counter_module

import amaranth as amrth

class Counter(amrth.Elaboratable):
    """
    A basic Counter

    Parameters
    ----------
    width : int
        Bit width of this Counter

    Attributes
    ----------
    en : Signal, input
        Enables the counter if ``en`` is asserted, ignores inputs otherwise.
    ovf: Signal, output
        Is asserted when the counter reaches its limit.
    """

    def __init__(self, width: int):
        self.width = width
        self._maxval = (2 ** self.width) - 1

        # Ports
        self.en = amrth.Signal()
        self.ovf = amrth.Signal()

        # Internal state
        self.count = amrth.Signal(self.width)

    def elaborate(self, platform):
        m = amrth.Module()

        m.d.comb += self.ovf.eq(self.count == self._maxval)

        with m.If(self.en):
            with m.If(self.ovf):
                m.d.sync += self.count.eq(0)
            with m.Else():
                m.d.sync += self.count.eq(self.count + 1)

        return m