVal u)

instance NFData (Unsigned n) where
  rnf (U i) = rnf i `seq` ()
  {-# NOINLINE rnf #-}
  -- NOINLINE is needed so that CLaSH doesn't trip on the "Unsigned ~# Integer"
  -- coercion

instance Show (Unsigned n) where
  show (U i) = show i
  {-# NOINLINE show #-}

-- | None of the 'Read' class' methods are synthesisable.
instance KnownNat n => Read (Unsigned n) where
  readPrec = fromIntegral <$> (readPrec :: ReadPrec Word)

instance BitPack (Unsigned n) where
  type BitSize (Unsigned n) = n
  pack   = pack#
  unpack = unpack#

{-# NOINLINE pack# #-}
pack# :: Unsigned n -> BitVector n
pack# (U i) = BV i

{-# NOINLINE unpack# #-}
unpack# :: BitVector n -> Unsigned n
unpack# (BV i) = U i

instance Eq (Unsigned n) where
  (==) = eq#
  (/=) = neq#

{-# NOINLINE eq# #-}
eq# :: Unsigned n -> Unsigned n -> Bool
eq# (U v1) (U v2) = v1 == v2

{-# NOINLINE neq# #-}
neq# :: Unsigned n -> Unsigned n -> Bool
neq# (U v1) (U v2) = v1 /= v2

instance Ord (Unsigned n) where
  (<)  = lt#
  (>=) = ge#
  (>)  = gt#
  (<=) = le#

lt#,ge#,gt#,le# :: Unsigned n -> Unsigned n -> Bool
{-# NOINLINE lt# #-}
lt# (U n) (U m) = n < m
{-# NOINLINE ge# #-}
ge# (U n) (U m) = n >= m
{-# NOINLINE gt# #-}
gt# (U n) (U m) = n > m
{-# NOINLINE le# #-}
le# (U n) (U m) = n <= m

-- | The functions: 'enumFrom', 'enumFromThen', 'enumFromTo', and
-- 'enumFromThenTo', are not synthesisable.
instance KnownNat n => Enum (Unsigned n) where
  succ           = (+# fromInteger# 1)
  pred           = (-# fromInteger# 1)
  toEnum         = fromInteger# . toInteger
  fromEnum       = fromEnum . toInteger#
  enumFrom       = enumFrom#
  enumFromThen   = enumFromThen#
  enumFromTo     = enumFromTo#
  enumFromThenTo = enumFromThenTo#

{-# NOINLINE enumFrom# #-}
{-# NOINLINE enumFromThen# #-}
{-# NOINLINE enumFromTo# #-}
{-# NOINLINE enumFromThenTo# #-}
enumFrom#       :: Unsigned n -> [Unsigned n]
enumFromThen#   :: Unsigned n -> Unsigned n -> [Unsigned n]
enumFromTo#     :: Unsigned n -> Unsigned n -> [Unsigned n]
enumFromThenTo# :: Unsigned n -> Unsigned n -> Unsigned n -> [Unsigned n]
enumFrom# x             = map U [unsafeToInteger x ..]
enumFromThen# x y       = map U [unsafeToInteger x, unsafeToInteger y ..]
enumFromTo# x y         = map U [unsafeToInteger x .. unsafeToInteger y]
enumFromThenTo# x1 x2 y = map U [unsafeToInteger x1, unsafeToInteger x2 .. unsafeToInteger y]

instance KnownNat n => Bounded (Unsigned n) where
  minBound = minBound#
  maxBound = maxBound#

{-# NOINLINE minBound# #-}
minBound# :: Unsigned n
minBound# = U 0

{-# NOINLINE maxBound# #-}
maxBound# :: KnownNat n => Unsigned n
maxBound# = let res = U ((2 ^ natVal res) - 1) in res

instance KnownNat n => Num (Unsigned n) where
  (+)         = (+#)
  (-)         = (-#)
  (*)         = (*#)
  negate      = negate#
  abs         = id
  signum bv   = resize# (unpack# (reduceOr bv))
  fromInteger = fromInteger#

(+#),(-#),(*#) :: KnownNat n => Unsigned n -> Unsigned n -> Unsigned n
{-# NOINLINE (+#) #-}
(+#) (U i) (U j) = fromInteger_INLINE (i + j)

{-# NOINLINE (-#) #-}
(-#) (U i) (U j) = fromInteger_INLINE (i - j)

{-# NOINLINE (*#) #-}
(*#) (U i) (U j) = fromInteger_INLINE (i * j)

{-# NOINLINE negate# #-}
negate# :: KnownNat n => Unsigned n -> Unsigned n
negate# u@(U i) = sz `seq` U (sz - i)
  where
    sz = 2 ^ natVal u

{-# NOINLINE fromInteger# #-}
fromInteger# :: KnownNat n => Integer -> Unsigned n
fromInteger# = fromInteger_INLINE

{-# INLINE fromInteger_INLINE #-}
fromInteger_INLINE :: forall n . KnownNat n => Integer -> Unsigned n
fromInteger_INLINE i = sz `seq` U (i `mod` (shiftL 1 sz))
  where
    sz = fromInteger (natVal (Proxy :: Proxy n))

instance (KnownNat (1 + Max m n), KnownNat (m + n)) =>
  ExtendingNum (Unsigned m) (Unsigned n) where
  type AResult (Unsigned m) (Unsigned n) = Unsigned (1 + Max m n)
  plus  = plus#
  minus = minus#
  type MResult (Unsigned m) (Unsigned n) = Unsigned (m + n)
  times = times#

plus#, minus# :: KnownNat (1 + Max m n) => Unsigned m -> Unsigned n
              -> Unsigned (1 + Max m n)
{-# NOINLINE plus# #-}
plus# (U a) (U b) = fromInteger_INLINE (a + b)

{-# NOINLINE minus# #-}
minus# (U a) (U b) = fromInteger_INLINE (a - b)

{-# NOINLINE times# #-}
times# :: KnownNat (m + n) => Unsigned m -> Unsigned n -> Unsigned (m + n)
times# (U a) (U b) = fromInteger_INLINE (a * b)

instance KnownNat n => Real (Unsigned n) where
  toRational = toRational . toInteger#

instance KnownNat n => Integral (Unsigned n) where
  quot        = quot#
  rem         = rem#
  div         = quot#
  mod         = rem#
  quotRem n d = (n `quot#` d,n `rem#` d)
  divMod  n d = (n `quot#` d,n `rem#` d)
  toInteger   = toInteger#

quot#,rem# :: Unsigned n -> Unsigned n -> Unsigned n
{-# NOINLINE quot# #-}
quot# (U i) (U j) = U (i `quot` j)
{-# NOINLINE rem# #-}
rem# (U i) (U j) = U (i `rem` j)

{-# NOINLINE toInteger# #-}
toInteger# :: Unsigned n -> Integer
toInteger# (U i) = i

instance (KnownNat n, KnownNat (n + 1), KnownNat (n + 2)) => Bits (Unsigned n) where
  (.&.)             = and#
  (.|.)             = or#
  xor               = xor#
  complement        = complement#
  zeroBits          = 0
  bit i             = replaceBit i high 0
  setBit v i        = replaceBit i high v
  clearBit v i      = replaceBit i low  v
  complementBit v i = replaceBit i (BV.complement# (v ! i)) v
  testBit v i       = v ! i == high
  bitSizeMaybe v    = Just (size# v)
  bitSize           = size#
  isSigned _        = False
  shiftL v i        = shiftL# v i
  shiftR v i        = shiftR# v i
  rotateL v i       = rotateL# v i
  rotateR v i       = rotateR# v i
  popCount u        = popCount (pack# u)

{-# NOINLINE and# #-}
and# :: Unsigned n -> Unsigned n -> Unsigned n
and# (U v1) (U v2) = U (v1 .&. v2)

{-# NOINLINE or# #-}
or# :: Unsigned n -> Unsigned n -> Unsigned n
or# (U v1) (U v2) = U (v1 .|. v2)

{-# NOINLINE xor# #-}
xor# :: Unsigned n -> Unsigned n -> Unsigned n
xor# (U v1) (U v2) = U (v1 `xor` v2)

{-# NOINLINE complement# #-}
complement# :: KnownNat n => Unsigned n -> Unsigned n
complement# (U i) = fromInteger_INLINE (complement i)

shiftL#, shiftR#, rotateL#, rotateR# :: KnownNat n => Unsigned n -> Int
                                     -> Unsigned n
{-# NOINLINE shiftL# #-}
shiftL# (U v) i
  | i < 0     = error
              $ "'shiftL undefined for negative number: " ++ show i
  | otherwise = fromInteger_INLINE (shiftL v i)

{-# NOINLINE shiftR# #-}
shiftR# (U v) i
  | i < 0     = error
              $ "'shiftR undefined for negative number: " ++ show i
  | otherwise = fromInteger_INLINE (shiftR v i)

{-# NOINLINE rotateL# #-}
rotateL# _ b | b < 0 = error "'shiftL undefined for negative numbers"
rotateL# bv@(U n) b   = fromInteger_INLINE (l .|. r)
  where
    l    = shiftL n b'
    r    = shiftR n b''

    b'   = b `mod` sz
    b''  = sz - b'
    sz   = fromInteger (natVal bv)

{-# NOINLINE rotateR# #-}
rotateR# _ b | b < 0 = error "'shiftR undefined for negative numbers"
rotateR# bv@(U n) b   = fromInteger_INLINE (l .|. r)
  where
    l   = shiftR n b'
    r   = shiftL n b''

    b'  = b `mod` sz
    b'' = sz - b'
    sz  = fromInteger (natVal bv)

instance (KnownNat n, KnownNat (n + 1), KnownNat (n + 2)) => FiniteBits (Unsigned n) where
  finiteBitSize = size#

instance Resize Unsigned where
  resize     = resize#
  zeroExtend = resize#
  signExtend = resize#
  truncateB  = resize#

{-# NOINLINE resize# #-}
resize# :: KnownNat m => Unsigned n -> Unsigned m
resize# (U i) = fromInteger_INLINE i

instance Default (Unsigned n) where
  def = minBound#

instance KnownNat n => Lift (Unsigned n) where
  lift u@(U i) = sigE [| fromInteger# i |] (decUnsigned (natVal u))
  {-# NOINLINE lift #-}

decUnsigned :: Integer -> TypeQ
decUnsigned n = appT (conT ''Unsigned) (litT $ numTyLit n)

instance (KnownNat n, KnownNat (1 + n), KnownNat (n + n)) =>
  SaturatingNum (Unsigned n) where
  satPlus SatWrap a b = a +# b
  satPlus w a b = case msb r of
                    0 -> resize# r
                    _ -> case w of
                           SatZero  -> minBound#
                           _        -> maxBound#
    where
      r = plus# a b

  satMin SatWrap a b = a -# b
  satMin _ a b = case msb r of
                    0 -> resize# r
                    _ -> minBound#
    where
      r = minus# a b

  satMult SatWrap a b = a *# b
  satMult w a b = case rL of
                    0 -> unpack# rR
                    _ -> case w of
                           SatZero  -> minBound#
                           _        -> maxBound#
    where
      r       = times# a b
      (rL,rR) = split r

instance KnownNat n => Arbitrary (Unsigned n) where
  arbitrary = arbitraryBoundedIntegral
  shrink    = BV.shrinkSizedUnsigned

instance KnownNat n => CoArbitrary (Unsigned n) where
  coarbitrary = coarbitraryIntegral

type instance Index   (Unsigned n) = Int
type instance IxValue (Unsigned n) = Bit
instance KnownNat n => Ixed (Unsigned n) where
  ix i f s = unpack# <$> BV.replaceBit# (pack# s) i
                     <$> f (BV.index# (pack# s) i)