class Rotator(Elaboratable):
    def __init__(self, datain, dataout, rotation=0, comb=True):
        assert len(datain) == len(dataout)

        self.datain = datain
        self.dataout = dataout
        self.rotation = rotation
        self.comb = comb

        self.ports = [
            self.datain,
            self.dataout,
            self.rotation,
        ]

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

        length = len(self.datain)
        with m.Switch(self.rotation):
            for i in range(length):
                with m.Case(i):
                    if self.comb:
                        m.d.comb += self.dataout.eq(Cat(self.datain[i:length], self.datain[0:i]))
                    else:
                        m.d.sync += self.dataout.eq(Cat(self.datain[i:length], self.datain[0:i]))

        return m