    {-|
    Copyright  :  (C) 2015-2016, University of Twente,
                      2017     , Google Inc.
                      2019     , Myrtle Software Ltd,
                      2021-2022, QBayLogic B.V.
    License    :  BSD2 (see the file LICENSE)
    Maintainer :  QBayLogic B.V. <devops@qbaylogic.com>

    ROMs
    -}

    {-# LANGUAGE BangPatterns #-}
    {-# LANGUAGE CPP #-}
    {-# LANGUAGE GADTs #-}
    {-# LANGUAGE RankNTypes #-}

    {-# LANGUAGE Trustworthy #-}

    {-# OPTIONS_GHC -fplugin GHC.TypeLits.KnownNat.Solver #-}
    {-# OPTIONS_HADDOCK show-extensions #-}

    module Clash.Explicit.ROM
      ( -- * Synchronous ROM synchronized to an arbitrary clock
        rom
      , romPow2
        -- * Internal
      , rom#
      )
    where

    import Data.Array             (listArray)
    import Data.Array.Base        (unsafeAt)
    import GHC.Stack              (withFrozenCallStack)
    import GHC.TypeLits           (KnownNat, type (^))
    import Prelude hiding         (length)

    import Clash.Annotations.Primitive (hasBlackBox)
    import Clash.Signal.Internal
      (Clock (..), KnownDomain, Signal (..), Enable, fromEnable)
    import Clash.Sized.Unsigned   (Unsigned)
    import Clash.Sized.Vector     (Vec, length, toList)
    import Clash.XException       (deepErrorX, seqX, NFDataX)

    -- | A ROM with a synchronous read port, with space for 2^@n@ elements
    --
    -- * __NB__: Read value is delayed by 1 cycle
    -- * __NB__: Initial output value is /undefined/, reading it will throw an
    -- 'Clash.XException.XException'
    --
    -- === See also:
    --
    -- * See "Clash.Sized.Fixed#creatingdatafiles" and "Clash.Explicit.BlockRam#usingrams"
    -- for ideas on how to use ROMs and RAMs.
    -- * A large 'Vec' for the content may be too inefficient, depending on how it
    -- is constructed. See 'Clash.Explicit.ROM.File.romFilePow2' and
    -- 'Clash.Explicit.ROM.Blob.romBlobPow2' for different approaches that scale
    -- well.
    romPow2
      :: (KnownDomain dom, KnownNat n, NFDataX a)
      => Clock dom
      -- ^ 'Clock' to synchronize to
      -> Enable dom
      -- ^ 'Enable' line
      -> Vec (2^n) a
      -- ^ ROM content
      --
      -- __NB__: __MUST__ be a constant
      -> Signal dom (Unsigned n)
      -- ^ Read address @r@
      -> Signal dom a
      -- ^ The value of the ROM at address @r@ from the previous clock cycle
    romPow2 :: forall (dom :: Domain) (n :: Nat) a.
    (KnownDomain dom, KnownNat n, NFDataX a) =>
    Clock dom
    -> Enable dom
    -> Vec (2 ^ n) a
    -> Signal dom (Unsigned n)
    -> Signal dom a
    romPow2 = Clock dom
    -> Enable dom
    -> Vec (2 ^ n) a
    -> Signal dom (Unsigned n)
    -> Signal dom a
    forall (dom :: Domain) (n :: Nat) a addr.
    (KnownDomain dom, KnownNat n, NFDataX a, Enum addr) =>
    Clock dom
    -> Enable dom -> Vec n a -> Signal dom addr -> Signal dom a
    rom
    {-# INLINE romPow2 #-}

    -- | A ROM with a synchronous read port, with space for @n@ elements
    --
    -- * __NB__: Read value is delayed by 1 cycle
    -- * __NB__: Initial output value is /undefined/, reading it will throw an
    -- 'Clash.XException.XException'
    --
    -- === See also:
    --
    -- * See "Clash.Sized.Fixed#creatingdatafiles" and "Clash.Explicit.BlockRam#usingrams"
    -- for ideas on how to use ROMs and RAMs.
    -- * A large 'Vec' for the content may be too inefficient, depending on how it
    -- is constructed. See 'Clash.Explicit.ROM.File.romFile' and
    -- 'Clash.Explicit.ROM.Blob.romBlob' for different approaches that scale well.
    rom
      :: (KnownDomain dom, KnownNat n, NFDataX a, Enum addr)
      => Clock dom
      -- ^ 'Clock' to synchronize to
      -> Enable dom
      -- ^ 'Enable' line
      -> Vec n a
      -- ^ ROM content, also determines the size, @n@, of the ROM
      --
      -- __NB__: __MUST__ be a constant
      -> Signal dom addr
      -- ^ Read address @r@
      -> Signal dom a
      -- ^ The value of the ROM at address @r@ from the previous clock cycle
    rom :: forall (dom :: Domain) (n :: Nat) a addr.
    (KnownDomain dom, KnownNat n, NFDataX a, Enum addr) =>
    Clock dom
    -> Enable dom -> Vec n a -> Signal dom addr -> Signal dom a
    rom = \Clock dom
    clk Enable dom
    en Vec n a
    content Signal dom addr
    rd -> Clock dom
    -> Enable dom -> Vec n a -> Signal dom Int -> Signal dom a
    forall (dom :: Domain) (n :: Nat) a.
    (KnownDomain dom, KnownNat n, NFDataX a) =>
    Clock dom
    -> Enable dom -> Vec n a -> Signal dom Int -> Signal dom a
    rom# Clock dom
    clk Enable dom
    en Vec n a
    content (addr -> Int
    forall a. Enum a => a -> Int
    fromEnum (addr -> Int) -> Signal dom addr -> Signal dom Int
    forall (f :: Type -> Type) a b. Functor f => (a -> b) -> f a -> f b
    <$> Signal dom addr
    rd)
    {-# INLINE rom #-}

    -- | ROM primitive
    rom#
      :: forall dom n a
       . (KnownDomain dom, KnownNat n, NFDataX a)
      => Clock dom
      -- ^ 'Clock' to synchronize to
      -> Enable dom
      -- ^ 'Enable' line
      -> Vec n a
      -- ^ ROM content, also determines the size, @n@, of the ROM
      --
      -- __NB__: __MUST__ be a constant
      -> Signal dom Int
      -- ^ Read address @rd@
      -> Signal dom a
      -- ^ The value of the ROM at address @rd@ from the previous clock cycle
    rom# :: forall (dom :: Domain) (n :: Nat) a.
    (KnownDomain dom, KnownNat n, NFDataX a) =>
    Clock dom
    -> Enable dom -> Vec n a -> Signal dom Int -> Signal dom a
    rom# !Clock dom
    _ Enable dom
    en Vec n a
    content =
      a -> Signal dom Bool -> Signal dom Int -> Signal dom a
    go
        ((HasCallStack => a) -> a
    forall a. HasCallStack => (HasCallStack => a) -> a
    withFrozenCallStack (String -> a
    forall a. (NFDataX a, HasCallStack) => String -> a
    deepErrorX String
    "rom: initial value undefined"))
        (Enable dom -> Signal dom Bool
    forall (dom :: Domain). Enable dom -> Signal dom Bool
    fromEnable Enable dom
    en)
     where
      szI :: Int
    szI = Vec n a -> Int
    forall (n :: Nat) a. KnownNat n => Vec n a -> Int
    length Vec n a
    content
      arr :: Array Int a
    arr = (Int, Int) -> [a] -> Array Int a
    forall i e. Ix i => (i, i) -> [e] -> Array i e
    listArray (Int
    0,Int
    szIInt -> Int -> Int
    forall a. Num a => a -> a -> a
    -Int
    1) (Vec n a -> [a]
    forall (n :: Nat) a. Vec n a -> [a]
    toList Vec n a
    content)

      go :: a -> Signal dom Bool -> Signal dom Int -> Signal dom a
    go a
    o (Bool
    e :- Signal dom Bool
    es) rd :: Signal dom Int
    rd@(~(Int
    r :- Signal dom Int
    rs)) =
        let o1 :: a
    o1 = if Bool
    e then Int -> a
    safeAt Int
    r else a
    o
        -- See [Note: register strictness annotations]
        in  a
    o a -> Signal dom a -> Signal dom a
    forall a b. a -> b -> b
    `seqX` a
    o a -> Signal dom a -> Signal dom a
    forall (dom :: Domain) a. a -> Signal dom a -> Signal dom a
    :- (Signal dom Int
    rd Signal dom Int -> Signal dom a -> Signal dom a
    forall a b. a -> b -> b
    `seq` a -> Signal dom Bool -> Signal dom Int -> Signal dom a
    go a
    o1 Signal dom Bool
    es Signal dom Int
    rs)

      safeAt :: Int -> a
      safeAt :: Int -> a
    safeAt Int
    i =
        if (Int
    0 Int -> Int -> Bool
    forall a. Ord a => a -> a -> Bool
    <= Int
    i) Bool -> Bool -> Bool
    && (Int
    i Int -> Int -> Bool
    forall a. Ord a => a -> a -> Bool
    < Int
    szI) then
          Array Int a -> Int -> a
    forall i. Ix i => Array i a -> Int -> a
    forall (a :: Type -> Type -> Type) e i.
    (IArray a e, Ix i) =>
    a i e -> Int -> e
    unsafeAt Array Int a
    arr Int
    i
        else
          (HasCallStack => a) -> a
    forall a. HasCallStack => (HasCallStack => a) -> a
    withFrozenCallStack
            (String -> a
    forall a. (NFDataX a, HasCallStack) => String -> a
    deepErrorX (String
    "rom: address " String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ Int -> String
    forall a. Show a => a -> String
    show Int
    i String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++
                         String
    " not in range [0.." String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ Int -> String
    forall a. Show a => a -> String
    show Int
    szI String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ String
    ")"))
      {-# INLINE safeAt #-}
    -- See: https://github.com/clash-lang/clash-compiler/pull/2511
    {-# CLASH_OPAQUE rom# #-}
    {-# ANN rom# hasBlackBox #-}