from nmigen import *
from nmigen.cli import main


class ParMux(Elaboratable):
    def __init__(self, width):
        self.s = Signal(3)
        self.a = Signal(width)
        self.b = Signal(width)
        self.c = Signal(width)
        self.o = Signal(width)

    def elaborate(self, platform):
        m = Module()
        with m.Switch(self.s):
            with m.Case("--1"):
                m.d.comb += self.o.eq(self.a)
            with m.Case("-1-"):
                m.d.comb += self.o.eq(self.b)
            with m.Case("1--"):
                m.d.comb += self.o.eq(self.c)
            with m.Case():
                m.d.comb += self.o.eq(0)
        return m


if __name__ == "__main__":
    pmux = ParMux(width=16)
    main(pmux, ports=[pmux.s, pmux.a, pmux.b, pmux.c, pmux.o])