Clash.Annotations.TopEntity

TopEntity annotations allow us to control hierarchy and naming aspects of the Clash compiler. We have the Synthesize and TestBench annotation.

Synthesize annotation

The Synthesize annotation allows us to:

• Assign names to entities (VHDL) / modules ((System)Verilog), and their ports.
• Put generated HDL files of a logical (sub)entity in their own directory.
• Use cached versions of generated HDL, i.e., prevent recompilation of (sub)entities that have not changed since the last run. Caching is based on a .manifest which is generated alongside the HDL; deleting this file means deleting the cache; changing this file will result in undefined behavior.

Functions with a Synthesize annotation must adhere to the following restrictions:

• Although functions with a Synthesize annotation can of course depend on functions with another Synthesize annotation, they must not be mutually recursive.
• Functions with a Synthesize annotation must be completely monomorphic and first-order, and cannot have any non-representable arguments or result.

Also take the following into account when using Synthesize annotations.

• The Clash compiler is based on the GHC Haskell compiler, and the GHC machinery does not understand Synthesize annotations and it might subsequently decide to inline those functions. You should therefor also add a {-# NOINLINE f #-} pragma to the functions which you give a Synthesize functions.
• Functions with a Synthesize annotation will not be specialized on constants.

Finally, the root module, the module which you pass as an argument to the Clash compiler must either have:

• A function with a Synthesize annotation.
• A function called topEntity.

You apply Synthesize annotations to functions using an ANN pragma:

{-# ANN f (Synthesize {t_name = ..., ...  }) #-}
f x = ...

For example, given the following specification:

module Blinker where

import Clash.Prelude
import Clash.Intel.ClockGen

createDomain vSystem{vName="DomInput", vPeriod=20000}
createDomain vSystem{vName="Dom50", vPeriod=50000}

topEntity
  :: Clock DomInput
  -> Reset DomInput
  -> Enable Dom50
  -> Signal Dom50 Bit
  -> Signal Dom50 (BitVector 8)
topEntity clk20 rstBtn enaBtn modeBtn =
  exposeClockResetEnable
    (mealy blinkerT initialStateBlinkerT . isRising 1)
    clk50
    rstSync
    enaBtn
    modeBtn
 where
  -- Start with the first LED turned on, in rotate mode, with the counter on zero
  initialStateBlinkerT = (1, False, 0)

  -- Signal coming from the reset button is low when pressed, and high when
  -- not pressed. We convert this signal to the polarity of our domain with
  -- unsafeFromLowPolarity.
  rst = unsafeFromLowPolarity (unsafeFromReset rstBtn)

  -- Instantiate a PLL: this stabilizes the incoming clock signal and indicates
  -- when the signal is stable. We're also using it to transform an incoming
  -- clock signal running at 20 MHz to a clock signal running at 50 MHz.
  (clk50, pllStable) =
    altpll
      @Dom50
      (SSymbol @"altpll50")
      clk20
      rst

  -- Synchronize reset to clock signal coming from PLL. We want the reset to
  -- remain active while the PLL is NOT stable, hence the conversion with
  -- unsafeFromLowPolarity
  rstSync =
    resetSynchronizer
      clk50
      (unsafeFromLowPolarity pllStable)

blinkerT
  :: (BitVector 8, Bool, Index 16650001)
  -> Bool
  -> ((BitVector 8, Bool, Index 16650001), BitVector 8)
blinkerT (leds,mode,cntr) key1R = ((leds',mode',cntr'),leds)
  where
    -- clock frequency = 50e6  (50 MHz)
    -- led update rate = 333e-3 (every 333ms)
    cnt_max = 16650000 -- 50e6 * 333e-3

    cntr' | cntr == cnt_max = 0
          | otherwise       = cntr + 1

    mode' | key1R     = not mode
          | otherwise = mode

    leds' | cntr == 0 = if mode then complement leds
                                else rotateL leds 1
          | otherwise = leds

The Clash compiler would normally generate the following topEntity.vhdl file:

-- Automatically generated VHDL-93
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;
use IEEE.MATH_REAL.ALL;
use std.textio.all;
use work.all;
use work.Blinker_topEntity_types.all;

entity topEntity is
  port(-- clock
       clk20   : in Blinker_topEntity_types.clk_DomInput;
       -- reset
       rstBtn  : in Blinker_topEntity_types.rst_DomInput;
       -- enable
       enaBtn  : in Blinker_topEntity_types.en_Dom50;
       modeBtn : in std_logic;
       result  : out std_logic_vector(7 downto 0));
end;

architecture structural of topEntity is
  ...
end;

However, if we add the following Synthesize annotation in the file:

{-# ANN topEntity
  (Synthesize
    { t_name   = "blinker"
    , t_inputs = [ PortName "CLOCK_50"
                 , PortName "KEY0"
                 , PortName "KEY1"
                 , PortName "KEY2" ]
    , t_output = PortName "LED"
    }) #-}

The Clash compiler will generate the following blinker.vhdl file instead:

-- Automatically generated VHDL-93
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;
use IEEE.MATH_REAL.ALL;
use std.textio.all;
use work.all;
use work.blinker_types.all;

entity blinker is
  port(-- clock
       CLOCK_50 : in blinker_types.clk_DomInput;
       -- reset
       KEY0     : in blinker_types.rst_DomInput;
       -- enable
       KEY1     : in blinker_types.en_Dom50;
       KEY2     : in std_logic;
       LED      : out std_logic_vector(7 downto 0));
end;

architecture structural of blinker is
  ...
end;

Where we now have:

• A top-level component that is called blinker.
• Inputs and outputs that have a user-chosen name: CLOCK_50, KEY0, KEY1, KEY2, LED, etc.

See the documentation of Synthesize for the meaning of all its fields.

TestBench annotation

Tell what binder is the test bench for a Synthesize-annotated binder.

entityBeingTested :: ...
entityBeingTested = ...
{-# NOINLINE entityBeingTested #-}
{-# ANN entityBeingTested (defSyn "entityBeingTested") #-}


myTestBench :: Signal System Bool
myTestBench = ... entityBeingTested ...
{-# NOINLINE myTestBench #-}
{-# ANN myTestBench (TestBench 'entityBeingTested) #-}

The TestBench annotation actually already implies a Synthesize annotation on the device under test, so the defSyn in the example could have been omitted. We recommend you supply defSyn explicitly nonetheless. In any case, it will still need the NOINLINE annotation.

Data types

data TopEntity

TopEntity annotation

Constructors

Synthesize

Instruct the Clash compiler to use this top-level function as a separately synthesizable component.

Fields

• t_name :: String

  The name the top-level component should have, put in a correspondingly named file.

• t_inputs :: [PortName]

  List of names that are assigned in-order to the inputs of the component.

• t_output :: PortName

  Name assigned in-order to the outputs of the component. As a Haskell function can only truly return a single value -- with multiple values "wrapped" by a tuple -- this field is not a list, but a single PortName. Use PortProduct to give names to the individual components of the output tuple.

TestBench Name

Tell what binder is the TestBench for a Synthesize-annotated binder.

{-# NOINLINE myTestBench #-}
{-# ANN myTestBench (TestBench 'entityBeingTested) #-}

Instances

Eq TopEntity

Defined in Clash.Annotations.TopEntity

Methods

(==) :: TopEntity -> TopEntity -> Bool

(/=) :: TopEntity -> TopEntity -> Bool

Data TopEntity

Defined in Clash.Annotations.TopEntity

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> TopEntity -> c TopEntity

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c TopEntity

toConstr :: TopEntity -> Constr

dataTypeOf :: TopEntity -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c TopEntity)

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c TopEntity)

gmapT :: (forall b. Data b => b -> b) -> TopEntity -> TopEntity

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> TopEntity -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> TopEntity -> r

gmapQ :: (forall d. Data d => d -> u) -> TopEntity -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> TopEntity -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> TopEntity -> m TopEntity

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> TopEntity -> m TopEntity

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> TopEntity -> m TopEntity

Show TopEntity

Defined in Clash.Annotations.TopEntity

Methods

showsPrec :: Int -> TopEntity -> ShowS

show :: TopEntity -> String

showList :: [TopEntity] -> ShowS

Generic TopEntity

Defined in Clash.Annotations.TopEntity

Associated Types

type Rep TopEntity :: Type -> Type

Methods

from :: TopEntity -> Rep TopEntity x

to :: Rep TopEntity x -> TopEntity

Lift TopEntity

Defined in Clash.Annotations.TopEntity

Methods

lift :: TopEntity -> Q Exp

liftTyped :: TopEntity -> Q (TExp TopEntity)

type Rep TopEntity

Defined in Clash.Annotations.TopEntity

type Rep TopEntity = D1 ('MetaData "TopEntity" "Clash.Annotations.TopEntity" "clash-prelude-1.6.4-inplace" 'False) (C1 ('MetaCons "Synthesize" 'PrefixI 'True) (S1 ('MetaSel ('Just "t_name") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 String) :*: (S1 ('MetaSel ('Just "t_inputs") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 [PortName]) :*: S1 ('MetaSel ('Just "t_output") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 PortName))) :+: C1 ('MetaCons "TestBench" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Name)))

data PortName

Give port names for arguments/results.

Give a data type and function:

data T = MkT Int Bool

{-# ANN f (defSyn "f") #-}
f :: Int -> T -> (T,Bool)
f a b = ...

Clash would normally generate the following VHDL entity:

entity f is
  port(a      : in signed(63 downto 0);
       b_0    : in signed(63 downto 0);
       b_1    : in boolean;
       result : out std_logic_vector(65 downto 0));
end;

However, we can change this by using PortNames. So by:

{-# ANN f
   (Synthesize
      { t_name   = "f"
      , t_inputs = [ PortName "a"
                   , PortName "b" ]
      , t_output = PortName "res" }) #-}
f :: Int -> T -> (T,Bool)
f a b = ...

we get:

entity f is
  port(a   : in signed(63 downto 0);
       b   : in std_logic_vector(64 downto 0);
       res : out std_logic_vector(65 downto 0));
end;

If we want to name fields for tuples/records we have to use PortProduct

{-# ANN f
   (Synthesize
      { t_name   = "f"
      , t_inputs = [ PortName "a"
                   , PortProduct "" [ PortName "b", PortName "c" ] ]
      , t_output = PortProduct "res" [PortName "q"] }) #-}
f :: Int -> T -> (T,Bool)
f a b = ...

So that we get:

entity f is
  port(a     : in signed(63 downto 0);
       b     : in signed(63 downto 0);
       c     : in boolean;
       res_q : out std_logic_vector(64 downto 0);
       res_1 : out boolean);
end;

Notice how we didn't name the second field of the result, and the second output port got PortProduct name, "res", as a prefix for its name.

Constructors

PortName String

You want a port, with the given name, for the entire argument/type

You can use an empty String ,"" , in case you want an auto-generated name.

PortProduct String [PortName]

You want to assign ports to fields of a product argument/type

The first argument of PortProduct is the name of:

1. The signal/wire to which the individual ports are aggregated.
2. The prefix for any unnamed ports below the PortProduct

You can use an empty String ,"" , in case you want an auto-generated name.

Instances

Eq PortName

Defined in Clash.Annotations.TopEntity

Methods

(==) :: PortName -> PortName -> Bool

(/=) :: PortName -> PortName -> Bool

Data PortName

Defined in Clash.Annotations.TopEntity

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> PortName -> c PortName

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c PortName

toConstr :: PortName -> Constr

dataTypeOf :: PortName -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c PortName)

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c PortName)

gmapT :: (forall b. Data b => b -> b) -> PortName -> PortName

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> PortName -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> PortName -> r

gmapQ :: (forall d. Data d => d -> u) -> PortName -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> PortName -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> PortName -> m PortName

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> PortName -> m PortName

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> PortName -> m PortName

Show PortName

Defined in Clash.Annotations.TopEntity

Methods

showsPrec :: Int -> PortName -> ShowS

show :: PortName -> String

showList :: [PortName] -> ShowS

Generic PortName

Defined in Clash.Annotations.TopEntity

Associated Types

type Rep PortName :: Type -> Type

Methods

from :: PortName -> Rep PortName x

to :: Rep PortName x -> PortName

Lift PortName

Defined in Clash.Annotations.TopEntity

Methods

lift :: PortName -> Q Exp

liftTyped :: PortName -> Q (TExp PortName)

type Rep PortName

Defined in Clash.Annotations.TopEntity

type Rep PortName = D1 ('MetaData "PortName" "Clash.Annotations.TopEntity" "clash-prelude-1.6.4-inplace" 'False) (C1 ('MetaCons "PortName" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 String)) :+: C1 ('MetaCons "PortProduct" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 String) :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 [PortName])))

Convenience functions

defSyn :: String -> TopEntity

Default Synthesize annotation which has no specified names for the input and output ports.

>>> defSyn "foo"
Synthesize {t_name = "foo", t_inputs = [], t_output = PortName ""}