ChiselのRTL生成＆テストの実装サンプル

Top.scala

import chisel3._
import chisel3.iotesters
import chisel3.iotesters.PeekPokeTester


class Top(in0Bits: Int, in1Bits: Int) extends Module {
  val io = IO(new Bundle {
    val in0 = Input(UInt(in0Bits.W))
    val in1 = Input(UInt(in0Bits.W))
    val out = Output(UInt((in0Bits+1).W))
  })

  // 入力のビット幅は最大で32bit
  require(in0Bits <= 32)
  require(in1Bits <= 32)

  io.out := RegNext(io.in0 +& io.in1)
}

object Elaborate extends App {
  Driver.execute(args, () => new Top(32, 32))
}


class TopTester(c: Top, in0bits: Int, in1bits: Int) extends PeekPokeTester(c) {
  import scala.util.Random
  // データを入力
  def feedData(in0: BigInt, in1: BigInt): Unit = {
    poke(c.io.in0, in0)
    poke(c.io.in1, in1)
  }

  def getData(): (BigInt, BigInt, BigInt) = {
    val in0Mask = (BigInt(1) << in0bits) - 1
    val in1Mask = (BigInt(1) << in1bits) - 1

    val in0 = BigInt(r.nextLong()) & in0Mask
    val in1 = BigInt(r.nextLong()) & in1Mask

    val eMask = (BigInt(1) << (in0bits + 1)) - 1
    val e = (in0 + in1) & eMask
    (in0, in1, e)
  }

  val r = new Random
  for (i <- 0 until 100) {
    println(s"- ${i} -")
    val (in0, in1, exp) = getData()
    feedData(in0, in1)
    step(1)
    println(s"io.in0 = 0x${peek(c.io.in0).toLong.toHexString}")
    println(s"io.in1 = 0x${peek(c.io.in1).toLong.toHexString}")
    println(s"io.out = 0x${peek(c.io.out).toLong.toHexString}")
    println(s"exp    = 0x${exp.toLong.toHexString}")
    expect(c.io.out, exp)
  }
}

object Test extends App {
  val (in0Bits, in1Bits) = (32, 32)
  iotesters.Driver.execute(args, () => new Top(in0Bits, in1Bits)) {
    c => new TopTester(c, in0Bits, in1Bits)
  }
}