Clash.Prelude.Testbench

Testbench functions for circuits

assert

Arguments

:: (Eq a, ShowX a, HiddenClock dom, HiddenReset dom)

=> String

Additional message

-> Signal dom a

Checked value

-> Signal dom a

Expected value

-> Signal dom b

Return value

-> Signal dom b

Compares the first two Signals for equality and logs a warning when they are not equal. The second Signal is considered the expected value. This function simply returns the third Signal unaltered as its result. This function is used by outputVerifier'.

Usage in clashi

NB: When simulating a component that uses assert in clashi, usually, the warnings are only logged the first time the component is simulated. Issuing :reload in clashi will discard the cached result of the computation, and warnings will once again be emitted.

NB: This function can be used in synthesizable designs.

assertBitVector

Arguments

:: (KnownNat n, HiddenClock dom, HiddenReset dom)

=> String

Additional message

-> Signal dom (BitVector n)

Checked value

-> Signal dom (BitVector n)

Expected value

-> Signal dom b

Return value

-> Signal dom b

The same as assert, but can handle don't care bits in its expected value.

ignoreFor

Arguments

:: HiddenClockResetEnable dom

=> SNat n

Number of cycles to ignore incoming signal

-> a

Value function produces when ignoring signal

-> Signal dom a

Incoming signal

-> Signal dom a

Either a passthrough of the incoming signal, or the static value provided as the second argument.

Ignore signal for a number of cycles, while outputting a static value.

outputVerifier'

Arguments

:: (KnownNat l, Eq a, ShowX a, HiddenClock dom, HiddenReset dom, 1 <= l)

=> Vec l a

Samples to compare with

-> Signal dom a

Signal to verify

-> Signal dom Bool

Indicator that all samples are verified

Compare a signal (coming from a circuit) to a vector of samples. If a sample from the signal is not equal to the corresponding sample in the vector, print to stderr and continue testing. This function is synthesizable in the sense that HDL simulators will run it.

NB: This function uses assert. When simulating this function in clashi, read the note.

Example:

expectedOutput
  :: HiddenClockResetEnable dom
  -> Signal dom Int -> Signal dom Bool
expectedOutput = outputVerifier' $(listToVecTH ([70,99,2,3,4,5,7,8,9,10]::[Int]))

>>> import qualified Data.List as List
>>> sampleN @System 12 (expectedOutput (fromList (0:[0..10] List.++ [10,10,10])))

cycle(<Clock: System>): 0, outputVerifier
expected value: 70, not equal to actual value: 0
[False
cycle(<Clock: System>): 1, outputVerifier
expected value: 70, not equal to actual value: 0
,False
cycle(<Clock: System>): 2, outputVerifier
expected value: 99, not equal to actual value: 1
,False,False,False,False,False
cycle(<Clock: System>): 7, outputVerifier
expected value: 7, not equal to actual value: 6
,False
cycle(<Clock: System>): 8, outputVerifier
expected value: 8, not equal to actual value: 7
,False
cycle(<Clock: System>): 9, outputVerifier
expected value: 9, not equal to actual value: 8
,False
cycle(<Clock: System>): 10, outputVerifier
expected value: 10, not equal to actual value: 9
,False,True]

If you're working with BitVectors containing don't care bits you should use outputVerifierBitVector'.

outputVerifierBitVector'

Arguments

:: (KnownNat l, KnownNat n, HiddenClock dom, HiddenReset dom, 1 <= l)

=> Vec l (BitVector n)

Samples to compare with

-> Signal dom (BitVector n)

Signal to verify

-> Signal dom Bool

Indicator that all samples are verified

Same as outputVerifier', but can handle don't care bits in its expected values.

stimuliGenerator

Arguments

:: (KnownNat l, HiddenClock dom, HiddenReset dom)

=> Vec l a

Samples to generate

-> Signal dom a

Signal of given samples

Example:

testInput
  :: HiddenClockResetEnable dom
  => Signal dom Int
testInput = stimuliGenerator $(listToVecTH [(1::Int),3..21])

>>> sampleN @System 13 testInput
[1,1,3,5,7,9,11,13,15,17,19,21,21]

tbClockGen :: KnownDomain testDom => Signal testDom Bool -> Clock testDom

Clock generator to be used in the testBench function.

To be used like:

clkSystem en = tbClockGen @System en

Example

module Example where

import Clash.Explicit.Prelude
import Clash.Explicit.Testbench

-- Fast domain: twice as fast as "Slow"
createDomain vSystem{vName="Fast", vPeriod=10}

-- Slow domain: twice as slow as "Fast"
createDomain vSystem{vName="Slow", vPeriod=20}

topEntity
  :: Clock "Fast"
  -> Reset "Fast"
  -> Enable "Fast"
  -> Clock "Slow"
  -> Signal "Fast" (Unsigned 8)
  -> Signal "Slow" (Unsigned 8, Unsigned 8)
topEntity clk1 rst1 en1 clk2 i =
  let h = register clk1 rst1 en1 0 (register clk1 rst1 en1 0 i)
      l = register clk1 rst1 en1 0 i
  in  unsafeSynchronizer clk1 clk2 (bundle (h, l))

testBench
  :: Signal "Slow" Bool
testBench = done
  where
    testInput      = stimuliGenerator clkA1 rstA1 $(listToVecTH [1::Unsigned 8,2,3,4,5,6,7,8])
    expectedOutput = outputVerifier   clkB2 rstB2 $(listToVecTH [(0,0) :: (Unsigned 8, Unsigned 8),(1,2),(3,4),(5,6),(7,8)])
    done           = expectedOutput (topEntity clkA1 rstA1 enableGen clkB2 testInput)
    notDone        = not <$> done
    clkA1          = tbClockGen @"Fast" (unsafeSynchronizer clkB2 clkA1 notDone)
    clkB2          = tbClockGen @"Slow" notDone
    rstA1          = resetGen @"Fast"
    rstB2          = resetGen @"Slow"

tbEnableGen :: Enable tag

Enable signal that's always enabled. Because it has a blackbox definition this enable signal is opaque to other blackboxes. It will therefore never be optimized away.

tbSystemClockGen :: Signal System Bool -> Clock System

Clock generator for the System clock domain.

NB: Can be used in the testBench function

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

clockToDiffClock

Arguments

:: KnownDomain dom

=> Clock dom

Single-ended input

-> DiffClock dom

Differential output

Convert a single-ended clock to a differential clock

The tbClockGen function generates a single-ended clock. This function will output the two phases of a differential clock corresponding to that single-ended clock.

This function is only meant to be used in the testBench function, not to create a differential output in hardware.

Example:

clk = clockToDiffClock $ tbClockGen (not <$> done)