Clash.Explicit.Signal

Clash has synchronous Signals in the form of:

Signal (dom :: Symbol) a

Where a is the type of the value of the Signal, for example Int or Bool, and dom is the clock- (and reset-) domain to which the memory elements manipulating these Signals belong.

The type-parameter, dom, is of the kind Domain - a simple string. That string refers to a single synthesis domain. A synthesis domain describes the behavior of certain aspects of memory elements in it. More specifically, a domain looks like:

DomainConfiguration
  { _name:: Symbol
  -- ^ Domain name
  , _period :: Nat
  -- ^ Clock period in ps
  , _edge :: ActiveEdge
  -- ^ Active edge of the clock
  , _reset :: ResetKind
  -- ^ Whether resets are synchronous (edge-sensitive) or asynchronous (level-sensitive)
  , _init :: InitBehavior
  -- ^ Whether the initial (or "power up") value of memory elements is
  -- unknown/undefined, or configurable to a specific value
  , _polarity :: ResetPolarity
  -- ^ Whether resets are active high or active low
  }

Check the documentation of each of the types to see the various options Clash provides. In order to specify a domain, an instance of KnownDomain should be made. Clash provides a standard implementation, called System, that is configured as follows:

instance KnownDomain System where
  type KnownConf System = 'DomainConfiguration System 10000 'Rising 'Asynchronous 'Defined 'ActiveHigh
  knownDomain = SDomainConfiguration SSymbol SNat SRising SAsynchronous SDefined SActiveHigh

In words, "System" is a synthesis domain with a clock running with a period of 10000 ps (100 MHz). Memory elements update their state on the rising edge of the clock, can be reset asynchronously with regards to the clock, and have defined power up values if applicable.

In order to create a new domain, you don't have to instantiate it explicitly. Instead, you can have createDomain create a domain for you. You can also use the same function to subclass existing domains.

• NB: "Bad things"™ happen when you actually use a clock period of 0, so do not do that!
• NB: You should be judicious using a clock with period of 1 as you can never create a clock that goes any faster!
• NB: For the best compatibility make sure your period is divisible by 2, because some VHDL simulators don't support fractions of picoseconds.
• NB: Whether System has good defaults depends on your target platform. Check out IntelSystem and XilinxSystem too!

Explicit clocks and resets, and meta-stability

When using multiple clocks and/or reset lines there are ways to accidentally introduce situations that are prone to metastability. These bugs are incredibly hard to debug as they often cannot be simulated, so it's best to prevent them in the first place. This section outlines the situations in which metastability arises and how to prevent it.

Two types of resets exist: synchronous and asynchronous resets. These reset types are encoded in a synthesis domain. For the following examples we assume the following exist:

DomainConfiguration "SyncExample" _period _edge Synchronous _init
DomainConfiguration "AsyncExample" _period _edge Asynchronous _init

See the previous section on how to use domains.

We now go over the clock and reset line combinations and explain when they can potentially introduce situations prone to meta-stability:

• Reset situation 1:

  f :: Reset "SyncExample" -> Reset "SyncExample" -> ..
  f x y = ..
  

  There are no problems here, because although x and y can have different values, components to these reset lines are reset synchronously, and there is no metastability situation.

• Reset situation 2:

  g :: Reset "AsyncExample" -> Reset "AsyncExample" -> ..
  g x y = ..
  

  This situation can be prone to metastability, because although x and y belong to the same domain according to their domain, there is no guarantee that they actually originate from the same source. This means that one component can enter its reset state asynchronously to another component, inducing metastability in the other component.

• Clock situation:

  k :: Clock dom -> Clock dom -> ..
  k x y = ..
  

  The situation above is potentially prone to metastability, because even though x and y belong to the same domain according to their domain, there is no guarantee that they actually originate from the same source. They could hence be connected to completely unrelated clock sources, and components can then induce metastable states in others.

Synchronous signal

data Signal (dom :: Domain) a

Clash has synchronous Signals in the form of:

Signal (dom :: Domain) a

Where a is the type of the value of the Signal, for example Int or Bool, and dom is the clock- (and reset-) domain to which the memory elements manipulating these Signals belong.

The type-parameter, dom, is of the kind Domain - a simple string. That string refers to a single synthesis domain. A synthesis domain describes the behavior of certain aspects of memory elements in it.

• NB: "Bad things"™ happen when you actually use a clock period of 0, so do not do that!
• NB: You should be judicious using a clock with period of 1 as you can never create a clock that goes any faster!
• NB: For the best compatibility make sure your period is divisible by 2, because some VHDL simulators don't support fractions of picoseconds.
• NB: Whether System has good defaults depends on your target platform. Check out IntelSystem and XilinxSystem too!

Signals have the type role

>>> :i Signal
type role Signal nominal representational
...

as it is safe to coerce the underlying value of a signal, but not safe to coerce a signal between different synthesis domains.

See the module documentation of Clash.Signal for more information about domains.

Instances

Lift a => Lift (Signal dom a :: Type)

Defined in Clash.Signal.Internal

Methods

lift :: Signal dom a -> Q Exp

liftTyped :: Signal dom a -> Q (TExp (Signal dom a))

AssertionValue dom (Signal dom Bool)

Stream of booleans, originating from a circuit

Defined in Clash.Verification.Internal

Methods

toAssertionValue :: Signal dom Bool -> Assertion dom

Functor (Signal dom)

Defined in Clash.Signal.Internal

Methods

fmap :: (a -> b) -> Signal dom a -> Signal dom b

(<$) :: a -> Signal dom b -> Signal dom a

Applicative (Signal dom)

Defined in Clash.Signal.Internal

Methods

pure :: a -> Signal dom a

(<*>) :: Signal dom (a -> b) -> Signal dom a -> Signal dom b

liftA2 :: (a -> b -> c) -> Signal dom a -> Signal dom b -> Signal dom c

(*>) :: Signal dom a -> Signal dom b -> Signal dom b

(<*) :: Signal dom a -> Signal dom b -> Signal dom a

Foldable (Signal dom)

NB: Not synthesizable

NB: In "foldr f z s":

• The function f should be lazy in its second argument.
• The z element will never be used.

Defined in Clash.Signal.Internal

Methods

fold :: Monoid m => Signal dom m -> m

foldMap :: Monoid m => (a -> m) -> Signal dom a -> m

foldMap' :: Monoid m => (a -> m) -> Signal dom a -> m

foldr :: (a -> b -> b) -> b -> Signal dom a -> b

foldr' :: (a -> b -> b) -> b -> Signal dom a -> b

foldl :: (b -> a -> b) -> b -> Signal dom a -> b

foldl' :: (b -> a -> b) -> b -> Signal dom a -> b

foldr1 :: (a -> a -> a) -> Signal dom a -> a

foldl1 :: (a -> a -> a) -> Signal dom a -> a

toList :: Signal dom a -> [a]

null :: Signal dom a -> Bool

length :: Signal dom a -> Int

elem :: Eq a => a -> Signal dom a -> Bool

maximum :: Ord a => Signal dom a -> a

minimum :: Ord a => Signal dom a -> a

sum :: Num a => Signal dom a -> a

product :: Num a => Signal dom a -> a

Traversable (Signal dom)

Defined in Clash.Signal.Internal

Methods

traverse :: Applicative f => (a -> f b) -> Signal dom a -> f (Signal dom b)

sequenceA :: Applicative f => Signal dom (f a) -> f (Signal dom a)

mapM :: Monad m => (a -> m b) -> Signal dom a -> m (Signal dom b)

sequence :: Monad m => Signal dom (m a) -> m (Signal dom a)

Fractional a => Fractional (Signal dom a)

Defined in Clash.Signal.Internal

Methods

(/) :: Signal dom a -> Signal dom a -> Signal dom a

recip :: Signal dom a -> Signal dom a

fromRational :: Rational -> Signal dom a

Num a => Num (Signal dom a)

Defined in Clash.Signal.Internal

Methods

(+) :: Signal dom a -> Signal dom a -> Signal dom a

(-) :: Signal dom a -> Signal dom a -> Signal dom a

(*) :: Signal dom a -> Signal dom a -> Signal dom a

negate :: Signal dom a -> Signal dom a

abs :: Signal dom a -> Signal dom a

signum :: Signal dom a -> Signal dom a

fromInteger :: Integer -> Signal dom a

Show a => Show (Signal dom a)

Defined in Clash.Signal.Internal

Methods

showsPrec :: Int -> Signal dom a -> ShowS

show :: Signal dom a -> String

showList :: [Signal dom a] -> ShowS

Arbitrary a => Arbitrary (Signal dom a)

Defined in Clash.Signal.Internal

Methods

arbitrary :: Gen (Signal dom a)

shrink :: Signal dom a -> [Signal dom a]

CoArbitrary a => CoArbitrary (Signal dom a)

Defined in Clash.Signal.Internal

Methods

coarbitrary :: Signal dom a -> Gen b -> Gen b

Default a => Default (Signal dom a)

Defined in Clash.Signal.Internal

Methods

def :: Signal dom a

NFDataX a => NFDataX (Signal domain a)

Defined in Clash.Signal.Internal

Methods

deepErrorX :: String -> Signal domain a

hasUndefined :: Signal domain a -> Bool

ensureSpine :: Signal domain a -> Signal domain a

rnfX :: Signal domain a -> ()

Clocks (Clock c1, Signal pllLock Bool)

Defined in Clash.Clocks

Associated Types

type ClocksCxt (Clock c1, Signal pllLock Bool)

type NumOutClocks (Clock c1, Signal pllLock Bool) :: Nat

Methods

clocks :: forall (domIn :: Domain). (KnownDomain domIn, ClocksCxt (Clock c1, Signal pllLock Bool)) => Clock domIn -> Reset domIn -> (Clock c1, Signal pllLock Bool)

Clocks (Clock c1, Clock c2, Signal pllLock Bool)

Defined in Clash.Clocks

Associated Types

type ClocksCxt (Clock c1, Clock c2, Signal pllLock Bool)

type NumOutClocks (Clock c1, Clock c2, Signal pllLock Bool) :: Nat

Methods

clocks :: forall (domIn :: Domain). (KnownDomain domIn, ClocksCxt (Clock c1, Clock c2, Signal pllLock Bool)) => Clock domIn -> Reset domIn -> (Clock c1, Clock c2, Signal pllLock Bool)

Clocks (Clock c1, Clock c2, Clock c3, Signal pllLock Bool)

Defined in Clash.Clocks

Associated Types

type ClocksCxt (Clock c1, Clock c2, Clock c3, Signal pllLock Bool)

type NumOutClocks (Clock c1, Clock c2, Clock c3, Signal pllLock Bool) :: Nat

Methods

clocks :: forall (domIn :: Domain). (KnownDomain domIn, ClocksCxt (Clock c1, Clock c2, Clock c3, Signal pllLock Bool)) => Clock domIn -> Reset domIn -> (Clock c1, Clock c2, Clock c3, Signal pllLock Bool)

type HasDomain dom1 (Signal dom2 a)

Defined in Clash.Class.HasDomain.HasSpecificDomain

type HasDomain dom1 (Signal dom2 a) = DomEq dom1 dom2

type TryDomain t (Signal dom a)

Defined in Clash.Class.HasDomain.HasSingleDomain

type TryDomain t (Signal dom a) = 'Found dom

type ClocksCxt (Clock c1, Signal pllLock Bool)

Defined in Clash.Clocks

type ClocksCxt (Clock c1, Signal pllLock Bool) = (KnownDomain c1, KnownDomain pllLock)

type NumOutClocks (Clock c1, Signal pllLock Bool)

Defined in Clash.Clocks

type NumOutClocks (Clock c1, Signal pllLock Bool) = 1

type ClocksCxt (Clock c1, Clock c2, Signal pllLock Bool)

Defined in Clash.Clocks

type ClocksCxt (Clock c1, Clock c2, Signal pllLock Bool) = (KnownDomain c1, KnownDomain c2, KnownDomain pllLock)

type NumOutClocks (Clock c1, Clock c2, Signal pllLock Bool)

Defined in Clash.Clocks

type NumOutClocks (Clock c1, Clock c2, Signal pllLock Bool) = 2

type ClocksCxt (Clock c1, Clock c2, Clock c3, Signal pllLock Bool)

Defined in Clash.Clocks

type ClocksCxt (Clock c1, Clock c2, Clock c3, Signal pllLock Bool) = (KnownDomain c1, KnownDomain c2, KnownDomain c3, KnownDomain pllLock)

type NumOutClocks (Clock c1, Clock c2, Clock c3, Signal pllLock Bool)

Defined in Clash.Clocks

type NumOutClocks (Clock c1, Clock c2, Clock c3, Signal pllLock Bool) = 3

data BiSignalIn (ds :: BiSignalDefault) (dom :: Domain) (n :: Nat)

The in part of an inout port. BiSignalIn has the type role

>>> :i BiSignalIn
type role BiSignalIn nominal nominal nominal
...

as it is not safe to coerce the default behaviour, synthesis domain or width of the data in the signal.

data BiSignalOut (ds :: BiSignalDefault) (dom :: Domain) (n :: Nat)

The out part of an inout port

Wraps (multiple) writing signals. The semantics are such that only one of the signals may write at a single time step.

BiSignalOut has the type role

>>> :i BiSignalOut
type role BiSignalOut nominal nominal nominal
...

as it is not safe to coerce the default behaviour, synthesis domain or width of the data in the signal.

Instances

Semigroup (BiSignalOut defaultState dom n)

NB: Not synthesizable

Defined in Clash.Signal.BiSignal

Methods

(<>) :: BiSignalOut defaultState dom n -> BiSignalOut defaultState dom n -> BiSignalOut defaultState dom n

sconcat :: NonEmpty (BiSignalOut defaultState dom n) -> BiSignalOut defaultState dom n

stimes :: Integral b => b -> BiSignalOut defaultState dom n -> BiSignalOut defaultState dom n

Monoid (BiSignalOut defaultState dom n)

Monoid instance to support concatenating

NB: Not synthesizable

Defined in Clash.Signal.BiSignal

Methods

mempty :: BiSignalOut defaultState dom n

mappend :: BiSignalOut defaultState dom n -> BiSignalOut defaultState dom n -> BiSignalOut defaultState dom n

mconcat :: [BiSignalOut defaultState dom n] -> BiSignalOut defaultState dom n

type HasDomain dom1 (BiSignalOut ds dom2 n)

Defined in Clash.Signal.BiSignal

type HasDomain dom1 (BiSignalOut ds dom2 n) = DomEq dom1 dom2

type TryDomain t (BiSignalOut ds dom n)

Defined in Clash.Signal.BiSignal

type TryDomain t (BiSignalOut ds dom n) = 'Found dom

data BiSignalDefault

Used to specify the default behavior of a "BiSignal", i.e. what value is read when no value is being written to it.

Constructors

PullUp

inout port behaves as if connected to a pull-up resistor

PullDown

inout port behaves as if connected to a pull-down resistor

Floating

inout port behaves as if is floating. Reading a floating "BiSignal" value in simulation will yield an errorX (undefined value).

Instances

Show BiSignalDefault

Defined in Clash.Signal.BiSignal

Methods

showsPrec :: Int -> BiSignalDefault -> ShowS

show :: BiSignalDefault -> String

showList :: [BiSignalDefault] -> ShowS

Domain

type Domain = Symbol

class (KnownSymbol dom, KnownNat (DomainPeriod dom)) => KnownDomain (dom :: Domain) where

A KnownDomain constraint indicates that a circuit's behavior depends on some properties of a domain. See DomainConfiguration for more information.

Associated Types

type KnownConf dom :: DomainConfiguration

Methods

knownDomain :: SDomainConfiguration dom (KnownConf dom)

Returns SDomainConfiguration corresponding to an instance's DomainConfiguration.

Example usage:

>>> knownDomain @System
SDomainConfiguration {sName = SSymbol @"System", sPeriod = SNat @10000, sActiveEdge = SRising, sResetKind = SAsynchronous, sInitBehavior = SDefined, sResetPolarity = SActiveHigh}

Instances

KnownDomain XilinxSystem

System instance with defaults set for Xilinx FPGAs

Defined in Clash.Signal.Internal

Associated Types

type KnownConf XilinxSystem :: DomainConfiguration

Methods

knownDomain :: SDomainConfiguration XilinxSystem (KnownConf XilinxSystem)

KnownDomain IntelSystem

System instance with defaults set for Intel FPGAs

Defined in Clash.Signal.Internal

Associated Types

type KnownConf IntelSystem :: DomainConfiguration

Methods

knownDomain :: SDomainConfiguration IntelSystem (KnownConf IntelSystem)

KnownDomain System

A clock (and reset) dom with clocks running at 100 MHz

Defined in Clash.Signal.Internal

Associated Types

type KnownConf System :: DomainConfiguration

Methods

knownDomain :: SDomainConfiguration System (KnownConf System)

type KnownConfiguration dom conf = (KnownDomain dom, KnownConf dom ~ conf)

data ActiveEdge

Determines clock edge memory elements are sensitive to. Not yet implemented.

Constructors

Rising

Elements are sensitive to the rising edge (low-to-high) of the clock.

Falling

Elements are sensitive to the falling edge (high-to-low) of the clock.

Instances

Eq ActiveEdge

Defined in Clash.Signal.Internal

Methods

(==) :: ActiveEdge -> ActiveEdge -> Bool

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

Data ActiveEdge

Defined in Clash.Signal.Internal

Methods

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

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

toConstr :: ActiveEdge -> Constr

dataTypeOf :: ActiveEdge -> DataType

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

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

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

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

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

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

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

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

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

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

Ord ActiveEdge

Defined in Clash.Signal.Internal

Methods

compare :: ActiveEdge -> ActiveEdge -> Ordering

(<) :: ActiveEdge -> ActiveEdge -> Bool

(<=) :: ActiveEdge -> ActiveEdge -> Bool

(>) :: ActiveEdge -> ActiveEdge -> Bool

(>=) :: ActiveEdge -> ActiveEdge -> Bool

max :: ActiveEdge -> ActiveEdge -> ActiveEdge

min :: ActiveEdge -> ActiveEdge -> ActiveEdge

Read ActiveEdge

Defined in Clash.Signal.Internal

Methods

readsPrec :: Int -> ReadS ActiveEdge

readList :: ReadS [ActiveEdge]

readPrec :: ReadPrec ActiveEdge

readListPrec :: ReadPrec [ActiveEdge]

Show ActiveEdge

Defined in Clash.Signal.Internal

Methods

showsPrec :: Int -> ActiveEdge -> ShowS

show :: ActiveEdge -> String

showList :: [ActiveEdge] -> ShowS

Generic ActiveEdge

Defined in Clash.Signal.Internal

Associated Types

type Rep ActiveEdge :: Type -> Type

Methods

from :: ActiveEdge -> Rep ActiveEdge x

to :: Rep ActiveEdge x -> ActiveEdge

Binary ActiveEdge

Defined in Clash.Signal.Internal

Methods

put :: ActiveEdge -> Put

get :: Get ActiveEdge

putList :: [ActiveEdge] -> Put

NFData ActiveEdge

Defined in Clash.Signal.Internal

Methods

rnf :: ActiveEdge -> ()

Hashable ActiveEdge

Defined in Clash.Signal.Internal

Methods

hashWithSalt :: Int -> ActiveEdge -> Int

hash :: ActiveEdge -> Int

type Rep ActiveEdge

Defined in Clash.Signal.Internal

type Rep ActiveEdge = D1 ('MetaData "ActiveEdge" "Clash.Signal.Internal" "clash-prelude-1.8.0-inplace" 'False) (C1 ('MetaCons "Rising" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "Falling" 'PrefixI 'False) (U1 :: Type -> Type))

data SActiveEdge (edge :: ActiveEdge) where

Singleton version of ActiveEdge

Constructors

SRising :: SActiveEdge 'Rising

SFalling :: SActiveEdge 'Falling

Instances

Show (SActiveEdge edge)

Defined in Clash.Signal.Internal

Methods

showsPrec :: Int -> SActiveEdge edge -> ShowS

show :: SActiveEdge edge -> String

showList :: [SActiveEdge edge] -> ShowS

data InitBehavior

Constructors

Unknown

Power up value of memory elements is unknown.

Defined

If applicable, power up value of a memory element is defined. Applies to registers for example, but not to blockRam.

Instances

Eq InitBehavior

Defined in Clash.Signal.Internal

Methods

(==) :: InitBehavior -> InitBehavior -> Bool

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

Data InitBehavior

Defined in Clash.Signal.Internal

Methods

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

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

toConstr :: InitBehavior -> Constr

dataTypeOf :: InitBehavior -> DataType

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

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

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

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

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

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

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

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

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

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

Ord InitBehavior

Defined in Clash.Signal.Internal

Methods

compare :: InitBehavior -> InitBehavior -> Ordering

(<) :: InitBehavior -> InitBehavior -> Bool

(<=) :: InitBehavior -> InitBehavior -> Bool

(>) :: InitBehavior -> InitBehavior -> Bool

(>=) :: InitBehavior -> InitBehavior -> Bool

max :: InitBehavior -> InitBehavior -> InitBehavior

min :: InitBehavior -> InitBehavior -> InitBehavior

Read InitBehavior

Defined in Clash.Signal.Internal

Methods

readsPrec :: Int -> ReadS InitBehavior

readList :: ReadS [InitBehavior]

readPrec :: ReadPrec InitBehavior

readListPrec :: ReadPrec [InitBehavior]

Show InitBehavior

Defined in Clash.Signal.Internal

Methods

showsPrec :: Int -> InitBehavior -> ShowS

show :: InitBehavior -> String

showList :: [InitBehavior] -> ShowS

Generic InitBehavior

Defined in Clash.Signal.Internal

Associated Types

type Rep InitBehavior :: Type -> Type

Methods

from :: InitBehavior -> Rep InitBehavior x

to :: Rep InitBehavior x -> InitBehavior

Binary InitBehavior

Defined in Clash.Signal.Internal

Methods

put :: InitBehavior -> Put

get :: Get InitBehavior

putList :: [InitBehavior] -> Put

NFData InitBehavior

Defined in Clash.Signal.Internal

Methods

rnf :: InitBehavior -> ()

Hashable InitBehavior

Defined in Clash.Signal.Internal

Methods

hashWithSalt :: Int -> InitBehavior -> Int

hash :: InitBehavior -> Int

type Rep InitBehavior

Defined in Clash.Signal.Internal

type Rep InitBehavior = D1 ('MetaData "InitBehavior" "Clash.Signal.Internal" "clash-prelude-1.8.0-inplace" 'False) (C1 ('MetaCons "Unknown" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "Defined" 'PrefixI 'False) (U1 :: Type -> Type))

data SInitBehavior (init :: InitBehavior) where

Constructors

SUnknown :: SInitBehavior 'Unknown

SDefined :: SInitBehavior 'Defined

Instances

Show (SInitBehavior init)

Defined in Clash.Signal.Internal

Methods

showsPrec :: Int -> SInitBehavior init -> ShowS

show :: SInitBehavior init -> String

showList :: [SInitBehavior init] -> ShowS

data ResetKind

Constructors

Asynchronous

Elements respond asynchronously to changes in their reset input. This means that they do not wait for the next active clock edge, but respond immediately instead. Common on Intel FPGA platforms.

Synchronous

Elements respond synchronously to changes in their reset input. This means that changes in their reset input won't take effect until the next active clock edge. Common on Xilinx FPGA platforms.

Instances

Eq ResetKind

Defined in Clash.Signal.Internal

Methods

(==) :: ResetKind -> ResetKind -> Bool

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

Data ResetKind

Defined in Clash.Signal.Internal

Methods

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

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

toConstr :: ResetKind -> Constr

dataTypeOf :: ResetKind -> DataType

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

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

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

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

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

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

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

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

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

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

Ord ResetKind

Defined in Clash.Signal.Internal

Methods

compare :: ResetKind -> ResetKind -> Ordering

(<) :: ResetKind -> ResetKind -> Bool

(<=) :: ResetKind -> ResetKind -> Bool

(>) :: ResetKind -> ResetKind -> Bool

(>=) :: ResetKind -> ResetKind -> Bool

max :: ResetKind -> ResetKind -> ResetKind

min :: ResetKind -> ResetKind -> ResetKind

Read ResetKind

Defined in Clash.Signal.Internal

Methods

readsPrec :: Int -> ReadS ResetKind

readList :: ReadS [ResetKind]

readPrec :: ReadPrec ResetKind

readListPrec :: ReadPrec [ResetKind]

Show ResetKind

Defined in Clash.Signal.Internal

Methods

showsPrec :: Int -> ResetKind -> ShowS

show :: ResetKind -> String

showList :: [ResetKind] -> ShowS

Generic ResetKind

Defined in Clash.Signal.Internal

Associated Types

type Rep ResetKind :: Type -> Type

Methods

from :: ResetKind -> Rep ResetKind x

to :: Rep ResetKind x -> ResetKind

Binary ResetKind

Defined in Clash.Signal.Internal

Methods

put :: ResetKind -> Put

get :: Get ResetKind

putList :: [ResetKind] -> Put

NFData ResetKind

Defined in Clash.Signal.Internal

Methods

rnf :: ResetKind -> ()

Hashable ResetKind

Defined in Clash.Signal.Internal

Methods

hashWithSalt :: Int -> ResetKind -> Int

hash :: ResetKind -> Int

type Rep ResetKind

Defined in Clash.Signal.Internal

type Rep ResetKind = D1 ('MetaData "ResetKind" "Clash.Signal.Internal" "clash-prelude-1.8.0-inplace" 'False) (C1 ('MetaCons "Asynchronous" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "Synchronous" 'PrefixI 'False) (U1 :: Type -> Type))

data SResetKind (resetKind :: ResetKind) where

Singleton version of ResetKind

Constructors

SAsynchronous :: SResetKind 'Asynchronous

SSynchronous :: SResetKind 'Synchronous

Instances

Show (SResetKind reset)

Defined in Clash.Signal.Internal

Methods

showsPrec :: Int -> SResetKind reset -> ShowS

show :: SResetKind reset -> String

showList :: [SResetKind reset] -> ShowS

data ResetPolarity

Determines the value for which a reset line is considered "active"

Constructors

ActiveHigh

Reset is considered active if underlying signal is True.

ActiveLow

Reset is considered active if underlying signal is False.

Instances

Eq ResetPolarity

Defined in Clash.Signal.Internal

Methods

(==) :: ResetPolarity -> ResetPolarity -> Bool

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

Data ResetPolarity

Defined in Clash.Signal.Internal

Methods

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

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

toConstr :: ResetPolarity -> Constr

dataTypeOf :: ResetPolarity -> DataType

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

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

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

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

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

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

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

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

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

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

Ord ResetPolarity

Defined in Clash.Signal.Internal

Methods

compare :: ResetPolarity -> ResetPolarity -> Ordering

(<) :: ResetPolarity -> ResetPolarity -> Bool

(<=) :: ResetPolarity -> ResetPolarity -> Bool

(>) :: ResetPolarity -> ResetPolarity -> Bool

(>=) :: ResetPolarity -> ResetPolarity -> Bool

max :: ResetPolarity -> ResetPolarity -> ResetPolarity

min :: ResetPolarity -> ResetPolarity -> ResetPolarity

Read ResetPolarity

Defined in Clash.Signal.Internal

Methods

readsPrec :: Int -> ReadS ResetPolarity

readList :: ReadS [ResetPolarity]

readPrec :: ReadPrec ResetPolarity

readListPrec :: ReadPrec [ResetPolarity]

Show ResetPolarity

Defined in Clash.Signal.Internal

Methods

showsPrec :: Int -> ResetPolarity -> ShowS

show :: ResetPolarity -> String

showList :: [ResetPolarity] -> ShowS

Generic ResetPolarity

Defined in Clash.Signal.Internal

Associated Types

type Rep ResetPolarity :: Type -> Type

Methods

from :: ResetPolarity -> Rep ResetPolarity x

to :: Rep ResetPolarity x -> ResetPolarity

Binary ResetPolarity

Defined in Clash.Signal.Internal

Methods

put :: ResetPolarity -> Put

get :: Get ResetPolarity

putList :: [ResetPolarity] -> Put

NFData ResetPolarity

Defined in Clash.Signal.Internal

Methods

rnf :: ResetPolarity -> ()

Hashable ResetPolarity

Defined in Clash.Signal.Internal

Methods

hashWithSalt :: Int -> ResetPolarity -> Int

hash :: ResetPolarity -> Int

type Rep ResetPolarity

Defined in Clash.Signal.Internal

type Rep ResetPolarity = D1 ('MetaData "ResetPolarity" "Clash.Signal.Internal" "clash-prelude-1.8.0-inplace" 'False) (C1 ('MetaCons "ActiveHigh" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "ActiveLow" 'PrefixI 'False) (U1 :: Type -> Type))

data SResetPolarity (polarity :: ResetPolarity) where

Singleton version of ResetPolarity

Constructors

SActiveHigh :: SResetPolarity 'ActiveHigh

SActiveLow :: SResetPolarity 'ActiveLow

Instances

Show (SResetPolarity polarity)

Defined in Clash.Signal.Internal

Methods

showsPrec :: Int -> SResetPolarity polarity -> ShowS

show :: SResetPolarity polarity -> String

showList :: [SResetPolarity polarity] -> ShowS

data DomainConfiguration

A domain with a name (Domain). Configures the behavior of various aspects of a circuits. See the documentation of this record's field types for more information on the options.

See module documentation of Clash.Explicit.Signal for more information on how to create custom synthesis domains.

Constructors

DomainConfiguration

Fields

• _name :: Domain

  Domain name

• _period :: Nat

  Period of clock in ps

• _activeEdge :: ActiveEdge

  Active edge of the clock

• _resetKind :: ResetKind

  Whether resets are synchronous (edge-sensitive) or asynchronous (level-sensitive)

• _initBehavior :: InitBehavior

  Whether the initial (or "power up") value of memory elements is unknown/undefined, or configurable to a specific value

• _resetPolarity :: ResetPolarity

  Whether resets are active high or active low

data SDomainConfiguration (dom :: Domain) (conf :: DomainConfiguration) where

Singleton version of DomainConfiguration

Constructors

SDomainConfiguration

Fields

• :: { sName :: SSymbol dom

  Domain name

•    , sPeriod :: SNat period

  Period of clock in ps

•    , sActiveEdge :: SActiveEdge edge

  Active edge of the clock (not yet implemented)

•    , sResetKind :: SResetKind reset

  Whether resets are synchronous (edge-sensitive) or asynchronous (level-sensitive)

•    , sInitBehavior :: SInitBehavior init

  Whether the initial (or "power up") value of memory elements is unknown/undefined, or configurable to a specific value

•    , sResetPolarity :: SResetPolarity polarity

  Whether resets are active high or active low

•    } -> SDomainConfiguration dom ('DomainConfiguration dom period edge reset init polarity)

Instances

Show (SDomainConfiguration dom conf)

Defined in Clash.Signal.Internal

Methods

showsPrec :: Int -> SDomainConfiguration dom conf -> ShowS

show :: SDomainConfiguration dom conf -> String

showList :: [SDomainConfiguration dom conf] -> ShowS

Configuration type families

type DomainPeriod (dom :: Domain) = DomainConfigurationPeriod (KnownConf dom)

Convenience type to help to extract a period from a domain. Example usage:

myFunc :: (KnownDomain dom, DomainPeriod dom ~ 6000) => ...

type DomainActiveEdge (dom :: Domain) = DomainConfigurationActiveEdge (KnownConf dom)

Convenience type to help to extract the active edge from a domain. Example usage:

myFunc :: (KnownDomain dom, DomainActiveEdge dom ~ 'Rising) => ...

type DomainResetKind (dom :: Domain) = DomainConfigurationResetKind (KnownConf dom)

Convenience type to help to extract the reset synchronicity from a domain. Example usage:

myFunc :: (KnownDomain dom, DomainResetKind dom ~ 'Synchronous) => ...

type DomainInitBehavior (dom :: Domain) = DomainConfigurationInitBehavior (KnownConf dom)

Convenience type to help to extract the initial value behavior from a domain. Example usage:

myFunc :: (KnownDomain dom, DomainInitBehavior dom ~ 'Defined) => ...

type DomainResetPolarity (dom :: Domain) = DomainConfigurationResetPolarity (KnownConf dom)

Convenience type to help to extract the reset polarity from a domain. Example usage:

myFunc :: (KnownDomain dom, DomainResetPolarity dom ~ 'ActiveHigh) => ...

Convenience types

Simplifying

If you want to write part of your Clash design as domain-polymorphic functions, it can be practical to define a design-wide constraint synonym that captures the characteristics of the clock domains of the design. Such a constraint synonym can be used as a constraint on all domain-polymorphic functions in the design, regardless of whether they actually need the constraints from this section.

type DesignDomain dom =
  ( HasSynchronousReset dom
  , HasDefinedInitialValues dom
  )

type DesignDomainHidden dom =
  ( DesignDomain dom
  , HiddenClockResetEnable dom
  )

myFunc ::
  DesignDomainHidden dom =>
  Signal dom [...]

This way, you don't have to think about which constraints the function you're writing has exactly, and the constraint is succinct.

type HasSynchronousReset (dom :: Domain) = (KnownDomain dom, DomainResetKind dom ~ 'Synchronous)

Convenience type to constrain a domain to have synchronous resets. Example usage:

myFunc :: HasSynchronousReset dom => ...

Using this type implies KnownDomain.

Click here for usage hints

type HasAsynchronousReset (dom :: Domain) = (KnownDomain dom, DomainResetKind dom ~ 'Asynchronous)

Convenience type to constrain a domain to have asynchronous resets. Example usage:

myFunc :: HasAsynchronousReset dom => ...

Using this type implies KnownDomain.

Click here for usage hints

type HasDefinedInitialValues (dom :: Domain) = (KnownDomain dom, DomainInitBehavior dom ~ 'Defined)

Convenience type to constrain a domain to have initial values. Example usage:

myFunc :: HasDefinedInitialValues dom => ...

Using this type implies KnownDomain.

Note that there is no UnknownInitialValues dom as a component that works without initial values will also work if it does have them.

Click here for usage hints

Default domains

type System = "System" :: Domain

A clock (and reset) dom with clocks running at 100 MHz. Memory elements respond to the rising edge of the clock, and asynchronously to changes in reset signals. It has defined initial values, and active-high resets.

See module documentation of Clash.Explicit.Signal for more information on how to create custom synthesis domains.

type XilinxSystem = "XilinxSystem" :: Domain

A clock (and reset) dom with clocks running at 100 MHz. Memory elements respond to the rising edge of the clock, and synchronously to changes in reset signals. It has defined initial values, and active-high resets.

See module documentation of Clash.Explicit.Signal for more information on how to create custom synthesis domains.

type IntelSystem = "IntelSystem" :: Domain

A clock (and reset) dom with clocks running at 100 MHz. Memory elements respond to the rising edge of the clock, and asynchronously to changes in reset signals. It has defined initial values, and active-high resets.

See module documentation of Clash.Explicit.Signal for more information on how to create custom synthesis domains.

vSystem :: VDomainConfiguration

Convenience value to allow easy "subclassing" of System domain. Should be used in combination with createDomain. For example, if you just want to change the period but leave all other settings intact use:

createDomain vSystem{vName="System10", vPeriod=10}

vIntelSystem :: VDomainConfiguration

Convenience value to allow easy "subclassing" of IntelSystem domain. Should be used in combination with createDomain. For example, if you just want to change the period but leave all other settings intact use:

createDomain vIntelSystem{vName="Intel10", vPeriod=10}

vXilinxSystem :: VDomainConfiguration

Convenience value to allow easy "subclassing" of XilinxSystem domain. Should be used in combination with createDomain. For example, if you just want to change the period but leave all other settings intact use:

createDomain vXilinxSystem{vName="Xilinx10", vPeriod=10}

Domain utilities

data VDomainConfiguration

Same as SDomainConfiguration but allows for easy updates through record update syntax. Should be used in combination with vDomain and createDomain. Example:

createDomain (knownVDomain @System){vName="System10", vPeriod=10}

This duplicates the settings in the System domain, replaces the name and period, and creates an instance for it. As most users often want to update the system domain, a shortcut is available in the form:

createDomain vSystem{vName="System10", vPeriod=10}

Constructors

VDomainConfiguration

Fields

• vName :: String

  Corresponds to _name on DomainConfiguration

• vPeriod :: Natural

  Corresponds to _period on DomainConfiguration

• vActiveEdge :: ActiveEdge

  Corresponds to _activeEdge on DomainConfiguration

• vResetKind :: ResetKind

  Corresponds to _resetKind on DomainConfiguration

• vInitBehavior :: InitBehavior

  Corresponds to _initBehavior on DomainConfiguration

• vResetPolarity :: ResetPolarity

  Corresponds to _resetPolarity on DomainConfiguration

Instances

Eq VDomainConfiguration

Defined in Clash.Signal.Internal

Methods

(==) :: VDomainConfiguration -> VDomainConfiguration -> Bool

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

Read VDomainConfiguration

Defined in Clash.Signal.Internal

Methods

readsPrec :: Int -> ReadS VDomainConfiguration

readList :: ReadS [VDomainConfiguration]

readPrec :: ReadPrec VDomainConfiguration

readListPrec :: ReadPrec [VDomainConfiguration]

Show VDomainConfiguration

Defined in Clash.Signal.Internal

Methods

showsPrec :: Int -> VDomainConfiguration -> ShowS

show :: VDomainConfiguration -> String

showList :: [VDomainConfiguration] -> ShowS

Generic VDomainConfiguration

Defined in Clash.Signal.Internal

Associated Types

type Rep VDomainConfiguration :: Type -> Type

Methods

from :: VDomainConfiguration -> Rep VDomainConfiguration x

to :: Rep VDomainConfiguration x -> VDomainConfiguration

Binary VDomainConfiguration

Defined in Clash.Signal.Internal

Methods

put :: VDomainConfiguration -> Put

get :: Get VDomainConfiguration

putList :: [VDomainConfiguration] -> Put

NFData VDomainConfiguration

Defined in Clash.Signal.Internal

Methods

rnf :: VDomainConfiguration -> ()

type Rep VDomainConfiguration

Defined in Clash.Signal.Internal

type Rep VDomainConfiguration = D1 ('MetaData "VDomainConfiguration" "Clash.Signal.Internal" "clash-prelude-1.8.0-inplace" 'False) (C1 ('MetaCons "VDomainConfiguration" 'PrefixI 'True) ((S1 ('MetaSel ('Just "vName") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 String) :*: (S1 ('MetaSel ('Just "vPeriod") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Natural) :*: S1 ('MetaSel ('Just "vActiveEdge") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 ActiveEdge))) :*: (S1 ('MetaSel ('Just "vResetKind") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 ResetKind) :*: (S1 ('MetaSel ('Just "vInitBehavior") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 InitBehavior) :*: S1 ('MetaSel ('Just "vResetPolarity") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 ResetPolarity)))))

vDomain :: SDomainConfiguration dom conf -> VDomainConfiguration

Convert SDomainConfiguration to VDomainConfiguration. Should be used in combination with createDomain only.

createDomain :: VDomainConfiguration -> Q [Dec]

Convenience method to express new domains in terms of others.

createDomain (knownVDomain @System){vName="System10", vPeriod=10}

This duplicates the settings in the System domain, replaces the name and period, and creates an instance for it. As most users often want to update the system domain, a shortcut is available in the form:

createDomain vSystem{vName="System10", vPeriod=10}

The function will create two extra identifiers. The first:

type System10 = ..

You can use that as the dom to Clocks/Resets/Enables/Signals. For example: Signal System10 Int. Additionally, it will create a VDomainConfiguration that you can use in later calls to createDomain:

vSystem10 = knownVDomain @System10

It will also make System10 an instance of KnownDomain.

If either identifier is already in scope it will not be generated a second time. Note: This can be useful for example when documenting a new domain:

-- | Here is some documentation for CustomDomain
type CustomDomain = ("CustomDomain" :: Domain)

-- | Here is some documentation for vCustomDomain
createDomain vSystem{vName="CustomDomain"}

knownVDomain :: forall dom. KnownDomain dom => VDomainConfiguration

Like 'knownDomain but yields a VDomainConfiguration. Should only be used in combination with createDomain.

clockPeriod :: forall dom period. (KnownDomain dom, DomainPeriod dom ~ period) => SNat period

Get the clock period from a KnownDomain context

activeEdge :: forall dom edge. (KnownDomain dom, DomainActiveEdge dom ~ edge) => SActiveEdge edge

Get ActiveEdge from a KnownDomain context. Example usage:

f :: forall dom . KnownDomain dom => ....
f a b c =
  case activeEdge @dom of
    SRising -> foo
    SFalling -> bar

resetKind :: forall dom sync. (KnownDomain dom, DomainResetKind dom ~ sync) => SResetKind sync

Get ResetKind from a KnownDomain context. Example usage:

f :: forall dom . KnownDomain dom => ....
f a b c =
  case resetKind @dom of
    SAsynchronous -> foo
    SSynchronous -> bar

initBehavior :: forall dom init. (KnownDomain dom, DomainInitBehavior dom ~ init) => SInitBehavior init

Get InitBehavior from a KnownDomain context. Example usage:

f :: forall dom . KnownDomain dom => ....
f a b c =
  case initBehavior @dom of
    SDefined -> foo
    SUnknown -> bar

resetPolarity :: forall dom polarity. (KnownDomain dom, DomainResetPolarity dom ~ polarity) => SResetPolarity polarity

Get ResetPolarity from a KnownDomain context. Example usage:

f :: forall dom . KnownDomain dom => ....
f a b c =
  case resetPolarity @dom of
    SActiveHigh -> foo
    SActiveLow -> bar

Enabling

data Enable dom

A signal of booleans, indicating whether a component is enabled. No special meaning is implied, it's up to the component itself to decide how to respond to its enable line. It is used throughout Clash as a global enable signal.

Instances

type HasDomain dom1 (Enable dom2)

Defined in Clash.Class.HasDomain.HasSpecificDomain

type HasDomain dom1 (Enable dom2) = DomEq dom1 dom2

type TryDomain t (Enable dom)

Defined in Clash.Class.HasDomain.HasSingleDomain

type TryDomain t (Enable dom) = 'Found dom

toEnable :: Signal dom Bool -> Enable dom

Convert a signal of bools to an Enable construct

fromEnable :: Enable dom -> Signal dom Bool

Convert Enable construct to its underlying representation: a signal of bools.

enableGen :: Enable dom

Enable generator for some domain. Is simply always True.

Clock

data Clock (dom :: Domain)

A clock signal belonging to a domain named dom.

Instances

Show (Clock dom)

Defined in Clash.Signal.Internal

Methods

showsPrec :: Int -> Clock dom -> ShowS

show :: Clock dom -> String

showList :: [Clock dom] -> ShowS

ClocksSync (Clock c1, Reset c1)

Defined in Clash.Clocks

Associated Types

type ClocksSyncClocksInst (Clock c1, Reset c1) domIn

type ClocksResetSynchronizerCxt (Clock c1, Reset c1)

Methods

clocksResetSynchronizer :: forall (domIn :: Domain). (KnownDomain domIn, ClocksResetSynchronizerCxt (Clock c1, Reset c1)) => ClocksSyncClocksInst (Clock c1, Reset c1) domIn -> Clock domIn -> (Clock c1, Reset c1)

Clocks (Clock c1, Signal pllLock Bool)

Defined in Clash.Clocks

Associated Types

type ClocksCxt (Clock c1, Signal pllLock Bool)

type NumOutClocks (Clock c1, Signal pllLock Bool) :: Nat

Methods

clocks :: forall (domIn :: Domain). (KnownDomain domIn, ClocksCxt (Clock c1, Signal pllLock Bool)) => Clock domIn -> Reset domIn -> (Clock c1, Signal pllLock Bool)

Clocks (Clock c1, Clock c2, Signal pllLock Bool)

Defined in Clash.Clocks

Associated Types

type ClocksCxt (Clock c1, Clock c2, Signal pllLock Bool)

type NumOutClocks (Clock c1, Clock c2, Signal pllLock Bool) :: Nat

Methods

clocks :: forall (domIn :: Domain). (KnownDomain domIn, ClocksCxt (Clock c1, Clock c2, Signal pllLock Bool)) => Clock domIn -> Reset domIn -> (Clock c1, Clock c2, Signal pllLock Bool)

ClocksSync (Clock c1, Reset c1, Clock c2, Reset c2)

Defined in Clash.Clocks

Associated Types

type ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2) domIn

type ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2)

Methods

clocksResetSynchronizer :: forall (domIn :: Domain). (KnownDomain domIn, ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2)) => ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2) domIn -> Clock domIn -> (Clock c1, Reset c1, Clock c2, Reset c2)

Clocks (Clock c1, Clock c2, Clock c3, Signal pllLock Bool)

Defined in Clash.Clocks

Associated Types

type ClocksCxt (Clock c1, Clock c2, Clock c3, Signal pllLock Bool)

type NumOutClocks (Clock c1, Clock c2, Clock c3, Signal pllLock Bool) :: Nat

Methods

clocks :: forall (domIn :: Domain). (KnownDomain domIn, ClocksCxt (Clock c1, Clock c2, Clock c3, Signal pllLock Bool)) => Clock domIn -> Reset domIn -> (Clock c1, Clock c2, Clock c3, Signal pllLock Bool)

ClocksSync (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3)

Defined in Clash.Clocks

Associated Types

type ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3) domIn

type ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3)

Methods

clocksResetSynchronizer :: forall (domIn :: Domain). (KnownDomain domIn, ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3)) => ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3) domIn -> Clock domIn -> (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3)

type HasDomain dom1 (Clock dom2)

Defined in Clash.Class.HasDomain.HasSpecificDomain

type HasDomain dom1 (Clock dom2) = DomEq dom1 dom2

type TryDomain t (Clock dom)

Defined in Clash.Class.HasDomain.HasSingleDomain

type TryDomain t (Clock dom) = 'Found dom

type ClocksResetSynchronizerCxt (Clock c1, Reset c1)

Defined in Clash.Clocks

type ClocksResetSynchronizerCxt (Clock c1, Reset c1) = KnownDomain c1

type ClocksCxt (Clock c1, Signal pllLock Bool)

Defined in Clash.Clocks

type ClocksCxt (Clock c1, Signal pllLock Bool) = (KnownDomain c1, KnownDomain pllLock)

type NumOutClocks (Clock c1, Signal pllLock Bool)

Defined in Clash.Clocks

type NumOutClocks (Clock c1, Signal pllLock Bool) = 1

type ClocksSyncClocksInst (Clock c1, Reset c1) domIn

Defined in Clash.Clocks

type ClocksSyncClocksInst (Clock c1, Reset c1) domIn = (Clock c1, Signal domIn Bool)

type ClocksCxt (Clock c1, Clock c2, Signal pllLock Bool)

Defined in Clash.Clocks

type ClocksCxt (Clock c1, Clock c2, Signal pllLock Bool) = (KnownDomain c1, KnownDomain c2, KnownDomain pllLock)

type NumOutClocks (Clock c1, Clock c2, Signal pllLock Bool)

Defined in Clash.Clocks

type NumOutClocks (Clock c1, Clock c2, Signal pllLock Bool) = 2

type ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2)

Defined in Clash.Clocks

type ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2) = (KnownDomain c1, KnownDomain c2)

type ClocksCxt (Clock c1, Clock c2, Clock c3, Signal pllLock Bool)

Defined in Clash.Clocks

type ClocksCxt (Clock c1, Clock c2, Clock c3, Signal pllLock Bool) = (KnownDomain c1, KnownDomain c2, KnownDomain c3, KnownDomain pllLock)

type NumOutClocks (Clock c1, Clock c2, Clock c3, Signal pllLock Bool)

Defined in Clash.Clocks

type NumOutClocks (Clock c1, Clock c2, Clock c3, Signal pllLock Bool) = 3

type ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2) domIn

Defined in Clash.Clocks

type ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2) domIn = (Clock c1, Clock c2, Signal domIn Bool)

type ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3)

Defined in Clash.Clocks

type ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3) = (KnownDomain c1, KnownDomain c2, KnownDomain c3)

type ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3) domIn

Defined in Clash.Clocks

type ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3) domIn = (Clock c1, Clock c2, Clock c3, Signal domIn Bool)

data DiffClock (dom :: Domain)

A differential clock signal belonging to a domain named dom. The clock input of a design with such an input has two ports which are in antiphase. The first input is the positive phase, the second the negative phase. When using makeTopEntity, the names of the inputs will end in _p and _n respectively.

To create a differential clock in a test bench, you can use clockToDiffClock.

Instances

Show (DiffClock dom)

Defined in Clash.Signal.Internal

Methods

showsPrec :: Int -> DiffClock dom -> ShowS

show :: DiffClock dom -> String

showList :: [DiffClock dom] -> ShowS

periodToHz :: (HasCallStack, Fractional a) => Natural -> a

Calculate the frequency in Hz, given the period in ps

I.e., to calculate the clock frequency of a clock with a period of 5000 ps:

>>> periodToHz 5000
2.0e8

Note that if p in periodToHz (fromIntegral p) is negative, fromIntegral will give an Underflow :: ArithException without a call stack, making debugging cumbersome.

Before Clash 1.8, this function always returned a Ratio Natural. To get the old behavior of this function, use a type application:

>>> periodToHz @(Ratio Natural) 5000
200000000 % 1

NB: This function is not synthesizable

hzToPeriod :: (HasCallStack, Integral a) => Ratio Natural -> a

Calculate the period in ps, given a frequency in Hz

I.e., to calculate the clock period for a circuit to run at 240 MHz we get

>>> hzToPeriod 240e6
4166

If the value hzToPeriod is applied to is not of the type Ratio Natural, you can use hzToPeriod (realToFrac f). Note that if f is negative, realToFrac will give an Underflow :: ArithException without a call stack, making debugging cumbersome.

Before Clash 1.8, this function always returned a Natural. To get the old behavior of this function, use a type application:

>>> hzToPeriod @Natural 240e6
4166

• NB: This function is not synthesizable
• NB: This function is lossy. I.e., periodToHz . hzToPeriod /= id.

Synchronization primitive

unsafeSynchronizer

Arguments

:: forall dom1 dom2 a. (KnownDomain dom1, KnownDomain dom2)

=> Clock dom1

Clock of the incoming signal

-> Clock dom2

Clock of the outgoing signal

-> Signal dom1 a

-> Signal dom2 a

The unsafeSynchronizer function is a primitive that must be used to connect one clock domain to the other, and will be synthesized to a (bundle of) wire(s) in the eventual circuit. This function should only be used as part of a proper synchronization component, such as the following dual flip-flop synchronizer:

dualFlipFlop
  :: Clock domA
  -> Clock domB
  -> Enable domA
  -> Enable domB
  -> Bit
  -> Signal domA Bit
  -> Signal domB Bit
dualFlipFlop clkA clkB enA enB dflt =
  delay clkB enB dflt . delay clkB enB dflt . unsafeSynchronizer clkA clkB

The unsafeSynchronizer works in such a way that, given 2 clocks:

createDomain vSystem{vName="Dom7", vPeriod=7}

clk7 :: Clock Dom7
clk7 = clockGen

en7 :: Enable Dom7
en7 = enableGen

and

createDomain vSystem{vName="Dom2", vPeriod=2}

clk2 :: Clock Dom2
clk2 = clockGen

en2 :: Enable Dom2
en2 = enableGen

Oversampling followed by compression is the identity function plus 2 initial values:

delay clkB enB dflt $
unsafeSynchronizer clkA clkB $
delay clkA enA dflt $
unsafeSynchronizer clkB clkA $
delay clkB enB s

==

dflt :- dflt :- s

Something we can easily observe:

oversampling clkA clkB enA enB dflt =
  delay clkB enB dflt
    . unsafeSynchronizer clkA clkB
    . delay clkA enA dflt
almostId clkA clkB enA enB dflt =
  delay clkB enB dflt
    . unsafeSynchronizer clkA clkB
    . delay clkA enA dflt
    . unsafeSynchronizer clkB clkA
    . delay clkB enB dflt

>>> sampleN 37 (oversampling clk7 clk2 en7 en2 0 (fromList [(1::Int)..10]))
[0,0,1,1,1,2,2,2,2,3,3,3,4,4,4,4,5,5,5,6,6,6,6,7,7,7,8,8,8,8,9,9,9,10,10,10,10]
>>> sampleN 12 (almostId clk2 clk7 en2 en7 0 (fromList [(1::Int)..10]))
[0,0,1,2,3,4,5,6,7,8,9,10]

veryUnsafeSynchronizer

Arguments

:: Either Int (Signal dom1 Int)

Period of clock belonging to dom1. Left if clock has a static period, Right if periods are dynamic.

-> Either Int (Signal dom2 Int)

Period of clock belonging to dom2. Left if clock has a static period, Right if periods are dynamic.

-> Signal dom1 a

-> Signal dom2 a

Same as unsafeSynchronizer, but with manually supplied clock periods.

Note: this unsafeSynchronizer is defined to be consistent with the vhdl and verilog implementations however as only synchronous signals are represented in Clash this cannot be done precisely and can lead to odd behavior. For example,

sample $ unsafeSynchronizer Dom2 Dom7 . unsafeSynchronizer Dom7 Dom2 $ fromList [0..10]
> [0,4,4,4,7,7,7,7,11,11,11..

is quite different from the identity,

sample $ fromList [0..10]
> [0,1,2,3,4,5,6,7,8,9,10..

with values appearing from the "future".

Reset

data Reset (dom :: Domain)

A reset signal belonging to a domain called dom.

The underlying representation of resets is Bool.

Instances

ClocksSync (Clock c1, Reset c1)

Defined in Clash.Clocks

Associated Types

type ClocksSyncClocksInst (Clock c1, Reset c1) domIn

type ClocksResetSynchronizerCxt (Clock c1, Reset c1)

Methods

clocksResetSynchronizer :: forall (domIn :: Domain). (KnownDomain domIn, ClocksResetSynchronizerCxt (Clock c1, Reset c1)) => ClocksSyncClocksInst (Clock c1, Reset c1) domIn -> Clock domIn -> (Clock c1, Reset c1)

ClocksSync (Clock c1, Reset c1, Clock c2, Reset c2)

Defined in Clash.Clocks

Associated Types

type ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2) domIn

type ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2)

Methods

clocksResetSynchronizer :: forall (domIn :: Domain). (KnownDomain domIn, ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2)) => ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2) domIn -> Clock domIn -> (Clock c1, Reset c1, Clock c2, Reset c2)

ClocksSync (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3)

Defined in Clash.Clocks

Associated Types

type ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3) domIn

type ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3)

Methods

clocksResetSynchronizer :: forall (domIn :: Domain). (KnownDomain domIn, ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3)) => ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3) domIn -> Clock domIn -> (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3)

type HasDomain dom1 (Reset dom2)

Defined in Clash.Class.HasDomain.HasSpecificDomain

type HasDomain dom1 (Reset dom2) = DomEq dom1 dom2

type TryDomain t (Reset dom)

Defined in Clash.Class.HasDomain.HasSingleDomain

type TryDomain t (Reset dom) = 'Found dom

type ClocksResetSynchronizerCxt (Clock c1, Reset c1)

Defined in Clash.Clocks

type ClocksResetSynchronizerCxt (Clock c1, Reset c1) = KnownDomain c1

type ClocksSyncClocksInst (Clock c1, Reset c1) domIn

Defined in Clash.Clocks

type ClocksSyncClocksInst (Clock c1, Reset c1) domIn = (Clock c1, Signal domIn Bool)

type ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2)

Defined in Clash.Clocks

type ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2) = (KnownDomain c1, KnownDomain c2)

type ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2) domIn

Defined in Clash.Clocks

type ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2) domIn = (Clock c1, Clock c2, Signal domIn Bool)

type ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3)

Defined in Clash.Clocks

type ClocksResetSynchronizerCxt (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3) = (KnownDomain c1, KnownDomain c2, KnownDomain c3)

type ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3) domIn

Defined in Clash.Clocks

type ClocksSyncClocksInst (Clock c1, Reset c1, Clock c2, Reset c2, Clock c3, Reset c3) domIn = (Clock c1, Clock c2, Clock c3, Signal domIn Bool)

unsafeToReset :: KnownDomain dom => Signal dom Bool -> Reset dom

unsafeToReset is unsafe. For asynchronous resets it is unsafe because it can introduce combinatorial loops. In case of synchronous resets it can lead to meta-stability issues in the presence of asynchronous resets.

NB: You probably want to use unsafeFromActiveLow or unsafeFromActiveHigh.

unsafeFromReset :: Reset dom -> Signal dom Bool

unsafeFromReset is unsafe because it can introduce:

• meta-stability

For asynchronous resets it is unsafe because it can cause combinatorial loops. In case of synchronous resets it can lead to meta-stability in the presence of asynchronous resets.

NB: You probably want to use unsafeToActiveLow or unsafeToActiveHigh.

unsafeToActiveHigh :: forall dom. KnownDomain dom => Reset dom -> Signal dom Bool

Convert a reset to an active high reset. Has no effect if reset is already an active high reset. Is unsafe because it can introduce:

• meta-stability

For asynchronous resets it is unsafe because it can cause combinatorial loops. In case of synchronous resets it can lead to meta-stability in the presence of asynchronous resets.

unsafeToActiveLow :: forall dom. KnownDomain dom => Reset dom -> Signal dom Bool

Convert a reset to an active low reset. Has no effect if reset is already an active low reset. It is unsafe because it can introduce:

• meta-stability

For asynchronous resets it is unsafe because it can cause combinatorial loops. In case of synchronous resets it can lead to meta-stability in the presence of asynchronous resets.

unsafeFromActiveHigh

Arguments

:: forall dom. KnownDomain dom

=> Signal dom Bool

Reset signal that's True when active, and False when inactive.

-> Reset dom

Interpret a signal of bools as an active high reset and convert it to a reset signal corresponding to the domain's setting.

For asynchronous resets it is unsafe because it can cause combinatorial loops. In case of synchronous resets it can lead to meta-stability in the presence of asynchronous resets.

unsafeFromActiveLow

Arguments

:: forall dom. KnownDomain dom

=> Signal dom Bool

Reset signal that's False when active, and True when inactive.

-> Reset dom

Interpret a signal of bools as an active low reset and convert it to a reset signal corresponding to the domain's setting.

For asynchronous resets it is unsafe because it can cause combinatorial loops. In case of synchronous resets it can lead to meta-stability in the presence of asynchronous resets.

Basic circuit functions

andEnable :: Enable dom -> Signal dom Bool -> Enable dom

Merge enable signal with signal of bools by applying the boolean AND operation.

dflipflop :: (KnownDomain dom, NFDataX a) => Clock dom -> Signal dom a -> Signal dom a

Special version of delay that doesn't take enable signals of any kind. Initial value will be undefined.

delay

Arguments

:: (KnownDomain dom, NFDataX a)

=> Clock dom

Clock

-> Enable dom

Global enable

-> a

Initial value

-> Signal dom a

-> Signal dom a

"delay clk s" delays the values in Signal s for once cycle, the value at time 0 is dflt.

>>> sampleN 3 (delay systemClockGen enableGen 0 (fromList [1,2,3,4]))
[0,1,2]

delayMaybe

Arguments

:: (KnownDomain dom, NFDataX a)

=> Clock dom

Clock

-> Enable dom

Global enable

-> a

Initial value

-> Signal dom (Maybe a)

-> Signal dom a

Version of delay that only updates when its third argument is a Just value.

>>> let input = fromList [Just 1, Just 2, Nothing, Nothing, Just 5, Just 6, Just (7::Int)]
>>> sampleN 7 (delayMaybe systemClockGen enableGen 0 input)
[0,1,2,2,2,5,6]

delayEn

Arguments

:: (KnownDomain dom, NFDataX a)

=> Clock dom

Clock

-> Enable dom

Global enable

-> a

Initial value

-> Signal dom Bool

Enable

-> Signal dom a

-> Signal dom a

Version of delay that only updates when its third argument is asserted.

>>> let input = fromList [1,2,3,4,5,6,7::Int]
>>> let enable = fromList [True,True,False,False,True,True,True]
>>> sampleN 7 (delayEn systemClockGen enableGen 0 enable input)
[0,1,2,2,2,5,6]

register

Arguments

:: (KnownDomain dom, NFDataX a)

=> Clock dom

clock

-> Reset dom

Reset, register outputs the reset value when the reset is active

-> Enable dom

Global enable

-> a

Reset value. If the domain has initial values enabled, the reset value will also be the initial value.

-> Signal dom a

-> Signal dom a

"register clk rst en i s" delays the values in Signal s for one cycle, and sets the value to i the moment the reset becomes False.

>>> sampleN 5 (register systemClockGen resetGen enableGen 8 (fromList [1,1,2,3,4]))
[8,8,1,2,3]

regMaybe

Arguments

:: (KnownDomain dom, NFDataX a)

=> Clock dom

Clock

-> Reset dom

Reset, regMaybe outputs the reset value when the reset value is active

-> Enable dom

Global enable

-> a

Reset value. If the domain has initial values enabled, the reset value will also be the initial value.

-> Signal dom (Maybe a)

-> Signal dom a

Version of register that only updates its content when its fourth argument is a Just value. So given:

sometimes1 clk rst en = s where
  s = register clk rst en Nothing (switch <$> s)

  switch Nothing = Just 1
  switch _       = Nothing

countSometimes clk rst en = s where
  s     = regMaybe clk rst en 0 (plusM (pure <$> s) (sometimes1 clk rst en))
  plusM = liftA2 (liftA2 (+))

We get:

>>> sampleN 9 (sometimes1 systemClockGen resetGen enableGen)
[Nothing,Nothing,Just 1,Nothing,Just 1,Nothing,Just 1,Nothing,Just 1]
>>> sampleN 9 (count systemClockGen resetGen enableGen)
[0,0,0,1,1,2,2,3,3]

regEn

Arguments

:: (KnownDomain dom, NFDataX a)

=> Clock dom

Clock

-> Reset dom

Reset, regEn outputs the reset value when the reset value is active

-> Enable dom

Global enable

-> a

Reset value. If the domain has initial values enabled, the reset value will also be the initial value.

-> Signal dom Bool

Enable signal

-> Signal dom a

-> Signal dom a

Version of register that only updates its content when its fourth argument is asserted. So given:

oscillate clk rst en = let s = register clk rst en False (not <$> s) in s
count clk rst en     = let s = 'regEn clk rst en 0 (oscillate clk rst en) (s + 1) in s

We get:

>>> sampleN 9 (oscillate systemClockGen resetGen enableGen)
[False,False,True,False,True,False,True,False,True]
>>> sampleN 9 (count systemClockGen resetGen enableGen)
[0,0,0,1,1,2,2,3,3]

mux :: Applicative f => f Bool -> f a -> f a -> f a

The above type is a generalization for:

mux :: Signal Bool -> Signal a -> Signal a -> Signal a

A multiplexer. Given "mux b t f", output t when b is True, and f when b is False.

Simulation and testbench functions

clockGen :: KnownDomain dom => Clock dom

Clock generator for simulations. Do not use this clock generator for the testBench function, use tbClockGen instead.

To be used like:

clkSystem = clockGen @System

See DomainConfiguration for more information on how to use synthesis domains.

resetGen :: forall dom. KnownDomain dom => Reset dom

Reset generator for simulation purposes. Asserts the reset for a single cycle.

To be used like:

rstSystem = resetGen @System

See tbClockGen for example usage.

NB: While this can be used in the testBench function, it cannot be synthesized to hardware.

resetGenN

Arguments

:: forall dom n. (KnownDomain dom, 1 <= n)

=> SNat n

Number of initial cycles to hold reset high

-> Reset dom

Reset generator for simulation purposes. Asserts the reset for the first n cycles.

To be used like:

rstSystem5 = resetGen @System d5

Example usage:

>>> sampleN 7 (unsafeToActiveHigh (resetGenN @System d3))
[True,True,True,False,False,False,False]

NB: While this can be used in the testBench function, it cannot be synthesized to hardware.

systemClockGen :: Clock System

Clock generator for the System clock domain.

NB: Should only be used for simulation, and not for the testBench function. For the testBench function, used tbSystemClockGen

systemResetGen :: Reset System

Reset generator for use in simulation, for the System clock domain. Asserts the reset for a single cycle.

NB: While this can be used in the testBench function, it cannot be synthesized to hardware.

Example

topEntity :: Vec 2 (Vec 3 (Unsigned 8)) -> Vec 6 (Unsigned 8)
topEntity = concat

testBench :: Signal System Bool
testBench = done
  where
    testInput      = pure ((1 :> 2 :> 3 :> Nil) :> (4 :> 5 :> 6 :> Nil) :> Nil)
    expectedOutput = outputVerifier' ((1:>2:>3:>4:>5:>6:>Nil):>Nil)
    done           = exposeClockResetEnable (expectedOutput (topEntity <$> testInput)) clk rst
    clk            = tbSystemClockGen (not <$> done)
    rst            = systemResetGen

Boolean connectives

(.&&.) :: Applicative f => f Bool -> f Bool -> f Bool infixr 3

The above type is a generalization for:

(.&&.) :: Signal Bool -> Signal Bool -> Signal Bool

It is a version of (&&) that returns a Signal of Bool

(.||.) :: Applicative f => f Bool -> f Bool -> f Bool infixr 2

The above type is a generalization for:

(.||.) :: Signal Bool -> Signal Bool -> Signal Bool

It is a version of (||) that returns a Signal of Bool

Product/Signal isomorphism

class Bundle a where

Isomorphism between a Signal of a product type (e.g. a tuple) and a product type of Signals.

Instances of Bundle must satisfy the following laws:

bundle . unbundle = id
unbundle . bundle = id

By default, bundle and unbundle, are defined as the identity, that is, writing:

data D = A | B

instance Bundle D

is the same as:

data D = A | B

instance Bundle D where
  type Unbundled clk D = Signal clk D
  bundle   s = s
  unbundle s = s

For custom product types you'll have to write the instance manually:

data Pair a b = MkPair { getA :: a, getB :: b }

instance Bundle (Pair a b) where
  type Unbundled dom (Pair a b) = Pair (Signal dom a) (Signal dom b)

  -- bundle :: Pair (Signal dom a) (Signal dom b) -> Signal dom (Pair a b)
  bundle   (MkPair as bs) = MkPair $ as * bs

  -- unbundle :: Signal dom (Pair a b) -> Pair (Signal dom a) (Signal dom b)
  unbundle pairs = MkPair (getA $ pairs) (getB $ pairs)

Minimal complete definition

Nothing

Associated Types

type Unbundled (dom :: Domain) a = res | res -> dom a

type Unbundled dom a = Signal dom a

Methods

bundle :: Unbundled dom a -> Signal dom a

Example:

bundle :: (Signal dom a, Signal dom b) -> Signal dom (a,b)

However:

bundle :: Signal dom Bit -> Signal dom Bit

default bundle :: Signal dom a ~ Unbundled dom a => Unbundled dom a -> Signal dom a

unbundle :: Signal dom a -> Unbundled dom a

Example:

unbundle :: Signal dom (a,b) -> (Signal dom a, Signal dom b)

However:

unbundle :: Signal dom Bit -> Signal dom Bit

default unbundle :: Unbundled dom a ~ Signal dom a => Signal dom a -> Unbundled dom a

Instances

Bundle Bool

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom Bool = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom Bool -> Signal dom Bool

unbundle :: forall (dom :: Domain). Signal dom Bool -> Unbundled dom Bool

Bundle Double

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom Double = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom Double -> Signal dom Double

unbundle :: forall (dom :: Domain). Signal dom Double -> Unbundled dom Double

Bundle Float

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom Float = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom Float -> Signal dom Float

unbundle :: forall (dom :: Domain). Signal dom Float -> Unbundled dom Float

Bundle Int

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom Int = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom Int -> Signal dom Int

unbundle :: forall (dom :: Domain). Signal dom Int -> Unbundled dom Int

Bundle Integer

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom Integer = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom Integer -> Signal dom Integer

unbundle :: forall (dom :: Domain). Signal dom Integer -> Unbundled dom Integer

Bundle ()

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom () = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom () -> Signal dom ()

unbundle :: forall (dom :: Domain). Signal dom () -> Unbundled dom ()

Bundle Bit

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom Bit = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom Bit -> Signal dom Bit

unbundle :: forall (dom :: Domain). Signal dom Bit -> Unbundled dom Bit

Bundle EmptyTuple

See commit 94b0bff5 and documentation for TaggedEmptyTuple.

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom EmptyTuple = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom EmptyTuple -> Signal dom EmptyTuple

unbundle :: forall (dom :: Domain). Signal dom EmptyTuple -> Unbundled dom EmptyTuple

Bundle (Maybe a)

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom (Maybe a) = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom (Maybe a) -> Signal dom (Maybe a)

unbundle :: forall (dom :: Domain). Signal dom (Maybe a) -> Unbundled dom (Maybe a)

Bundle (BitVector n)

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom (BitVector n) = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom (BitVector n) -> Signal dom (BitVector n)

unbundle :: forall (dom :: Domain). Signal dom (BitVector n) -> Unbundled dom (BitVector n)

Bundle (Index n)

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom (Index n) = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom (Index n) -> Signal dom (Index n)

unbundle :: forall (dom :: Domain). Signal dom (Index n) -> Unbundled dom (Index n)

Bundle (Unsigned n)

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom (Unsigned n) = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom (Unsigned n) -> Signal dom (Unsigned n)

unbundle :: forall (dom :: Domain). Signal dom (Unsigned n) -> Unbundled dom (Unsigned n)

Bundle (Signed n)

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom (Signed n) = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom (Signed n) -> Signal dom (Signed n)

unbundle :: forall (dom :: Domain). Signal dom (Signed n) -> Unbundled dom (Signed n)

Bundle (Either a b)

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom (Either a b) = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom (Either a b) -> Signal dom (Either a b)

unbundle :: forall (dom :: Domain). Signal dom (Either a b) -> Unbundled dom (Either a b)

Bundle (a1, a2)

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom (a1, a2) = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom (a1, a2) -> Signal dom (a1, a2)

unbundle :: forall (dom :: Domain). Signal dom (a1, a2) -> Unbundled dom (a1, a2)

KnownNat n => Bundle (Vec n a)

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom (Vec n a) = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom (Vec n a) -> Signal dom (Vec n a)

unbundle :: forall (dom :: Domain). Signal dom (Vec n a) -> Unbundled dom (Vec n a)

KnownNat d => Bundle (RTree d a)

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom (RTree d a) = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom (RTree d a) -> Signal dom (RTree d a)

unbundle :: forall (dom :: Domain). Signal dom (RTree d a) -> Unbundled dom (RTree d a)

Bundle (a1, a2, a3)

NB: The documentation only shows instances up to 3-tuples. By default, instances up to and including 12-tuples will exist. If the flag large-tuples is set instances up to the GHC imposed limit will exist. The GHC imposed limit is either 62 or 64 depending on the GHC version.

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom (a1, a2, a3) = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom (a1, a2, a3) -> Signal dom (a1, a2, a3)

unbundle :: forall (dom :: Domain). Signal dom (a1, a2, a3) -> Unbundled dom (a1, a2, a3)

Bundle (Fixed rep int frac)

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom (Fixed rep int frac) = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom (Fixed rep int frac) -> Signal dom (Fixed rep int frac)

unbundle :: forall (dom :: Domain). Signal dom (Fixed rep int frac) -> Unbundled dom (Fixed rep int frac)

Bundle ((f :*: g) a)

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom ((f :*: g) a) = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom ((f :*: g) a) -> Signal dom ((f :*: g) a)

unbundle :: forall (dom :: Domain). Signal dom ((f :*: g) a) -> Unbundled dom ((f :*: g) a)

data EmptyTuple

See TaggedEmptyTuple

Constructors

EmptyTuple

Instances

Bundle EmptyTuple

See commit 94b0bff5 and documentation for TaggedEmptyTuple.

Defined in Clash.Signal.Bundle

Associated Types

type Unbundled dom EmptyTuple = (res :: Type)

Methods

bundle :: forall (dom :: Domain). Unbundled dom EmptyTuple -> Signal dom EmptyTuple

unbundle :: forall (dom :: Domain). Signal dom EmptyTuple -> Unbundled dom EmptyTuple

Bundle EmptyTuple

See commit 94b0bff5 and documentation for TaggedEmptyTuple.

Defined in Clash.Signal.Delayed.Bundle

Associated Types

type Unbundled dom d EmptyTuple = (res :: Type)

Methods

bundle :: forall (dom :: Domain) (d :: Nat). Unbundled dom d EmptyTuple -> DSignal dom d EmptyTuple

unbundle :: forall (dom :: Domain) (d :: Nat). DSignal dom d EmptyTuple -> Unbundled dom d EmptyTuple

type Unbundled dom EmptyTuple

Defined in Clash.Signal.Bundle

type Unbundled dom EmptyTuple = TaggedEmptyTuple dom

type Unbundled dom d EmptyTuple

Defined in Clash.Signal.Delayed.Bundle

type Unbundled dom d EmptyTuple = TaggedEmptyTuple dom d

data TaggedEmptyTuple (dom :: Domain)

Helper type to emulate the "old" behavior of Bundle's unit instance. I.e., the instance for Bundle () used to be defined as:

class Bundle () where
  bundle   :: () -> Signal dom ()
  unbundle :: Signal dom () -> ()

In order to have sensible type inference, the Bundle class specifies that the argument type of bundle should uniquely identify the result type, and vice versa for unbundle. The type signatures in the snippet above don't though, as () doesn't uniquely map to a specific domain. In other words, domain should occur in both the argument and result of both functions.

TaggedEmptyTuple tackles this by carrying the domain in its type. The bundle and unbundle instance now looks like:

class Bundle EmptyTuple where
  bundle   :: TaggedEmptyTuple dom -> Signal dom EmptyTuple
  unbundle :: Signal dom EmptyTuple -> TaggedEmptyTuple dom

dom is now mentioned both the argument and result for both bundle and unbundle.

Constructors

TaggedEmptyTuple

Simulation functions (not synthesizable)

simulate :: (NFDataX a, NFDataX b) => (Signal dom1 a -> Signal dom2 b) -> [a] -> [b]

Simulate a (Signal a -> Signal b) function given a list of samples of type a

>>> simulate (register systemClockGen resetGen enableGen 8) [1, 1, 2, 3]
[8,8,1,2,3...
...

NB: This function is not synthesizable

simulateB

Arguments

:: (Bundle a, Bundle b, NFDataX a, NFDataX b)

=> (Unbundled dom1 a -> Unbundled dom2 b)

The function we want to simulate

-> [a]

Input samples

-> [b]

Simulate a (Unbundled a -> Unbundled b) function given a list of samples of type a

>>> simulateB (unbundle . register systemClockGen resetGen enableGen (8,8) . bundle) [(1,1), (1,1), (2,2), (3,3)] :: [(Int,Int)]
[(8,8),(8,8),(1,1),(2,2),(3,3)...
...

NB: This function is not synthesizable

simulateWithReset

Arguments

:: forall dom a b m. (KnownDomain dom, NFDataX a, NFDataX b, 1 <= m)

=> SNat m

Number of cycles to assert the reset

-> a

Reset value

-> (KnownDomain dom => Clock dom -> Reset dom -> Enable dom -> Signal dom a -> Signal dom b)

Circuit to simulate

-> [a]

-> [b]

Same as simulate, but with the reset line asserted for n cycles. Similar to simulate, simulateWithReset will drop the output values produced while the reset is asserted. While the reset is asserted, the first value from [a] is fed to the circuit.

simulateWithResetN

Arguments

:: (KnownDomain dom, NFDataX a, NFDataX b, 1 <= m)

=> SNat m

Number of cycles to assert the reset

-> a

Reset value

-> Int

Number of cycles to simulate (excluding cycle spent in reset)

-> (KnownDomain dom => Clock dom -> Reset dom -> Enable dom -> Signal dom a -> Signal dom b)

Circuit to simulate

-> [a]

-> [b]

Same as simulateWithReset, but only sample the first Int output values.

runUntil

Arguments

:: forall dom a. (KnownDomain dom, NFDataX a, ShowX a)

=> (a -> Bool)

Condition checking function, should return True to finish run

-> Signal dom a

Signal we want to sample for the condition

-> IO ()

Simulate a component until it matches a condition

It prints a message of the form

Signal sampled for N cycles until value X

NB: This function is not synthesizable

Example with test bench

A common usage is with a test bench using outputVerifier.

NB: Since this uses assert, when using clashi, read the note at Clash.Explicit.Testbench.

import Clash.Prelude
import Clash.Explicit.Testbench

topEntity
  :: Signal System Int
  -> Signal System Int
topEntity = id

testBench
  :: Signal System Bool
testBench = done
 where
  testInput = stimuliGenerator clk rst $(listToVecTH [1 :: Int .. 10])
  expectedOutput =
    outputVerifier' clk rst $(listToVecTH $ [1 :: Int .. 9] <> [42])
  done = expectedOutput $ topEntity testInput
  clk = tbSystemClockGen (not <$> done)
  rst = systemResetGen

> runUntil id testBench


cycle(<Clock: System>): 10, outputVerifier
expected value: 42, not equal to actual value: 10
Signal sampled for 11 cycles until value True

When you need to verify multiple test benches, the following invocations come in handy:

> mapM_ (runUntil id) [ testBenchA, testBenchB ]

or when the test benches are in different clock domains:

testBenchA :: Signal DomA Bool
testBenchB :: Signal DomB Bool

> sequence_ [ runUntil id testBenchA, runUntil id testBenchB ]

lazy versions

simulate_lazy :: (Signal dom1 a -> Signal dom2 b) -> [a] -> [b]

Simulate a (Signal a -> Signal b) function given a list of samples of type a

>>> simulate (register systemClockGen resetGen enableGen 8) [1, 1, 2, 3]
[8,8,1,2,3...
...

NB: This function is not synthesizable

simulateB_lazy

Arguments

:: (Bundle a, Bundle b)

=> (Unbundled dom1 a -> Unbundled dom2 b)

The function we want to simulate

-> [a]

Input samples

-> [b]

Lazily simulate a (Unbundled a -> Unbundled b) function given a list of samples of type a

>>> simulateB (unbundle . register systemClockGen resetGen enableGen (8,8) . bundle) [(1,1), (1,1), (2,2), (3,3)] :: [(Int,Int)]
[(8,8),(8,8),(1,1),(2,2),(3,3)...
...

NB: This function is not synthesizable

Automaton

signalAutomaton :: forall dom a b. (Signal dom a -> Signal dom b) -> Automaton (->) a b

Build an Automaton from a function over Signals.

NB: Consumption of continuation of the Automaton must be affine; that is, you can only apply the continuation associated with a particular element at most once.

List <-> Signal conversion (not synthesizable)

sample :: (Foldable f, NFDataX a) => f a -> [a]

The above type is a generalization for:

sample :: Signal a -> [a]

Get an infinite list of samples from a Signal

The elements in the list correspond to the values of the Signal at consecutive clock cycles

sample s == [s0, s1, s2, s3, ...

NB: This function is not synthesizable

sampleN :: (Foldable f, NFDataX a) => Int -> f a -> [a]

The above type is a generalization for:

sampleN :: Int -> Signal a -> [a]

Get a list of n samples from a Signal

The elements in the list correspond to the values of the Signal at consecutive clock cycles

sampleN 3 s == [s0, s1, s2]

NB: This function is not synthesizable

sampleWithReset

Arguments

:: forall dom a m. (KnownDomain dom, NFDataX a, 1 <= m)

=> SNat m

Number of cycles to assert the reset

-> (KnownDomain dom => Clock dom -> Reset dom -> Enable dom -> Signal dom a)

Signal to sample

-> [a]

Get a list of samples from a Signal, while asserting the reset line for n clock cycles. sampleWithReset does not return the first n cycles, i.e., when the reset is asserted.

NB: This function is not synthesizable

sampleWithResetN

Arguments

:: forall dom a m. (KnownDomain dom, NFDataX a, 1 <= m)

=> SNat m

Number of cycles to assert the reset

-> Int

Number of samples to produce

-> (KnownDomain dom => Clock dom -> Reset dom -> Enable dom -> Signal dom a)

Signal to sample

-> [a]

Get a fine list of m samples from a Signal, while asserting the reset line for n clock cycles. sampleWithReset does not return the first n cycles, i.e., while the reset is asserted.

NB: This function is not synthesizable

fromList :: NFDataX a => [a] -> Signal dom a

Create a Signal from a list

Every element in the list will correspond to a value of the signal for one clock cycle.

>>> sampleN 2 (fromList [1,2,3,4,5])
[1,2]

NB: This function is not synthesizable

fromListWithReset :: forall dom a. (KnownDomain dom, NFDataX a) => Reset dom -> a -> [a] -> Signal dom a

Like fromList, but resets on reset and has a defined reset value.

>>> let rst = unsafeFromActiveHigh (fromList [True, True, False, False, True, False])
>>> let res = fromListWithReset @System rst Nothing [Just 'a', Just 'b', Just 'c']
>>> sampleN 6 res
[Nothing,Nothing,Just 'a',Just 'b',Nothing,Just 'a']

NB: This function is not synthesizable

lazy versions

sample_lazy :: Foldable f => f a -> [a]

The above type is a generalization for:

sample :: Signal a -> [a]

Get an infinite list of samples from a Signal

The elements in the list correspond to the values of the Signal at consecutive clock cycles

sample s == [s0, s1, s2, s3, ...

NB: This function is not synthesizable

sampleN_lazy :: Foldable f => Int -> f a -> [a]

The above type is a generalization for:

sampleN :: Int -> Signal a -> [a]

Get a list of n samples from a Signal

The elements in the list correspond to the values of the Signal at consecutive clock cycles

sampleN 3 s == [s0, s1, s2]

NB: This function is not synthesizable

fromList_lazy :: [a] -> Signal dom a

Create a Signal from a list

Every element in the list will correspond to a value of the signal for one clock cycle.

>>> sampleN 2 (fromList [1,2,3,4,5] :: Signal System Int)
[1,2]

NB: This function is not synthesizable

QuickCheck combinators

testFor :: Foldable f => Int -> f Bool -> Property

The above type is a generalization for:

testFor :: Int -> Signal Bool -> Property

testFor n s tests the signal s for n cycles.

NB: This function is not synthesizable

Type classes

Eq-like

(.==.) :: (Eq a, Applicative f) => f a -> f a -> f Bool infix 4

The above type is a generalization for:

(.==.) :: Eq a => Signal a -> Signal a -> Signal Bool

It is a version of (==) that returns a Signal of Bool

(./=.) :: (Eq a, Applicative f) => f a -> f a -> f Bool infix 4

The above type is a generalization for:

(./=.) :: Eq a => Signal a -> Signal a -> Signal Bool

It is a version of (/=) that returns a Signal of Bool

Ord-like

(.<.) :: (Ord a, Applicative f) => f a -> f a -> f Bool infix 4

The above type is a generalization for:

(.<.) :: Ord a => Signal a -> Signal a -> Signal Bool

It is a version of (<) that returns a Signal of Bool

(.<=.) :: (Ord a, Applicative f) => f a -> f a -> f Bool infix 4

The above type is a generalization for:

(.<=.) :: Ord a => Signal a -> Signal a -> Signal Bool

It is a version of (<=) that returns a Signal of Bool

(.>=.) :: (Ord a, Applicative f) => f a -> f a -> f Bool infix 4

The above type is a generalization for:

(.>=.) :: Ord a => Signal a -> Signal a -> Signal Bool

It is a version of (>=) that returns a Signal of Bool

(.>.) :: (Ord a, Applicative f) => f a -> f a -> f Bool infix 4

The above type is a generalization for:

(.>.) :: Ord a => Signal a -> Signal a -> Signal Bool

It is a version of (>) that returns a Signal of Bool

Bisignal functions

veryUnsafeToBiSignalIn :: (HasCallStack, KnownNat n, Given (SBiSignalDefault ds)) => BiSignalOut ds d n -> BiSignalIn ds d n

Converts the out part of a BiSignal to an in part. In simulation it checks whether multiple components are writing and will error accordingly. Make sure this is only called ONCE for every BiSignal.

readFromBiSignal

Arguments

:: (HasCallStack, BitPack a)

=> BiSignalIn ds d (BitSize a)

A BiSignalIn with a number of bits needed to represent a

-> Signal d a

Read the value from an inout port

writeToBiSignal

Arguments

:: (HasCallStack, BitPack a, NFDataX a)

=> BiSignalIn ds d (BitSize a)

-> Signal d (Maybe a)

Value to write

• Just a writes an a value
• Nothing puts the port in a high-impedance state

-> BiSignalOut ds d (BitSize a)

Write to an inout port

mergeBiSignalOuts :: (HasCallStack, KnownNat n) => Vec n (BiSignalOut defaultState dom m) -> BiSignalOut defaultState dom m

Combine several inout signals into one.

Deprecated

unsafeFromHighPolarity

Arguments

:: forall dom. KnownDomain dom

=> Signal dom Bool

Reset signal that's True when active, and False when inactive.

-> Reset dom

Deprecated: Use unsafeFromActiveHigh instead. This function will be removed in Clash 1.12.

Interpret a signal of bools as an active high reset and convert it to a reset signal corresponding to the domain's setting.

For asynchronous resets it is unsafe because it can cause combinatorial loops. In case of synchronous resets it can lead to meta-stability in the presence of asynchronous resets.

unsafeFromLowPolarity

Arguments

:: forall dom. KnownDomain dom

=> Signal dom Bool

Reset signal that's False when active, and True when inactive.

-> Reset dom

Deprecated: Use unsafeFromActiveLow instead. This function will be removed in Clash 1.12.

Interpret a signal of bools as an active low reset and convert it to a reset signal corresponding to the domain's setting.

For asynchronous resets it is unsafe because it can cause combinatorial loops. In case of synchronous resets it can lead to meta-stability in the presence of asynchronous resets.

unsafeToHighPolarity :: forall dom. KnownDomain dom => Reset dom -> Signal dom Bool

Deprecated: Use unsafeToActiveHigh instead. This function will be removed in Clash 1.12.

Convert a reset to an active high reset. Has no effect if reset is already an active high reset. Is unsafe because it can introduce:

• meta-stability

For asynchronous resets it is unsafe because it can cause combinatorial loops. In case of synchronous resets it can lead to meta-stability in the presence of asynchronous resets.

unsafeToLowPolarity :: forall dom. KnownDomain dom => Reset dom -> Signal dom Bool

Deprecated: Use unsafeToActiveLow instead. This function will be removed in Clash 1.12.

Convert a reset to an active low reset. Has no effect if reset is already an active low reset. It is unsafe because it can introduce:

• meta-stability

For asynchronous resets it is unsafe because it can cause combinatorial loops. In case of synchronous resets it can lead to meta-stability in the presence of asynchronous resets.