Asynchronous adder

This example creates a Component out of combinational logic that does some simple arithmetic on 3 operands.

The test bench performs the following steps 100 times:

Initialize a, b, and c to random integers in the 0..255 range.

Stimulate the DUT’s matching a, b, c inputs.

Wait 1 simulation timestep (to allow the inputs to propagate).

Check for correct output.

import spinal.sim._
import spinal.core._
import spinal.core.sim._

import scala.util.Random


object SimAsynchronousExample {
  class Dut extends Component {
    val io = new Bundle {
      val a, b, c = in UInt (8 bits)
      val result = out UInt (8 bits)
    }
    io.result := io.a + io.b - io.c
  }

  def main(args: Array[String]): Unit = {
    SimConfig.withWave.compile(new Dut).doSim{ dut =>
      var idx = 0
      while(idx < 100){
        val a, b, c = Random.nextInt(256)
        dut.io.a #= a
        dut.io.b #= b
        dut.io.c #= c
        sleep(1) // Sleep 1 simulation timestep
        assert(dut.io.result.toInt == ((a + b - c) & 0xFF))
        idx += 1
      }
    }
  }
}