Chisel: Access to Module Parameters from Tester - scala

Question

How does one access the parameters used to construct a Module from inside the Tester that is testing it?
In the test below I am passing the parameters explicitly both to the Module and to the Tester. I would prefer not to have to pass them to the Tester but instead extract them from the module that was also passed in.
Also I am new to scala/chisel so any tips on bad techniques I'm using would be appreciated :).
import Chisel._
import math.pow
class TestA(dataWidth: Int, arrayLength: Int) extends Module {
val dataType = Bits(INPUT, width = dataWidth)
val arrayType = Vec(gen = dataType, n = arrayLength)
val io = new Bundle {
val i_valid = Bool(INPUT)
val i_data = dataType
val i_array = arrayType
val o_valid = Bool(OUTPUT)
val o_data = dataType.flip
val o_array = arrayType.flip
}
io.o_valid := io.i_valid
io.o_data := io.i_data
io.o_array := io.i_array
}
class TestATests(c: TestA, dataWidth: Int, arrayLength: Int) extends Tester(c) {
val maxData = pow(2, dataWidth).toInt
for (t <- 0 until 16) {
val i_valid = rnd.nextInt(2)
val i_data = rnd.nextInt(maxData)
val i_array = List.fill(arrayLength)(rnd.nextInt(maxData))
poke(c.io.i_valid, i_valid)
poke(c.io.i_data, i_data)
(c.io.i_array, i_array).zipped foreach {
(element,value) => poke(element, value)
}
expect(c.io.o_valid, i_valid)
expect(c.io.o_data, i_data)
(c.io.o_array, i_array).zipped foreach {
(element,value) => poke(element, value)
}
step(1)
}
}
object TestAObject {
def main(args: Array[String]): Unit = {
val tutArgs = args.slice(0, args.length)
val dataWidth = 5
val arrayLength = 6
chiselMainTest(tutArgs, () => Module(
new TestA(dataWidth=dataWidth, arrayLength=arrayLength))){
c => new TestATests(c, dataWidth=dataWidth, arrayLength=arrayLength)
}
}
}

Answer 1

If you make the arguments dataWidth and arrayLength members of TestA you can just reference them. In Scala this can be accomplished by inserting val into the argument list:
class TestA(val dataWidth: Int, val arrayLength: Int) extends Module ...
Then you can reference them from the test as members with c.dataWidth or c.arrayLength