tb_counter

#! ../env/bin/python

import argparse

from amaranth.sim import Simulator

from counter import Counter

parser = argparse.ArgumentParser(prog='Basic Amaranth Counter',
                                 description='Configures and tests a binary counter',
                                 epilog='Lets see if it works')

parser.add_argument('width', type=int, default=4, choices=range(1, 32), help='Bit width of the counter to create')

args = parser.parse_args()

dut = Counter(args.width)

def testbench():
    #What's our max val?
    maxval = (2**args.width) - 1

    #Check that the enable works
    yield dut.en.eq(0)
    for _ in range(maxval + 1):
        yield
        assert not (yield dut.ovf)

    #Enable it and check the counter
    yield dut.en.eq(1)
    for _ in range(maxval):
        yield
        assert not (yield dut.ovf)
    yield
    assert (yield dut.ovf)

    #check that overflow clears on the next clock
    yield
    assert not (yield dut.ovf)


if __name__ == "__main__":
    sim = Simulator(dut)
    sim.add_clock(1e-6)
    sim.add_sync_process(testbench)

    with sim.write_vcd("counter.vcd"):
        sim.run()